摘要: |
以Fe/Cr/C粉末为添加粉末,采用CO2激光扫描和电子束扫描在903钢表面原位合成(Cr,Fe)7C3表面复合层。对两种熔覆层进行金相分析、扫描电镜(SEM)和X射线衍射(XRD)分析对比。结果表明: 电子束熔覆层的组织均匀性较好,表层有大量(Cr,Fe)7C3初生碳化物,底部则为初生奥氏体枝状晶和(Cr,Fe)7C3/γFe共晶组织。基于电子束扫描时束流可变的工艺特点,实际应用时容易制备可控组织梯度的熔覆层。激光熔覆层也具有一定的组织梯度,但其组织均匀性较差,表层主要有γFe枝状晶和(Cr,Fe)7C3/γFe共晶组织及马氏体组织,底部则主要为马氏体组织。两种熔覆层的显微硬度体现了其中碳化物的数量及分布,电子束熔覆层碳化物含量较高,其显微硬度也较大。低应力磨损状态下,电子束熔覆层和激光熔覆层的相对耐磨性分别是基材的10.5倍和4.3倍。 |
关键词: 表面复合层 激光熔覆 电子束熔覆 碳化物 |
DOI:10.3969/j.issn.1007-9289.2014.04.012 |
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Comparision of Microstructure and Wear Resistance of (Cr,Fe)7C3 Composite Layers Synthesized by Laser Scanning and Electron Beam Scanning |
LU Binfeng, TANG Puhong, LU Fenggui, TANG Xinhua1,2
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1. School of Mechanical and Automotive Engineering, Jiaxing Vocational Technical College, Jiaxing 314036, Zhejiang;2. College of Material Science and Engineering, Shanghai Jiaotong University, Shanghai 200240
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Abstract: |
(Cr,Fe)7C3 composite layers were synthesized with Fe/Cr/C powder additives on low carbon steel by CO2 laser scanning and electron beam scanning. Both composite layers were analyzed with optical microscope, scanning electron microscope (SEM) and Xray diffraction (XRD) analysis. The structure of the electron beam cladding layer shows good uniformity, and there are large amounts of primary (Cr,Fe)7C3 carbides in the upper surface layer. The structure in the bottom layer is mainly austenitic dendrites and eutectic (Cr,Fe)7C3/γFe. Due to the changeability of beam current in the electron beam processing, it′s convenient to synthesize the composite layer with gradual change microstructure. The structure of the laser cladding layer also changes from the upper surface to the bottom, however, shows poor uniformity. The structure in the upper surface is mainly γFe dendrite, eutectic (Cr,Fe)7C3/γFe, and martensite. The structure in the bottom layer is mainly martensite. Microhardness of the two cladding reflects the amount and distribution of carbides. Electron beam cladding layer shows higher microhardness due to high carbides amount. Under low stress abrasion condition, the relative wear resistance of the electron beam cladding layer and laser cladding layer is 10.5 times and 4.3 times of the substrate, respectively. |
Key words: surface composite layers laser cladding electron beam cladding carbides |