Spot joining of AA 5754 and high strength steel sheets by consumable bit

Abstract

Spot joining of dissimilar metal alloys is difficult because of differences in melting temperature as well as differences in composition. If a fusion welding process like resistance spot welding is employed, then alloys mix in the fusion zone and can create brittle intermetallic compounds during solidification. When self-piercing riveting (SPR) is used, the alloys to be joined must be ductile enough to be formed around the rivet. In this paper, a new approach to joining dissimilar metal alloys has been studied, where a consumable bit has been used to create a spot joint between dissimilar alloys. The resulting joint has both metallurgical and mechanical bonding characteristics and can be made between very soft and very hard alloys, like dual phase (DP) 590 and DP 980 and light metals like AA 5754. Lap shear strengths of joints made by friction bit joining (FBJ) are similar to or better than comparable joints made by self-piercing riveting.

Joining of dissimilar materials

“…The FBJ joint strength for 1.8 mm Al 5754-O to 1.6 mm DP590 averaged 6.4 kN, which was greater than the 5.0 kN achieved for SPR joints. No explanation for this is provided though, [152] since the fracture mode for both are fracture of the Al top sheet. The final joint strength is found to be a function of both bit design and process parameters [152].…”

Editorial

“…In an alternative approach to spot joining, Miles et al 9 use a consumable tool to penetrate overlapping steel and aluminium alloy sheets, followed by rotational friction heating, and finally the separation of the part of the tool which does not lie within the sheets. In this so called friction bit joining process, the lap shear strength is found to be similar to that associated with self-piercing rivets, whereas the latter process is restricted to ductile materials.…”

Joining steel to aluminum alloy by resistance spot welding with a rivet

“…Spot joining is a common welding process in the field of automotive manufacturing; therefore, the spot joining of steel to aluminum alloy has attracted great attention [2]. To overcome the problem of interfacial reaction, several solid state joining methods are being employed to join dissimilar materials, such as steel and aluminum alloy.…”