INVESTIGATION ON EFFECT OF WELDING CURRENT ON WELDING SPEED AND HARDNESS OF HAZ AND WELD METAL OF MILD STEEL

Merchant Samir Y

Abstract: The effect of welding current on welding speed and hardness of heat effected zone and weld metal of mild steel material is investigated in this paper. Mild steel weldment was welded under varying welding current i.e. 80, 85, 90, 95 & 100 ampere by using MMAW process in 1G position. The edge preparation, electrode diameter and electrode type, CCV, welding technique, polarity and welder remained constant during the test. The test specimen was then grinded and hardness of each specimen was measured at three point i.e. parent metal, HAZ and weld metal by using Brinell hardness tester. It was observed that with increase in welding current melting rate of electrode was increased hence welding time was reduced. So welding speed was increased. With increase in welding current hardness of HAZ and weld metal was also decreased due to increase in heat input. With increase in welding speed heat input decreased and hardness of the joint increased.

Keywords: MMAW, welding current, welding speed, Hardness, Parent metal, HAZ, weld metal, cooling rate

DOI: https://doi.org/10.15623/ijret.2015.0403006