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采用拉伸性能及电导率测试、透射电镜观察、低应变拉伸试验等手段 ,研究了不同时效工艺对低频电磁铸造Al Zn Mg Cu合金组织和性能的影响。发现合金的T6态峰值时效制度为 12 0℃× 4 8h ,T6处理可使合金强度达到峰值 ,但抗应力腐蚀性能差 ;T73处理后合金强度下降了 5 %～ 6 % ,抗应力腐蚀性能大幅度提高 ;而RRA时效 (回归再时效 )处理基本保持了T6态的强度 ,且抗应力腐蚀性能接近T73态。微观组织分析表明 ,不同时效制度下合金性能的差异主要是由晶内和晶界析出相的大小、形貌及其分布状态决定的。T73和RRA时效处理改善了合金晶界特性 ,有助于阻止氢脆、减缓晶界阳极溶解速度 ,提高合金的抗应力腐蚀能力
The effects of different aging processes on the microstructures and properties of Al Zn Mg Cu alloy fabricated by low frequency electromagnetic casting were investigated by means of tensile test, electrical conductivity test, transmission electron microscope observation and low strain tensile test. It is found that the peak aging of T6 state is 12 0 ℃ × 4 8h, T6 treatment can make the alloy peak strength, but the stress corrosion resistance is poor; the strength of alloy after T73 treatment is reduced by 5% ~ 6%, and the stress corrosion resistance is big While the RRA aging (regression re-aging) treatment basically maintained the strength of the T6 state, and the stress corrosion resistance was close to the T73 state. The microstructure analysis shows that the difference of the alloy properties under different aging regimes is mainly determined by the size, morphology and distribution of precipitates in the grain boundaries and grain boundaries. T73 and RRA aging treatment improve the grain boundary properties of the alloy, help to prevent hydrogen embrittlement, slow the dissolution rate of the grain boundary anodes and improve the stress corrosion resistance of the alloy