Finite element simulation of butt welded 2·25Cr–1·6W steel pipe incorporating bainite phase transformation

Abstract

This article presents a newly developed global optimisation method for the finite element simulation of welding process considering bainite transformation. In this method, the pattern search algorithm was applied to determine kinetic parameters in Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation during a continuous cooling process. Meanwhile, the JMAK equation was modified into an explicit form as a function of welding temperature field to improve calculation efficiency in the optimisation process. This methodology improves the accuracy as calculating the temperature dependent volume fraction of bainite transformation in finite element simulation. The calculated welding residual stresses considering phase transformation effects exhibited better agreement with the measured results than those calculated without phase transformation. The influences of variable cooling rates on welding residual stresses were also investigated.

Keywords:

• Welding residual stress
• Pattern search method
• Finite element modelling
• Bainite transformation
• Optimisation

This work was supported by the National Natural Science Foundation of China (Grant Nos. 50975176 and 51105251) and National Science and Technology Major Project (No. 2012ZX04010-091).

Notes

This paper is part of a special issue on computed-aided welding engineering