中-低温循环对2A14铝合金力学及疲劳性能的影响

国内对航天用2A14铝合金在中-低温循环条件下力学及疲劳性能的变化规律研究不足，为掌握该材料在上述工况下的力学表现及疲劳损伤情况，对2A14铝合金开展了室温—低温（-196 ℃×4 h）—室温，室温—中温（150 ℃/180 ℃×0.5 h）—室温两种工况循环条件下的力学、疲劳性能及组织变化规律研究。结果表明，在上述两种工况下循环5次，2A14铝合金的晶粒尺寸、粗大相形貌及分布均无显著变化，仍保持高强度及良好的塑韧性；随着应力幅值的降低，2A14铝合金的疲劳寿命逐渐延长；应力比为-1时，2A14铝合金的疲劳极限为150～175 MPa，上述两种工况下循环5次，不会改变2A14铝合金的韧性断裂机制。

Effect of middle-cryogenic temperature cycling on mechanical and fatigue properties of 2A14 aluminum alloy

The research on the changes in mechanical and fatigue properties of 2A14 aluminum alloy used in aerospace under middle-cryogenic temperature cycling conditions in China is still insufficient. In order to understand the mechanical behavior and fatigue damage of the material under the above working conditions, the mechanical, fatigue properties and microstructure changes of 2A14 aluminum alloy under the two working conditions of room temperature-low temperature (-196 °C×4 h)-room temperature and room temperature-medium temperature (150 °C/180 °C×0.5 h)- room temperature were studied. The results show that the grain size, coarse phase morphology and distribution of 2A14 aluminum alloy are not significantly changed under the above two working conditions for 5 cycles, and high strength and good plasticity toughness are still maintained. With the decrease of stress amplitude, the fatigue life of 2A14 aluminum alloy is gradually extended. When the stress ratio is -1, the fatigue limit of 2A14 aluminum alloy is 150-175 MPa, and the ductile fracture mechanism of 2A14 aluminum alloy is not changed under the above two working conditions for 5 cycles.