Microstructure and property of cobalt alloy by laser cladding on 304LN stainless steel surface

In order to improve the wear resistance of 304LN stainless steel and prolong the service life of the control rod guide cylinder assembly, a Stellite6 cobalt-based layer was prepared on the surface of 304LN stainless steel by laser cladding technology. The microstructure, composition, microhardness, friction and wear resistance and corrosion behavior of the cladding layer were analyzed by optical microscope (OM), energy dispersive spectrometer (EDS), microhardness tester, friction and wear tester, corrosion test device and other test equipment. The processing parameters of the multi-layer cobalt-based cladding layer were determined. A metallurgical bond is formed between the cladding layer and the matrix, and the microstructure is mainly composed of planar crystal regions, cellular and columnar crystal regions, dendrite regions and equiaxed crystal regions. The hardness of the cladding layer is 500 ~ 550 HV, the friction and wear coefficient is 0.3 ~ 0.35, and the uniform corrosion rate and crevice corrosion rate of the cladding layer are 0.153 mg/(dm²·d) and 0.143 mg/(dm²·d) respectively. Laser cladding cobalt base alloy can effectively improve the hardness, wear resistance and corrosion resistance of 304LN stainless steel surface.