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以Φ1.2 mm纯Ni焊丝为填充金属,母材硬质合金侧开坡口或不开坡口,利用熔化极惰性气体保护焊(MIG)弧焊机器人实现了低粘结相WC-TiC-Ni系硬质合金与304不锈钢的异质连接。利用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)以及电子探针(EPMA)研究了焊缝组织、形貌及界面元素扩散。讨论了接头硬质合金侧界面碳化钨溶解特征、异常晶粒长大(AGG)特征及影响因素。结果表明:采用该焊接方法在最佳焊接参数条件下:焊接速度v=45 cm·min-1,送丝速度v’=2.0 m·min-1,电压设定值18 V,保护气体流量15.8 L·min-1,单边开30°坡口,可以获得具有良好冶金结合的焊接接头,而且单边开坡口不留间隙较不开坡口留间隙的焊接效果好;在硬质合金侧界面区,与无填充焊接相比,焊缝中碳化钨溶解量很少;发现碳化钨稀疏层和η相层,通过硬质合金→致密(WC,TiC)/Ni→稀疏(WC,TiC)/Ni(母材中Ni和焊缝中Ni)→η相层实现硬质合金与钢的冶金结合。
Using Φ1.2 mm pure Ni wire as filler metal and base metal cemented carbide with side groove or no groove, MIG arc welding robot was used to realize low-binder WC-TiC- Ni-based cemented carbide and 304 stainless steel heterogeneous connection. The microstructure, morphology and interfacial diffusion of the weld were investigated by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) and electron probe (EPMA) The characteristics of tungsten carbide dissolution, abnormal grain growth (AGG) and its influencing factors at the cemented carbide interface were discussed. The results show that the optimum welding parameters are as follows: welding speed v = 45 cm · min-1, wire feeding speed v ’= 2.0 m · min-1, voltage setting value 18 V and shielding gas flow rate 15.8 L · min-1, unilateral open 30 ° bevel, you can get a good metallurgical bond welded joints, and unilateral groove without leaving gap groove gap better welding effect; in the cemented carbide side In the interfacial region, the amount of tungsten carbide dissolved in the weld is small when compared with the unfilled weld. The tungsten carbide sparse layer and the η phase were found to pass through the cemented carbide → dense (WC, TiC) / Ni → sparse (WC, TiC) / Ni (Ni in base metal and Ni in weld) → η phase layer to achieve metallurgical bonding between cemented carbide and steel.