为揭示我国新一代运载火箭焊接构件在超低温环境下的力学性能与失效机理,并为提高焊接质量与贮箱的承载能力提供科学依据,本项目开展了超低温环境下非均质焊接件的力学性能研究。首先,叙述了基于数字图像相关方法(DIC)的铝合金焊接件低温力学性能试验原理并建立开放式超低温载荷环境模拟系统;其次,分别对熔焊和搅拌摩擦焊两种不同焊接工艺的焊接件进行详细的试验研究,分析了应力应变关系、沿载荷方向全场应变分布、应变集中系数等,结果表明搅拌摩擦焊试件整体的力学性能要优于熔焊试件。最后本文还对比分析了测试区域大小对测试结果的影响,表明在热影响区2~8mm范围内进行测量,其测量误差不超过8.8%。本文研究结果将为我国新一代运载火箭低温贮箱焊接工艺优化与改进提供科学依据。 In order to reveal the mechanical properties and failure mechanism of a new generation of rocket welding components in China under ultra-low temperature environment and to provide a scientific basis for improving welding quality and carrying capacity of tanks, the project carried out the mechanical properties of heterogeneous welded parts under ultra-low temperature the study. Firstly, the experimental principle of low temperature mechanical properties of aluminum alloy welding parts based on digital image correlation method (DIC) is described and an open simulation system of ultra-low temperature load environment is established. Secondly, the welding conditions of welding and friction stir welding A detailed experimental study was carried out. The stress-strain relationship, strain distribution along the load direction, strain concentration coefficient and so on were analyzed. The results show that the mechanical properties of the friction stir welded specimens are better than the welded specimens. Finally, this paper also comparative analysis of the test area size of the test results, indicating that the heat affected zone 2 ~ 8mm range of measurements, the measurement error does not exceed 8.8%. The results of this paper will provide a scientific basis for the optimization and improvement of the welding process of a new generation of cryogenic tanks for launch vehicles in China.