Research on high-temperature friction and wear performances of Stellite 12 laser cladding layer against coated boron steels

The stellite 12 layer was applied on H13 steel by laser cladding to increase the surface wear resistance at high-temperature. The tribological performance of stellite 12 laser cladding layer was compared with heat-treated H13 steel by pin-on-disc dry sliding tests against with Al-Si, GA (galvannealed), GI (galvanized) coated boron steels at 700 degrees C. The results indicated stellite 12 layer is composed of columnar, dendritic and equiaxed crystals along the section from substrate interface to the top surface without obvious cracks and other defects. Stellite 12 layer represents good wear resistance with the three kinds of coated boron steels, where the coefficients of friction (COFs) are lower than heat-treated H13 steel by 18.9%, 20.6% and 25.6% respectively, and wear rates are lower by 20%, 43% and 38% respectively. The wear mechanism of stellite 12 layer, i.e., a complex synergism involving oxidation, adhesion, diffusion, and plastic deformation, is mainly adhesive wear and oxidized wear. Compacting the oxide layer on the surface of stellite 12 pin is the key to reducing wear. In addition, the com-pacted oxide layer formed on the stellite 12 layer is mainly composed of oxides of Co, Cr, and transferred Al, Zn. Stellite 12 layer can improve the wear resistance of H13 steel, and friction and wear performances are affected by the compacted oxide layer. Compared with Al-Si coating, the stellite 12 cladding layer has a better antifriction effect on Zn-based steel sheet due to its thicker oxide layer. It has verified the development prospect of stellite 12 layer on reducing the surface wear at high-temperature.