In view of the lunar environment temperature change situation, the influence of long time low temperature immersion (-196 V) and high-low temperature alternation processing (-196-200 V) on the mechanical properties, microstructures and fracture surfaces of AZ31 magnesium alloy at 20 °C was studied. The results indicate that there are no significant changes on the mechanical properties of AZ31 magnesium alloy after liquid nitrogen immersion or temperature alternation cycle treatment. The σb and δ of AZ31 magnesium alloy at room temperature are 288 Mpa and ' 18.3%, respectively, after 10 d cryogenic processing, they will reach 292 Mpa and 18.7%, respectively, σb and δ after 10 times high-low temperature alternation processing are 294 Mpa and 16.9%, individually. SEM observation and XRD results show that the fracture surface and phase constitutions do not change obviously after low temperature or high-low temperature alternation processing. And the fractures are both quasi-cleavage crack.%针对月球环境温度变化情形,研究了长时间低温浸泡(-196℃)和多次高低温交变循环处理(-196～200℃)对挤压态AZ31镁合金在20℃下的力学性能、显微组织以及断口形貌的影响.研究表明:AZ31镁合金经过长时间液氮浸泡和高低温交变循环处理后,力学性能无明显变化；室温态合金的σb和δ分别为288 MPa和18.3％,经过10 d低温浸泡后σb和δ分别为292 MPa和18.7％,经过10次高低温循环后合金的σb和δ分别为294 MPa和16.9％；低温和高低温交变处理对断口形貌和相组成没有明显影响,均为准解理断裂.
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