摘要
目的研究不同时效时间对Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc合金强度的影响,以及室温和-40℃这2种温度环境对该合金疲劳行为的影响。方法在不同时效时间下对Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc合金进行热处理,并采用透射电镜观察其显微结构以解释不同时效时间下强度变化的原因。在不同外加总应变幅的条件下,对T6态该合金进行低周疲劳实验,对比研究Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc合金在不同温度环境下的低周疲劳行为。结果随着时效时间的延长,不同温度环境下Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc合金的屈服强度和抗拉强度都先升高后降低,-40℃环境下的屈服强度和抗拉强度均高于室温环境下的。在低应变幅时,合金的循环应力响应行为特征总体呈稳定趋势,在高应变幅时,合金的循环应力响应行为先表现为循环稳定特征,后表现为循环硬化特征。同一应变幅下,-40℃环境下合金的循环应力幅值高于室温环境下的,而合金的低周疲劳寿命则随着温度的降低而下降。此外,在室温和-40℃低周疲劳加载条件下,疲劳变形机制为平面滑移机制。当应变幅为0.4%和0.6%时,合金疲劳变形区位错组态为位错阵列,当应变幅为1.0%时,合金位错组态为位错网格。
The work aims to study the effects of different aging time on the strength of Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc alloy,as well as the effects of room temperature and-40℃on the fatigue behavior of the alloy.The Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc alloy was subject to heat treatment with different aging time,and transmission electron microscope was adopted to observe its microstructure to explain the reason for the strength change of different aging time.For the T6 alloy under different applied total strain amplitudes,low-cycle fatigue experiments were carried out,and the comparative study on low-cycle fatigue behavior of Al-7Zn-2.5Mg-2.0Cu-0.1Zr-0.2Sc alloy in different temperature environments was conducted.The experimental results showed that at different temperature,the yield strength and tensile strength of alloy first increased and then decreased with the increase of aging time.The yield strength and tensile strength at -40℃ were both higher than those at room temperature.At low strain amplitude,the alloy exhibited stable cyclic stress response behavior.But it showed cyclic stability first and then cyclic hardening at high strain amplitude.At the same strain amplitude,the cyclic stress amplitude of the alloy at -40℃ was higher than that at room temperature,while the low cycle fatigue life of the alloy decreased with the decrease of temperature.In addition,the fatigue deformation mechanism was plane slip mechanism at room temperature and -40℃ low cycle fatigue loading.When the strain amplitude was 0.4% and 0.6%,the dislocation configuration in the fatigue deformation zone of the alloy was dislocation array,and when the strain amplitude was 1.0%,the dislocation configuration of the alloy was dislocation grid.
作者
李佳航
车欣
蒋学禹
尹淑英
LI Jia-hang;CHE Xin;JIANG Xue-yu;YIN Shu-ying(School of Materials Science and Engineering,Shenyang University of Technology,Shenyang 110870,China)
出处
《精密成形工程》
北大核心
2022年第8期140-147,共8页
Journal of Netshape Forming Engineering
基金
辽宁省教育厅科学技术研究服务地方项目(201724141)。
关键词
铝合金
温度
强度
低周疲劳
微观结构
aluminium alloy
temperature
strength
low-cycle fatigue
microstructure
