Abstract
Surface is the only part of the component, which has to co-exist with external environment. Majority of engineering failures originates from the surfaces and components degrade in service leading to failures such as fatigue, wear, corrosion, and oxidation.The present study deals with the surface modification of steel base through diffusion of aluminium by hot dip aluminizing, for improving wear and corrosion resistance. The material chosen for study is medium carbon steel. Effect of varying dip times at different diffusion temperatures and times on the microstructure and microhardness of aluminized and diffused specimens was studied. The studies were conducted based on statistical techniques such as of Taguchi in order to reduce the experimentation efforts. Considering a non-porous surface and the increased case depth, the dip time of 3 minutes and diffusion temperature of 1023 K seems to be the optimum condition. However, higher diffusion temperature yielded porous surface and lower dip time showed a thin layer of case depth. The surface hardness of steel could be increased to a maximum of 1000 HV 0.1 when aluminized and diffused. X-Ray diffraction studies have confirmed the presence of aluminides in the surface layer, which could be instrumental in the significant increase in surface hardness. This could be used for components in automotive and other engineering applications, where wear resistance is considered as critical.
Keywords: Aluminizing, diffusion, microhardness, aluminides, x-ray diffraction