热镀锌工艺对无Si含P的TRIP钢力学性能影响

利用光学显微镜、透射电镜、X射线衍射和拉伸试验等方法,分析测试了热镀锌工艺对无Si含P的TRIP钢力学性能和微观组织的影响.结果表明:实验用钢可获得780 MPa以上的抗拉强度和24%以上的断后延伸率.在热镀锌工艺中,两相区加热温度和贝氏体等温温度对钢的力学性能影响较小,而贝氏体等温时间的影响最为显著.当贝氏体等温时间由20 s增加到60 s时,实验用钢的屈服强度上升了65 MPa,抗拉强度下降了45 MPa,延伸率大幅度增加,从23.01%增加到27.56%,出现最佳的综合力学性能.无Si含P热镀锌TRIP钢的微观组织由铁素体、贝氏体、残余奥氏体和马氏体组成,随着贝氏体等温时间的减少,钢中残余奥氏体含量和稳定性降低,相应地,马氏体含量明显增加,实验用钢从典型的TRIP钢力学特征慢慢转变为与双相钢相似的力学特征.

Effect of hot galvanizing processes on the mechanical properties of non-Si and P-added TRIP steel

The effect of hot galvanizing processes on the mechanical properties and microstructure of non-Si and P-added TRIP steel was studied by using optical microscopy,transmission electron microscopy,X-ray diffraction and tensile test.It is shown that the steel with tensile strength over 780 MPa and percentage elongation after fracture over 24% can be obtained.The temperatures of intercritical annealing and isothermal bainitic transformation(IBT) have little influence on the mechanical properties,while IBT time plays significant contribution to them.When the IBT time prolongs from 20 s to 60 s,the sample reaches the best performance.Its yielding strength rises by 65 MPa,tensile strength decreases by 45 MPa,and elongation increases obviously from 23.01% to 27.56%,respectively.The microstructure of non-Si and P-added TRIP steel consists of ferrite,bainite,retain austenite and martensite.As the IBT time shortens,the amount and stability of austenite get decreased,the content of martensite increases markedly,and the mechanical characteristics of the steel transform from TRIP steel's to dual-phase steel's gradually.