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

To explore the size effect on the yielding behavior of ultrathin superalloy strip 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 indicate that the yield locus of ultrathin superalloy strip shrinks inward entirely with the increase of grain size, and the shape of yield locus also changes from ellipse to square, indicating the grain size dependence of yield locus of superalloy strip. In addition, the four typical macroscopic yield criteria (Mises, Hill48, Barlat89, Yld2000-2d) were selected for comparative analysis of the ability to predict yield loci for superalloy strips with different thicknesses and grain sizes. The results show that the Yld2000-2d yield criterion keeps the best prediction accuracy and can more accurately describe the yield behavior of ultrathin superalloy strip with different thicknesses and grain sizes.