Effect of rare earth on microstructure and properties of 38CrMoAl steel plasma nitrided case

The effect of rare earth on microstructure and properties of 38CrMoAl steel plasma nitrided case was studied. The results show that the quantity of γ′ phase is obviously more in the RE plasma nitrided compound layer than conventional plasma nitrided one, and there are many dislocation loops, dislocations, cell substructure in the RE plasma nitrided diffusion layer at a distance of 0.08 mm from surface. The surface hardness of the RE plasma nitrided case is similar to the conventional plasma nitrided one. The RE plasma nitrided case exhibits better wear resistance and thermal fatigue resistance when the case depth is increased, while the case brittleness does not increase.