On the quality of A354 ingots and its impact on cast product

Abstract

A study in an automotive casting plant was targeted to address the problem of high rejection rate of a cylinder head casting made from an A354 alloy. Ingots of an A354 alloy from three different suppliers, A, B and C, were analyzed by the reduced pressure test (RPT) and the pressure filtration (PREFIL) test, individually as well as in combination. Hydrogen measurements during casting trials was carried out with an ALSPEK H? analyzer. The results have shown a good agreement with the scrap rate data of the final cast product, and the problem of higher scrap rate was significantly reduced when the ingots of an A354 alloy with the highest oxide content from supplier C were replaced. In order to study the influence of transfer and de-gassing on the melt quality, reduced pressure tests were also conducted along the production line. The effect of melt holding time on the quality of the cast product is also presented. The results from these trials shows that the bifilm index data from the RPT has a potential to be used in an industrial environment for routine melt quality control as the cause of high scrap was successfully identified with this technique.