Developments in Plate Steels


2–5 June 2024The Hythe Vail • Vail, CO USA


Sunday 2, June 2024

4-6 p.m.


5-6 p.m.


Monday, 3 June 2024

7 a.m.


8 a.m.

Opening Remarks, Rick Bodnar, SSAB Iowa Inc.

Session I: Slab Reheating and Hot Rolling

Session Chairs: John Speer, CSM and Rick Bodnar, SSAB

8:15 a.m. 

Overview of Computational Modeling of Slab Reheating Furnace
N. Walla, A. Silaen, C. Zhou, M. Syed, A. Kolakotla, Purdue University Northwest
The steel industry supplies one of the most critical materials for U.S. manufacturing, infrastructure and defense. The slab reheating furnace, an essential steelmaking process, is energy-intensive and generates significant CO2 emissions from natural gas combustion. Computational fluid dynamics (CFD) simulation has become a powerful tool for research and development to optimize furnace performance and to increase energy efficiency and productivity, as well to explore alternative fuels such as hydrogen to reduce CO2 emissions. This paper presents an overview of state-of-the-art CFD simulations of industry-scale reheating furnaces. Examples from Purdue University Northwest’s Center for Innovation Through Visualization and Simulation (CIVS) and Steel Manufacturing Simulation and Visualization Consortium (SMSVC) will be included.

8:40 a.m.

Evaluation of Solute Evolution for Varying Reheating Temperatures in HSLA Steels With Nb and Nb-Ti Additions
J. Barrirero, D. Britz, Materials Engineering Center Saarland; T. Staudt, E. Detemple, Dillinger; P. Lalley, CBMM; F. Mücklich, Materials Engineering Center Saarland
Niobium, one of the most important microalloying elements, is often used in combination with titanium. The effect of the addition of Niobium alone in contrast to the addition of Niobium-Titanium was evaluated for ten reheating temperatures from 1,050°C to 1,300°C in high-strength, low-alloyed steels. Two metallographic etching procedures together with a deep learning segmentation solution were used to determine the prior austenite grain size evolution. These results were validated by austenite parent reconstruction of EBSD maps. Furthermore, the solute evolution was quantitatively analyzed. Finally, Matcalc stability calculations were used together with the experimental characterization to evaluate and discuss the solute evolution.

9 a.m.  

The Effect of Initial Void Shape in the Slab on the Void Closure During Plate Rolling
K. Hinata, M. Horie, H. Takahashi, JFE Steel Corp.
Thick steel plates, manufactured through plate rolling, are widely used in structures like pressure vessels and buildings. The recent trend toward larger structures has increased demand for thicker plates. However, this thickness increase reduces the total rolling reduction ratio, resulting in more remaining voids. This requires a comprehensive understanding of the manufacturing limits. To date, numerous experiments and analyses have been conducted on the closure of voids in the rolling process, mainly focusing on spherical voids and voids that penetrate in the width and thickness directions of the plate. In contrast, in the multi-pass rolling process, it is essential to understand the transformation of void shape with each rolling pass, considering effects on the void closure. The objective of this study is to clarify the deformation of voids with different initial shapes in a multi-pass rolling process using the finite element method.

9:20 a.m.  

Microstructure Control and Toughness of Heavy-Gauge Coiled Plate Produced by the Compact Strip Process
D. Tsvetkov, C. Enloe, P. Nell, J. Lyon, Steel Dynamics Inc.          
The production of heavy-gauge, high-toughness coiled plate by the compact strip process has historically been limited by both cast slab thickness and thermo-mechanical processing capability of stand-alone tandem finishing. By decoupling the roughing and finishing rolling stages of an intermediate thickness slab (120 mm – 130 mm) in a manner similar to traditional hot strip rolling, and through optimization of both the microalloying strategy and transfer bar cooling practices, the strength-toughness balance of high-strength, low-alloy coiled plate is markedly improved for heavy gauges (0.375-inch – 1 inch). The effects of both reduction and thermal schedules with respective microalloying strategies with niobium, titanium and vanadium are supported by austenite conditioning modeling. Beneficial effects on strength- toughness balance are observed for reductions in solute nitrogen via titanium addition and limitation of post-recrystallization grain growth prior to finish rolling with the magnitude of the latter effect being dependent on alloy design.

9:40 a.m.

Effect of Rolling Reduction Rate/Pass in TMCP on the Mechanical Properties and Texture of Steel Plate for Shipbuilding
N. Takayama, S. Tachibana, S. Takagi, JFE Steel Corp.
Thick steel plates used in steel structures require toughness, and thermomechanically controlled processing (TMCP) is applied to achieve this property. Texture is also developed during TMCP, resulting in steel with greater arrestability. Thus, texture controlling has become important in the field of steel plates for shipbuilding. In this study, the effect of rolling reduction rate/pass during controlled rolling on the toughness and the texture were investigated in lab-rolled steel plates. Toughness was improved by increasing the rolling reduction rate/pass from 6.0% to 10.7%, but there was no change at 20.2%. Regarding the texture, (001)[-1-10] and (112)[-1-10] components, which contributed to the arrestability, became stronger when the rolling reduction rate/pass increased from 6.0% to 10.7%. In contrast, the strength decreased at 20.2%. Thus, it was clarified that it would be important to the optimization of rolling reduction rate/pass.

10 a.m.


Session II: Accelerated Cooling 

Session Chairs: Ian Robinson, Primetals and Matthias Militzer, UBC

10:15 a.m. 

Best Practices for Controlling the Flatness of Accelerated Cooled Plates
I. Robinson, Primetals Technologies Ltd.; R. Bodnar, C. Rawlinson, D. Bai, SSAB Americas; J. Hinton, Primetals Technologies Ltd.
The use of in-line accelerated cooling to process steel plates is now standard practice within the industry. These plates must meet the end users’ requirements, having uniform mechanical properties, meeting the flatness requirements set out by the industry standards and having an acceptable surface finish. This paper reviews and summarizes the key factors that affect the flatness of plates which have undergone accelerated cooling based on an extensive literature survey and site experience. The topic is introduced by defining the most common flatness defects which have been observed post-cooling and the process of how such defects develop. Secondly, the key factors which can influence the flatness are discussed, including temperature uniformity, the as-rolled plate state, different types of surface scale, phase transformations and pre-leveling. Finally, the paper will review how flatness is controlled within the cooling process including the mechanical actuators, process automation and the influence of controlling the through-process from the reheating furnace to the cooling bed.

10:40 a.m.

Modeling of Accelerated Cooling of Steel Plates
V. Prodanovic, S. Zhou, Z. Li, A. Doustahadi, M. Militzer, The University of British Columbia
Accelerating cooling is a key technology to manufacture thermomechanically controlled processed steel plates and to engineer through austenite decomposition the microstructures required for demanding applications in construction, energy and transportation. A review on the status of heat transfer modeling will be provided that is based on the underlying boiling mechanisms, i.e., nucleate, film and transition boiling, as a function of process parameters including nozzle design, water flow rates and temperatures. These models are useful tools to evaluate the design of advanced cooling systems and their operation. Strengths and limitations of these simulations are critically analyzed to identify directions of further accelerated cooling studies.

11 a.m.

An Innovative Approach for Minimizing Scatter of Tensile Properties for Mass Production of Heavy Plates
E. Parteder, R. Egger, voestalpine Grobblech GmbH    
An innovative approach for minimizing scatter of tensile properties (e.g., yield and tensile strength) for mass production of heavy plates (e.g., line pipe steels) will be presented. Based on a phenomenological model, the tensile properties depending on the chemical composition of each individual slab and essential process parameters are calculated. In combination with an optimization algorithm, adapted target values for accelerated cooling and leveling are calculated for each slab. With this approach, the standard deviation of the Gaussian distribution of the tensile properties is reduced significantly and a new standard for process automation is implemented.

