Characterization and experimental investigation of pack boronizing process off various stainless steel grades using anova and machine learning approacjes

Abstract

Stainless steels are the ideal materials for cryogenic, elevated temperature and marine applications. This is mainly due to their excellent high-temperature strength, low-temperature toughness and corrosion resistance. Stainless steels are often utilized in the manufacture of industrial valve components and pumps exposed to corrosive fluids. The service life of these components are limited as they are subjected to relative motion with the parts leading to their poor wear resistance. Typically, the valve components often have metal-to-metal contact during their operation. To extend the useful service life of components, surface treatments are applied to combat wear. In the present study, five different grades of stainless steel such as martensitic stainless steel (SS410), austenitic stainless steel (Nitronic-50 and SS316) and super duplex stainless steel (S31803 and S32750) are used in valve components considered for surface modification. Among the various methods of surface treatment, the case hardening process plays a vital role to improve the hardness and wear resistance. Boronizing is one of the case hardening process (thermo chemical diffusion process) which offers an extremely high hardness and wear resistance as compared to the conventional heat treatment process. The pack boronizing technique is a cost-effective solution that can be applied even in intricate parts. In this work, pack boronizing process was carried out using 4.5 kW Indfurr electric furnace. To study the surface characteristics, the input process parameters such as temperature, time and gas pressure were considered with three different levels in each parameter. The Taguchi L9 orthogonal array was used to design the process parameters and to evaluate the impact of pack boronizing process. From the experimentation, diffusion kinetics, activation energy, boron layer thickness growth, surface hardness and wear resistance were analyzed. iv The various testing methods like metallographic, microscopic and mechanical examinations were carried out on t