A low-carbon Ti-microalloyed chemistry was selected for the development of a family of cold-rolled and batch-annealed high-strength high-formable uncoated sheet steels. The batch annealing practice was opti-mized to retain precipitate strengthening in the final fully processed steel and microstructural attributes that resulted in superior forming characteristics. Production strategy, material characterization and formability of high-strength low-alloy steels with minimum yield strength of 550 MPa cold-rolled batch-annealed uncoated sheet steel will be discussed, and results will be presented.

The demand for high-quality clean steel requires the mitigation of non-metallic inclusions; this is particularly significant in the manufacturing of ultralow-carbon steels for automotive exposed applications. During the gal-vanization process, there is an increase in the probability of inclusions being revealed. Inclusions can originate from various sources such as deoxidation and reoxidation, entrapment of slag, wear of refractory materials, and undesired chemical reactions. To fine-tune a process method to meet those requirements, adjustments were implemented in the production parameters, starting from initial stages of steel production in the converter until continuous casting, aiming to mitigate the formation and entrapment of non-metallic inclusions.

This article introduces an innovative technology for steel level measurement in open-stream casting based on the “thermal profile” of the mold copper tube. This technology is contactless and based on ultrasound waves, therefore no sensors embedded in the copper tube are required. Some additional features of this solution are presented, as well as some figures in comparison with the radiometric system in terms of measuring range and response time.

The multimode continuous casting and rolling (MCCR) process at Shougang Jingtang Steel is a newly designed multimode thin-slab continuous casting and rolling line which can continuously produce coils without cutting before the coiling machine. Under high-casting-speed conditions, the quality of rolled plates is more sensitive to changes in casting speed. To guarantee a balance between the high steel throughput and the high steel quality, a reasonable high casting speed is required. In the current study, the effect of casting speed on the distribution of inclusions in a low-carbon aluminum-killed steel rolled plate produced by the MCCR process was investigated. Inclusions in the rolled plate were of a Al₂O₃-CaO-MgO-CaS system. There was only a slight difference in the inclusion composition along the width of rolled plates, with an approximately average composition of 70 wt. % Al₂O₃, 20 wt. % CaO, and <10 wt. % MgO and CaS. As the casting speed increased from 4.7 to 5.2 m/minute, the average CaO content in inclusions decreased firstly at casting speeds lower than 4.9 m/minute and then slightly increased at casting speed higher than 5.0 m/minute. The CaS content presented an opposite changing trend. Meanwhile, the distribution patterns of the number density and area fraction of >2 μm inclusions along the width of rolled plates roughly changed from the “L” shape to the “M” shape. By comparison, there was the smallest number density and area fraction of >2 μm inclusions at 4.7 m/minute, while the number density and area fraction of >2 μm inclusions was the highest at 5.2 m/minute. However, the uniformity of the inclusion distribution along the plate width was the smallest at 4.7 m/minute and the highest at 5.0 m/minute.