11:20 a.m. 

An Innovative Production Process for Heavy Plates With Outstanding Toughness Properties
M. Klima, R. Egger, E. Parteder, voestalpine Grobblech GmbH
An innovative production process for heavy plates with outstanding toughness properties will be presented. Most commonly, heavy plates for the line pipe and offshore industry are produced via the thermomechanical controlled process (TMCP) followed by subsequent accelerated cooling. It is well known that toughness properties get worse and the gradient between the toughness properties near the surfaces and the mid-thickness of the plates enlarges when the thickness of the plate increases. With the new process, which is already implemented and applicable for TMCP plates, the through-thickness gradient is eliminated and the ductile-to-brittle transition is shifted to significantly lower temperatures.

11:40 a.m.

A Study on Phase Transformation During Accelerated Cooling and Coiling of Line Pipe Steel
M. Gaudet, L. Good, EVRAZ
The transformation from austenite during accelerated cooling and the precipitation of carbonitrides during coiling is critical to properties such as strength and toughness. The transformation and precipitation depend upon the prior microstructure condition (e.g., austenite grain size, dislocation density, solute Nb) and cooling/coiling temperature-time pathways. To study these effects, dilatometry experiments are performed on line pipe steel with a Gleeble 3800. Several sets of programs were carried out that varied the simulated reheat, strain and cooling/coiling pathway. In conjunction with dilatometry, microstructure characterization and hardness measurements reveal how the phase transformation and precipitation proceed during accelerated cooling and coiling.

12 p.m.

Optimization Strategy of Plate Rolling Mill to Develop Lean Chemistry API X70 Grade With Improved Productivity
L. Hegde, P. Agarwal, M. Shetter, D. Mishra, D. Panda, JSW Steel
Since May 2023, JSW Anjar Plate Mill has been producing plates in various quality and grades. The accelerated cooling installed in June 2023 pave the path to develop thicker sections in the plate mill with improved quality and productivity. A metallurgical model has been built to define microstructure at each stage of rolling and cooling sections to address the earlier difficulties like high holding time of transfer bar, hook up at head end, shape distortion and uneven mechanical properties. Accomplishing the preliminary criteria of mechanical properties and toughness, an architectural innovation is carried out in X70 grade TMCP rolling.

12:20 p.m.


1:25 p.m.    

Improving the Toughness and Strength by Nb Doping and Process Controlling of High-Strength Structural Steel
X. Deng, Northeastern University; Y. Zhang, CITIC Metal Co. Ltd.; H. Ma, Q. Yan, xx; R. Lino, CBMM
This paper discusses tests conducted on the microstructure and properties of medium-carbon Nb-containing and Nb-free high-strength structural steel plates under different controlled rolling and cooling processes. The authors carried out new medium-carbon Nb-containing high-strength and high toughness steel plates by industrial production and achieved good results.

Session III: Mill Modernization 

Session Chairs: Mike Cooke, SSAB and Mike Schmidt, John Deere

1:45 p.m.

A Multiplier of Opportunities for Added-Value Plate Production
A. Comelli, M. Bulfone, Danieli and C. Officine Meccaniche S.p.A.
This paper will discuss the latest installation of Danieli’s MultiPlate® technology at Nucor Steel Brandenburg. One single facility can now produce wide-heavy plates and light discrete or coiled plate with yield strengths up to 1,800 MPa. The mill makes use of a layout that can process both ingots and slabs, make straight or cross-rolling, and roll in flat as well as in Steckel mode. The in-line quenching Exstream II system, multipurpose EVO6 levelers and off-line heat treat facilities will be discussed, as well as a suite of automation packages that supervises and controls each plant area and the complete plant as a unit.

2:10 p.m.

NLMK’s Upgraded Plate Mill Restarts at Clabecq, Belgium
P. Hernaut, T. Le Petit, NLMK Clabecq; A. Comelli, M. Bulfone, Danieli and C. Officine Meccaniche S.p.A.
This paper will review a unique 4-stand finishing rolling mill configuration installed at NLMK Clabecq. New technological packages implemented by Danieli using a two-part shutdown strategy include hydraulic actuators for gap control (HAGC) for stands 3 and 4, a brand-new hydraulic bending system, as well as new loopers for stands 1 to 4, connected to a new hydraulic power unit. New level of thickness tolerances boasts weight savings and improved bending performance for very high elastic limits. But it also reduces the rate of second choice and revise the reheating programs downwards, with a gain in terms of CO2 emissions.

2:30 p.m.

Process Technology for Continuous Improvement of Specialty Plates Quench and Temper Process
S. Fauske, T. Ros-Yanez, T. Graver, A. Fleming, Cleveland-Cliffs Inc.
Cleveland-Cliffs Coatesville produces Navy-grade alloy steel plates for the construction of surface ships, aircraft carriers and submarines. These plates must meet rigorous standards for flatness, surface quality and mechanical properties. They are heat-treated either in a continuous roller hearth furnace or batch car bottom furnaces, depending on weight and dimensions. This paper discusses the application of innovative austenitic alumina-forming alloy for dry furnace rolls that will operate at temperatures up to 1,150°C expanding the capabilities of the continuous process. This innovation prevents scale pickup and triples the roll’s service life. A first-of-its-kind 4.5 m width x 44 m long austenitizing furnace utilizing this technology has been commissioned for the continuous processing of heavy plates needed for various Navy platforms and other specialty applications. A new two-level setup was developed and fine-tuned, and new heat treatment methodologies have been demonstrated to optimize performance. Additionally, modifications were made to the rest of the quench and temper line and finishing operations to align with the new heat treatment practices.

2:50 p.m.

Plate and Operation Tracking System
E. LaBruna, Janus Automation
This paper discusses the benefits of implementing a plate and operation tracking system, including automatic plate tracking, operation tracking, UT automation and transportation tracking.

3:10 p.m.


3:25 p.m.

A New Life for Old-Timers: The Conversion of Algoma’s 166-Inch Plate Mill to the State of the Art
A. Comelli, M. Bulfone, Danieli and C. Officine Meccaniche S.p.A.           
This paper reviews the complete upgrade of Algoma Steel’s 166-inch-wide plate mill using Danieli technology. The fundamental transformation project included new equipment and automation, which expanded the mill’s portfolio to a wider range of products. This enhancement furthermore elevated product shape and surface quality, as well as material logistics. The new key equipment includes the descaling system, the hot leveler, the rocking-type dividing shear, the magnetic piler, the two parallel disc-type cooling beds and a comprehensive automation package to control the entire mill.

Session IV: Structural and Clean Steels

Session Chairs: Hardy Mohrbacher, NiobelCon and Tanya Ros, Cleveland-Cliffs Inc.

3:45 p.m.

Novel Aspects of Niobium Precipitation in Plate Steels
H. Mohrbacher, NiobelCon BV
The dualism of niobium’s metallurgical functionality to act in solute as well as in precipitated state has been the platform for efficient thermomechanical conditioning of austenite for decades. Nevertheless, specific details of precipitate formation particularly in dual microalloyed NbTi high-strength, low-alloy (HSLA) steels were not fully understood. Recent investigations allowed a detailed tracing of the sequence of precipitate formation in austenite using atom probe tomography in combination with other techniques. Particles with a completely random mixture of Nb, Ti, C and N atoms were identified. These entropy-stabilized precipitates have a better thermal stability than binary microalloy carbides. Theoretical and experimental evidence of this effect will be demonstrated. These particles can be particularly helpful for better controlling the microstructure in the heat affected zone caused by welding. Solute niobium precipitating in ferrite during or after transformation forms extremely fine-sized particles delivering a considerable contribution to strength. Specific experiments were performed to identify the optimum conditions and magnitude of this effect. The results indicate that with increasing niobium microalloy content the strength contribution increases, however, in a non-linear way. The reason as to why the number of particles cannot be arbitrarily increased by adding more microalloy to the steel will be detailed. Besides strength increase, the nanosized and coherent precipitates formed in ferrite can also act as hydrogen trapping sites. Based on dedicated hydrogen permeation as well as desorption tests the potential of this effect will be discussed.

