变形温度对316LN奥氏体不锈钢组织和性能的影响

Effect of deformation temperatures on microstructure and mechanical properties of 316LN austenitic stainless steel

以316LN奥氏体不锈钢为研究对象,分别在不同温度（室温和液氮）下对其进行轧制变形实验（变形量30%和90%）,借助光学显微镜（OM）、扫描电镜（SEM）、透射电镜（TEM）、X射线衍射仪（XRD）、显微硬度计、微力拉伸试验机等对其变形过程中的微观组织演变与力学性能变化规律进行研究。结果表明：两种变形条件下316LN奥氏体不锈钢均可发生形变诱导马氏体转变,且马氏体体积分数随着变形量的增大而增加,同一变形量下深冷轧制态马氏体转变量显著高于室温冷轧态。深冷轧制比室温轧制更有效地加速马氏体转变,可使奥氏体组织完全转化成马氏体的同时将其细化至纳米级别。深冷轧制态下的强度和硬度均高于室温冷轧态,但其伸长率低于室温冷轧态,拉伸断口形貌从典型的韧性断裂向韧性和准解理混合型断裂转变。

The rolling deformation experiments（deformation of 30% and 90%） at different temperatures（room temperature and liquid nitrogen temperature） of 316LN stainless steel were carried out,and microstructural evolution and mechanical properties of the rolled 316LN stainless steel were investigated by means of optical microscope,scanning electron microscopy,transmission electron microscopy,X-ray diffractometer,micro-hardness tester and micro-tensile testing system.The results show that the deformation-induced martensitic transformation can occur in the 316LN austenitic stainless steel under two kinds of deformation conditions,and the volume fraction of martensite increases with the increase of deformation.Under the same deformation,the martensitic transformation of cryogenic rolling（CR） state is significantly higher than that of room temperature cold rolling（RTR） state.The cryogenic rolling can accelerate the martensitic transformation more efficiently than room temperature cold rolling,which can make austenite structure completely transformed into martensite and refine it to nanoscale.The strength and hardness of the 316LN stainless steel after cryogenic rolling are higher than that of after room temperature cold rolling,but the elongation is obviously lower,and the tensile fracture morphology is transformed from typical ductile fracture to ductile and quasi-cleavage mixed mode fracture.