Solidification cracking susceptibility associated with a teardrop-shaped weld pool

Abstract

For straight columnar dendritic grains growing side by side, |dT/d(f S ) 1/2 | (T: temperature; f S : fraction solid) near their roots can be the crack-susceptibility index as verified against welds made with an elliptical weld pool. This study showed the index is also valid for welds made with a teardrop-shaped pool. In both cases, at the mushy-zone centreline, the tips of such grains grow and finally become the roots as the mushy-zone moves forward. This validity is consistent with:(1) the crack-susceptibility ranking of alloys in arc welding (typically elliptical pool) being similar to that in laser-or electron-beam welding (typically teardrop-shaped pool), and (2) the ranking calculated based on the index being consistent with that observed in laser-or electron-beam welding.

An analytical model for intergranular liquid feeding and its effect on solidification cracking

“…Considering the rates of the transverse tensile strain, lateral grain growth and liquid feeding, Kou [5] proposed | dT / d(f S ) 1/2 | near f S = 1 as a crack susceptibility index. This index was found to agree with the crack-susceptibility ranking among aluminium alloys [6, 7], magnesium alloys [8], steels [9, 10] and Ni-base alloys [11]. More recently, machine learning based on deep neural network [12] and computational fluid dynamics (CFD) [13, 14] were also developed to predict the crack susceptibility of alloys.…”

A review: Suppression of the solidification cracks in the laser welding process by controlling the grain structure and chemical compositions

“…The weld pool shape as a function of the oscillation is also a sign of creating solidification cracks because it shows the strain distribution. Teardrop weld pool shape is more susceptible to cracking rather than an elliptical shape due to the concentration of the strain in the center line weld (Agarwal et al, 2019;Cross, 2005;Kou, 2021). Fig.…”

Hot-Cracking Mechanism of Laser Welding of Aluminum Alloy 6061 in Lap Joint Configuration

“…This model predicts the likelihood of cracking during welding by evaluating the local deformation of the material. Various other hot-cracking models and criteria have been explored and analyzed in the referenced studies [17][18][19][20][21].…”