4:10 p.m.

Alloy Design and Processing Considerations for the Production of Light- and Heavy-Gauge Structural Plates Using Low-C, Low-Mn and Ultralow-Nb Additions Concept
T. Ros-Yanez, M. Kapustin, I. Cayetano, Cleveland-Cliffs Inc.; C.I. Garcia, L. Felipe Simoes, M. Moritugui University of Pittsburgh​
C-Mn commodity structural steel plates are widely used across various applications in the construction and infrastructure sectors. While this ferrite-pearlite steels are well developed and applied in the industry, recent studies have demonstrated the benefits of ultralow Nb additions to generate notable strengthening contributions permitting a reduction of 30–40% of Mn content in the alloy. Reduction of Mn content is leading to cost savings, improved castability, reduced centerline segregation and microstructural banding, among other advantages. Cleveland-Cliffs has adopted this concept, and this work focuses on the development of a new version of the traditional ASTM A36 steel plates using this approach. This includes not only a reduction in manganese, but also in carbon content and targeted 0.007% Nb additions. This paper discusses alloy design and rolling practices for light and heavy plate production. The strengthening mechanisms were examined and associated with the presence of fine nanoclusters of Nb(C) particles embedded in a non-crystalline network. Mechanical properties and microstructure of the produced plates are compared with conventional A36 plates and other alloys that employ a similar concept but with higher carbon and Nb contents.

4:30 p.m.

Production of High-Strength C-Mn Steel Plate Using TMCP
K. Banks, R. Maubane, University of Pretoria; M. Coleman, ArcelorMittal
A temperature-microstructure model and industrial trials were used to implement full-scale production of C-Mn plate to EN10025-2-S355J0+AR. Thermomechanical (TMCP) rolling schedules were developed and optimized to produce air-cooled plate with yield strengths of 380–400 MPa, adequate impact toughness and good shape. The necessary extended delay times, TMCP reduction ratios and mill exit temperatures required to refine the austenite microstructure to meet final properties were determined. Relatively large pass reductions were necessary in the early finishing passes to 1. encourage adequate grain refinement through alternate stages of strain accumulation and recrystallisation in the low austenite temperature region and 2. prevent high roll forces in the final finishing passes which potentially lead to poor shape.

4:50 p.m.

Offshore 690 MPa Heavy-Gauge Steel Plates Required in Modern Wind Turbine Installation Vessels
D. Quidort, A. Chaize, V. Ngomo, G. Hauden, J-C. Milek Industeel, ArcelorMittal Group​
The demand for modern wind turbine installation vessels (WTIVs) to install large offshore wind farms has recently increased due to the number of active large-scale offshore wind projects and the ever-increasing output power of wind turbines. Jack-up racks used for the legs of WTIVs require stronger teeth to withstand the enhanced wear and fatigue caused by the higher frequency of up and down operations compared to classical oil and gas drilling platforms. This application specifies high-strength offshore structural steel with a minimum yield stress of 690 MPa and up to 250 mm thickness. For such heavy rack plates, maintaining consistent mechanical properties and low-temperature impact toughness across the whole thickness while ensuring good welding and flame cutting behavior during fabrication is anything but trivial. This paper will detail the key features of 210 mm and 250 mm thick base metal plates recently produced by Industeel in France for the construction of different WTIVs.

Tuesday, 4 June 2024

Session IV: Structural and Clean Steels

Session Chairs: Hardy Mohrbacher, NiobelCon and Tanya Ros, Cleveland-Cliffs Inc.

8 a.m.

Clean Steels for More Reliable and Cost-Effective Steel Products
R. Bruna, Fernando Actis, Ternium Argentina
The continuous demand from customers for more reliable and cost-effective steel products involves understanding of the intrinsic relationships between product design, steel processing and mechanical properties. By adopting this fundamental metallurgical approach, Ternium implemented a tailor-made best practice to produce clean steels adaptable to different steel plant configurations and products. This leads to improved product reliability and enhanced customer satisfaction. This novel approach demonstrates the importance of identifying and controlling key process parameters to improve steel cleanliness and product reliability.

Session V: Bainitic Steels

Session Chairs: Matt Merwin, US Steel and Dengqi Bai, SSAB

8:20 a.m.

The Relationship Between Hole Expansion Capacity and Fracture Toughness of Ferritic and Bainitic High-Strength Hot-Rolled Steels
A. Rijkenberg, T. Chezan, M. Aarnts, S. Sengo, M. de Bruine, Tata Steel
In this paper the relationship between hole expansion capacity, fracture behavior, and toughness is discussed for a range of hot-rolled precipitation-strengthened ferritic and transformation-hardened bainitic steels with tensile strength levels ranging from 800 to 1,200 MPa. These steels are made from various alloy compositions and processed under laboratory conditions with different finish rolling and coiling temperatures. In addition to hole expansion capacity testing and Charpy V-notch impact toughness testing as a function of temperature, a new in-house-developed deep-drawing test method was used to assess crack susceptibility and a measure for the fracture toughness. The outcome of these tests, combined with results from quantitative microstructure and texture analyses, was used to study processing-microstructure-properties relationships to learn more how hole expansion capacity relates to fracture toughness.

8:40 a.m.

Development of Light-Gauge S700 Mechanical Properties With a Low-Carbon Fine Bainite Microstructure Utilizing Austenite Evolution, Phase Transformation and Strength Prediction Models
D. Stalheim, DGS Metallurgical Solutions Inc.; A. Yaylaci, C. Bora Derin, Istanbul Tech University; R. Tutuk, Çolakoğlu Metalurji; E. Faria, CBMM; P. Uranga, CEIT
High-strength S700 typically is produced with a low-carbon polygonal ferrite microstructure with significant TiC interphase/random precipitation to achieve the necessary strength levels. However, TiC precipitation strengthening can negatively affect ductility properties of Charpy toughness or formability. An alternative approach to S700 strength levels is to develop a low-carbon fine bainite microstructure with appropriate strength levels with stable ductility properties. Optimizing the alloy design for the optimum fine bainitic microstructure can be done through time-consuming and costly production trials. An alternative approach to optimizing the alloy/processing design can be done utilizing available off-line MicroSim austenite evolution, PhasTranSim phase transformation and empirical strength prediction models to give guidance in developing successful production trials.

9 a.m.

Phase Transformations, Clustering and Strengthening in Modern Line Pipe Steels
F. Fazeli, C. Scott, B. Shalchi Amirkhiz, CANMETMaterials; S. Zhang, B. Langelier, H. Zurob, McMaster University; M. Gaudet, M. Arafin, EVRAZ
This paper discusses the kinetics of bainite transformation during accelerated cooling and tempering of fresh bainite during coiling in experimental line pipe steel plates. The scope is the microstructure evolution and strengthening of bainite with a focus on the role of microalloying elements. Microalloying elements in solid solution shift bainite transformation temperatures whereas V-C and V-N clusters suppress the softening of bainite. Vanadium interactions with carbon atoms influence the tendency of carbon segregation to dislocations, thus changing the initial yielding of bainite. Some guidelines to exploit these findings for the development of advanced line pipe steels will be provided.

9:20 a.m.

