Hot Tearing in Cast Al Alloys: Mechanisms and Process Controls

Hot tearing has been an issue for many casting alloys, and much work has been devoted over the years to understanding the underlying mechanism, and to be able to mitigate it during casting. Unfortunately, the literature and therefore our understanding to date has been a bit muddled, as conflicting data and theories exist. In addition, many of the tests that have been developed to evaluate hot tearing have been qualitative in nature. Through the Light Metals Alliance, WPI’s Metal Processing Institute and CANMET joined forces in 2006 to clarify our understanding of hot tearing and to enable us to control it during casting. This paper contains an overview of the authors’ work; describes the quantitative test that was developed and discusses the processing variables that are needed to control and to mitigate hot tearing.