Study on arc and TIG welding of earthquake-resistant structural steels with a higher carbon equivalent

High strength rebars are generally developed by increasing carbon and manganese contents depending on the size and strength capacity requirement. These elements in steel beyond certain level adversely affect weldability and impact toughness which are very critical for structural steels. In this study, an attempt has been made to analyse and optimize the welding parameters on higher carbon equivalent (0.60) of 36-mm-diameter structural rebar by Arc and TIG welding process to arrive at exact preheating temperature for obtaining desired weld properties at minimum possible cost. The basic aim of this work is to establish the welding process parameters on structural steel to use as an earthquake-resistant steel without compromising the properties such as yield strength, tensile strength, tensile strength to yield strength ratio, and minimum uniform elongation. Before and after the welding, changes in the microstructure and mechanical properties in the fusion zone and heat affected zone (HAZ) of the welds were investigated. From the results, it was observed that 150 °C is the optimum preheating temperature to obtain good welds. The microstructural studies revealed that martensite is not present in the HAZ of the 150 °C preheated sample and the same was substantiated from resultant mechanical properties also.