Effect of pre-recovery heat treatment on microstructure and mechanical properties of cold extruded 2219-0.89Ti aluminum alloy

The influence of two kinds of pre-recovery heat treatment (250 degrees C x 6 h + 350 degrees C x 6 h + 450 degrees C x 2 h and 250 degrees C x 6 h + 350 degrees C x 6 h + 450 degrees C x 2 h + 500 degrees C x 2 h) on the microstructure and properties of cold extruded 2219-0.89Ti aluminum alloy with high content of Ti after solid solution treatment at 535 degrees C x 3 h and aging at 191 degrees C x 6 h has been investigated. The results show that the content of insoluble phase in the alloy was reduced, the grain size was refined and the strength at room temperature was increased due to the pre-recovery heat treatment. The hardness and conductivity of the second kind of pre-recovery heat treatment were 150.60 HV and 23.53% IACS respectively. Compared with the alloy without pre-recovery heat treatment, the tensile strength at room temperature was increased by 40.47 MPa to 457.14 MPa, and the extension rate after fracture was increased to 12.8%. The resistance of intergranular corrosion was improved, and the maximum intergranular corrosion depth was reduced from 193.90 mu m to 151.60 mu m.