钎剂复合型4047钎料组织及钎焊性能分析

Research on Microstructure and Brazing Properties of Flux-containing 4047 Filler Metals

摘要:

采用粉末锻造法制备了钎剂复合型铝硅共晶4047复合钎料，并对比研究了自制钎剂复合4047钎料与市售药芯钎料、进口钎剂复合钎料的组织与钎焊性能。结果表明：钎剂复合4047钎料存在两个吸热峰，钎剂熔点略低于钎料合金熔点。钎剂复合4047钎料的润湿铺展面积为363 mm2，与进口钎料（353 mm2）接近，二者均优于药芯钎料（311 mm2）。在85%湿度、35 ℃环境条件下，钎剂复合4047钎料与进口钎料的抗吸潮性优良，药芯钎料放置72 h、144 h、216 h的吸潮率分别为3.88%、4.02%、4.27%，钎剂吸潮增重明显。钎剂复合4047钎料组织分析结果表明，钎剂颗粒被钎料合金包裹、固定在基体组织内，钎剂尺寸细小、分布均匀，压实系数高。钎剂复合4047钎料钎焊性能较好，钎缝区组织致密，钎着率高，6061/3003搭接接头断裂强度平均达107.5 MPa，断裂发生在3003侧热影响区。

Abstract:

A novel flux-containing 4047 composite brazing filler metal was prepared by powder forging method. The microstructure and brazing performances of the self-made composite filler metal, commercial flux-cored and imported brazing filler metal were investigated comparatively. Experimental results showed that there are two endothermic peaks in the melting curve of the self-made composite filler metal, and the melting point of flux was relatively lower than that of the 4047 filler alloy. The spreading area of the self-made composite filler metal was 363 mm2, which was close to that of imported filler metal (353 mm2) and was significantly larger than that of flux-cored ones (311 mm2). Under the environmental conditions of 85% humidity and 35 ℃, the self-made and imported filler metals showed excellent moisture absorption resistance, while the flux-cored one showed a remarkable increase in mass due to moisture absorption of flux. The moisture absorption rates of the flux-cored ones placed in humid environment for 72 h, 144 h and 216 h were 3.88%, 4.02% and 4.27%, respectively. The results of microstructure analysis showed that the flux particles of the self-made composite filler metal were small in size and evenly distributed, which were firmly wrapped in the matrix of the 4047 filler alloy. The average fracture strength of the brazed AA6061/AA3003 dissimilar lap joints was 107.5 MPa, and the fracture position was located in heat-affected zone of the AA3003 side. The dense structure of the brazed seam showed that the self-made composite filler metal has good brazing performance and high brazed rate.