Study On Technology And Microstructure Of A Microalloyed High-strength Steel On CSP

Using a microalloyed high strength steel produced in CSP plant of Lianyuan Iron and Steel Co. as the rough material, thermal simulating tests at different deformation technology parameters were carried out using the THERMECMASTER-Z and the stress-strain curves during deformation were measured. The metallographic structures were analysized using optical microscope for samples after thermal simulation tests, and the non-metallic inclusions of samples are analysed by SEM (NOVA 400 Nano) and EDS (OXFORDINCA IE350) at Wuhan University of Science and Technology.Thermal simulating tests at different deformation temperature, strain and strain rate were carried out and the stress-strain curves during deformation were measured. Based on the experimental results and the discussions of those factors, several existing flow stress models were analysed. Through regression analysis of models by thermal simulating experimental data, that modified model proved to have good curve fitting characteristics, relatively high prediction precision.Thermal Simulation tests under different rolling parameters were conducted on thermal simulator. The effects of different rolling parameters on microstructure and properties of a microalloyed high strength steel produced by CSP line were studied. The results revealed that the microalloyed high strength steels with high yield strength can be produced by optimizing such technology parameters as the pass strain, strain rate, deformation temperature and the cooling rate et al.Micro-structures of different samples are similar, but the properties are not the same. So the inclusions in samples were analyzed and classified using metallurgical microscope. The type of inclusions was determined using SEM and EDS to study the effects of non-metallic inclusions on yield strength. The type and shape of inclusions in CSP HSLA steel are determined. In addition, the yield strength of experimental steel will decrease with the increasing of number of inclusions and size.