Abstract
In the present study, a large-scale finite element analysis of welding thermal elastic-plastic behavior was
conducted for the purpose of estimating the residual stress distribution at dissimilar welds between a cast-
iron pipe and steel flange. Based on the calculation results, the effect of welding pass and heat input
conditions on the distribution of residual stress was investigated. The results showed that tensile residual
stress occurred along the interface between a cast-iron pipe and steel flange, regardless of the welding pass
and heat input conditions. Note that the calculated tensile residual stress becomes smaller for a large-
heat-input and small-pass-number condition, compared to a small-heat-input and large-pass-number condition.
This is because transverse residual stress induced by welding is strongly affected by the balance of plate
thickness and heat input, which is a cause of the bending moment at welds. Thus, we concluded that the
transverse residual stress could be controlled along the interface between a cast-iron pipe and steel flange
by optimizing the welding conditions according to the weld joint configuration. Through a welding test and an
experiment using deep hole drilling, a relatively small tensile residual stress was obtained for a large-
heat-input and small-pass-number condition.
