EFFECT OF WELDING PROCESS ON MECHANICAL AND MICROSTRUCTURAL PROPERTIES OF HARDFACED WELD DEPOSITS-A COMPARATIVE STUDY

Abstract

Hardfacing is generally used to cope up with problems of wear associated phenomena in most of the engineering applications due to high efficiency and economy. Adhesive wear is one of the primary aspects relating to the deterioration of a machine component during service life having metal-to-metal contact e.g. gear teeth, engine shaft, sprockets etc. l-lardfacing deposits hold high weight percentage of alloying elements which are accountable for the enhanced hardness and wear resistance of the deposit, although the base metal typically has relatively smaller percentage of these elements. For hardfacing numerous methods are used as per requirement including welding. Modified welding techniques like tubular electrodes, powder preplacement technique etc. also promise enhanced properties of the deposit. In this study, two different welding processes, namely Shielded Metal Arc Welding (SMAW) process and Gas Tungsten Arc Welding (GTAW) process, used to deposit the alloy by Powder Preplacement Technique were compared. The processes were compared on the basis of heat inputs used for depositing alloy on the substrate. A simple composition of Fe-Cr-C alloy was deposited on Mild Steel (AlSI 1020 Steel) by applying paste of the powdered alloy. To observe the mechanical properties, hardness tests and wear tests were conducted while microstructural properties of the deposits were analyzed by Scanning Electron Microscope (SEM). Energy-Dispersive X-ray (EDX) spectroscopy etc. Adhesive wear tests were performed by using an EN-3 I steel plate as hard surface by varying sliding velocity while keeping other parameters the same. The alloys deposited by Powder Preplacement Technique using SMAW process were comparable, in terms of mechanical properties, to the alloys deposited by same technique using GTAW process regarding mechanical properties. The alloys deposited using SMAW process even demonstrated greater wear resistance than that of GTAW at higher sliding velocities in the adhesive wear test.