Phase Transformation Products in a Low-Mn High-Nb X65 Steel Produced by Accelerated Cooling
D. Bojikian Matsubara, Gerdau; C. Serra Batista Castro, C. Ribeiro de Oliveira, R. Nolasco de Carvalho, CIT SENAI; P. Haddad, CBMM
Identification of acicular ferrite (AF) and bainite (B) in line pipe steels is important for the determination of toughness by means of drop weight tear test (DWTT), as those microconstituents give different responses for crack propagation during pipe usage. Phase transformation behavior in a low-Mn, Nb-microalloyed plate was investigated for characterization of AF and B, through dilatometry and scanning electron microscope (SEM) examination. Local misorientations were determined by electron backscatter diffraction for further assessment of the microstructure. Results suggest that AF and B cannot be separated by distinguishable process conditions in this particular steel and other toughening mechanisms should be activated to improve the response to crack propagation.

9:40 a.m.

Effect of Hot Rolling on Bainite Phase Transformation in High-Strength, Low-Alloy Steel
B. Saha, H. Haffner, J. Reutter, M. Buchely, K. Chandrashekhara, S. Lekakh, R. O’Malley, Missouri University of Science and Technology
This study investigates the impact of hot rolling on the acicular/bainite phase transformation in high-strength low-alloy (HSLA) steel, particularly focusing on steel microalloyed with Nb, V, and Ti. These microalloying elements play a vital role in grain refinement by retarding austenite recrystallization through (C, N) precipitation. The research involves an initial step of austenitization at 1,200°C to dissolve carbon-nitrides, followed by laboratory-scale hot rolling at ~900°C. Subsequent air cooling reveals distinct ferrite and bainite phase transformations. Notably, the cooling rate between 1 and 10°C/s exhibits significant morphological variations, primarily attributed to the pinning effect of microalloying elements.

10 a.m.


10:15 a.m.

Design and Application of 600–800 MPa High-Strength Steel
Y. Luo, CITIC Metal Co. Ltd.
Almost all microstructures of steel plates with yield strength below 500 MPa are ferrite + pearlite (steel grade Q345 to Q460 in Chinese standard GB1591). With the upgrading of the strength of downstream applications of steel plates such as machinery, more and more applications of steel plates are needed with yield strength grades of 500 to 800 Mpa (steel grade Q460 to Q550), which are difficult to obtain only by adding alloy on the basis of ferrite + pearlite. However, the medium-temperature transition microstructure of steel – bainite can meet their strength requirements, while considering the low-temperature impact toughness and welding performance. In this paper, the composition of C-Mn-Nb-B was designed in the laboratory, and yield strength of 600 to 800 Mpa was obtained by adjusting different final cooling temperatures. Based on these, corresponding steel plates were obtained in mass production, and were successfully applied in machinery and hydraulic supports in coal mines.

Session VI: Line Pipe and Hydrogen Transport

Session Chairs: Doug Stalheim, DGS Metallurgical Solutions, Qiulin Yu, Nucor-Tuscaloosa, and Kip Findley, CSM

10:35 a.m.

Repurposing Existing Pipelines and New Pipelines Considerations for Gaseous/Blended Hydrogen and CO2 Applications
D. Stalheim, DGS Metallurgical Solutions Inc.
In the future, both existing and new pipelines will be evaluated for their capability to transport not only oil or natural gas, but also their capability to transport gaseous/blended hydrogen and CO2. Flexibility in existing pipeline systems or any new pipeline systems built to move various energy sources or being involved in CO2 sequestering will be advantageous for efficient and economical operation. Efficient and economical operation typically requires the highest operating pressure possible. The question is what considerations need to be evaluated to determine the optimum pressure and more importantly for how long an existing pipeline or new pipeline system can operate at that pressure in the safest manner possible.

11 a.m.

Fatigue and Fracture Behavior of Weld and Heat-Affected Zone of an X70 Pipeline in Gaseous Hydrogen
M. Agnani, J. Ronevich, C. San Marchi, Sandia National Laboratories; M. Cristea, Tenaris
Natural gas pipelines can be used for transporting gaseous hydrogen (GH2); however, it is necessary to evaluate the fatigue and fracture resistance of the different microstructures present in the pipelines in GH2. In-situ fatigue crack growth (FCG) and fracture tests were conducted on compact tension samples extracted from the base metal, seam-weld and heat-affected zone of an X70 pipeline section in high-purity GH2 (210 bar pressure). Additionally, a seamless X65 pipeline microstructure (comparable strength) was also evaluated. The different microstructures had comparable FCG rates in GH2 while the fracture resistance generally decreased with increasing average hardness of the microstructure.

11:20 a.m.

Microstructural Engineering and Post-Processing of High-Mn Duplex and Austenitic Plate Steels for Hydrogen Storage and Delivery Applications
Y. Kong, P. Kathayat, L. Cho, J. Speer, K. Findley, Colorado School of Mines
The cost and reliability of hydrogen storage and delivery infrastructure pose significant challenges to the widespread adoption of hydrogen energy technologies. High-Ni austenitic stainless steels, known for their excellent hydrogen embrittlement resistance, are relatively costly. To address this issue, the present study focused on the alloy and processing design for cost-effective high-manganese (Mn) steel plates for hydrogen storage and transport applications. The designed alloys include austenitic and duplex (ferrite and austenite) steel. The alloy design was informed by thermodynamic calculations and a literature review focusing on the impact of various alloying elements on the stacking fault energy, a parameter known to be correlated with the mechanical stability of austenite and resistance to hydrogen embrittlement (HE). The HE properties of the designed alloys in various thermomechanical processing conditions were evaluated using rising-displacement tests with in-situ electrochemical hydrogen charging.

11:40 a.m.

Effect of Controlled-Rolling Parameters Using Accelerated Cooling on HSLA Grade 80 Mechanical Properties
Q. Yu, Nucor Steel Tuscaloosa Inc.
The direct quenching and accelerated cooling (DQ-ACC) process at Nucor Steel Tuscaloosa Inc. has successfully produced HSLA Grade 80 steel with uniform acicular ferrite and upper bainite, resulting in exceptional strength, toughness and formability. This study investigates the impact of controlled rolling parameters on HSLA Grade 80 mechanical properties. Findings indicate significant influence, offering potential for expanding applications to API 5L X80M line pipes. HSLA Grade 80 steel proves versatile and promising for varied engineering needs.

12 p.m.


1:05 p.m.

Pushing the Metallurgical Limits to Achieve DWTT, Stability and Cost Performance in the Production of 25 x 3,600 mm API X70 Plate
D. Stalheim, DGS Metallurgical Solutions Inc.; M. Shettar, L. Hegde, P. Agarwal, JSW; J. Souto, CBMM; S. Vashisht, Sojitz India; P. Uranga, CEIT
Low-temperature stable drop weight tear test (DWTT) performance at an optimum cost performance in heavy-gauge wide API plate is very challenging for most steel producers. The major metallurgical challenge is to achieve through-thickness microstructural attributes needed for this DWTT performance. The challenge comes from slab dimensions that do not allow for a proper total metallurgical reduction ratio ≥ 7:1 after the typical plate rolling dimensional/broadsiding passes. Being near to or below the 7:1 metallurgical reduction ratio creates DWTT performance stability issues or complete failure in meeting the minimum requirements. In these cases, thinking and working “outside of the box” requires pushing the metallurgical limits in the alloy/process design along with working within the physical restraints from the available slab dimensions and hot rolling/cooling equipment capabilities to achieve the desired DWTT performance. Utilization of prior knowledge along with various available metallurgical modeling tools can effectively assist, give direction, and reduce the time and costs in designing the alloy/processing strategy that gives the overall best mechanical property and production cost performance in these challenging API plate dimensions.

1:25 p.m.

