Influence of Treatment Time and Temperature on the Surface Property of Active Screen Plasma-Nitrided EN41B Low Alloy Steel

Large gains in surface hardness and corrosion resistance of EN41B have been achieved for the AS_PN process. However, the effect of the AS_PN process parameters, like treatment time and temperature, on the hardness, corrosion, and wear of EN41B have not been investigated. Thus, in this study, EN41B samples have been treated at 500 °C and 550 °C for 2 h, 4 h and 6 h with a gas flow ratio of $${\text{H}}_{2} /{\text{N}}_{2} = 4:1$$ . Scanning electron microscopy analysis showed that the compound layers varied from 15.251 µm to 25.045 µm, and also revealed the formation of transformed austenite phases. X-ray diffraction analysis has revealed the formation of $$\varepsilon - {\text{Fe}}_{2 - 3} {\text{N}}$$ and $$\gamma^{\prime} - {\text{Fe}}_{4} {\text{N}}$$ phases on the surface of the samples. The microhardness test has revealed that the maximum gain in the hardness after treatment is 4.2 times that of the base material. Finally, it was observed from potentiodynamic polarization testing that the sample treated at 550 °C for 6 h has a minimum corrosion rate of 419.10 mm/year ×10−3.