Effect of Ti interlayers on microstructure and mechanical properties of laser spiral fusion welded steel/aluminum lap joints
Shuang Huang, Han Yu, Ming Lou, Lidong Xu, Rundong Lu, Zhuoran Li, Yongbing Li
Abstract
The effects of Ti foil on microstructure and mechanical property of steel/aluminum laser spiral fusion welding joints were investigated. The results revealed that the addition of a Ti interlayer effectively increased the laser absorptance, resulting in increased penetration depth. During welding, while the internal flow patterns within the joint remained unchanged, modifications to the microstructure were observed. Notably, the addition of Ti promoted grain refinement, reducing the average grain sizes in the upper weld region and the solute band by 56.1% and 27.3%, respectively, due to the dispersion of TiO particles. Furthermore, the formation of Fe 2 Al 5 and Fe 4 Al 13 was inhibited, and Fe 2 Ti phases were formed through a eutectic reaction between Fe and Ti atoms. These microstructural changes contributed to improved joint performance, with the shear tensile strength and coach peel strength increasing by 27.86% and 15.06%, respectively. This work demonstrated that the introduction of a Ti interlayer significantly enhanced the microstructural homogeneity and mechanical performance of laser welded Steel/Al joints.