摘要
经两次调质热处理细化的30CrMnSiA 钢在770℃以■=2.78×10^(-4)·S^(-1)的应变速率拉伸下呈现了良好的超塑性:δ=867%,σ=34.3MN/m^2,m=0.41。在拉伸时,经预处理的非平衡组织会经碎化而变成微细等轴的晶粒组织,并具有两相体积分数近似相等的α+v 双相组织。这种组织在超塑性流变过程中具有很高的稳定性。此钢对空洞的敏感性比较低,但在变形后期,由于空洞的形成、长大和连接而导致试样呈空洞型沿晶断裂。
30CrMnSiA steel refined through quenching-tempering treatments in twice exhibited good superplastieity under optimal condition of tensile deformation (T=770℃,■=2.78×10^(-4)S^(-1))and the results were as follows:elongtion δ= 867%, flow stress,σ=34.3MN/m^2,and strain rate sensitive index m=0.41.In tensile tests, the needle-type austenite resulting from the heating of nonequilibrium structure gradually broke up and was transformed into fine and equiaxed microstructures which contained ferrite and austenite with approximatelly equal-volume fractions. The structure had a high stability during deformation. Although the steel was insensitive to cavitations,the formation and i■erlinkage of caviations in the later stages of deformation resulted in cavitation and intergranular fracture of specimens.
基金
国家自然科学基金
