ABSTRACT. In view of the fact that welding thermal cycle could adversely affect the mechanical properties of heat affected zone (HAZ) for quenched and tempered (QT) high strength steel (HSS) due to the transformation of microstructures, experiments were conducted to find out the correlation of welding heat input, hardness, microstructure and the tensile strength of HSS butt joints. Effect of heat input, heat treatment on microstructure and When the heat input to the weld was higher, weld will remain at elevated temperature for a longer duration which will lead to grain coarsening and softening of the matrix. But, when the heat input was lower, the grain will be finer and hardening of the matrix occurs.
The yield strengths are related to the heat input near the welded region and to the grain size of SZ. In the welding process, increasing heat input can make material of welding region softer , resulting in a slight decrease of the yield strength. Considering the microstructural aspect, the lack of heat input has a greater influence on grain refinement by the welding tool. Studies on Effects of Welding Parameters on the In this work, the effect of heat input on the mechanical properties of low-carbon steel was studied using two welding processes:OxyAcetylene Weld- ing (OAW) and Shielded Metal Arc Welding (SMAW). The Effect of Heat input on the Mechanical Properties of mechanical properties are varied with respect to the heat input. This heat input is depending upon voltage, current and speed flow rate of wire. In this present work input is considered into two conditions. i) low heat input dissimilar joints i.e. in IS 2062-IS 45 C8 (3.6189 kj/mm )and in IS 2062-IS 103 Cr 1
For all heat inputs, the base metal had the lowest hardness in comparison with the weld metal and HAZ in the joint, while a higher heat input could induce a lower hardness in the weld metal.