Simulating and Predicting Weld Solidification Cracks

Abstract

Weld solidification cracks result from the competition between the material resistance and driving force to the cracks. The material resistance, namely the ductility curve in BTR, was obtained by in-situ observation and measurement of local strain at the trail of weld pool using a CCD-camera in the Trans-Varestraint Test. The driving force, i.e. mechanical strains against temperatures at the trail of a weld pool, was modeled with the finite element method (FEM) in three steps. Firstly, thermal distributions in both 3 mm and 10 mm thickness welds were modeled by two-dimensional and three-dimensional thermal models, respectively. Secondly, the strain/stress distributions arising during welding of 3 mm stainless steels were simulated by a two-dimensional model on the basis of the simulated thermal distributions. Thirdly, the driving force behind weld solidification cracking was determined from the simulated thermal cycle (temperature against time) and from the mechanical strain against time in the weld center line. Furthermore, a computer system was developed on the basis of two-dimensional simulation which provides a simple way of conducting complex work for simulating and predicting weld solidification cracking.