Multi-layer laser cladding analysis and high-temperature oxidative wear behavior of cast iron with a low expansion coefficient

Abstract

Laser cladding is among the critical processes for repairing and strengthening cast iron parts. To further improve the application of laser cladding on cast iron and provide a feasible technical approach for its surface cladding. In this paper, different alloy powders were clad on the surface of ductile cast iron and gray cast iron, commonly used cast iron materials in engine cylinder blocks. The multi-layer claddings of various powders on the cast iron surface were analyzed, and the oxidative wear behaviors of Fe-based coatings at high temperatures were discussed. The results show that the primary defects of the cladding layer were cracks and edge warping. The average stress relationship of each coating was: ∣dσNi∣<∣dσFe∣<∣dσCo∣, and the Ni-based layer internal stress was the minimum. The internal stress was mainly caused by the difference between the physical properties of the coating and the substrate, and cladding defects were easy to occur if the internal stress was too enormous. Ni-based coating with lower cladding stress can be a transition layer to avoid defects. The average wear of Fe-based coatings at room temperature, 100, 250, 500, and 750 °C was 2.83, 1.94, 4.46, 6.43 and 9.72 mg, respectively. The wear amount was the minimum at 100 °C. Temperature rising, the oxidation of the specimens intensified, and the wear amount increased.