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电子束粉末床熔融成形M2高速钢耐腐蚀性能

Corrosion resistance of M2 high-speed steels fabricated by electron beam powder bed fusion

  • 摘要: 作为高碳高合金钢,M2高速钢常被应用于切削工具领域,在高速切削极端工况下,高速钢表面与冷却液发生热-化学交互作用,常引发其腐蚀-磨损耦合失效。采用电子束粉末床熔融增材制造技术制备了M2高速钢,研究了输入能量密度对相对密度、显微组织及腐蚀行为的影响,并与铸锻M2高速钢对比分析了在质量分数3.5% NaCl溶液中的耐腐蚀性能。结果表明:电子束粉末床熔融成形M2高速钢晶粒尺寸细小(5~8 μm),碳化物主要呈细小(<2 μm)弥散分布,形状为近球形或短棒状,未发现铸锻M2钢中常见的粗大一次碳化物的存在;当能量密度为43.3 J·mm−3时,电子束粉末床熔融成形M2高速钢的相对密度最高(99.8%),其在3.5% NaCl溶液中的腐蚀电流密度与电荷转移电阻分别为铸锻件的71.3%和123.7%,展现出更优异的耐腐蚀性能。

     

    Abstract: As the high-carbon and high-alloy steels, the M2 high-speed steels (HSS) are widely used in cutting tool applications. Under the extreme conditions (high-speed cutting), the surface of high-speed steels interacts with the coolant in thermal-chemical interaction, leading to the corrosion-wear coupling failure. The M2 high-speed steels were fabricated by electron beam powder bed fusion (EB-PBF) in this paper. The effects of input energy density (VED) on relative density, microstructure, and corrosion behavior were systematically investigated, the comparative analysis was conducted on the corrosion resistance between EB-PBF fabricated and wrought M2 HSS in 3.5% NaCl solution (mass fraction). In the results, the EB-PBF fabricated M2 HSS exhibits the refined grain size (5~8 μm) with homogeneously dispersed carbides (<2 μm) in near-spherical or short rod-like morphologies; notably, the coarse primary carbides commonly observed in wrought M2 HSS are absent. At the optimal VED of 43.3 J·mm−3, the EB-PBF fabricated M2 HSS achieves the peak relative density (99.8%), and the corrosion current density and charge transfer resistance in 3.5% NaCl solution are 71.3% and 123.7% of those of wrought M2 HSS, respectively, demonstrating the significant enhanced corrosion resistance.

     

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