双级固溶处理对7A04铝合金组织与力学性能的影响

Effects of Two-Stage Solution Treatment on Microstructure and Mechanical Properties of 7A04 Aluminum Alloy

对7A04铝合金进行了双级固溶+单级时效处理,采用正交试验研究了固溶温度和时间对该合金显微组织与力学性能的影响,得到了较优的双级固溶处理工艺。结果表明:优化的双级固溶处理工艺为450℃×30min+505℃×60min,采用该工艺固溶处理再经120℃×24h时效处理后,该铝合金的抗拉强度、屈服强度、伸长率和冲击功分别达到658.43 MPa,593.07 MPa,10.25%,9.681J;一级固溶是影响7A04铝合金力学性能的主要因素,而较高温度的二级固溶能使第二相、共晶夹杂物和金属间化合物大量溶入固溶体,并在随后的时效过程中以强化相的形式析出,进而改善合金的综合性能。

A two-stage solution and aging treatment was conducted on 7A04 aluminum alloy, and then the effects of solution temperature and time on the microstructure and mechanical properties of the alloy were investigated by the orthogonal experiment. The optimal two-stage solution process was obtained. The results show that the optimal two-stage solution process was determined as： 450 ℃ × 30 mind- 505 ℃ × 60 min. Under this optimal process and followed by aging at 120 ℃ for 24 h, the tensile strength, yield strength, elongation and impact energy of the aluminum alloy reached 658.43 MPa, 593.07 MPa, 10.25%0 and 9.681 J, respectively. The first stage solution is the main influence factor on the mechanical properties of 7A04 aluminum alloy. However, the second stage solution at a relatively high temperature can remarkably improve the dissolution of the second phase, eutectie inclusions and intermetallic compounds, which precipitate as strengthening phases during the following aging treatment, and then results in the improvement of comprehensive performance of the alloy.