2022 Volume 94 Issue 2 Pages 55-61
Owing to its low specific gravity together with high strength and high ductility, aluminum alloy die castings are being increasingly applied to the body structural parts to reduce the weight of automobiles. Generally, the tensile test is used for evaluating the properties of die castings, but this method tends to overestimate the effects of porosity defects. Focusing on the main property required of body structural parts, i.e., the ductility which guarantees that the parts will not break even if bent in case of collision, we examined the possibility to evaluate this ductility by the three-point bending test.
In the tensile test, porosities reduce the actual cross-sectional area of the test piece, thus their macro effects on mechanical properties can be assessed. However, it is difficult to evaluate their effects on surrounding local ductility. On the other hand, it was found that with the 3-point bending test, the influence of porosities on ductility can be assessed according to their positions with respect to the pushing point, i.e., the collision site. Artificial defects were therefore formed and their effects on ductility evaluated. The results showed that porosities more than 8 mm away from the pushing position or more than 0.5 mm inside the surface of castings do not have significant impact on bending ductility.
