Effect of isothermal martensite and bainite transformation on microstructure and properties in a medium-carbon high-strength Q&P steel  

作　　者：Ya-jun Liu Jun-yu Tian Man Liu Xiao-long Gan Sheng Liu Guang Xu 

机构地区：[1]The State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan,430081,Hubei,China [2]Joint International Research Laboratory of Refractories and Metallurgy,Ministry of Education,Wuhan,430081,Hubei,China

出　　处：《Journal of Iron and Steel Research International》2024年第12期3095-3108,共14页钢铁研究学报(英文版)

基　　金：The authors gratefully acknowledge the financial supports from the National Natural Science Foundation of China(No.52104381);the China Postdoctoral Science Foundation(No.2023M732721);also the help on microstructure analysis from Dr.Zhen Wang at the Analytical and Testing Center of Wuhan University of Science and Technology.

摘　　要：The effect of the amount of isothermal martensite and bainite on the microstructure and properties in a medium-carbon quenching and partitioning(Q&P)steel was investigated by designing the different Q&P treatment parameters.The results show that the amount of isothermal martensite increased gradually with the increase in quenching time.The increase in isothermal martensite amount improved the product of strength and elongation(PSE)of Q&P steels.In addition,the increase in carbides amount and the recovery in prior martensite with longer partitioning time led to an increase in PSE first and then,a decrease.It implies that a higher PSE could be obtained by the selection of a suitable partitioning time.Furthermore,the effect of bainite transformation during partitioning on PSE was investigated by designing the different partitioning temperatures,including 300,400(below bainite starting temperature,B_(s))and 480℃(above B_(s)).The results show that compared with the samples partitioned at temperature above B_(s),the bainite transformation was only detected when the samples were partitioned at temperature below B_(s).The bainite transformation amount increased with the decreasing partitioning temperature,leading to the inhibition of carbides precipitation and more stable RA and thus,resulting in the highest PSE.

关 键 词：Q&P steel Isothermal martensite Bainite transformation CARBIDE Mechanical property 

分 类 号：TG156.9[金属学及工艺—热处理] TG142.1[金属学及工艺—金属学]