Prediction of Hot Cracks of T-Joints in Full-Penetration Welding Process

In this study, the influence of welding conditions on the formation of a pear-shaped bead crack is examined through experiments on full-penetration welding of T-joints. These problems are analyzed using the finite element method (FEM). The formation and growth of a pear-shaped bead crack in T-joints welded by full-penetration, high-current pulsed MAG (Metal Active Gas) welding is simulated using temperature-dependent interface elements, which are introduced in the thermal-elastic-plastic FEM analysis. The experimental results show that a pear-shaped bead crack does not occur when the heat input is greater than 2 500 J/mm, or when the penetration bead is formed. However, according to commonly accepted knowledge, both large heat input and a large penetration bead (deep penetration relative to the penetration width) lead to hot crack formation. To understand these experimental results, FEM simulations are conducted and the influences of heat input and the size of the penetration bead are investigated.