Abstract: The cavity during superplastic deformation for the half-hardened brass H62 and the alluminium alloy LY12CZ without any pre-treatment and its influence on the mechanical properties of the superplastically-deformed materials at room temperature are studied. The experimental results show that: ①for the same material,superplastically-deformed under different conditions, the slower the rate of cavitation as the strain increases,the higher the superplasticity is; ②the mechanical properties of superplastically-deformed materials at room temperature decrease as the superplastically-deformed strain increases, i. e. , a noteworthy decrease in elasticity modulus E, yield strength σ s , ultimate strength σ b and notch toughness α k at room temperature begins to appear as the level of cavitation by area comes up to about 4%, while at the same level the reduction in area φ drops down a very large quantity; ③ as the level of cavitation increases in degree,the superplastically-deformed material changes from ductile to brittle gradually.

Key words: superplastic, deformation, cavities, mechanics, propert ies