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采用Ag-Cu-Ti合金钎料,在不同的超高频感应连续钎焊工艺条件下实现了金刚石磨粒与大尺寸钢基体的连接。借助扫描电镜(SEM)对钎焊后的金刚石界面微观结构进行观察,采用Raman光谱对钎焊后金刚石的残余应力状态进行了测试分析。结果显示,超高频感应连续钎焊金刚石表面Ti C晶体的生成处于非平衡态的过程。随着扫描速度的变化,Ti C晶体呈现球状和岛状,偏离了理想的正八面体形态。钎料层内部出现富Cu枝晶组织,而在45#钢基体表层形成了马氏体组织。钎焊后的金刚石磨粒顶部受到残余压应力,最大值为500 MPa,磨粒底部受到残余拉应力,最大值为150 MPa,这种分布趋势与传统真空炉中钎焊方法获得的残余应力分布刚好相反。
The Ag-Cu-Ti alloy brazing filler metal is used to connect the diamond abrasive grains with the large-size steel substrate under different conditions of continuous brazing with UHF induction. The microstructure of the brazed diamond interface was observed by scanning electron microscopy (SEM), and the residual stress state of brazed diamond was analyzed by Raman spectroscopy. The results show that the formation of TiC crystals on the diamond surface by continuous high frequency induction welding is in a non-equilibrium state. With the change of scanning speed, TiC crystals appear spherical and island shape, deviating from the ideal octahedron morphology. The Cu-rich dendrite structure appears in the brazing filler metal layer, while the martensite structure is formed on the surface of 45 # steel substrate. Residual compressive stress was applied to the top of the brazed diamond abrasive grains at a maximum of 500 MPa and residual tensile stress at the bottom of the abrasive grains at a maximum of 150 MPa. This distribution tendency is in line with the residual stress distribution obtained by brazing in a conventional vacuum furnace Just the opposite.