Research on morphology, porosity, mechanical properties of 7075 aluminum alloy repaired by arc welding and laser shock forging

Abstract

There are many problems in the arc welding repair of aluminum alloy parts, such as excessive pores, coarse grains, and low hardness. Introducing external energy excitation is an effective solution. In this paper, 7075 aluminum alloy parts are repaired using the arc welding - laser shock forging technique. The effects of laser-wire spacing, laser pulse energy and frequency, welding current and speed, and V-groove depth on the surface morphology, section geometric characteristics, and porosity of the repaired layer are studied. Additionally, the hardness and microstructure of the repaired layer formed by arc welding - laser shock forging and arc welding are compared. The results show that a fine surface morphology of the repaired layer can be achieved by selecting reasonable laser-wire spacing, welding current, welding speed, and V-groove depth. It is also advised to select the maximum laser pulse energy and frequency possible, in order to increase the aspect ratio, reduce the residual coefficient, minimize porosity, and decrease the maximum pore diameter of the repaired layer. When compared to arc welding alone, arc welding - laser shock forging has the advantage of reducing grain size and improving the hardness of the repaired layer.