激光熔覆铁基合金涂层的组织及耐蚀性能

采用激光熔覆技术在DH36钢基体上制备铁基合金涂层,利用X射线衍射(XRD)、扫描电镜(SEM)、显微硬度计等手段对涂层的物相结构、显微组织和显微硬度进行分析,采用极化曲线对比分析Fe基涂层和基体在人工海水中的耐蚀性。结果表明:涂层和基体结合良好,涂层中生成(Cr,Fe)7C3、Fe3C硬质相和双重致密的氧化膜,涂层的结合区主要为平面晶和定向向上生长的柱状晶,中上部为细小的树枝晶,由于合金元素的固溶强化、碳化物的弥散强化和细晶强化的共同作用,涂层的平均显微硬度为1 026.11 HV0.2,为基体硬度的5.21倍,涂层的耐蚀性明显改善。

Microstructure and Properties of Fe-based Alloy Coating by Laser Cladding

The Fe-based coating was prepared on the surface of DH36 steel by laser cladding.XRD,SEM and micro-hardness tester were used to analyze the phase composition,microstructure and micro-hardness of the coating.The corrosion resistance of Fe-based coatings and substrates was analyzed in artificial seawater by polarization curves.The result show that the coating is fairly bonded to the substrate,(Cr,Fe)7C3,Fe3C hard phase and double dense oxide films are existed in the coating.The microstructure of the bonding zone of the coating is mainly composed of plane crystal and columnar crystal growing upward directionally while that of the upper and middle parts is consists of fine dendrites,due to the combined effect of solid solution strengthening,carbide dispersion strengthening and fine grain strengthening of alloy elements,the average micro-hardness of the coating is 1 026.11 HV0.2,which is about 5.21 times higher than that of the matrix,the corrosion resistance of the coating has been significantly improved.