Advanced Microstructure Characterization of Line Pipe Steel Plates Processed With Intensified Accelerated Cooling
J. Su, D. Bai, R. Bodnar, SSAB Americas
Optimization of microstructure via thermomechanical controlled processing (TMCP) is essential to achieve a good combination of strength and toughness for line pipe steels. In this work, line pipe steels processed through different rolling and cooling schedules using a MULPIC (Multi-Purpose Interrupted Cooling) system were studied. The aim is to investigate the effects of finish rolling temperature, total reduction, and cooling condition on product grain size, grain boundary characteristics, phase constituents, crystallographic texture, and through-thickness microstructure uniformity. Detailed microstructure and texture were characterized by optical microscopy and scanning electron microscopy (SEM) with electron backscattered diffraction (EBSD) techniques. The impacts of various metallurgical factors on mechanical properties will be discussed.

1:45 p.m.

Carbonitride Precipitation During Thick-Slab Casting and Reheating of API X80 Ti-Nb Steel
M. J. Gaudet, EVRAZ; D. Ivey, B. Shalchi Amirkhiz, University of Alberta; F. Fazeli, CanmetMATERIALS
During continuous casting of X80 line pipe steels, microalloying elements such as Ti and Nb form carbonitride precipitates. These precipitates evolve during the cooling and subsequent reheating of the slab, affecting subsequent thermomechanical controlled processing. This work examines an industrially cast X80 with Ti and Nb additions and compares two vacuum induction melted and cast ingots with different sizes (e.g., cooling rates) and two Ti contents. Precipitates are studied and quantified using transmission electron microscopy (TEM) in the as-cast condition and in a simulated reheat condition. Differences in the precipitates between the casting and reheat conditions are reviewed.

2:05 p.m.

Microstructural Features of a X65 Line Pipe Steel Produced by Pilot and Production Trials
F. Fazeli, CanmetMATERIALS; M. Gaudet, E. Seo, M. Rashid EVRAZ; D. Ivey, B. Shalchi Amirkhiz, University of Alberta 
Pilot-scale trials offer a cost- and time-effective method to study line pipe alloying and processing designs. However, understanding the differences between pilot and production trials is critical to validate the applicability of knowledge generated in pilot-scale studies. Here, an API X65 steel was processed with various schedules at CanmetMATERIALS’ pilot facility and compared with a production pipe. Detailed microstructure characterization was conducted to reveal the differences between pilot and production rolled materials. Factors contributing to the differences between pilot and production plates, and strategies to improve pilot simulations are discussed.

2:25 p.m.

Modeling the Temperature Profile of Water-Cooled Transfer Bars in Thermo-Mechanical Controlled Processing of High Toughness Linepipe Steel in a Hot Strip Mill
A. Kannan Iyengar, AM/NS Calvert LLC
The cornerstone of thermomechanical-controlled process used to produce line pipe steel with low-temperature fracture toughness in the hot strip mill is finish-rolling the transfer bar at a temperature lower than the temperature of no-recrystallization. Application of pressurized water on the transfer bar prior to its entry in the finishing train is one of the fastest cooling methods employed industrially. Inherently, the surface of the transfer bar is colder than its core and the temperature profile depends on its thickness, thermal properties and the cooling parameters. While the pyrometers in the hot strip mill can measure the surface temperature, a reliable model is required to accurately calculate the core temperature which is a key parameter in determining product quality and process design. A simple model has been developed using the finite difference method and the one-dimensional transient heat equation to calculate the temperature profile of the transfer bar during this cooling process. A novel and inexpensive approach has been developed to determine the heat transfer coefficients (HTC) specific to this cooling process using on-line surface temperature measurements instead of the typical approaches such as the use of simple but generic HTCs prescribed in literature, or the highly expensive but specific lab experiments and three-dimensional CFD simulations. Simulation results from this model are consistent with temperatures and roll forces measured during production. This model reduces the cost of evaluating new cooling practices, product development and characterization of cooling system upgrades.

2:45 p.m.

Alternative Corrosion-Resistant Alloy Solutions for Clad Line Pipe
T. Auinger, M. Kirschner, voestalpine Grobblech GmbH
The use of roll-bonded clad plates for line pipe is usually limited to a few corrosion-resistant alloy (CRA) materials. Typical austenitic CRA materials (e.g., 316L) for lower corrosion properties and nickel-based alloys (e.g., Alloy 625 or 825) for higher requirements. The gap between these CRA materials in corrosion behavior is quite large and not really used for line pipe applications. For example, the two CRA materials N08904 and S31254 have proven to be suitable solutions from a technical point of view. Additionally, by improving the rolling and measuring processes, a reduction of the CRA thickness, especially for nickel-based alloys, is possible at the final product and could be a beneficial option for future projects.

3:05 p.m.


3:20 p.m.

Development of Innovative Heavy-Gauge 38.5 mm X80 Pipeline Steel Plate Designed via High Niobium
Z. Yongqing, CITIC Metal Co. Ltd.; N. Wenjin, Shasteel; Z. Chuanguo, Baosteel; D. Han, xx; A. Litschewski, R. Lino, CBMM
Since the Second West-East Pipeline Route was built in China in 2008, X80 steel with low carbon (<0.07 wt.%) and high niobium (Nb) (>0.08 wt.%) has been the mainstream product for long-distance high-pressure natural gas pipeline projects. Aiming at dramatic increased delivery value of natural gas, X80 pipeline steel plate has reached up to 38.5 mm wall thickness and 1,422 mm diameter using innovative design of chemical composition and rolling procedure. In this study, the metallurgical design through chemical composition of high Nb and optimized rolling procedure have been relied on for qualified heavy-gauge 38.5 mm X80 via industrial trial. Meanwhile, the weldability and girth welding of OD 1,422 mm × 38.5 mm X80 steel pipes have been investigated and assessed.

Session VII: Abrasion-Resistant Steels

Session Chairs: Keith Taylor, SSAB and Patrick Zhao, CAT

3:40 p.m.

Effect of Novel Fast Heating Processing Route on the Formation of Martensitic Microstructures and the Subsequent Impact on Mechanical Properties of 0.2–0.3%C Steels for Abrasion-Resistant Plates
T. Ros-Yanez, Cleveland-Cliffs Inc.; F. Castro Cerda, University of Santiago de Chile
Abrasion-resistant (AR) steel plates, particularly the 500 HBW grade, are extensively used in both wear and structural applications. These plates are designed for service conditions that demand a combination of abrasion resistance, strength and toughness. The primary ordering requirement for AR steel plates is hardness. Hardness is achieved through effective quenching, which results in a martensitic microstructure. However, achieving a balance of high strength, toughness and ductility is challenging, especially for plates with a hardness of 500 HB or above. This paper introduces a novel alloy and method for producing AR plates using fast heating followed by water quenching and tempering. The proposed approach successfully offers the desired properties using leaner chemistries and comparatively lower carbon levels. The resulting plates exhibit an excellent combination of toughness, strength, ductility and formability up to 25 mm thickness, attributed to the presence of a high-strength martensitic matrix with retained austenite. This paper also compares the microstructure, mechanical properties and abrasion resistance of the produced plates with the novel method with conventional quenched and tempered 500 HB and 400 HB plate products.

4:05 p.m.

Microstructure, Mechanical Properties and Wear Behavior of a New MnSi-Alloyed Multi-Phase Abrasion-Resistant Steel
D. Quidort, C. Knafou, A. Giorgi,  Industeel, ArcelorMittal Group
In this paper, the authors investigate a new 4MnSi steel treated by a different soft quenching process to produce a multiphase microstructure having a typical hardness of 450 HB in the as delivery condition. Microstructure and mechanical properties evolution is presented together with the high-stress abrasion resistance and formability. The wear rate of tempered martensite and retained austenite microstructure significantly decreases compared with a fully martensitic steel. The impact toughness and bending properties show a high dependence on the process parameters.

4:25 p.m.

