航空发动机蜂窝薄壁与基板间类T型结构件电阻点焊定位工艺研究

Research on Resistance Spot Welding Positioning Technology for T-shaped Parts Between Thin Wall of Honeycomb and Substrate in Aeronautic Engine

针对1:50超大厚度比下航空发动机GH3536蜂窝和K423A基板T型结构连接时的定位焊难题,采用功率55 kVA、频率4 kHz的逆变电阻点焊机,通过设计纯铜编织线包覆纯铜块(蜂窝侧)/铬锆铜圆柱(基板侧)异构电极,增大定位点焊有效导电面积,抑制电流集肤效应。结果显示,在最佳焊接工艺参数I=1.75 kA、t=65 ms、F=27 N条件下,能够实现蜂窝与基板的冶金连接,且蜂窝表面平整度高,蜂窝芯壁未发生弯曲。SEM、EDS微观组织分析结果表明,最佳定位点焊接头界面处Ni、Ti、Cr元素含量变化较为明显,熔合界面层厚度约为3μm,其中Mo元素含量先下降再增加,并在焊接区形成了含Mo的M6C和M23C6碳化物,这些化合物在高温条件下具有较高的强度,能够满足蜂窝/基板连接时的优质定位需求。

To address the positioning welding challenge for the T-shaped structure connection(Thickness ratio is 1:50)between GH3536 honeycomb and K423A substrate in aircraft engines,an inverter resistance spot welding machine with a power of 55 kVA and a frequency of 4 kHz was utilized.A pair of asymmetric electrodes of pure copper braided wire wrapped with pure copper blocks(honeycomb side)/chromium-zirconium copper cylinders(substrate side)were designed for increasing the effective conductive area of spot welding and supressing the current skin effect.Under the optimal welding process parameters of I=1.75 kA,t=65 ms,and F=27 N,the metallurgical connection between the honeycomb and substrate was achieved,with a high degree of surface flatness of the honeycomb and no bending of the core wall.Corresponding SEM images and EDS spectra revealed significant changes in the content of Ni,Ti,and Cr elements at the optimal positioning welding,with a fusion thickness of ca.3μm.The content of Mo element first decreased and then increased in the joint.And Mo-containing M6C and M23C6 carbides were created in the weld zone,which have high strength under high-temperature service environment,meeting the high-quality positioning requirements for the honeycomb/substrate connection.