Banded structure control of low carbon microalloyed steel based on oxide metallurgy

Banded structure is a common harmful microstructure for low carbon microalloyed steel, which seriously shortens the service life of processed parts. In order to study the effect of oxide metallurgy on improving banded structure, the Ti–Zr deoxidized low carbon microalloyed steel that can play the oxide metallurgical role of inclusion was chosen as the research object, and the inclusion characteristics, microstructure and transverse and longitudinal mechanical properties after hot rolling were analyzed. The results showed the inclusion number density increased in all experimental steels after hot rolling, and a large number of long strip inclusions with aspect ratio greater than 3 appeared along the rolling direction. In addition, after hot rolling, there were element segregation bands in the experimental steels, and granular bainite bands were formed in the element enrichment zone. However, the intragranular ferrite generated in the cooling process destroyed the continuity of granular bainite bands, so that the microstructure anisotropy indexes of experimental steels were small. The mechanical properties analysis showed that the anisotropy of performance was mainly reflected in plasticity and toughness in the experimental steels. Among them, the difference ratio of elongation, section shrinkage and impact energy of No. 2 steel was 1.69%, 3.87% and 1.69%, respectively, which were less than those of No. 1 steel and No. 3 steel. The anisotropy of microstructure and mechanical properties of No. 2 steel that full played the role of oxide metallurgy were improved, and the banded structure control of low carbon microalloyed steel can be realized by oxide metallurgy technology.