Influence of Retained Austenite and Microstructure on Abrasive Wear Performance of Bainitic Steels
C. Brown, E. De Moor, J. Speer, Colorado School of Mines
In this work, the influence of retained austenite content and morphology on the scratching abrasion resistance of 9260 and 6150 steels was evaluated. Two separate carbide-free bainitic (CFB) microstructures were designed with the 9260 alloy such that considerable differences in retained austenite content and morphology were achieved. These conditions were compared to lower bainitic conditions from the 6150 alloy of similar hardness. Quenched and tempered microstructures were additionally evaluated and compared with the bainitic conditions. Profilometry revealed that at loads ≤ 20 N, scratching behavior was independent of hardness for the CFB conditions, and both conditions produced similar scratch dimensions. For the lower bainitic conditions, however, scratching abrasion resistance trended similarly with hardness data, with the harder samples producing a smaller scratch. At a constant hardness, the CFB conditions had the best resistance to scratching abrasion.

6 p.m.

Reception and Dinner

Wednesday, 5 June 2024

Session VIII: Heat-Treated Steels

Session Chairs: Thorsten Staudt, Dillinger and Pello Uranga, CEIT-BRTA          

8:00 a.m.

Metallurgical Considerations for the Alloy Design and Processing Conditions of High-Strength Quenched and Tempered Thick Plates
P. Uranga, CEIT-BRTA and University of Navarra; X. Azpeitia, U. Mayo, N. Isasti, CEIT; E. Detemple, Dillinger Hüttenwerke AG; H. Mohrbacher, NiobelCon BV
Quenched and tempered high-strength plates with substantial thicknesses encounter metallurgical complexities when striving for a balance between high strength and good toughness properties. Incorporating various alloying elements, such as molybdenum and nickel, alters both the microstructural evolution during hot working and phase transformation characteristics during the quenching and tempering processes. For the thickest gauges, the achievable cooling rates during quenching are constrained, thereby rendering the attainment of through-thickness full martensitic structures a formidable challenge. This contribution involves an analysis of hot working behavior via hot torsion tests and phase transformation kinetics study using dilatometry. In cases where the quenching conditions pose greater challenges, the benefits of boron additions are explored. These additions aim to enhance hardenability and reduce the likelihood of softer structure formation in the central regions of thicker plates.

8:25 a.m.

Maximizing the Hardness of Normalized 4140/4142 Steel Plates
R. Bodnar, K. Taylor, C. Rawlinson, C. Rollins, SSAB Americas
Dually-certified 4140/4142 is a workhorse steel that is often supplied in the oil- or water-quenched and tempered or the normalized and tempered conditions. The present investigation explores the possibility of producing 4140/4142 steel in the normalized condition to meet a hardness range of 269 to 321 HBW. To maximize the hardness of such a product, the metallurgical approaches explored include: (1) increased bainitic hardenability and refinement of the bainite by working to the high side of the allowable chemistry ranges; (2) increased austenite grain size by reducing the nitrogen content, thereby increasing bainitic hardenability; and (3) use of a small vanadium addition to promote V(C,N) precipitation strengthening of any soft ferrite present. This work shows that the target hardness range can be achieved in plate thicknesses up to at least 3 inches.

8:45 a.m.

State-of-the-Art Production of Quenched and Tempered Green Steel Heavy
A. Rost, Ilsenburger Grobblech        
Based on recent CO2 emissions caused by the German steel industry, Salzgitter AG —Germany’s second-biggest steel company – will start a transformation to 100% green steel production beginning in 2026. This paper introduces the Salzgitter Low-CO2 Steelmaking (SALCOS) project. Green steel slabs will be rolled and heat treated in a state-of-the-art line for production of modern quenched and tempered steel plates.

9:05 a.m.

Designing Autotempered Steels – Opportunities and Challenges
M. Rupinen, J. Speer, Colorado School of Mines
Martensitic steel applications often specify target values of hardness/strength and toughness. Recently a tempering parameter-based model was developed to describe changes in hardness due to autotempering. While the model was developed using a single high hardenability steel, it may be used to generally describe and predict autotempering effects for steels with different martensite start temperatures or to predict autotempering effects for a single steel that experiences a gradient in cooling rates during quenching. This approach may be useful in moving toward a design approach that incorporates autotempering into the heat treatment process along with or in place of tempering. The initial model was developed for a silicon-free steel. Due to potential interest in employing higher silicon levels in steels for plate applications, a study on the effect of Si on autotempering was initiated. The results showed that the addition of Si may have profound implications in the design and properties of autotempered steels by altering the change in hardness with increased autotempering and by significantly increasing the fraction of retained austenite at lower cooling rates.

9:25 a.m.

A New 1,400 MPa-Class Pre-Hardened Steel Grade for Plastic Molding and Mechanical Engineering Applications
D. Quidort, M. Lachal, M. Guatteri, Industeel, ArcelorMittal Group; D. Delagnes, Institut Clément Ader; M. Dehmas, CIRIMAT; M. Dumont, Arts et Métiers Institute of Technology
This paper will present the characteristics of a new special steel grade obtained by quenching and tempering and having up to a thickness of 250 mm and a typical hardness in the delivery condition of 44 HRC (1,400 MPa UTS) with excellent machinability. Besides plastic molding applications, the overall good balance between strength and toughness will open the door to the manufacture of many tools, dies and machine parts used in mechanical engineering applications. The role of the as-quenched microstructure on the microstructural evolution and the simultaneous precipitation of stable or metastable alloyed carbides that precipitate during tempering will be discussed. In-situ high-energy X-ray diffraction (HEXRD) tests have been carried out to follow for different time, temperature and heating rates for the decomposition of the retained austenite during tempering from the martensitic and bainitic matrix.

9:45 a.m.

Modeling and Input Feature Analysis of Alloy Carbide and Austenite of Ultrahigh-Performance Steels
D. Field, H. Murdoch, D. Magagnosc, K. Limmer, M. Rupinen, U.S. Army Research Laboratory
Commercial Ni-Co steels with ultrahigh-strength and toughness were examined using a combination of modeling and experimentation. In order to accurately model the microstructure during tempering, it was found that several aspects of both precipitation and diffusion CALPHAD simulations needed to be tuned, particularly the mobility. A parameter study was performed using literature data to determine the optimum feature parameters to match the carbide and reverted austenite evolution in a prototypical alloy. Experimental tempers were characterized with transmission electron microscopy and modeled using the optimized parameters and found to fit with good agreement.            

10:05 a.m.


Session IX: High-Alloy Steels and Special Processing

Session Chairs: Dan Field, U.S. Army Research Laboratory and Matt Draper, Naval Surface Warfare Carderock Division  

10:20 a.m.

Microstructure Response to Intermediate Reheating in Hot Strip Processing
M. Merwin, United States Steel Corporation; P. Uranga, U. Mayo, CEIT
New production processes for hot-rolled steel strips that incorporate reheating during the rolling sequence are being implemented at various locations around the world. For example, the first Arvedi Endless Strip Production (ESP) in North America is currently being built at Big River Steel Works in Arkansas, USA. The direct rolling of cast slabs followed by induction reheating prior to finish rolling represents a different paradigm that thermomechanical processing compared to historical methods for conventional hot strip rolling. The potential for different austenite and precipitate conditions entering the finish rolling sequence prompted a study of the behavior of two alloy types: Ti-Mo and Nb-Ti microalloyed steels. This paper explores the response of two example alloys to laboratory thermomechanical process simulations of the Arvedi ESP process.

10:45 a.m.  

