Research on Anti-Nitriding Coatings for 38CrMoAl Steel

When nitriding 38CrMoAl steel, there are areas that need to be protected, as the process may interfere with subsequent steps. The large-scale demand for anti-nitriding coatings has driven the investigation and development of more effective anti-nitriding coatings. In this study, various anti-nitriding coating formulations were applied to the surface of 38CrMoAl steel samples via brushing. Following the nitriding treatment, SEM, EDS, and hardness tests were performed to systematically investigate the effects of the considered formulations on the mechanical and microstructural properties of the 38CrMoAl steel. The experimental results indicated that the hardness values for all the samples remained below 600 HV, demonstrating that coatings composed of tin powder, lead powder, and various oxides possess anti-nitriding abilities, to a certain degree. The lead powder formulation exhibited the best anti-nitriding performance, achieving an average surface hardness of 273.48 HV. No nitriding layer was observed in the cross-section, and no nitrogen (N) was detected on either the surface or in the cross-section. In comparison, the samples coated with tin/lead and tin/lead/alumina formulas demonstrated relatively lower anti-nitriding capabilities, with an average surface hardness below 320 HV, satisfying the hardness requirements for anti-nitriding coatings while preventing the formation of a nitriding layer.