Experimental Study on Superplasticity of Commercial LC9 Aluminum Alloy
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 from 410℃ to 510℃.The optimal superplastic deformation condition is at 450℃ and 3.3×10-4 s-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 recrystallization 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 fracture of the specimen.