Analysis of the structure and properties of Ni-based alloys on the surface of 42CrMo steel with plasma cladding

Abstract

As a kind of structural alloy steel, 42CrMo steel is widely used in a variety of mechanical components, especially in high-load conditions. The surface of 42CrMo steel is very unlikely to work properly in lasting bad conditions. The failure is mostly because the steel wears. And sometimes the steel cracks or even breaks. Since it is difficult to repair the steel once it fails, this paper proposes a surface repair method for 42CrMo steel based on plasma cladding technology. Firstly, using plasma cladding technology, Ni-based cladded layers were prepared on the surface of 42CrMo steel. Then, the microstructure, hardness and wear of the cladded layers were observed through specialized equipment. Finally, the effect of process parameters on the temperature of the molten pool was analyzed with the simulation software. It has been found out that the substrate is mainly compose of ferrite and pearlite and the zone affected by heat is mainly composed of coarse grains and strip grains. It has also been found that the cladded layer is composed of-Ni and-(Fe,Ni) phases, which results in a significant increase of hardness, namely from 282 HV0.2 to 516 HV0.2. The average friction coefficients of the substrate and the cladded layer are 0.910 and 0.569, respectively. Correspondingly, the wear amounts are 5.39E-6 mm3·N-1·m-1 and 2.24E-6 mm3·N-1·m-1, and the wear volumes are 3.88E-3 mm3 and 1.61E-3 mm3. This means that the wear resistance of the cladded layer is higher than that of the substrate. With the help of analysis of simulation, it is concluded that the width and depth of the molten pool of the cladded layer grows when the current grows. The width and depth of the molten pool of the cladded layer decreases when the speed gets higher.