Characterisation of hot tearing in Al cast alloys: methodology and procedures

Hot tearing is perhaps the pivotal issue defining castability. It is affected by alloy composition as well as processing conditions and variables. Hot tearing is a complex phenomenon in that it lies at the intersection of heat flow, fluid flow and mass flow. Over the years, many theories and models have been proposed, and accordingly, many tests have been developed. Unfortunately, many of the tests that have been proposed are qualitative in nature. The need exists for a simple, reliable and repeatable quantitative test to evaluate hot tearing. The Metal Processing Institute and the CANMET-Materials Technology Laboratory, both members of the Light Metal Alliance, joined forces to address this need. A quantitative hot tearing test was developed, and the methodology is presented and discussed. The test has been applied to study hot tearing of A356 and M206 alloys. The results are presented and discussed. Protocol and standardised procedures that can be adapted by the metal casting industry is presented.