微米/纳米复合结构逆转变奥氏体组织控制

Structure control of micrometer/nanometer scale reverse transformation austenite

为了控制微米/纳米复合结构逆转变奥氏体组织,研究了冷变形及退火工艺参数对316L奥氏体不锈钢逆转变组织和力学性能的影响.首先,对样品进行冷变形;然后,对不同变形量的样品进行退火处理.利用光学显微镜和扫描电镜以不同尺度对样品进行组织观察,通过X射线衍射、磁性测量进行组成相分析,利用维式硬度和单向拉伸试验对样品进行力学性能测试.结果表明：冷变形量为90％时,钢中应变诱导马氏体含量接近71.72％,硬度由原始试样的193.10 Hv增加到475.77 Hv;在820～ 870℃保温60 s,退火后可以获得微米/纳米复合结构组织,其中850℃退火后的样品其逆转变奥氏体组织的百分含量为100％,粒径≤500 nm的晶粒占29.6％,粒径＞0.5μm的约占70.4％,其抗拉强度可达959.24 MPa,延伸率为44.6％,强塑性结合好于原始试样.

To control the micrometer/nanometer scale reverse transformation austenite structure,the effects of cold deformation and annealing parameters on the microstructural development and mechanical properties of the 316 L austenite were investigated.First,the cold deformation was performed for the specimens,and then the specimens with different deformations were annealed.The microstructural evolutions of the specimens were analyzed by using a optical microscope and a scanning electron microscopy,the composed phases of the specimens were researched by a magnetic measurement and X-ray diffraction and their mechanical properties were determined by Vickers hardness method and tensile tests.The results show that the stain-induced martensite is almost 71.72％ at 90％ cold deformation,and the hardness value increases from 193.10 Hv to 475.77 Hv.The resultant micrometer/nanometer grained steel can be obtained after annealing at 820-870 ℃ for 60 s and austenite grains with a size greater than 0.5 μm （70.4％）and less than 500 nm（29.6％） can be obtained after annealing at 850 ℃ for 60 s.Moreover,the specimens are completely reversed to austenite （100％）.The resultant micrometer/nanometer grained steel not only exhibits a high strength level about 959.24 MPa,but also a desirable elongation of about 44.6 ％.