Effects of prefabricated hole structure on cold-pressing joining reliability between dissimilar sheets

Abstract

The structural form of prefabricated holes is one of the important factors to determine the quality and reliability of cold-pressing joining between dissimilar sheets. Different numbers of holes with the same area will lead to different wall thickness distributions and joining strengths. This paper takes the cold-pressing joining between AA1100 pure aluminum sheet and SS304 stainless steel sheet as an example, the further study results show that the end of aluminum sheet has an increasing tendency along the directions of length and width in the process of cold-pressing joining. The wall thickness of joints shows a symmetrical distribution on both sides and the joining thickness decreases from the center to both sides sequentially. With the continuous increase of the punch loading pressure, the average thinning ratio of the joints becomes larger. By contrast, when the other parameters are all the same, the joining strength is the most ideal when the punch loading pressure is 250 kN. The loading pressure which is too small or large is easy to cause an insufficient joining strength or defects. This paper provides a scientific basis in this aspect for optimizing the cold-pressing joining plan and designing a reasonable joint structure. It can also promote the existing cold-pressing joining technologies to be mature, and enrich the existing solid-state joining technology.