钢/铅双金属结构熔滴沉积复合TIG电弧增材制造工艺与界面组织研究

Investigation on the interfacial microstructure of the steel/lead bimetallic structure fabricated by the hybrid TIG arc and droplet deposition manufacturing

摘要:

采用熔滴沉积复合钨极氩弧焊(TIG)电弧增材制造工艺实现了45钢/锡铅合金双金属结构的直接冶金结合. 利用金相显微镜、扫描电镜、X射线衍射等研究了钢/铅双金属增材制造结构界面不同位置特征区域的金相组织、界面元素分布和主要物相. 结果表明,采用熔滴沉积复合TIG电弧增材制造工艺成形的钢/铅双金属结构界面无明显裂纹、孔隙等宏观冶金缺陷；根据钢/铅界面金属间化合物(IMCs)的分布状态判定,铅合金熔滴在45钢表面的冲击、铺展过程中,同时存在“反应性润湿”和“惰性润湿”,反应性润湿界面存在微小波动并且界面处IMCs为FeSb₂和FeSn₂,惰性润湿界面未析出反应产物且存在微孔隙缺陷. 熔池中心处的界面IMCs层厚最大,IMCs层厚约为6 μm,随着测试位置逐渐远离熔池中心,界面IMCs层厚呈非线性递减趋势。

Abstract:

The direct metallurgical bonding of C45 steel/tin-lead alloy bimetallic structures was achieved by the hybrid TIG arc and droplet deposition manufacturing. The microstructure, interface element distribution and main phases of the steel/lead bimetallic structure were studied by metallurgical microscopy, scanning electron microscopy and X-ray diffraction. The results indicated that the steel/lead bimetallic structure interface formed by the droplet deposition composite TIG arc additive manufacturing process are no obvious cracks, pores and other macroscopic metallurgical defects; According to the distribution of intermetallic compounds (IMCs) at the steel/lead interface, there is both "reactive wetting" and "inert wetting" during the impact and spreading of lead alloy droplets on the C45 steel substrate, where the reactive wetting interface has small fluctuations and the IMCs at the interface are FeSb₂ and FeSn₂, and the inert wetting interface does not precipitate reaction products and has tiny pore defects. The IMCs layer thickness at the center of the molten pool is the largest, and the IMCs layer thickness is about 6 μm. The IMCs layer thickness at the interface shows a non-linear decreasing trend as the test position gradually moves away from the center of the molten pool.