高温合金超薄带材屈服轨迹的晶粒尺度依赖性研究

为了研究高温合金超薄带材屈服轨迹的晶粒尺度依赖性，通过单向拉伸试验和不同加载比例的双向拉伸试验获得了不同厚度和晶粒尺寸的高温合金超薄带材的试验屈服轨迹。结果表明，随着高温合金带材晶粒尺寸的增大，屈服轨迹整体向内收缩，且形状由椭圆形向方形转变，证明了高温合金带材屈服轨迹存在晶粒尺度依赖性。同时，评估了四种典型宏观屈服准则预测不同厚度与晶粒尺寸高温合金带材屈服轨迹的能力，发现Yld2000-2d屈服准则拟合精度最高，但随着带材厚度减小或晶粒尺寸增大，其预测精度逐渐下降。

Research on Grain Size Effect on Yield Locus of Ultrathin Superalloy Sheet

To explore the size effect on the yielding behavior of ultrathin superalloy sheets with different thicknesses and grain sizes, the experimental yield loci were obtained via uniaxial tensile and biaxial tensile tests under different loading ratios. The results indicated that the yield locus of ultrathin superalloy sheet shrink inward entirely with the increase of grain size, and the shape of yield locus is also changed from ellipse to square, indicating the grian size dependence of yield locus. In addition, the four typical macroscopic yield criteria were selected for comparative analysis, and results showed that the Yld2000-2d yield criterion keeps the best precision for describing the yielding behavior of ultrathin superalloy sheet. However, the prediction accuracy is degraded with the increase of grain size.