Effect of Quenched and Partitioned Processing Parameters on Hardness and Impact Toughness in Plate Steels
M. Dupree Bell, J. Speer, K. Findley, T. Marsh, Colorado School of Mines; D. Field, K. Limmer, U.S. Army Research Laboratory
Commercially produced quenched and partitioned (Q&P) steels for automobile structures primarily target sheet products requiring strength and formability. This paper explores the Q&P processing response in a 0.29C-1.52Si-1.51Mn-0.30Cr steel alloy subjected to varying Q&P heat treatments for application in thicker sections requiring strength and toughness in a hardness range within 500 to 560 HV. The microstructure evolution and mechanical behavior were analyzed through scanning electron microscopy, X-ray diffraction and Vickers hardness. Charpy V-notch and tensile tests were utilized to assess the influence of modifications in processing parameters on the hardness and impact toughness. One finding reveals that reducing the quenching and partitioning temperature enhances the hardness while reducing the retained austenite content. This paper will provide insights into potential enhancements in the Q&P process to achieve improved combinations of hardness and impact toughness.

11:05 a.m.

On the Effect of Nickel Alloying for Improving the Brittle Fracture Resistance of Structural Plate Steels
H. Mohrbacher, NiobelCon BV; A. Kern, thyssenkrupp Steel Europe AG
Nickel is an important and widely used alloying element in carbon steels which can significantly improve toughness, especially at low temperatures. This effect is explicitly used in alloys for cryogenic steels where nickel contents of up to 9 mass percent are used. In structural steels with minimum yield strength of 355–460 MPa, the nickel alloy content is limited per specification to 0.7 (DIN EN 10225) or 1.0 (Norsok) mass percent. Nevertheless, even comparably low nickel additions can be beneficial to toughness performance of structural plate steels. Particularly in heavy-gauge plates where rolling deformation in the center area and hence microstructural refinement is limited, nickel alloying may be the only metallurgical means to achieve toughness improvement. The evaluation of brittle fracture resistance of structural plate steels for either onshore or offshore constructions predominantly relies on the crack tip opening displacement (CTOD) concept. This criterion characterizes the local deformation capacity of the steel close to the crack tip and is valid for the considered structural steels, due to their elasto-plastic material behavior. This contribution briefly summarizes the physical-metallurgical mechanism as to why nickel alloying improves low-temperature toughness. Regarding the magnitude of the effect in structural steels, an ad-hoc evaluation of industrially produced plates of grade S355N with nickel alloying of up to 0.6 mass percent was performed. CTOD values were measured as a function of test temperature allowing identification of the transition behavior. The effect of nickel on the transition temperature was clearly reflected by improvements of up to 80 K. In selected cases this analysis was also performed in the heat affected zone after welding of such steels, and likewise indicated the beneficial effect of nickel. The CTOD analysis is subsequently used for estimating the fatigue performance based on fracture mechanics concepts, i.e., crack growth behavior. This study demonstrates that nickel alloying can indeed improve the fatigue life of welded constructions, which is of significant importance when designing with higher-strength steel grades.

11:25 a.m.

Microstructure and Property Evolution in Ultrahigh-Strength, High-Toughness Steels Toward Enabling Industrial Implementation of 10Ni QLT Steels
S. Miklas, K. Findley, E. De Moor, Colorado School of Mines
The development of high-strength materials with high toughness that maintain their performance at low temperatures is of significant interest for cryogenic storage as well as naval structural applications. The use of high-nickel-containing steels in conjunction with the quench, lamellarize and temper (QLT) heat treatment has been proposed to develop steels that exhibit both high strength and toughness due to the stabilization of retained austenite films in the microstructure. In this work, thermodynamic simulations are implemented to optimize the retained austenite volume fraction in QLT-treated 10Ni steels while mechanical properties and microstructure are assessed. Thermodynamic simulations were performed using Fe-Ni, Fe-Ni-C and Fe-Ni-C-Mn alloys and the model was used to predict the maximum amount of retained austenite stabilized by solute enrichment as well as the optimum temperature to achieve it. The amount of retained austenite stabilized by solute enrichment in a 0.1C-10.6Ni-0.54Mn steel was predicted to be 30 vol pct when intercritically annealed at 525°C. The predicted stabilization of retained austenite is compared to measured retained austenite content. Additionally, the application of the QLT heat treatment to a high-nickel steel is investigated, where the temperature of the lamellarization step is varied. Mechanical testing is conducted, evaluating the influence of heat treatment on the tensile and Charpy impact properties. Finally, microstructural characterization is completed, evaluating the influence of retained austenite levels, morphology and stability on mechanical properties.

11:45 p.m.


Session X: Mechanical Testing   

Session Chairs: Mario Buchely, Missouri S&T and Matt Enloe, Steel Dynamics Inc.

12:50 p.m.

Effect of Test Specimen Thickness on Charpy V-Notch Impact Toughness of Some Heat-Treated Plate Steels
K. Taylor, W. Woods, J. O'Grady, SSAB
Three commercial heat-treated plate steels were selected for investigation of effects of specimen thickness on Charpy V-notch impact testing results. The selected steels included quenched and tempered 960 and 690 MPa minimum yield strength structural or pressure vessel steels and a normalized ferrite-pearlite pressure vessel steel. Samples were cut from 35 and 38 mm thick production plates. Test specimens were prepared from the sample quarter-thickness location and tested in accordance with ASTM A370, at temperatures from –80°C to room temperature. Specimen thicknesses were 2.5, 5.0, 7.5 and 10.0 mm. Effects of test-specimen thickness on absorbed energy, lateral expansion and impact transition behavior are examined. Results are compared with literature data as well as with available SSAB production testing.

1:10 p.m.

Sample Size Effect on the Impact Absorbed Energy in Carbon Steel With Different Microstructures
R. Ueji, K. Tsuzaki, A. Shibata, National Institute for Materials Science; D. Sasaki, R. Maeda, A. Matsuyama, National Institute of Technology
Impact absorbed energy was examined by both conventional Charpy impact test and miniaturized impact test to overcome deep understanding of toughness with perspective of the effect of test piece size. Different types of microstructures were prepared with the high-carbon steel (SAE9254). Concerning pearlite, the sample was austenitized followed by air cooling to obtain as-heat-treated pearlite. The as-heat-treated sample was cold worked by 84% caliver rolling to obtain the sample with elongated pearlite. The Charpy impact test (10 mm square with V-notch) at room temperature clarified that the cold-rolled sample shows about 8 times higher absorbed energy than the as-heat-treated sample. Meanwhile, the ratio of the absorbed energy between these two pearlitic steels with miniaturized impact tests (1 mm or 1.5 mm square) decreases to 1.3 times at both sizes. This drastic change implies that the size effect on the absorbed energy is dependent on metallurgical microstructure.

1:30 p.m.

A Novel Approach to Hardness Testing
A. Carlestam, SSAB Special Steels
This paper introduces a novel approach to material hardness measurement, diverging from the traditional 2D Brinell tests. 3D data acquisition through laser triangulation is conducted employing software that can distinguish the non-deformed surface from an indentation. The method involves fitting a sphere to find the indentation origin with the volume of the indentation as the output, ensuring exceptional accuracy, and is applicable to even the most challenging materials. Importantly, this approach eliminates the need for destructive surface preparation, rendering the method non-destructive. Positioned as a potential industry standard aligned with ISO 6506-1:2006, the method seamlessly integrates into production lines, enabling real-time quality control across diverse materials and applications. The potential for cost reduction and product quality enhancement positions the method as a transformative tool, offering precision and efficiency in steel hardness testing.

1:55 p.m.

Finite Element Modeling of 3D HB Indents and Material Properties
A. Carlestam, SSAB Special Steel
This paper presents a consequential outcome of SSAB's novel hardness measurement method, utilizing the volume of a Brinell indentation to evaluate hardness while exploring its connection to material deformation behavior. Employing the finite element (FE) model, LS-DYNA, an HBW indentation is simulated, characterizing steel behavior using the Voce equation for tensile flow and work hardening. Through calibration using SSAB's martensitic steels, a robust correlation between measured properties and simulated data is achieved. This calibrated model facilitates the conversion of 3D Brinell system measurements into a comprehensive description of steel deformation behavior through reverse engineering. This innovative approach aligns with SSAB's commitment to supply customers with precise data for dimensioning. Moreover, the FE model of the HBW indentation also enhances the measurement precision when handling varying steel thicknesses, and deepens understanding of material properties.

