生物医用316L奥氏体不锈钢的形变组织

借助扫描电镜、电子背散射衍射和透射电镜组织观察,对生物医用奥氏体不锈钢316L的形变组织进行了多尺度深入研究,其工程应变量范围为2%~40%。结果表明,当应变>20%时,316L奥氏体不锈钢中的<001>和<111>取向平行于拉伸方向,即出现了大量的变形孪晶和马氏体。从微米尺度和纳米尺度对孪晶和马氏体相变做详细分析发现,形变首先诱发形成变形孪晶,由于孪晶界减小了位错平均自由程而引起位错塞积,进一步诱发马氏体的转变。随着变形量的增加出现了更多的孪晶和α-马氏体,马氏体相变的过程只有γ→α转变,α马氏体主要分布在孪晶界附近,特别是孪晶交叉的位置。其中,奥氏体基体和α-马氏体之间的取向关系为:011]_γ//011]_α,(420)_γ//(123)_α。

Deformation microstructure of biomedical 316L austenitic stainless steel

Deformation behaviour in engineering strain range of 2%-40% of the 316L biomedical austenitic stainless steel was investigated in depth at multiple scales by means of EBSD, SEM and TEM. The results indicate that when the strain is more than 20%, the <001> and <111> orientations in 316L austenitic stainless steel are gradually parallel to the tensile direction, and a large number of deformation twins and martensite appear during the deformation process. From the micro-scale and nano-scale, based on the detailed analysis of the twins and martensitic transition, it is found that the deformation firstly induces the formation of deformotiou twins. The twin boundary reduces the mean free path of dislocations and causes dislocation pile-up packing, which further induces the formation of deformation twins. With the increase of deformation, more twins and α-martensite appear. The process of martensitic transition is only γ→α, which α-martensite is mainly distributed near the twin boundaries, especially at the twin intersection. The orientation relationships between the austenitic matrix and the α-martensite are 011]_γ//011]_α and (420)_γ//(123)_α.