Estudo de viabilidade técnica da nitretação localizada utilizando equipamento de soldagem TIG

Abstract

The surface hardening of steels by means of heat and thermochemical processes is a widely used technique in industrial practice. Among nitriding processes, plasma nitriding is increasing its market share in the last years, and its limitations are basically related to the dimensions of the parts to be nitrided. This work aims to test the viability of a different process compared to the conventional plasma nitriding. It was used a TIG welding equipment with the most simple particulars commercially founded, with the addition of nitrogen to the argon protective atmosphere, to do this work, because the electrical arc phenomenon that is generated between the electrode and the part during TIG welding can be compared with the plasma between the reactor and the part, during plama nitriding. After nitriding experience with TIG equipment, specimens were characterized by means of optical microscopy, scanning electron microscopy, energy dispersive spectroscopy (EDS), and X-ray diffraction. Microhardness profiles of treated samples were also measured. Results showed that with the current equipment configuration and process parameters, it was impossible to avoid the surface melting, which is undesirable in this case, however both EDS and X-ray analyses indicated some nitrogen incorporation in the alloy with subsequent surface hardening.