表面毛化对巴氏合金MIG堆焊层界面组织及结合强度的影响

目的 利用MIG焊在表面毛化处理的Q235钢基体上堆焊SnSb11Cu6合金,研究表面毛化作用对界面组织及结合强度的影响.方法 设计毛化形貌分别为直槽和网格槽的毛化形式,槽深分别为0.15、0.3 mm,槽间距分别为1、1.5 mm,采用MIG焊方法在毛化钢基板上堆焊巴氏合金.利用X射线衍射仪分析巴氏合金堆焊层的组织成分.利用金相显微镜、扫描电镜和X射线能谱仪表征巴氏合金堆焊层的界面组织、微观形貌和元素分布.利用电子万能试验机、体视显微镜检测巴氏合金与钢基体间的结合强度以及润湿角.结果 毛化处理虽然会降低巴氏合金与钢基体的浸润性,但是增加了巴氏合金与钢基体间的接触面积;毛化凹槽中嵌合部分巴氏合金,使基体与合金层之间产生机械咬合作用;毛化轮廓边缘的材料易于熔化,从而促进了界面反应.以上因素的共同作用下,巴氏合金与钢基板之间的结合强度由无毛化试样的39.67 MPa提升至毛化试样的50.14 MPa.虽然网格槽毛化试样可以获得比直槽毛化试样更大的接触面积,但增强了毛化轮廓峰对三相线位移产生的钉扎作用,巴氏合金在网格槽毛化基体表面的浸润性更差,使得不同毛化参数试样的结合强度变化不大.结论 通过增加接触面积、生成金属间化合物以及机械咬合等因素共同作用,毛化处理可以有效提升巴氏合金与钢基体之间的结合强度.

Effect of Surface Texturing on the Interfacial Microstructure and Bonding Strength of Babbitt Alloy Cladding by MIG Welding

To study the effect of surface texturing on the interface microstructure and bonding strength, the SnSb11Cu6 alloy cladding was prepared by MIG welding on the Q235 steel substrates which were pre-textured. The texturing morphology of straight grooves and grids with the depths of 0.1 mm and 0.3 mm, the spacings of 1 mm and 1.5 mm were used. The composition of the Babbitt alloy cladding layer was analyzed through XRD. Metallurgical microscope, SEM and EDS were applied to characterize the interfacial microstructure, microscopic morphology and element distribution of the interface. The bonding strength and the wetting angle were tested by using universal testing machines and stereo microscope respectively. Although the texturing treatment reduces the wettability of the Babbitt alloy with the steel matrix, it increases the contact area between the Babbitt alloy and the steel substrate; the texturing grooves are filled with parts of Babbitt alloy, which causes the mechanical interlocking effect between the substrate and the alloy layer; the material at the edge of the texturing contour is easy to melt, which would promote the interface reaction. Under the combined effect of the above factors, the bonding strength between the Babbitt alloy and the steel substrate was increased from 39.67 MPa for the untextured sample to 51.14 MPa for the textured sample. Grids texturing samples can obtain a larger contact area than straight groove texturing samples, but it enhances the pinning effect of the texture peak on the three-phase line displacement, and the wettability of the grids texturing sample is worse. So, the bonding strength of the texturing samples with different texturing parameters is similar. The bonding strength of the texturing samples with different texturing parameters is similar. Grids texturing samples can obtain a larger contact area than straight groove texturing samples, but the wettability of the grids texturing sample is worse. The texturing treatment effectively improves the bonding strength between the Babbitt alloy and the steel matrix due to the combined effect of the contact area increase, the intermetallic compounds formation, and mechanical interlocking effect.