挤压温度对Al-Zn-Mg合金力学性能的影响

he effect of extrusion temperature on the tensile properties and fracture toughness of an Al-Zn-Mg alloy was investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile tests and Kahn tear tests. The results showed that after extrusion the alloy possesses a surface layer composed of fine equiaxed grains with higher toughness in the L-T orientation than that of its center layer, which composed of fiber-like texture and recrystallized grains, while the tensile strength of the center layer is higher than that of the surface layer. When the extrusion temperature increases from 440-450 to 480-490, the dynamic recrystallization becomes more serious, and the tensile properties and fracture toughness become lower and higher respectively. After aging the precipitates in grains become smaller and the precipitates at grain boundaries are coarsening and discontinuous. Taking the central layer for example, the volume fraction of recrystallized grains increases from 14.8% to 52.3%, correspondingly 0.2 increases from 280 MPa to 314 MPa, while UIE decrease from 229 Nmm-1 to 204 Nmm-1.