Residual Stresses in Circumferential Welding of Mild Steel Pipes

Abstract

The various thermo-mechanical effects of
circumferential welding of mild steel pipes were

studied in the current investigation. A thermo-
elasto-plastic finite element model was

developed to compute the temperature history
and the corresponding residual stress
distribution due to GMAW of mild steel pipes.
The non-linearity in the problem was accounted
for by the use of incremental solution procedure
considering appropriate boundary conditions.
However, the present analysis ignored the
effects of phase transformations. The input heat
source model was the typical double-ellipsoidal
heat flux density distribution and the element
birth-death technique was used to account for
the filler metal additions. The computed
temperature distribution compared fairly well
with the measured data. It was observed that the
effect of reverse heat flow was negligibly small
for large diameter pipes. Residual stresses were
computed considering both kinematic and
isotropic hardening plasticity models. In both
the cases it was observed that neither isotropic
hardening model nor the kinematic hardening
model had any significant impact on the
resulting residual stresses as well as
displacements.