How to avoid solidification cracking in arc welding of aluminum alloys: a review on weld metal grain refinement approaches

Abstract

Joining aluminum alloys with arc welding methods is frequently subject to literature and industrial applications. Although aluminum alloys have different difficulties in the arc welded process, the formation and elimination of solidification cracking defects is a more complex phenomenon. Since avoidance of this defect requires specific approaches and methods, special attempts and improvements have been studied frequently on this subject in recent years. Studies in the literature have clearly shown that this defect, which is often encountered in aluminum alloys, takes place along the grain boundaries. Therefore, the major approach to eliminate this defect is activating nucleation and decreasing the grain size. In this context, modification approaches in the literature, which are frequently used for arc welding of aluminum alloys, have been developed to use three different mechanisms including heterogeneous nucleation, dendrite fragmentation, and grain detachment. While it is aimed to increase heterogeneous nucleation by reinforcing filler metals with compounds in the inoculation approach; dendrite fragmentation and grain detachment are also aimed in the approaches where external effects and forces are used. Within the frame of references, it is also possible to review the external factors aiming to improve weld pool convection and thermal conditions under two headings, which are weld pool stirring and pulsed arc current approaches. The weld pool stirring approach also includes ultrasonic treatment and magnetic arc oscillation methods. In this study, solidification cracking defect that frequently occurs in the arc welding of aluminum alloys is explained fundamentally and the attempts to eliminate this defect are presented as a review paper in a comprehensive manner.