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针对铝合金电阻点焊过程中出现的电极烧损及使用寿命短的问题,采用物理模拟的方法,从点焊电极端面铜铝合金化的宏观及微观形貌、成分等方面,进行了铝合金点焊电极端面铜铝合金化反应的行为、铜铝金属间化的形成过程以及铜铝合金化机理等研究。结果表明:电极端面与工件接触界面发生铜铝合金化反应是铝合金点焊电极烧损的主要原因;同时发现,温度和时间是影响铜铝合金化反应的两个重要因素,且铝合金高温点焊时,电极端面反应生成了共晶合金(Al+Cu Al2),而Cu Al2相和铜基体扩散,将形成硬而脆的金属间化合物Cu9Al4和Cu Al4。 相似文献
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采用减压凝固试验法,研究了RE对A356铝合金熔体氢含量的影响规律。通过X射线衍射、扫描电镜等分析了RE对A356铝合金表面氧化膜成分及形貌的影响。结果表明,A356合金中加入一定量的RE后,熔体氢含量显著降低。加入RE后,表面氧化膜出现大量RE氧化物和铝氧化物形成的LaAl11O18的复合氧化物,这种复合氧化物使铝合金表面氧化膜更加致密。扫描电镜分析表明,不加RE的氧化膜表面凹凸不平,有明显开裂后愈合的痕迹,而添加RE后,表面比较平整,致密度显著增加,几乎没有看到开裂的现象,这大大减少了新鲜的铝液暴薅在空气中的几率,降低了熔体中的氢含量。 相似文献
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为研究深冷处理对铝合金点焊电极烧损的影响,采用深冷处理和未深冷处理两种铝合金点焊电极进行了点焊工艺试验,观测了两种电极端面宏观形貌和焊点表面宏观形貌。测试了达到未深冷处理电极寿命焊点数时两种电极端面的显微硬度。采用X射线衍射方法对达到未深冷处理电极寿命焊点数时的两种电极端面进行了分析。研究结果表明:在点焊工艺试验过程中,在一定的焊点数条件下,深冷处理电极端面和所焊焊点表面比较光亮、圆整;电极端面的显微硬度较低,并且分布均匀;电极端面未发现烧损后的产物,深冷处理使电极烧损程度显著降低。 相似文献
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分别研究了不同环境湿度条件下,铝合金型材表面氧化膜对MIG焊接接头性能及气孔率的影响。试验结果表明,在湿度较低时(相对湿度5%~10%),刮削去除氧化膜与不处理氧化膜两种情况下的焊缝均成形良好、探伤无气孔,二者金相组织及拉伸性能区别不大;在湿度较高时(相对湿度40% ~50%),刮削去除氧化膜与不处理氧化膜两种状态焊缝成形依然良好,但不处理氧化膜的焊缝有气孔产生,焊接热输入的增加可降低气孔率,对于6005A-T6高速列车车体型材,当热输入达到4 400 J/cm时,焊缝该类气孔消失,但热输入的提高会使得焊缝的抗拉强度降低约14%。
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采用交流氧化技术,通过对膜层厚度、耐蚀性、硬度等指标的测定及外观观察,讨论了多种有机和无机添加剂对LY12铸铝合金的氧化膜性能的影响。结果表明,适当的无机盐与有机酸以及醇类物质可显著改善LY12铝合金交流氧化膜的性能;对于直流法难以氧化的LY12铝合金,交流氧化膜的硬度达到了430Hv。 相似文献
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本实验分别测定了由硫酸氧化法制备的铝合金氧化膜封闭前后在K_2SO_4溶液中的交流阻抗谱(Bode图),由阻抗谱分析获得了有关阻挡层的几何尺寸、阻挡层和多孔层以及封闭产物的电学性质、时效对氧化膜的影响等信息。这些结果与迄今为止的对氧化膜构造的认识是一致的,交流阻抗谱技术在氧化膜结构、封闭机理和质量的研究中,有理论和应用两方面的价值。 相似文献
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《Science & Technology of Welding & Joining》2013,18(2):126-132
AbstractThis study investigated the electrode life and the electrode degradation characteristics during continuous resistance spot welding of aluminium alloy sheets. When a long welding time and dome radius type electrode were used, the electrode life was extended more than that when a short welding time and radius type electrode are used. The electrode tip is considered to degrade by the following mechanism: an Al–Cu alloy layer is formed at the electrode tip during continuous welding, and then it peels off from the electrode tip transferring to the surface of aluminium alloy sheet. Its peeling makes the electrode tip indented and finally the electrode tip flattens with increasing diameter of electrode tip. In order to eliminate the direct contact between electrode and worksheet, a special Cu foil insert device for resistance spot welding of aluminium alloy sheets was developed and an extremely long electrode life was achieved. 相似文献
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镀锌钢板电阻点焊时由于锌层的影响电极损耗非常严重。以厚0.8mm家电用热镀纯锌钢板DX51D+Z为研究对象,探究在正交试验优化焊接参数后,热镀锌钢连续点焊时焊接接头质量变化的规律和电极损耗的特点。结果表明,当采用I=11 kA、P=2 500 N、T=13 cyc的点焊工艺参数组合可获得力学性能最佳的点焊接头;连续点焊试验初期(150点前)焊点力学强度稳定且焊点成形较好,焊接后期(150~300点)接头力学强度波动大,焊接状况不稳定;电极损耗至失效是接头质量急剧下降的主要原因,电极失效形式为头部塑性变形、端面坑蚀和Cu-Zn合金化,在本试验条件下,Cr-Zr-Cu电极焊至150点后显现不稳定现象,电极寿命约280点;失效电极端面的Cu-Zn合金层约65μm。 相似文献
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研究了表面处理对微型点焊镀镍钢板和镍板时电极失效的影响.结果表明:微型点焊镀镍钢板和镍板时电极的失效主要是电极头部的塑性变形以及电极和镀镍板之间局部焊接的断裂发生在电极表面而导致的电极磨损;表面涂敷TiC的CuCrZr电极的寿命(1 200点)是CuCrZr电极寿命(600点)的两倍,表面处理能提高电极寿命的主要原因是表面涂敷的TiC颗粒能阻碍电极和镀镍板之间的局部焊接,以及减小电极表面的塑性变形. 相似文献
