The effect of sample thickness on micro-mesoscale tensile properties of 304SS, HT-9, and CuCrZr

Small scale mechanical testing has gained significant attention in recent times due to its advantages for materials research and development; however, the ability to extend small scale testing results to larger scale applications remains difficult, and questions remain with regards to quantifying macroscale properties from microscale tests. In this study, 304SS, HT-9, and CuCrZr samples of various conditions were tested using the SS-J sample geometry with thicknesses ranging from 800μm to 30μm. Starting at thicknesses below 200μm, significant reductions in material properties such as uniform elongation and ultimate tensile strength were observed. The presence and magnitude of the changes varied across material and material condition, indicating the coupling of both geometric and microstructural effects. Finite element analysis was performed on the overall test setup used, revealing potential flaws in using the SS-J and other related sample geometries to increasingly extreme sample aspect ratios. Microhardness and nanoindentation were also performed for comparison and revealed discrepancies in values at these different length scales.