2:15 p.m.

Three-Dimensional Crack Propagation Behavior and Deformation Microstructure Evolution of Hydrogen-Related Fracture in Martensitic Steel
A. Shibata, National Institute for Materials Science
Hydrogen embrittlement is one of the important technical challenges for wide application of high-strength steels. This study investigated three-dimensional propagation behavior of hydrogen-related intergranular cracks and development of deformation microstructure accompanying crack propagation in martensitic steel using X-ray computed tomography (CT), focused ion beam–scanning electron microscopy (FIB-SEM) serial sectioning, and advanced transmission electron microscopy (TEM) analysis. Macroscopic analysis using X-ray CT revealed that the crack morphology exhibited more continuously in the hydrogen-charged specimen. Through FIB-SEM serial sectioning, it was found that even very fine low-angle grain boundary segments (sub micro-meter size) could act as obstacles to hydrogen-related crack propagation. Moreover, intense localized plastic deformation was involved in the hydrogen-related quasi-cleavage crack propagation. Based on the results, the authors propose that misorientation of each grain boundary segment has a large influence on local crack arrestability of intergranular crack propagation.

2:35 p.m.


Session XI: Welding

Session Chairs: Murali Manohar, ArcelorMittal and John Procario, Lincoln Electric

2:50 p.m.

Economical and Performance Considerations for the Fabrication of Heavy-Section Wind Tower Foundations
A. Acuna, J. Procario, Lincoln Electric; S. Pape, J. Ward, Nucor Corp.
Welding heavy-section structural steel components required for wind tower foundations presents unique challenges. The welded joint must meet stringent requirements for cleanliness and geometry as well as high fracture toughness. Economic considerations drive the industry to maximize weld deposition rates and minimize total weld volume, which in turn increases the risks of high restraint and shrinkage strains. In order to maximize productivity while retaining high-quality welds, the base metal, welding consumables and process must be optimized and tightly controlled. This paper documents the relationship, requirements and results of combining a low-carbon-equivalent sustainable steel plate conforming to EN 10025 and 10225, high deposition multiple-arc long stick out submerged arc welding process technology and complementary welding consumables to weld thick plate with deep and narrow grooves successfully.

3:15 p.m.

Development of Heavy Plates for High-Energy Welding of Monopiles for the Construction of Offshore Wind Energy Plants
S. Scholl, J. Schütz, S. Lenhard, T. Lehnert, T. Staudt, W. Schütz, Dillinger Hüttenwerke AG
Welding of large structures like monopiles for wind turbines is very time-consuming and thus a key cost factor in the manufacturing process. The use of high heat inputs in submerged arc welding can shorten fabrication time by a multiple but impairs material properties in the heat-affected zone of standard steel grades, in particular toughness. Real multilayer weldments and physical weld simulations demonstrate the different effectiveness of various kinds of low-alloyed heavy plate steels. In-depth microstructure investigations disclose the metallurgical reason for the ability of special steels to resist against high energy welding and confirm the industrial applicability.

3:35 p.m.

Effect of V on the Strengthening and Fatigue Behavior of a High-Strength, Low-Alloy Steel Welded Joint
A. Tselikova, R. Schmidt, Vantage Alloys AG; A. Di Schino, G. Stornelli, University of Perugia
The development of high-strength low-alloy (HSLA) steels for structural applications, including wind towers, offshore structures, and shipbuilding requires a continuous effort to achieve the balance between high strength, toughness and weldability. During a multiple-pass weld, the intercritically reheated grain-coarsened heat-affected zone (IC GC HAZ) represents the most brittle section of HSLA steel welds. The presence of microalloying elements in HSLA steels induces the formation of microstructural constituents capable of improving the mechanical strengthening of welded joints, with possible loss of fatigue resistance and toughness. The scope of this study is to investigate the influence of vanadium addition on the behavior of IC GC HAZ in S355 steel grade, with the aim of obtaining a chemical composition that guarantees mechanical strengthening without compromising the fatigue behavior of a welded joint. The thermal cycles of a double-pass weld were simulated by Gleeble, considering five different inter-critical temperatures, between 720°C and 790°C. The addition of 0.1 wt.% vanadium was found to increase the mechanical strength of the IC GC HAZ of a welded joint while simultaneously improving the low cycle fatigue behavior. This result is obtained through a bainitic microstructure with dispersion of fine regions of residual austenite (less than 0.6%) and a fine and uniformly distributed precipitation (precipitates with size smaller than 60 nm of which more than 50% are smaller than 15 nm). The results were validated on real welded joints.

3:55 p.m.

Effect of Acicular Ferrite on Low-Temperature Impact Toughness of Continuously Cooled Vanadium-Microalloyed Plate Steels
A. Church, E. De Moor, K. Findley, Colorado School of Mines; A. Tselikova, R. Schmidt, Vantage Alloys AG
Microalloyed high-strength low-alloy (HSLA) steels are used in lower operating temperature load-bearing applications, including bridges and pipelines, due to the wide range of achievable strength and toughness values obtained in the as-rolled products. However, the low temperature toughness associated with welds in high-impact applications remains an opportunity for improvement due to the tendency to form brittle constituents. Acicular ferrite (AF) is being investigated as a microstructural constituent to improve low-temperature impact toughness in the coarse-grained heat-affected zone (CGHAZ) of welds while maintaining required tensile strength levels for such applications. In this study, the CGHAZ was simulated in two experimental V-microalloyed steels differing in N content by rapidly heating to 1,350°C and cooling at rates of 1, 3, 10 and 25°C/s to produce mixed AF/grain-boundary ferrite microstructures. A second set of specimens were heated similarly and cooled at a rate of 100°C/s to produce a mixed bainite/martensite microstructure for comparison. The hardness of these conditions increased as cooling rate increased, with the alloy containing more N producing a significantly greater hardness value only in the 25° and 100 C/s conditions compared to the low N alloy. Charpy impact toughness at –20°C and tensile properties of select conditions will be presented and correlated with microstructure.

4:15 p.m.

Closing Remarks
John Speer, CSM     

4:30 p.m.

Adjourn Conference



Properties and Processing of Medium-Mn Steel Plate: Understanding Composition and Heat Treatment Effects
K. Limmer, DEVCOM Army Research Laboratory; D. Field, J. Lloyd, D. Magagnosc
Microalloyed high-strength low-alloy (HSLA) steels are used in lower operating temperature load-bearing applications, including bridges and pipelines, due to the wide range of achievable strength and toughness values obtained in the as-rolled products. However, the low temperature toughness associated with welds in high-impact applications remains an opportunity for improvement due to the tendency to form brittle constituents. Acicular ferrite (AF) is being investigated as a microstructural constituent to improve low-temperature impact toughness in the coarse-grained heat-affected zone (CGHAZ) of welds while maintaining required tensile strength levels for such applications. In this study, the CGHAZ was simulated in two experimental V-microalloyed steels differing in N content by rapidly heating to 1,350°C and cooling at rates of 1, 3, 10 and 25°C/s to produce mixed AF/grain-boundary ferrite microstructures. A second set of specimens were heated similarly and cooled at a rate of 100°C/s to produce a mixed bainite/martensite microstructure for comparison. The hardness of these conditions increased as cooling rate increased, with the alloy containing more N producing a significantly greater hardness value only in the 25° and 100 C/s conditions compared to the low N alloy. Charpy impact toughness at –20°C and tensile properties of select conditions will be presented and correlated with microstructure.