Research On Recrystallization Of Hot-rolled Ferritic Stainless Steel

Three kinds of hot-rolled ferritic stainless steel were water quenched after annealing recrystallization at 760～830℃.The recrystallization and microstructural transformation of 410S hot-rolled ferritic stainless steel,with part of matensite, and 430 hot-rolled ferritic stainless steel,and recrystallization kinetics have been studied by means of series of comprehensible temperature-time anneal experiments. Because the grain is elongated into a bamboo-like in hot rolled process, we can clearly distinguish the deformation of tissue after rolling and the equiaxed grains after recrystallization by Austria MeF3 microstructure apparatus;Determination recrystallized fraction was statisticed with metal-lographic method;STA～449C DSC curves were measured in the thermal analysis apparatus to observe the changes of physical state about the 4 kinds of hot rolled stainless steel during heating process;the change of hardness between before annealing and after annealing is measured with HBR-150A-based Rockwell hardness apparatus.The results show that the time for breeding to put forward recrystallization of hot-rolled stainless steel completion is 2-5hour.Its speed increased to a highest point when the extent of recrystallization arrive 50%.The annealing-Microstructural transformation graph of 410S hot-rolled stainless steel were constructed and the optimum recrystallization annealing parameters were obtained (780～800℃,30～50h);The optimum recrystallization annealing parameters of 430 hot-rolled stainless steel were obtained (790～800℃,15～25h).The recrystallization process of ferritic stainless steel is described by Larson-Miller P=T(C+lgt) parameters. Recrystallization of 410S steel can be effectively described by the Larson-Miller parameter,determining the constant C as 19.5, which agrees with experimental results as a whole.The recrystallization process of 410S hot-rolled ferritic stainless steel is controlled by the diffusion of Cr atoms, and its recrystallization activation energy is 278.5 KJ/mol. Recrystallization kinetics curve of 410,430,430with the tensiledeformation has been drew。The recrystallization activation energy of 430 stainless steel is 260 kJ/mol; when the deformation is 20%, recrystallization activation energy is 198.6kJ/mol. The impact of the alloy elements and deformation on the recrystallization have been described.The relationship between the deformation and recrystallization activation energy have been studied by means of recrystallization nucleation mechanism.This passage played an important role in theory of recrystallization and guiding the actual production.