MICROSTRUCTURAL MODIFICATION OF STEEL BY PULSED CURRENT AUTOGENOUS TUNGSTEN INERT GAS WELDING

Abstract

newline newlineIn this work studies have been carried out to find the effect of a dimensionless factor in controlling heat input, its distribution and cooling in pulsed Tungsten Inert Gas arcing. At different values of this dimensionless factor, changes in microstructure analyzed and properties measured at FZ and HAZ. Changes in microstructure and hardness, wear and corrosion properties of fusion zone and heat affected zoneof Austenitic, Martensitic stainless steel and High carbon steel were observed.To achieve this, following method has been adopted newlineA Development of analytical models to generate isotherms and time temperature curves. newlineB Study of the experimentally modified surfaces and correlating the same with analytically drawn curves. newlineC Measuring different dimensions of the surface ripples of the modified surfaces and calculating cooling rate and primary solid growth rate pattern and correlating the same with observed micro structural variations. newlineD Measuring changes in surface properties and correlate the same with microstructures. newline E Suggesting optimum parameters to achieve desired surface modifications. newline It has been established that the dimensionless factor used in this work is able to control the pulsed Tungsten inert gas arcing heat input and its distribution. By increasing the value of the dimensionless parameter within experimental range the cooling rate, primary solid growth rate and hardness can be improved. So autogenous pulsed TIG, by controlling through a dimensionless parameter, can be used to modify surface properties studied in this work. newline newline newline