Abstract:

The effect of solution treatment at 495 ℃ for 1 h and 8 h on the microstructures and fatigue properties of aluminum alloy 2E12 is investigated by optical microscopy, scanning electron microscopy, X-ray energy dispersive spectrum and fatigue life testing. The amount of residual Al2CuMg phases is greatly reduced after solution treatment at 495 ℃ for 8h, which enhances the solid solubility of Cu and Mg in the matrix after water quenching. Therefore, the strength of the alloy is increased after T4 temper. The residual phases of larger sizes on the free surfaces of the specimens initiate fatigue crack by two types: selffracture of particles and detachment from the matrix. The presence of larger size particles also accelerates the growth of fatigue crack into the matrix, causes the connection between fatigue cracks with the minimum distance and promoted fatigue striations to form secondary cracks.Therefore,reducing the amount of residue phases by increasing solution treatment time may increase the fatigue life of aluminum alloy 2E12.

Key words: aluminum alloy, solution treatment, fatigue, residual phase, microstructure