固溶处理对7075/6009层状复合材料组织与性能的影响

通过分析7075/6009铝合金层状复合板材内层显微组织与显微硬度分布,研究了固溶处理对板材内层显微组织与力学性能的影响。结果表明:在470～500℃范围内,随着固溶温度的升高,板材内层和过渡区的显微硬度值呈先升后降的趋势,在485℃时达到峰值,而外层显微硬度值呈上升趋势;内层显微组织在485℃时残留的颗粒相数量最少,而在500℃时发生"过烧"。在15～300 min内,板材内层和过渡区显微硬度值在30 min时达到峰值,而外层显微硬度值变化不明显;内层显微组织随着固溶时间的延长而变粗大,残留颗粒相数量在30 min后趋于平衡。通过T6热处理工艺:485℃固溶30 min+水淬+175℃时效8 h,7075/6009铝合金层状复合板材可获得较高的力学性能:抗拉强度为404 MPa,屈服强度为364 MPa,伸长率为15.3%;同比T6热处理的6009铝合金板材,其抗拉强度提高36%,屈服强度提高75%,但伸长率降低16%。

Effect of solution treatment on microstructure and mechanical properties of 7075/6009 aluminum laminated composites

7075/6009 aluminum laminated composite plates were prepared by the process of double-stream-pouring continuous casting and hot rolling,and then the composite plates were solution-treated.Microstructure and microhardness distribution of the plates were analyzed.The effect of solution treatment on microstructure and mechanical properties of the plates were investigated.The results show that in the solution temperature of 470 ℃ to 500 ℃,microhardness of the internal layer of the plate increases to the maximum value at 485 ℃ and then dereases with increasing of temperature,and microhardness of the outer layer increases as the solution temperature is enhanced.The amount of the residual precipitated phase in the internal layer is the least as the solution temperature is 485 ℃,and the overburnt microstructure of the internal layer is observed at 500 ℃.Microhardness of the internal layer reaches the peak value and the amount of the precipitated phase particles approaches stable for the plates solution-treated at 485 ℃ for 30 min.Optimal mechanical properties of the 7075/6009 aluminum laminated plates could be obtained by T6 heat treatment,which is solution-treated at 485 ℃ for 30 min,following by cooling in water and artificial ageing at 175 ℃ for 8 h.Tensile strength,yield strength and elongation of the plates are 404 MPa,364 MPa and 15.3%,respectively.Comparing with the T6 heat-treated 6009 aluminum plate,the ultimate tensile strength and yield strength increase by 36% and 75%,respectively,however the elongation is 84 % of that of 6009 aluminum plate.