The Impact of Casting Conditions on Edge Cracking of AA5182 Ingots During Hot Rolling

Abstract

The hot rolling of large ingots is the predominant process for producing plate, sheet, and foil. During the hot rolling of aluminum/magnesium alloys, edge cracking tends to dramatically increase with increasing magnesium concentration, often resulting in significant unplanned scrap generation. It has been observed that significant cracking most frequently occurs in the start-up region of the ingot, which prompted the current investigation into the impact of casting conditions on edge cracking. By taking samples from the start-up and steady-state regions of AA5182 ingots and subjecting them to different simulated pre-heat rates, we were able to observe a noticeable difference in liquation and void formation behavior on the ingot surface. For a given casting condition, there appears to be a threshold pre-heat rate beyond which significant void formation occurs. Our investigation indicates that the start-up region of DC cast ingots has a lower threshold temperature, thus leading to increased edge cracking.