预应变对TRIP型双相不锈钢拉伸变形行为的影响

预变形通常作为工程构件服役前的关键预处理工艺,用以提高金属构件的力学性能.为了明确预应变对拉伸变形过程中力学行为和相变行为的影响,在INSTRON 8801试验机上进行了一系列准静态拉伸试验,研究了一种TRIP型双相不锈钢的拉伸变形行为及其预应变敏感性,同时结合TEM分析、EBSD分析和原位磁性测量讨论了微观机理.结果...

Influence of pre-strain on tensile deformation behavior of TRIP-assisted duplex stainless steel

Pre-deformation, as a key pretreatment process for serving, is usually used to improve the mechanical properties of metal components. In order to clarify the effect of pre-strain on the mechanical behavior and transformation behavior, a series of quasi-static tensile tests were carried out on INSTRON 8801 to investigate the tensile deformation behavior of a TRIP-assisted duplex stainless steel(DSS) and its dependence on pre-strain. The micro-mechanism was discussed by means of TEM analysis, EBSD analysis and in-situ magnetic measurement. The results showed that a typical “three-stage” hardening characteristic of TRIP-assisted DSS was reflected due to the occurrence of strain-induced martensite transformation (SIMT) of γ→ε→α' during tensile deformation, therefore enhanced work hardening ability and mechanical properties were obtained. The introduction of pre-deformation (unloading) did not change the nucleation and growth mechanism of α' martensite, but influenced the work hardening behavior and the mechanical properties of test steel by changing the martensite transformation kinetics in the subsequent deformation process. With the increase of pre-strain level, the (subsequent) yield stress increased and the elongation A decreased gradually. However, different changing trends were revealed in ultimate tensile strength and total elongation A_t (A_t=ε_Epre +A) with increasing pre-strain level, which was closely related to the difference of martensitic transformation kinetics (i.e. transformation degree and transformation rate) under different deformation conditions.