Effects of laser beam oscillation welding parameters on Al-Si coated 22MnB5 weld joint properties

Al-Si coated 22MnB5 steel is one of the primary materials to fulfill vehicle lightweight and improve its fuel efficiency. In this study, laser beam oscillation welding approach was introduced to weld the Al-Si coated 22MnB5 steel in a butt joint configuration. To improve the joint strength, the process parameters were optimized through orthogonal experiments. Furthermore, the tensile tests were applied to evaluate the tensile strength of the welded joint and the base metal. The microstructure and fracture morphology of the welded joint and the base metal were observed and compared by scanning electron microscopy. Experimental results showed that the laser power had the largest effect on the tensile strength of the welded joint, followed by the oscillation frequency, the welding speed, and the oscillation amplitude. In addition, the optimized values of the laser power, the welding speed, the oscillation frequency and the oscillation amplitude to obtain the best performance of the welded joint were 3200 W, 3.1 m/min, 240 Hz, and 0.6 mm, respectively. Under this set of parameters, the tensile strength and elongation of the welded joint were 1510.59 MPa and 2.56% still lower than the ultimate strength of 1603.20 MPa and the elongation of 6.90% of the base metal, respectively. The formation of alpha-ferrite in the fusion zone promoted the initiation and propagation of the cracks under the tensile loading, which was the main reason for the degraded mechanical properties.

Automated summary

In this study, the laser beam oscillation welding approach was used to weld the Al-Si coated 22MnB5 steel, and the process parameters were optimized to improve the joint strength. The experimental results showed that the laser power had the largest effect on the tensile strength of the welded joint.