Research on the welding process and microstructure of high-strength low-alloy steel for wheel hub based on autogenous laser welding and laser wire filler welding

In response to the defects of poor welding forming and difficult performance control of high-strength low-alloy steel, a study was conducted on the weld formation and microstructure distribution of autogenous laser welding and laser wire filler welding processes based on 4 mm thick low-alloy high-strength steel for wheel hubs. Combined with simulation and experiment results, the changes in temperature and stress fields during the welding process were explored. The results indicate that the simulation results can represent the actual welding state. The simulated and actual cross section of the weld seam is basically consistent. Establish nine sets of tracking points on one side of the weld seam, with the highest temperature of 700 °C and the highest equivalent stress of 660 MPa in the autogenous laser welding process. The laser wire filler welding process has a maximum temperature of 1600 °C and an equivalent force of nearly 700 MPa. The overall deformation of the actual substrate during the two processes is 0.1 and 0.15 mm, which is strictly controlled within the simulated deformation range. Establish a response surface experiment, where the wire feeding speed is positively correlated with the geometric dimensions of the weld seam. The filling metal effectively improves the performance of the weld seam, containing uniformly distributed ferrite, martensite, and some residual austenite inside. The hardness of welds filled with metal decreases. The average hardness values of autogenous laser welding and laser wire filler welding are 328.5 and 253.4 HV, respectively.