Numerical Simulation of Pear-shaped Bead Cracking in Narrow Gap Welding(Mechanics, Strength & Structural Design)

概要

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To achieve high efficiency and cost reduction, high heat input welding such as submerged arc welding (SAW) and CO_2 arc welding using large currents are employed. However, the high heat input given to the weld may produce coarse grains in the HAZ and a reduction of toughness. To avoid these problems, narrow gap welding which is effective in reducing heat input and achieving high productivity is often employed. However, in case of narrow gap welding, the welding conditions must be carefully selected to prevent the pear-shaped bead crack. The pear-shaped bead crack is one of the solidification cracking forms at the grain boundary during the solidification process of the weld metal. The mechanism of the crack formation has been mostly studied from the aspect of the arc welding process. The influence of mechanical factors, such as, stress and strain fields, on the formation of cracking has not yet been clarified. The object of this research is to develop a finite element method (FEM) which can predict the formation of the pear-shaped bead crack and to clarify its mechanism based on numerical simulation so that preventive measures can be proposed
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