Influence of conditioning time before artificial aging on the microstructure and properties of 7055 aluminium alloy extruded tube

The effect of conditioning time before artificial aging on the microstructure and properties of 7055 aluminum alloy extruded pipe was investigated by means of Vickers hardness test, room temperature tensile test, electrical conductivity test, slow strain tensile test and transmission electron microscopy (TEM). The results showed that GP region was precipitated first during the conditioning time, and provided nucleation sites for η and η', phases so that the nucleation density of η and η', phases increased. Therefore, the electrical conductivity and mechanical properties of the alloy improved. The tensile strength, elongation and electrical conductivity of the 7055 aluminium alloy were 677.9 MPa, 14.9 %, 29.8 % IACS, respectively, when the conditioning time was 6.5 h. With the prolongation of the conditioning time before artificial aging, the tensile strength of the alloy decreased and its conductivity increased. When the conditioning time was 48h, the tensile strength, elongation rate and electrical conductivity of 7055 aluminium alloy were 649.7 MPa, 10.6 %, 36.8 % IACS, respectively, and the alloy acquired its best comprehensive properties.