Study on the effect of welding current during laser beam-resistance seam welding of aluminum alloy 5052

The effect of welding current on the weld shape and tensile shear load during laser beam-resistance seam welding (LB-RSW) of aluminum alloy 5052 is studied. Experimental results show that the penetration depth, weld width,tensile shear load and the ratio of penetration depth to weld width of LB-RSW are bigger than those of laser beam welding(LBW) under the same conditions and the former three parameters increase as welding current rises. The weld shape of LB-RSW below 5 kA welding current is nearly the same as that of LBW. The weld morphology is protuberant under the condition of 5 kA welding current and 0.8 m/min welding speed. Furthermore, the microstructure of the weld seam of LB-RSW is coarser than that of LBW.     

Study of diffusion bonding of Ti-6Al-4V and ZQSn10-10 with metal interlayer

The diffusion bonding was carried out to join Ti alloy (Ti-6Al-4V) and tin-bronze (ZQSn10-10) with Ni and Ni Cu interlayer. The microstructures of the diffusion bonded joints were analyzed by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that when the interlayer is Ni or Ni Cu transition metals both could effectively prevent the diffusion between Ti and Cu and avoid the formation of the Cu-Ti intermetallic compounds (Cu3Ti, CuTi etc.). But the Ni-Ti intermetallic compounds (NiTi, Ni3Ti) are formed on the Ti-6Al-4V/Ni interface. When the interlayer is Ni, the optimum bonding parameters are 830℃/10 MPa/30min. And when the interlayer is Ni Cu, the optimum bonding parameters are 850℃/10MPa/20min. With the optimum bonding parameters, the tensile strength of the joints with Ni and Ni Cu interlayer both are 155.8MPa, which is 65 percent of the strength of ZQSn10-10 base metal.     

TC4／QAl10-3-1-5扩散接头残余应力的有限元数值模拟

采用有限元分析软件ANSYS对TC4与QAl10-3-1．5直接扩散连接和填加Ni中间层扩散连接接头残余应力分布进行了数值模拟。结果表明，对接头强度有害的轴向拉应力巩的最大值出现在靠近接头边缘的界面脆性相及焊缝TC4侧的狭小区域内，且拉应力σy随着向中心轴的靠近而迅速减小并逐渐转为压应力，因此该区域是接头的薄弱区；采用Ni中间层时，应力分布梯度相对缓和一些，最大残余应力出现在中间层Ni与TC4之间的金属间化合物NiTi、Ni3Ti上；而随着中间层厚度的增加，接头残余应力也相应的增大。中间层厚仅存在一个最佳值。     

镍、镍+铜中间层对TC4/ZQSn10-10扩散连接的影响

利用JSM6700F冷场发射扫描电镜及其自带的能谱仪等分别对采用镍、镍 铜两种中间层的TC4/ZQSn10-10异种材料扩散连接接头进行了微观分析.结果表明:镍中间层能有效地阻止元素钛与铜之间的扩散,避免产生金属间化合物(Cu3Ti、CuTi等);但在TC4/Ni界面上仍有金属间化合物NiTi、Ni3Ti生成,使接头的抗拉强度有所降低;在适当压力和保温时间、镍为中间层时,较佳连接温度为830℃;镍 铜为中间层时,较佳连接温度为850℃;两者所得接头强度(155.8MPa)相当,均为ZQSn10-10母材强度的65%.