Effect of thermo-mechanical distribution on the evolution of IMCs layer and mechanical properties of 2219 aluminum alloy/304 stainless steel joints by inertia friction welding

Abstract

The hybrid structure of 2219 aluminum alloy (Al alloy) and 304 stainless steel is effectively joined by inertia friction welding. There are the Cu-rich layer and the Fe4Al13 layer in the friction interface. The Cu-rich layer is discontinuous and its thickness is not uneven. While the Fe–Al layer is continuous and its thickness is closely related to the thermo-mechanical distribution at the interface. The thickness of the Fe–Al IMCs layer in the 1/2 radius zone is 6 fold of that in the center, while the center zone has unbonding defects due to low temperature and poor plastic flow of Al alloy. However, after changing the shape of the Al alloy end face, especially for the tapering surface joint, the homogeneous layer of Fe–Al IMCs forms in the center and 1/2 radius zones, which makes the tensile strength of different zones of the joint more balanced and improves the integral tensile strength. Meanwhile, the evolution of the two IMCs layers was investigated. It is found that the Cu-rich layer is formed through the precipitation of Al2Cu in the Al alloy. While the Fe–Al layer is formed through atomic interdiffusion and its growth is influenced not only by the thermo-mechanical coupling but also the precipitation of the Al2Cu phase.