加载方向对TRIP双相不锈钢板带拉伸性能的影响

Influence of loading direction on tensile properties of a TRIP-assisted duplex stainless steel sheet

为了研究加载方向对一种TRIP型双相不锈钢板带力学性能的影响,利用拉伸试验机研究了加载方向与轧制方向分别成0°、45°和90°条件下试验钢板带的拉伸变形行为。利用EBSD、TEM、XRD等分析手段对比研究了不同加载方向下形变组织演化的特点及形变诱导马氏体相变动力学规律,探讨了作用机理。结果表明,试验钢表现出明显的各向异性,其中各方向塑性和抗拉强度(由高到低)的变化规律为0°>45°>90°,但屈服强度对加载方向不敏感。钢中奥氏体相发生了形变诱导马氏体相变,主要演化机制为γ→ε→α′,从而形成TRIP效应。0°加载有助于TRIP效应的发生与发展,而90°加载时,两相间的应变配分延迟了马氏体相变的进程,抑制了TRIP效应。通过回归分析分别建立了不同加载方向下形变诱导马氏体相变动力学模型,可实现各加载方向下不同变形阶段马氏体转变量的预测。

To clarify the effect of loading direction on the tensile properties of a TRIP-assisted duplex stainless steel sheet,the tensile deformation behavior of the test sheet at loading directions of 0°,45° and 90° with rolling direction(RD)were investigated by tensile test.Microstructural characteristics,especially the kinetics of strain-induced martensitic transformation(SIMT)were comparatively analyzed through EBSD,TEM,XRD,etc.The results showed that the tensile properties exhibited a strong anisotropy.The tensile strength and the ductility increased in the order of 0°,45° and 90°,but the yield strength was not sensitive to the loading direction.Microstructural analysis showed that the SIMT occurred in the metastable austenite which caused the transformation induced plasticity(TRIP)with a mechanisms of γ→ε→α'.Loading at the loading direction of 0° was in favor of TRIP,while the SIMT was suppressed at the loading direction of 90°due to the strain partitioning between austenite and ferrite.Moreover,the quantitative models of the kinetics of SIMT at different loading directions were established,respectively,whereby the content of strain-induced martensite at different deformation stages could be predicted.