30Mn20Al3无磁钢加工硬化行为和组织变化

研究了30Mn20Al3无磁钢冷轧板经1 000和800℃固溶处理10 min后的拉伸变形加工硬化行为和组织结构变化.结果表明:该钢的加工硬化速率在不同变形阶段随真应变的变化呈现不同的规律,加工硬化指数随真应变增加而增加.OM和TEM观察显示,变形量小时,滑移为主要变形机制;变形量增大,变形机制以形变孪晶与位错及形变孪晶之间的交互作用为主;1 000℃固溶处理的晶粒尺寸较800℃大,变形过程中产生的形变孪晶较多,且随着变形量增加,形变孪晶可持续形成,增大了TWIP效应;晶粒尺寸减小使变形过程中的形变孪晶产生的临界应力增大,抑制形变孪晶的产生,从而减小了TWIP效应.

Strain Hardening Behavior and Microstructural Evolution of 30Mn20A13 Non-magnetic Steel

Cold rolled sheets of 30Mn20Al3 high manganese non-magnetic TWIP steel were tensile deformed after solution treatment at 1 000 and 800 ℃ for 10 minutes.Microstructure evolution was observed by OM and TEM.Results indicated that strain hardening rate followed different patterns along with changes in true strain under different deformation stage,and the strain hardening exponent increased with increasing true strain.Dislocation slip was the dominant deformation mechanism for small deformations.As deformation amount increased,deformation twins appeared and the main deformation mechanism was the interaction between dislocation and deformation twins or between deformation twins.Grain size increased with increasing solution treatment temperature.Microstructure observation demonstrated that the number of deformation twins increased with increasing grain size,resulting in a greater TWIP effect in coarse-grained specimens than in fine-grained specimen.This can be attributed to the dependence on grain size of the critical stress for twin formation.