Application of the Rappaz-Drezet-Gremaud Hot Tearing Criterion to Welding of Aluminium Alloys

Abstract

Hot tearing, a severe defect occurring during solidification is the conjunction of tensile stresses which are transmitted to the mushy zone by the coherent solid underneath and of insufficient liquid feeding to compensate for the volumetric change. The RDG (Rappaz Drezet Gremaud) criterion for the appearance of hot tears in metallic alloys [1] is based upon a mass balance performed over the liquid and solid phases and accounts for the tensile deformation of the solid skeleton perpendicular to the growing dendrites and for the induced interdendritic liquid feeding. When tackling the problem of hot tearing in welding of aluminium alloys, the RDG criterion can be used at three levels of increasing complexity by:-ranking the alloy with regards to their sensitivity to hot cracking -studying the risk of hot tearing in the process using only the thermal field (thermal criterion), -and studying the influence of the mechanical behaviour of the mushy alloy on the risk of hot cracking (thermo-mechanical criterion). Each level is illustrated by an example dealing with laser beam welding. Nevertheless, one of the critical issues in the RDG approach is the definition of a coherency point which, in low-concentration alloys, corresponds

Hot cracking investigation during laser welding of high-strength steels with multi-scale modelling approach

“…The Rappaz Drezet Gremaud (RDG) criterion [19] for hot cracking in metallic alloys is based upon a mass balance performed over the liquid and solid phases, which accounts for the tensile deformation of the solid skeleton perpendicular to the growing dendrites and for the induced inter-dendritic liquid feeding.…”

Modeling and simulation of weld solidification cracking part III

“…Drezet et al [7] used the RGD criterion [8] to study the susceptibility for solidification centerline cracking in laserwelded aluminum alloys. The RDG criterion states that hot cracking forms if the local pressure in the liquid falls below a given cavitation pressure [7].…”

Process Optimization of Dual-Laser Beam Welding of Advanced Al-Li Alloys Through Hot Cracking Susceptibility Modeling

“…Similar results have also been reported by Drezet. [19] In order to investigate the effects of Si and Cu, which are the main elements affecting the A parameter in the weld mixture, calculations were carried out by varying Si and Cu content respectively while keeping the other elements fixed at the same level as the mixture obtained by 1700 W laser power, as listed in Table VII. The composition level from 1700 W laser power was chosen because it provided an average reference of the weld mixture.…”