超塑变形过程中的空洞及其对变形后室温机械性能的影响

THE CAVITY DURING SUPERPLASTIC DEFORMATION AND ITS INFLUENCE ON MECHANICAL PROPERTIES OF SUPERPLASTICALLY-DEFORMED MATERIALS AT ROOM TEMPERATURE

研究了不经任何预先处理的半硬态黄铜Ｈ６２和铝合金ＬＹ１２ＣＺ超塑变形过程中的空洞及其对变形后室温机械性能的影响。实验表明：①同一材料，在不同的超塑变形条件下变形，如果其空洞化程度随应变增加得越慢，则其超塑性越好；②超塑变形后材料的室温机械性能随所经受过的超塑变形量的增加而下降，当超塑变形后材料中空洞的面积百分数达到４％左右时，其室温弹性模量Ｅ、屈服强度σｓ、极限强度σｂ以及冲击韧性开始显著地下降，而此时的室温断面收缩率φ已下降了相当大的程度；③随着空洞化程度的提高。

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.