Mechanisms of crack formation and suppression strategies in laser pulsed welding of 3J01 high elastic alloy and 1J22 soft magnetic alloy

Abstract

The joining of 3J01 and 1J22 alloys is widely used in precision electronic equipment and aviation system integration to meet structural demands for magnetic isolation and mechanical support. However, the welding process for these dissimilar materials often exhibits instability, frequently leading to defects such as cracks. Building upon this foundation, this study systematically investigates the thermal–mechanical behavior and crack formation mechanisms during laser pulsed welding of dissimilar 3J01 and 1J22 alloys through an integrated simulation-experimental approach. The results indicate that crack initiation is directly linked to stress concentration at the leading edge of the melt pool on the 3J01 base metal, and the excessive Ti content around the crack area increases the brittleness temperature range during the solidification process of melt pool. To mitigate this issue, a laser preheating technique was introduced, when the preheating parameters were set to a laser power of 1.2 kW, frequency of 30 Hz, pulse width of 4 ms, and welding speed of 8 mm/s, the peak stress was reduced by 13 % compared to the weld without preheating, with a significant reduction in high-stress regions. In conclusion, the preheating method significantly reduces the number of hot cracks in the welds of dissimilar 3J01 and 1J22 alloys during pulsed laser welding, effectively suppresses the propagation of transverse cracks, and greatly enhances the overall quality of the weld.