供应态LC9铝合金的超塑性试验研究

Experimental Study on Superplasticity of Commercial LC9 Aluminum Alloy

通过拉伸实验研究了供应态LC9铝合金经退火处理后的超塑性变形特性。在初始应变速率3.3×10-4s-1,拉伸温度410～510℃时,合金均具有超塑性,平均伸长率为106%～181%。最佳超塑性温度为450℃,最佳初始应变速率为3.3×10-4s-1,在此温度和应变速率条件下,合金平均伸长率达到181%,m值为0.41,流动应力仅为14.4MPa。显微组织和断口观察表明,在超塑性变形过程中发生了明显的动态再结晶,再结晶晶粒等轴、细小、均匀。空洞在晶界处形核、长大,最后连接,导致试样断裂。

The superplastic deformation behavior of commercial LC9 aluminium alloy via annealing at 400℃ was studied by tensile testing. The tensile specimens all present superplasticity （elongation 106% -181%） at the initial strain rate 3.3×10^-4S^-1 and the range of temperature fi＇om 410℃ to 510℃. The optimal superplastic deformation condition is at 450℃ and 3.3×10^-4S^-1, on which the average elongation is 181% ,the strain rate sensitivity index m is 0.41 and the flow stress is only 14.4 MPa. The microscopic structure and fracture observation show that, during its superplastic deformation, dynamic recrystaUization obviously occurrs and recrystal grain is fine, uniform and equiaxial. The cavities nucleate and grow up at triangular grain boundaries and finally join with each other, which lead to fi＇acture of the specimen.