Laser welding process of high-strength steel wires with novel oblique I-butt joint

High-strength steel wire is widely used in construction, bridge cables, and the power industry; however, its challenging welding process results in substantial waste. Conventional welding methods struggle to control heat input on small-diameter steel wires, disrupting the fiber texture of high-strength cold-drawn steel wires and resulting in a significant reduction in joint strength. So, double-sided laser welding was proposed to weld high-strength steel wire with a novel oblique I-butt joint. In the welding process, heat input for each welding pass was independently controlled, while the total heat input could be adjusted by modifying the joint dimensions. Microstructural analysis showed that optimizing laser power and welding speed while maintaining a constant total heat input can effectively reduce damage to the fiber texture. Phase transformation kinetics analysis revealed that this improvement is associated with the suppression of martensite phase transformation. The experimental results showed that the tensile strength of the welded joint obtained using the developed laser welding process can reach 1266.8 MPa, corresponding to 91.9% of the base metal. This strength is notably greater than that of traditional joining methods used for high-strength steel wires. These studies can support the research and development of the laser welding process of high-strength cold-drawn steel wire in the industry.