The process control of ductility quality is essential for aluminum alloy die castings used for automobile body parts. However, the evaluation of ductility by tensile testing is strongly affected by casting defects, which increases the difficulty of process control. To evaluate the ductility of die-cast materials with good reproducibility, instead of tensile tests, a punch rupture test was devised in which a pin was pressed into a small plate specimen to generate a crack on the surface, thereby reducing the variation in test results. One advantage of this method is the simplicity of the testing apparatus, since the specimen is not held in place. On the other hand, the test results can be influenced by the specimen size, which is a problem in manufacturing processes where same-size specimen preparation is difficult. The purpose of this study is to investigate the relationship between the effect of specimen size and dimension combination of the punch rupture setup through experiments and finite element analysis, and to clarify the conditions under which specimens of different sizes can be equally evaluated. Furthermore, to facilitate specimen preparation, the effect of setup dimensions was investigated, and downsizing was also examined. Specifically, A6061, a wrought aluminum alloy with little variation in material properties was used. The dimensions of the specimen and punch rupture setup combinations of die diameter, pin diameter, and pin shoulder radius were changed in the evaluations. For the investigation of downsizing, punch rupture tests were conducted with setups half of the initial conditions. As a result, it was found that the relationship between specimen size and die diameter strongly affected the load-displacement diagram. To minimize this effect, the length of one specimen should be at least twice the die diameter. Furthermore, when the setup dimensions were halved, no significant dimensional effect was observed, proving the validity of downsizing.
