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采用电子拉伸试验机、显微硬度计、洛氏硬度计、扫描电镜(SEM)、能谱分析(EDS)等对不同固溶状态下Al-Zn-Mg-Cu-Cr超高强铝合金的硬度、力学性能及组织等进行了系统的研究。结果表明,随固溶温度的升高,合金的硬度和强度不断升高,在753 K时合金的综合性能最好,σb=577 MPa,σ0.2=521 MPa,δ=11.7%;但当温度高于758 K时,合金的硬度、强度急剧下降。组织观察表明,随固溶温度的升高,时效组织中的析出相数量不断增多,均匀程度也不断提高,密度也不断增大,颗粒也变得细小,但当温度达到763 K时,在合金组织内部能观察到明显的过烧现象,组织中出现复熔组织。另外,随固溶温度的升高,合金的应力腐蚀敏感性先不断降低,然后又急剧上升。其中,753 K时合金的应力腐蚀敏感性最低,只有17.36%,相对于713 K时的合金抗应力腐蚀性能提高了约51.2%。
The tensile properties of Al-Zn-Mg-Cu-Cr ultra-high-strength aluminum alloy with different solid solution state were investigated by using electronic tensile tester, microhardness tester, Rockwell hardness tester, SEM and EDS. Hardness, mechanical properties and organization of a systematic study. The results show that with the increase of solution temperature, the hardness and strength of the alloy increase continuously. The alloy has the best comprehensive properties at 753 K, σb = 577 MPa, σ 0.2 = 521 MPa, δ = 11.7% When the temperature is higher than 758 K, the hardness and strength of the alloy drop sharply. The microstructure observation shows that with the increase of solution temperature, the amount of precipitated phase in aging microstructure increases, the uniformity increases, the density increases and the particles become smaller. However, when the temperature reaches 763 K, Within the organization can be observed obvious over-burning phenomenon, organizations appear complex melt organization. In addition, as the solution temperature increases, the stress corrosion sensitivity of the alloy decreases first and then increases sharply again. Among them, the stress corrosion resistance of the alloy at 753 K is the lowest, only 17.36%, which is about 51.2% higher than that of the alloy at 713 K.