Microstructure evolution in large billet during reduction pretreatment based on laboratory experiments  

作　　者：Yang Liu Jian-hua Liu Yang He 

机构地区：[1]National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing,University of Science and Technology Beijing,Beijing 100083,China

出　　处：《Journal of Iron and Steel Research International》2023年第6期1244-1257,共14页

基　　金：funded by the National Key Research and Development Program of China(2021YFE0113200);the Fundamental Research Funds for the Central Universities(FRF-TP-20-104A1).

摘　　要：The reduction pretreatment process has been proposed to improve the center quality of large billet and reduce the rolling ratio.The microstructure evolution during the reduction pretreatment was further understood.The austenite grains were refined after the reduction pretreatment experiment,especially those at the center of the billet.The effects of strain and strain rate on the average grain size were dependent on the deformation temperature.At a strain rate of 0.01 s-1 and 1200°C,the newly formed strain-free austenite grains grew very fast as the strain continued to increase,which resulted in the coarsening of austenite grains.The calculation results of the microstructure evolution model showed that at the same deformation temperature,the evolution curves of average grain size with different strain rates had the intersection points.With the increase in temperature,the position of intersection point moved to the downward direction of strain.The simulation results showed that when the reduction amount increased to 20%,the average grain size at the center was smaller than that near the surface.It could be inferred that when the reduction amount greatly exceeded 20%,the dynamic recrystallization at the center was mostly completed,and the austenite grain growth would become the main mechanism.

关 键 词：Large billet Reduction pretreatment Dynamic recrystallization Grain refinement Microstructure evolution model 

分 类 号：TG142[一般工业技术—材料科学与工程]