铁素体马氏体钢表面激光熔覆Al2O3和Al2O3/FeCrNi涂层的组织与性能研究

Microstructure and Property of Al2O3 and Al2O3/FeCrNi Coating Prepared on Ferritic/Martensitic Steel by Pulsed Laser Cladding

  • 摘要: 为改善铁素体/马氏体钢在液态铅铋环境下的磨蚀性能,采用脉冲激光熔覆技术在一种典型铁素体/马氏体钢表面成功制备出了单一Al2O3和Al2O3/FeCrNi复合涂层,并综合利用多种表征手段对两种涂层的相组成、微区成分、微观组织特征和硬度进行了研究和分析。研究发现,Al2O3和Al2O3/FeCrNi涂层熔覆区(CZ)的厚度分别约为260 μm和180 μm。Al2O3涂层CZ靠近样品表面的区域主要由较粗大的块状δ铁素体组成,而远离样品表面的区域由细小的板条状马氏体组成。Al2O3/FeCrNi涂层CZ微观组织较均匀,主要由细小的板条状马氏体组成。与此同时,两种涂层内均存在大量弥散分布的Al2O3颗粒。硬度测试显示,Al2O3和 Al2O3/FeCrNi涂层的硬度分别为(363±75) HV和(467±17) HV,均明显高于基体((267±5) HV)。综合分析发现,细晶强化和第二相强化的共同作用是Al2O3/FeCrNi涂层硬度更高的原因。

     

    Abstract: In order to improve the wear resistance of ferrite/Martensite steel in liquid lead bismuth environment, Al2O3 and Al2O3/FeCrNi coatings were successfully prepared on a typical ferritic/Martensitic steel by pulsed laser cladding, and the phase constitutions, compositions, microstructural characteristics and hardness of both the coatings were characterized and analyzed by jointly using X-ray diffraction, electron channeling contrast imaging, energy dispersive spectroscopy, electron backscatter diffraction and Vickers indenter. The results show that cladding zone (CZ) of the Al2O3 and the Al2O3/FeCrNi coatings are about 260 μm and 180 μm in depth, respectively. The part of the CZ near the Al2O3 coating surface is mainly consisting of bulk δ ferrite, while the part far away from the surface consists of martensitic plates. The CZ of Al2O3/FeCrNi coating has more uniform microstructures mainly comprised of martensitic plates. Hardnesses of the Al2O3 and the Al2O3/FeCrNi coatings are (363±75) HV and (467±17) HV, respectively, both of which are significantly higher than that of the substrate ((267±5) HV). Comprehensive analyses suggest that the higher hardness of Al2O3/FeCrNi coating can be attributed to grain refinement and second phase strengthening.

     

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