Three-dimensional finite element analysis of residual stresses in circumferential welds of 2205/X65 bimetallic pipe

Abstract

Corrosion has a great negative influence on the pipe service life, and high welding residual stress will accelerate corrosion and reduce the strength of the pipe. Traditional carbon pipe is highly susceptible to corrosion, especially in the oil transport industry, and the stainless steel pipe is expensive. So bimetallic steel is a good choice for high-pressure and corrosion-resistant pipe. Multi-pass butt-welded 2205/X65 bimetallic pipe in this article is simulated numerically in non-linear thermo-mechanical finite element method (FEM), a three-dimensional (3D) finite element model is developed, the temperature history and the residual stress distribution are plotted, and the results are compared with the available measured data to evaluate the accuracy of the finite element model. In addition, the stresses changing with weld pass and the effect of the welding speed on stress distribution are also studied. The results show that the tensile stresses after cooling are larger than the tensile stresses after pass four on the inside surface, and the compressive stresses after cooling are larger than the compressive stresses after pass four on the outside surface, and the position of the maximum stress is farther away from the weld center when the welding speed decreases.