Fe-Mn-Si-Al系和Fe-Mn-C系TWIP钢加工硬化行为

研究了在不同应变量下Fe-Mn-Si-Al系和Fe-Mn-C系孪晶诱导塑性(TWIP)钢的力学性能以及微观组织,分析了TWIP效应在两种不同系列TWIP钢中发挥的作用,阐明了TWIP钢的强化机制.两种系列的TWIP钢都具有高加工硬化能力,但层错能较低的Fe-Mn-C系TWIP钢加工硬化能力更强.两种系列的TWIP钢加工硬化表现为多加工硬化指数行为,这是由多种强化机理在不同阶段起主导作用的结果.微观组织形态与加工硬化强度之间存在着较强的关联性.位错的增殖和形变孪晶的产生对两个系列TWIP钢硬化曲线形态有着明显的影响.在高应变阶段,Fe-Mn-C系TWIP钢大量的第一位向形变孪晶T1和第二位向形变孪晶T2,以及附着在孪晶界旁的高密度位错区域是造成其具有高加工硬化能力的原因,而Fe-Mn-Si-Al系TWIP钢细密的第一位向形变条纹和孪晶片层间的位错是其高加工硬化原因,且其微观组织更为均匀细致.

Work hardening behavior of Fe-Mn-Si-A1 and Fe-Mn-C TWIP steels

The mechanical properties and microstructure of plastically deformed Fe-Mn-C and Fe-Mn-Si-AI series high manganese twinning induced plasticity (TWIP) steels were investigated at different strains. The roles of TWIP effect in the two series TWIP steels were analyzed so as to clarify the strengthening mechanisms. It is found that the two series TWIP steels have high work hardening ability, while the work hardening ability of Fe-Mn-C TWIP steel with a lower stacking fault energy (SFE) is stronger. The two series TWIP steels deformed under the same conditions exhibit different work hardening rates, since different deformation mechanisms play a leading role during different deformation stages. There is a strong correlation between the microstructure morphology and the work hardening behavior. Multiplication of dislocations and generation of deformation twins have obvious effect on the work hardening index curves of the two series TWIP steels. In high-strain stages, the plenty of primary deformation twins T1 and secondary deformation twins T2 in Fe-Mn-C TWIP steel and high-density dislocation areas adhering to twin boundaries lead to its high work hardening ability. But the close-set primary deformation twins T1 and dislocations between twins are the reasons for the high work hardening behavior of Fe-Mn-Si-Al TWIP steel, whose microstructure is more uniform and finer.