Comparative study of hardfacing of valve seat ring using MMAW process

In this present investigation, the hardfacing of valve seat ring is done by manual metal arc welding (MMAW) process by using three different electrodes in order to compare the performance of the weld overlays. MMAW process is selected as the component size is comparatively small and the process is an all-position process, highly versatile and most economical. In this study, main attention is focused on the influence of carbon and chromium variations on wear, hardenability, corrosion rate, effect on microstructure, etc., The main aim of the hardfacing chosen here as a method of repairing or improving or extending the service life of the valve seat ring economically is to provide excellent wear resistance, increasing hardness and better corrosion resistance. Full microstructural and other tests were carried out and complemented with a detailed hardness survey. It was found that carbon and chromium supports the improvement of wear resistance, hardness and refined microstructure, but postweld heat treatment (PWHT) results in drop in hardness on the weld overlays.