EFFECTS OF SURFACE FINISH, OF CERTAIN DEFECTS, AND OF REPAIR OF DEFECTS BY WELDING ON FATIGUE STRENGTH OF 355-T6nSAND-CASTINGS AND EFFECTS OF PRIOR FATIGUE STRESSING ON TENSILE PROPERTIES

摘要

Teats were made to evaluate the effects of various surface conditions, of certain defects, and of repair of some of these defects by welding on the fatigue strength of an aluminum sand-cast alloy. The surfaces studied included as-cast, machined, grit-blasted, and shot-blasted surfaces. The unsound conditions included different degrees of porosity and other kinds of defect sometimes present in castings which might affect their fatigue strength. Fatigue tests were made of 355-T6 sand-cast plate-type specimens subjected to direct stress from zero to a maximum value in tension, and tensile tests of those specimens that did not fail in fatigue were also made.