热镀锌TRIP钢中马氏体对力学性能的影响

来源期刊：金属学报2010年第5期

论文作者：定巍 唐荻 江海涛 黄伟

文章页码：595 - 599

关键词：热镀锌TRIP钢； 热处理； 马氏体量； 力学性能

Key words：hot-dip galvanized TRIP steel； heat treatment； martensite amount； mechanical property

摘    要：利用SEM,TEM,XRD,相变实验和拉伸实验等方法,分析测试了3种热处理工艺下热镀锌TRIP钢的微观组织、相变产物和力学性能,并运用碳扩散平衡理论分析了不同热处理工艺下实验用钢的马氏体量,研究了马氏体量对力学性能的影响.研究表明:贝氏体等温相变时间影响组织中的马氏体量,当贝氏体转变时间由20 s增加到60 s时,试样中马氏体量由7.08%减少到1.18%;马氏体量对力学性能有显著影响,马氏体量多,马氏体强化效果占主导,使试样拥有类似双相钢的力学性能,同时拥有比双相钢更好的延伸率;随着马氏体量下降,马氏体强化效果逐渐下降,当马氏体量减少到1.18%.实验用钢逐渐呈现出典型的TRIP钢的力学特性.

Abstract: The hot-dip galvanized transformation induced plasticity(TRIP) steel is an advanced automobile steel with excellent mechanical proprieties,which meets the requirements of energy preservation and environment protection.The microstructure and mechanical properties of hot-dip galvanized TRIP steel are different from conventional TRIP steel treated by continuous annealing processing.Three hot-dip galvanizing processes(main difference is isothermal bainitic transformation(IBT) time) arc designed according to the characteristics of hot dip galvanized TRIP steel manufacturing process to study the influence of microstructure on mechanical properties.By means of SEM,TEM,XRD,dilatometry and tensile test,the microstructure characteristic,phase transformation and mechanical properties were investigated.Combined these experimental results and the carbon diffusion balance theory,the content of martensite and its effect on mechanical properties were analyzed.The results show that the IBT time has a significant impact on the content of martensite.The volume fractions of martensite are 7.08%,4.17% and 1.18%.when IBT times are 20,30 and 60 s,respectively.Both the transformation induced plasticity of retained austenite and the martensite hardening are effective but the latter plays a dominant role,when the content of martensite is 7.08% the strength is similar as dual-phase steel,but a better elongation.When the volume fraction of martensite decrease to 1.18%,the mechanical properties are similar to the conventional TRIP steel,as so small amount of martensite has no obvious effect on the mechanical properties.By changing the hot dip galvanizing process,the amount of martensite and retained austenite can be controlled,and hot-dip galvanized TRIP steel with different mechanical properties can be obtained.