Optimization and control of gaseous nitriding of a 33CrMoV12-9 steel

Abstract

This work propose a new experimental methodology to optimize the gaseous nitriding process of 33CrMoV12-9 steel grade, widely used in the mechanical industry for the fabrication of gears, pinions, and bearings. Several nitriding experiments were conducted at a temperature of 520 °C in the interval between 4 and 55 h using both constant and variable nitriding potential K N . The obtained results allowed us to determine the optimal conditions and to propose a sequenced cycle consisting of three steps. Multiple characterizations using X-ray diffraction (XRD), optical microscopy (OM), Vickers microhardness testing (HV), and electron probe microanalysis (EPMA) indicate a surface hardness of 810 HV0.5, nitrogen diffusion depth of approximately 0.7 mm. finally, a metallurgical structure devoid of complex networks of nitrides and carbonitrides. The validation results confirmed the effectiveness of the proposed methodology, thereby paving the way for improving the nitriding process in the mechanical industry. This work represents a significant contribution to the optimization of thermochemical treatments for materials used in demanding environments.