2219 aluminum alloy has been widely used in aerospace industry due to its high specific strength, excellent weldability as well as outstanding ductility. The dual laser-beam bilateral synchronous welding (DLBSW) technology is employed in the joining of 2219-T87 aluminum alloy skin-stringer structure in T-joint. In order to establish the tensile strength of T-joints at room and cryogenic temperatures, the tensile testing is carried out. The microstructure of weld seam is observed for exploring the relationship between the grain size and tensile strength. In addition, the fracture morphology is observed by scanning electron microscope (SEM). The elemental analysis of fractured surface is done by energy dispersive spectrometer (EDS) and is used to study the effect of chemical element composition on tensile strength. The results show that the highest tensile strength of 360.01 MPa was achieved when the tensile test obtained at room temperature while the joint welded by same parameter exhibit a much higher tensile strength of 422 MPa when tested at cryogenic temperature. According to the results of microstructure analysis, grain size reduction was observed when the joint was exposed to cryogenic temperature. From the fracture morphology of joints, it was found that dimples of the sample tested at cryogenic temperature are bigger and deeper than that at room temperature. The results of EDS show that the amount of the Al₂Cu increases at 77 K which causes an increase in tensile strength.

2219铝合金以其高比强度，出色的可焊性以及出色的延展性而被广泛用于航空航天工业。双激光束双向同步焊接（DLBSW）技术用于在T型接头中连接2219-T87铝合金表皮纵梁结构。为了确定室温和低温下T形接头的拉伸强度，进行了拉伸试验。观察焊缝的微观结构，以探索晶粒尺寸与抗拉强度之间的关系。另外，通过扫描电子显微镜（SEM）观察断裂形态。断裂表面的元素分析是通过能量色散光谱仪（EDS）进行的，用于研究化学元素组成对拉伸强度的影响。结果表明，在室温下进行的拉伸试验中，以相同参数焊接的接头在低温下进行试验时，具有更高的422 MPa的拉伸强度，最高拉伸强度为360.01 MPa。根据显微组织分析的结果，当接头暴露于低温时观察到晶粒尺寸减小。从接头的断裂形态可知，与室温相比，在低温下测试的样品的凹坑更大，更深。EDS结果表明，Al的含量 根据显微组织分析的结果，当接头暴露于低温时观察到晶粒尺寸减小。从接头的断裂形态可知，与室温相比，在低温下测试的样品的凹坑更大，更深。EDS结果表明，Al的含量 根据显微组织分析的结果，当接头暴露于低温时观察到晶粒尺寸减小。从接头的断裂形态可知，与室温相比，在低温下测试的样品的凹坑更大，更深。EDS结果表明，Al的含量₂ Cu在77 K时增加，这导致拉伸强度增加。