Superplastic forming (SPF) of a TC4 alloy cylinder at 880益and strain rate 着· = 9. 8 ´10-4 s-1 were
conducted. The influences of superplastic deformation on room temperature strength、fatigue strength and metallurgical
structure of TC4 alloy were investigated. 摇Results show that grain size grows with SPF elongation increasing. Grain
size increases to about 20 mm from the initial dimension about 8 mm as SPF elongation equals to 55%. At room tem鄄
perature,yield strength, tensile strength and fatigue strength of TC4 alloy decrease with the increasing of SPF elonga鄄
tion. After TC4 alloy sheet subjected to a SPF elongation of 55%, the yield strength and tensile strength reduce 7%:
the fatigue strength reduces 10% at the fatigue life cycle of 106.