Effect of Microstructure and H. I. P. Treatment on Fatigue Strength of Aluminum Casting Alloys

Abstract

  Microstructure and fatigue strength of JIS AC4C Alloy (Al-7Si-0.3Mg) and JIS AC7A Alloy (Al-4.5Mg) treated with hot isostatic pressing (H.I.P.) were studied. Without H.I.P. treatment the fatigue strength falls as the microstructure grows coarser. After H.I.P. treatment, however, there is no effect of the size of the microstructure. The fatigue strength at 10⁷ cycles for AC4C Alloy and AC7A Alloy treated with H.I.P. is about 11kgf/mm² irrespective of the size of the microstructure.