2219 铝合金单、双道焊接头性能分析

通过对比2219 铝合金单道氩弧焊和氦弧打底+氩弧盖面双道焊接头的常温及液氮温度拉伸性
能、显微硬度分布、单向拉伸过程的数字散斑测量(DIC)结果,发现在常、低温条件下双道焊接头的拉伸强度和
延伸率均比单道焊接头高10% ~20%,单道焊接头焊缝及热影响区内材料的显微硬度值相比母材的降低程度
比双道焊接头更为显著,其主要原因是单道焊接头的一次性热输入大于双道焊,材料受热影响更严重,焊漏高
度及形状的可控性更差。     

2195铝锂合金弧焊技术研究现状

铝锂合金具有密度低、比模量高、比强度高、抗疲劳及腐蚀性能良好等特点,被认为是航空航天领域最有应用前途的结构材料之一.本文回顾了铝锂合金的发展历程,介绍了新一代2195铝锂合金的成分、组织结构及可焊接性,分析其焊接过程出现的主要问题,概述了国内外机构通过优化2195铝锂合金配用焊丝及弧焊工艺,改善接头组织结构及力学性能的...     

一种基于实测点云数据的壁板类零件修配加工路径计算方法

针对飞机壁板类零件采用修配法装配过程中需要精确获取修配加工路径的问题，提出一种基于实测点云数据的壁板类零件修配加工路径计算方法。首先设计一种基于法线差的特征点检测算法提取参考壁板的初始特征点。然后建立迭代收缩优化模型对初始特征点进行收缩优化，得到参考壁板的准确特征点。最后根据工装定位孔特征进行配准，将参考壁板的特征点映射到待修配壁板上，并将映射后的特征点按照一定顺序进行连接，得到待修配壁板的修配加工路径，按照修配路径进行加工，获得壁板装配配合边界。实验表明，该方法能够精确提取待修配壁板修配加工路径，并且经过加工验证，壁板试验件对缝间隙获得小于1.2 mm的实际效果。     

Effect of adding Nb foil on joint properties of laser fusion welding for TC4 titanium and 7075 aluminum alloy

It is difficult to gain effective Ti-Al fusion welding joints due to their differences in thermal properties and the appearance of brittle Ti-Al Intermetallic Compounds (IMCs). The experiments of laser fusion welding for TC4 titanium and 7075 aluminum alloy were carried out, temperature field and ductility/brittleness, as well as chemical potential of elements, were calculated, and the effect of adding Nb foil on mechanical properties of the weld was also investigated. The results suggested that Nb atoms tend to diffuse toward Al side, which is conducive to the participation of Nb in the metallurgical reaction and contributes to forming the Ti-Nb-Al IMC layer at the interface. As the thickness of Nb foil increases, the tensile-shear force of joint climbs first but then declines, and reaches the highest value of 1663 N with 0.10 mm-thickness Nb foil, representing 58.38% enhancement compared with the non-added one. Adding Nb foil slows down the heat transfer as a blocker, and thus both the melting amount of Al and the mixing area of Ti and Al decrease. In addition, Nb alloying reduces the brittleness of the Ti-Al compound. Hence, the joint properties of titanium/aluminum are improved with the addition of Nb foil.     

Through-thickness heterogeneity in creep properties of friction stir welding 7B50-T7451 aluminum alloy thick plate joint: Experiments and modeling

Through-thickness heterogeneity in creep properties of 7B50-T7451 aluminum alloy Friction Stir Welding(FSW) joints was investigated. Creep tests for three slices of the FSW joint were conducted at the temperature of 150–200 °C and applied stress of 60–225 MPa. The theta projection method was used to predict creep curves and minimum creep rate. The results show that the minimum creep rate increases and creep rupture life decreases with the increase of creep temperature and applied stress. Creep p...     

推进剂管理装置的可靠性增长及试验验证

采用原始的焊接方式焊接筛网式推进剂管理装置的收集器合格率低、可靠性差。为此,采用纯钛箔作为过渡层进行了不锈钢筛网与钛合金支压板的电阻缝焊试验以及随后这两者与钛合金骨架的电子束焊试验,然后进行了地面力学环境下的振动试验,以验证焊接方式改进后收集器的可靠性。焊接试验结果表明,纯钛箔过渡层一方面可以大幅降低筛网在电阻缝焊时的焊接热量,有效地减小筛网的热变形;另一方面可以在电阻缝焊后形成牢固、封闭的纯钛/不锈钢筛网焊缝过渡区,有效地增加电子束焊时筛网的变形抗力,从而使得焊接后试样的合格率和性能大幅提高。振动试验结果表明,焊接方式改进后收集器的可靠度置信下限从0.90增加到了0.96。