Nanomechanical properties of duplex treated 42CrMo4 steel

Active screen plasma nitriding (ASPN) has attracted interest from researchers and industries as it can overcome several intrinsic problems in direct current glow discharge plasma nitriding such as arcing, hollow cathode, edge effects and the strong temperature dependence on the shape of the samples. In this study, an advanced duplex system based on ASPN and chromium nitride coating was synthesised on 42CrMo4 steels. The effects of ASPN on the mechanical properties, nanoimpact resistance and scratch resistance at different load ranges were investigated. The results show that the surface hardness H, reduced elastic modulus E_r and the ratios of H/E_r and H ³/E_r ² can significantly be improved at the testing load range from 5 to 100 mN. The enhanced nanoimpact and scratch resistance can be well correlated to the improved H/E_r and H ³/E_r ².