Research on Cavitation Erosion Resistance of QT400-18 Ductile Iron Engine Block Repaired by Additive Manufacturing with Co-Cr-W Alloy

In order to improve the surface performance of ductile iron engine block and solve the problem of cavitation erosion caused by bubble collapse during use, laser cladding and argon arc welding were used to repair the surface of QT400-18 ductile iron, respectively. The microstructure, hardness, room temperature tensile performance and cavitation erosion resistance of the laser cladding layer and argon arc welding layer samples were analyzed. The results show that the repaired layers are mainly composed of small, staggered columnar crystals and dendritic crystals. The microstructure of the laser cladding layer is finer and harder than that of the argon arc welding layer.The tensile strengths of the two repaired layer samples are close to that of the matrix, but the plasticity decreases. After 8 h of cavitation erosion, the QT400-18 substrate is severely damaged, the laser cladding and argon arc welding samples have smoother surface, and the cavitation erosion resistance is obviously improved. Compared with that of QT400-18 substrate, the wear mass loss of the laser cladding and argon arc welding samples decreases by 95.32%and 93.58%, respectively.