INVESTIGATION ON EFFECT OF WELDING CURRENT AND POST WELD HEAT TREATMENT ON MECHANICAL PROPERTIES OF WELDMENT OF LOW CARBON STEEL

Merchant Samir Y

Abstract: Welding is one of the major metal joining process widely used in process equipment fabrication industry. In this paper effect of process variable and post weld heat treatment temperature on mechanical properties of weld joint is investigated. Different weld joints are welded with different welding current. The weld specimens of 10 mm thickness were welded at 80 A, 90 A and 100 A with arc voltage 25 V using E-6013 electrode with DCEP polarity. The weldments were then post weld heat treated by setting PWHT cycle as per ASME sec VIII Div 1 UCS 56 at different temperature 600 °C, 675 °C and 750 °C. Change in mechanical properties like hardness before and after PWHT was investigated. It was found that with increase in welding current hardness of weld joint decrease due to increase in heat input but it was very high than the unwelded base metal. It was observed that after PWHT below recrystallization temperature (lower critical temperature line- 723°C) hardness of weld metal and fusion boundary region did not change but hardness of HAZ and base metal region decreased with increase in PWHT temperature. When PWHT temperature increased above 723 °C hardness of all regions of weld joint decreased.

Keywords: Weld Joint, HAZ, Hardness, PWHT, Socking Temperature

DOI: https://doi.org/10.15623/ijret.2015.0412012