利用室温单向拉伸实验,结合OM、TEM、SEM-EBSD等观察手段,对比研究了2种Mn含量(13Mn和22Mn,质量分数,%) Fe-Mn-C系高锰奥氏体孪生诱发塑性(TWIP)钢的拉伸性能、孪生演化规律及应变硬化行为。结果表明,随Mn含量的增加,钢的屈服强度与抗拉强度降低而断裂延伸率增加。在低应变时,Mn含量的增加延缓了钢中形变孪晶的形成;但在高应变时,Mn含量的增加加快了孪晶的形成速率,进而使高锰钢中的孪晶体积分数反而比低锰钢中的高。同时,形变孪晶的厚度随Mn含量的增加而增加。最后,对2种Mn含量的Fe-Mn-C系TWIP钢的孪生及拉伸变形行为进行了讨论。

Twinning-induced plasticity (TWIP) steels exhibit excellent mechanical properties including high tensile strength and good plasticity owing to their high strain-hardening rate. The high strain-hardening rate results mainly from deformation twinning; in addition, plane slip and dynamic strain ageing also have some contribution to strain-hardening rate. Until now, the influences of some alloy elements such as C, Al and Si on tensile properties of Fe-Mn-C based TWIP steels have received much attention. However, the effect of Mn content on the microstructure and tensile properties of twinning-dominated Fe-Mn-C TWIP steels is still not clear. In this work, the microstructure, tensile properties and strain hardening behavior of two Fe-Mn-C TWIP steels (Fe-13Mn-1.0C and Fe-22Mn-1.0C, mass fraction, %) were studied by using OM, TEM, SEM-EBSD and monotonic tensile tests. The results show that the yield and tensile strengths of the steel decrease while the elongation to fracture increases with the increase of Mn content. At low tensile strains, the increase of Mn content delays the formation of deformation twins. However, at higher strain level, the deformation twinning rate becomes higher and hence more deformation twins are produced in the steel with higher Mn content than that in the steel with lower Mn content. Furthermore, the thickness of deformation twins increases with increasing the Mn content. The twinning and tensile deformation behavior in the two steels are also discussed.