316L不锈钢不同取向压痕应变率敏感性研究

本研究探讨了不同取向对激光选区熔化(SLM)成形316L不锈钢力学性能的影响．使用纳米压痕测试系统对SLM成形316L不锈钢扫描平面方向和叠加成形方向两个取向的试样进行测试，并通过相关计算得出了材料在这两个方向的弹性模量、硬度、应变率敏感性指数等力学参数．实验结果表明，扫描平面方向的弹性模量和叠加成形方向的弹性模量基本相同；在相同的压入应变率下，扫描平面方向的硬度大于叠加成形方向的硬度；而对于不同的压入应变率，在高应变率下的压痕硬度相对较大；随着压入深度的增加，硬度逐渐减小并趋于稳定值．此外，本研究分析了不同压入应变率下硬度和应变率敏感性指数m的压痕尺寸效应，并得到与尺寸无关的硬度和应变率敏感性指数m．最后，通过引入扫描平面方向准静态宏观压缩工况下的应变率敏感性指数m加以验证本研究的合理性，揭示了SLM成形316L不锈钢在不同取向上应变率敏感性的差异，进而为研究准静态宏观压缩下叠加成形方向的应变率敏感性提供了支撑．

Study on Strain Rate Sensitivity of 316L Stainless Steel Indentation with Different Orientations

The effect of different orientations on mechanical properties of 316L stainless steel formed by laser selective melting (SLM) was investigated. The nano-indentation testing system was used to test the samples of 316L stainless steel formed by SLM in the scanning plane direction and the superposition direction. The mechanical parameters of the material in these two directions, such as elastic modulus, hardness and strain rate sensitivity index, were obtained by relevant calculation. The experimental results show that the elastic modulus of scanning plane is basically the same as that of superposition forming. Under the same pressing strain rate, the hardness of scanning plane is greater than that of superposition forming direction. For different strain rates, the indentation hardness is relatively large at high strain rates. With the increase of pressing depth, the hardness gradually decreases and tends to be stable. In addition, the indentation size effect of hardness and strain rate sensitivity index m under different compressive strain rates was analyzed, and the hardness and strain rate sensitivity index m independent of size was obtained. Finally, by introducing the scanning plane direction of quasi-static compression macro conditions of strain rate sensitivity index m verified the rationality of this study, reveals the SLM forming 316L stainless steel strain rate sensitivity of the differences in different orientation, and to study under the quasi-static compression macro superposition underpinned by shaping the direction of the strain rate sensitivity.