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采用微束等离子熔覆技术,在Q235钢基板上制备出一定Al含量的Fe25铁基合金覆层。采用光学显微镜(OM)、X射线衍射仪(XRD)、电子探针(EPMA)、显微硬度计、高温氧化试验研究了覆层的组织、硬度和高温抗氧化性能。结果表明,随着Al的加入(0~6wt%),Fe25合金覆层的凝固形态发生显著改变,基体相由奥氏体转化为铁素体,出现初生δ铁素体及碳硼化物相,最终覆层呈现铁素体和粒状贝氏体相结构。随着Al含量的增加,覆层显微硬度先升后降。4wt%Al的覆层2层平均硬度为618 HV0.2,比纯Fe25覆层提高286 HV0.2。随着Al含量的增加,由于Al原子的溶入和生成金属间化合物Fe_2AlCr、Fe_3Al,以及形成更致密的氧化膜,Fe25合金覆层的高温抗氧化性显著增强。
The micro-beam plasma cladding technique was used to prepare Fe25 Fe-based alloy coating with certain Al content on Q235 steel substrate. The microstructure, hardness and high temperature oxidation resistance of the coating were studied by optical microscope (OM), X-ray diffraction (XRD), electron probe (EPMA), microhardness tester and high temperature oxidation test. The results show that with the addition of Al (0 ~ 6 wt%), the solidification morphology of Fe25 alloy coating changes significantly, the matrix phase is transformed from austenite to ferrite, and the primary δ ferrite and carboboride phase appear. The final coating presents a ferrite and granular bainite phase structure. With the increase of Al content, the microhardness of the coating first and then decreased. The average hardness of the 2 wt% Al cladding was 618 HV0.2, which was 286 HV0.2 higher than the pure Fe25 cladding. With the increase of Al content, the high-temperature oxidation resistance of Fe25 alloy coating is significantly enhanced due to the Al atoms’ dissolution and the formation of intermetallic compounds Fe 2 AlCr, Fe 3 Al and the formation of denser oxide film.