基于同步送粉法的锅炉管高频感应熔覆组织性能

High frequency induction cladding microstructure and properties of the boiler pipe based on synchronous powder feeding method

采用高频感应熔覆技术,在12Cr Mo V合金结构钢材质的锅炉管表面进行了采用热喷涂、水玻璃作为黏结剂冷预置涂层、高频感应同步送粉器直接将合金粉末送于锅炉管表面3种工艺方法制备Ni Cr Si B耐磨合金涂层实验研究,用SEM和能谱仪分析了基体与熔覆层界面和熔覆层间的微观组织及成分,开展了硬度测试实验.结果表明:在熔覆电流为830 A、熔覆频率为250 k Hz的条件下,热喷涂法得到的熔覆层与基体有明显的间隙;水玻璃作为黏结剂冷预置涂层法获得的熔覆层有夹渣且表面不平整;而同步送粉法得到的熔覆层表面平整,熔覆层和基体间有明显的锯齿状白亮带,表明熔覆层和基体形成良好的冶金结合,熔覆层平均硬度为310 HV,是基体硬度的2倍.可见同步送粉高频感应熔覆工艺相对于预涂层法高频感应熔覆具有环保、加工效率高、无空隙夹渣、圆柱面平整度高、低成本等明显优势。

The NiCrSiB alloy coating was fabricated on the surface of boiler tube with 12Cr MoV structural alloy steel by highfrequency induction cladding. The first kind of method is thermal spraying, the second is cold-preseting coatingmethod when water glass was used for binder, the third is a synchronous powder feeding method. The ScanningElectron Microscope and Energy Dispersive Spectrometer were used to analyze microstructure and composition ofthe cladding layers. The hardness experiment was carried out. The cladding current was set to be 830 A. The powerfrequency was given at the level of 250 kHz. The results show that the cladding layer and the substrate obtained bythe method of thermal spraying has obvious gap. Cladding layers had slag and its surface were roughness by thecold-preseting coating method. The surface of cladding layers were smooth by the way of synchronous powderfeeding method. And the result that serrated white bright band between the cladding layer and the substrate showstransitional zone forms metallurgical bonding. The hardness of cladding layer is 310 HV, which is 2 times higherthan that of substrate. This technology of high frequency induction cladding by the way of synchronous powderfeeding method has more advantages such as environment protection, higher machining efficiency, highersmoothness of cylindrical surface, no slag inclusion, lower processing cost, than that by pre-coating methods.