HOT TEAR SUSCEPTIBILITY OF Al-Mg-Si ALLOYS WITH VARYING IRON CONTENTS

摘要

Hot tear susceptibility in a cast 0.53Si-0.33Mg-xFe 6060 aluminum alloy was investigated using the CAST Hot Tear rig, designed to simulate hot tearing in DC casting. The rig has two cast bars, one that is used to measure the load response and one which is fixed at both ends to restrain thermal contraction so that hot tearing could be observed if it occurred. The iron (Fe) content, ranging from 0.02-0.5wt pet, was seen to have a major influence on the load response during solidification and the tear rating of these alloys. The findings are related to the influence of Fe content on the morphology, prevalence and precipitation sequence of the β-Al_5FeSi and α-AlFeSi Fe-containing intermetallic phases. Observations made of hot tear fracture surfaces show that these phases may play distinctly different roles within the mechanism of hot tearing in these alloys.