Effect of solid solution time on microstructure and properties of 7003 aluminum alloy

The microstructure and properties of 7003 aluminum alloy with and without ageing for different solid solution time were investigated respectively by means of microhardness tester,electronic tensile machine,optical microscope(OM),scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS).The results show that the solid solubility of the second-phase increases with increase of solid solution time,and then new second-phases separate out and grow,hence the strengthening of the second phases decreases firstly and then increases.Therefore,the strength and microhardness of 7003 aluminum alloy decrease firstly and then increase.The strength and micro-hardness of the aged 7003 aluminum alloy are evidently higher than those of the one without ageing,and the samples solutioned at 743 K for 70 min and then aged at 393 K for 50 h are of the highest strength and microhardness.Its microhardness,tensile strength,yield strength and elongation are 118 HV0.1,347.0 MPa,286.1 MPa,15.5%,respectively.