The interface control of butt joints in laser braze welding of aluminium-steel with coaxial powder feeding

Abstract

Laser braze welding of TG-1 steel and 5251 aluminium alloy was performed by coaxial feeding AlSi12 powder. From an analysis of the microstructure and mechanical properties of the welding joints, this paper proposed a zero-mean normalization research method for the correlation between the intermetallic compound (IMC) layer thickness and tensile strength. Based on differences in the welding joint strength for different thicknesses, the thickness of the IMC layer can be divided into three areas: the optimal area, stable area and decay area. The highest tensile strength of a welding joint in the optimal area achieved 64% of the aluminium alloy base strength. The heat position and the heat input energy are two key factors that affect the thickness of the aluminium-steel welding joint IMC layer. The average thickness of the IMC layer increases as the heat input energy increases. Temperature control of the reaction at the interface is more important than reaction time control. The average thickness of the IMC layer decreases and gradually stabilizes as the powder feeding rate increases. The results of the study provided a basis for the interface control study of laser braze welding for dissimilar materials.