Research on the Forming, Microstructures, and Mechanical Properties of High-Speed Laser Cladding 1Cr17Ni2 Stainless Steel on 1Cr17Ni5 Thin-Walled Tube

To study the forming, microstructures, and mechanical properties of high-speed laser cladding thin-walled tube, 1Cr17Ni2 powder was used to perform high-speed laser cladding on a 1Cr17Ni5 stainless steel tube with a thickness of 1 mm. The effects of powder feeding rate, laser power, rotation speed, protective gas flow rate, powder defocusing amount, and powder feeding gas flow rate on the width, height, and penetration depth of the weld beads were investigated. Subsequently, the cladding of multi-pass was carried out, and the microstructures and microhardness of the cladding layer were studied. The results showed that laser power had the most significant effect on the width of the weld bead, and the width gradually increased with the increase in power. The powder feeding rate had the most significant effect on the height of the weld bead, and the height gradually increased with the increase in powder feeding speed. The powder feeding rate also had the most significant effect on the penetration depth, and the penetration depth gradually decreased with the increase in powder feeding speed. When multiple passes overlap, the microstructure of the cladding layer exhibits a distinct periodic distribution. Large-sized primary austenite columnar crystals exist in the cladding layer, and the main microstructure in the columnar crystals is martensite and possesses a small amount of residual austenite. The base material is composed of austenite and a small amount of martensite. The average microhardness of the substrate is 366 HV, and the microhardness of the cladding layer gradually decreases with increasing distance from the fusion line, from 562 HV to 532 HV. Due to the heat effect of the cladding on the substrate, the microhardness of the substance near the fusion line is only 239 HV. As the distance from the fusion line increases, the influence of heat effect decreases, and the microhardness gradually increases.