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以所开发的铝合金点焊在线监测系统为基础,构建了在线监测数据库.数据库通过与基于LabVIEW开发环境的在线监测系统相连接,实现了焊点质量特征参数及焊点原始特征信息的实时记录与保存.数据库为用户提供了焊点信息及人员信息的多种查询、管理功能,实现了点焊生产的信息化管理,非常适合航空航天产品的生产管理及该厂的实际情况.数据库信息为在线监测系统提供参数优化数据源,通过均值控制图法实现对在线监测系统焊点质量判定临界阈值的优化.结果表明,数据库的参数优化功能使铝合金点焊在线监测系统达到了较高的判定精度,并已在航空航天产品的点焊生产中得到应用. 相似文献
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The application of aluminum alloy in the automotive and aviation fields is impeded by the wear and life of electrode for resistance spot welding (RSW). The alloying interaction between the copper elect... 相似文献
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Kenji Miyamoto Shigeyuki Nakagawa Chika Sugi Tomo Ogura Akio Hirose 《Welding International》2016,30(9):675-687
This research concerns a dissimilar metal joining of steel and aluminium (Al) alloys by means of zinc (Zn) insertion. The authors propose a joining concept for achieving strong bonded joints between Zn-coated steel and Al alloys. A eutectic reaction between Zn in the Zn coating and uniform Al–Fe intermetallic compound (IMC) layer at the joint interface, leading to a strong bonded joint. The ultimate aim of this research was to apply this joining concept in the resistance spot welding process for manufacturing vehicle bodies. As a practical issue characteristic to joints of dissimilar metals, anticorrosion measures against electrochemical corrosion must be undertaken. If there is moisture near a joint interface of dissimilar metals, electrochemical erosion will progress. Therefore, a sealing function that could prevent moisture intrusion is required. By applying the above-mentioned welding process to a set of metals with thermosetting resin spread in between, we realized seal spot welding, which not only prevented moisture intrusion but also retained high tensile strength. In this research, first, a cyclic corrosion test was performed on the seal spot-welded joint of galvanized (GI) steel, a steel grade widely distributed in Japan, and Al alloy was bonded by seal spot welding, and the following topics are discussed. Complete removal of sealant from the joint interface is the key to realizing the high tensile stress joint, because remaining sealant will lead to reduction in tensile strength. Therefore, heat generation at the interface was monitored by measuring electrical current and potential difference between the two electrodes, and a precise temperature control was performed. Moreover, the bonding process was clarified by stepwise analysis of the joint interface using optical microscopy, and a guideline for producing strong joints was proposed. And finally, a TEM observation also confirmed that the interface structure of the seal spot-welded joint was the same as joints without the resin; a thin and uniform Al–Fe IMC layer was formed and a strong metallurgical bonding was achieved. 相似文献
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R. Qiu N. Wang H. Shi K. Zhang S. Satonaka 《Science & Technology of Welding & Joining》2014,19(3):231-234
The effects of faying surface condition, pre-existing pores in base material and cover plate on the pore formation during resistance spot welding of magnesium alloy were investigated. The results reveal that the hydrogen rejection and the pre-existing pores in base material have little effect on the pore formation, and that the larger pore formation is mainly caused by shrinkage strain during resistance spot welding of magnesium alloy. 相似文献