Study on process and effective factors of high power disk laser welding for stainless steel with 10 mm thickness

To realize the single pass laser welding for 304 stainless steel with 10 mm thickness, full penetration welding process experiments had been carried out on the disk laser welding equipment with 10 kW laser power. The effects on the weld quality of welding speed, defocus length, laser power were studied. The appearance and dimension of the weld cross section were observed by optical microscope. The results showed that there was ablation on the top and bottom surface of welding bead when the welding speed was lower and there was root hump on the bottom surface of welding bead when the welding speed was higher. The defocusing length affected the focus position. When the defocus position under the top surface, it might decrease the energy efficiency using larger defocus length and it might lead to ablate using lower defocus length. For the workpiece with 10 mm thickness, it was better to have a defocus length of — 3 mm. The laser power had great influence on weld penetration. It couldn't form a full penetration weld when the laser power was lower. Tensile strength results showed that the tensile strength average was 639.6 MPa, yield strength average was 297.6 MPa, and elongation average was 61.2%, which reached 95.5%, 99.2%, 95.5% of the base material respectively