Residual Stress Optimization in Mild Steel Welded Joint using Finite Element Method

Abstract

Residual stress has detrimental effect on the quality, reliability and
service life of welded joints. Tungsten Inert Gas (TIG) welding is a
very popular gas shielding arc welding process used in many
industrial fields. Welded joints produced as a result of poor
combination of process parameters do not possess sufficient strength
required to sustain its useful service life. This study was carried out
with the aim of optimizing residual stress in mild steel weldment
using Finite Element Method (FEM). In order to address the problem
of residual stresses, the finite element method was employed. The
experimental matrix was made of thirty (30) runs, generated by the
design expert 7.01 software adopting the central composite design.
The parameters considered in this study were current, voltage, gas
flow rate and welding speed. The material used was 80mm x 60mm x
6mm mild steel plates. The response was measured using the
ultrasonic computerized complex and the finite element analysis of
residual stresses in Butt welding of the two similar plates was
performed with the ANSYS software. In this study, the FEM was
employed to optimize the residual stresses in the mild steel welded
joints. This study has shown that current, gas flow rate, welding
speed and voltage had a very strong influence on residual stress
formation. The model produced numerical optimal solution of
current 180 Amp, voltage of 16volt, welding speed of 351mm/min
and gas flow rate of 16Lit/min, which will produce a welded material
having a residual stress of 265MPa.