Optimization of plasma transferred arc welding process parameter for hardfacing of stellite 6B on duplex stainless steel using taguchi method

Abstract

Hardfacing involves the application of a deposition on the surface of a metallic workpiece by employing a welding method such as plasma transferrd arc (PTA) and has found widespread application in the steel, power, mining and in the petroleum industry. The process of hardfacing should be aimed at achieving a strong bond between the deposit and the base metal with a high deposition rate. Therefore, it is very important for the proper selection of PTA process parameters to improve weld qualities in hardfacing. The properties of the hardface materials such as mechanical strength, hardness are influenced not only by the chemical composition but also by the process parameters. The acceptable properties depends on heat input and the heat input, in turn, depends on welding current, arc voltage, etc. Therefore, weld hardfacing can be considered as a multi input, multi-output process , Stellite 6 has an outstanding resistance to seizing or galling as well as cavitation erosion and is extensively used to combat galling in valve trims, pump sleeves and liners. Hardfacing is a surface modification technology in which a specially designed alloy is surface welded in order to enhance surface properties depending on the characteristics of selected alloys. In this process, metallurgical bond forms between the coating and the substrate in this concern PTA welding process parameter are optimized for maximum hardness and defect free process, using Taguchi method for the hardfacing of Stellite on duplex stainless steel.