Ni35掺杂高碳铬铁粉激光熔覆涂层组织性能研究

Study on Microstructure and Properties of Ni35 with High Carbon Ferrochrome Powders by Laser Cladding

摘要:

Ni35粉末掺杂不同质量分数(含量分别为0%、25%、50%、75%、100%)高碳铬铁粉末，在27SiMn钢表面进行激光熔覆制备复合涂层。采用OM、SEM、EDS及XRD等表征手段，表征熔覆层显微组织及物相结构；利用硬度计、磨粒磨损机及电化学站等仪器，表征熔覆层力学及腐蚀性能。结果表明：未掺杂时，熔覆层物相主要有γ-Ni、FeNi3及Cr2Ni3，含量50%时，熔覆层物相有α-Cr和(Cr, Fe)7C3生成，同时Cr2Ni3相消失；随着含量增加，熔覆层中部板条状组织含量增多且形貌变得粗大；含量50%时，熔覆层上部花瓣状组织及中部板条状组织均出现Cr元素富集现象，浅灰色组织为γ-Ni；随着含量增加，熔覆层显微硬度呈上升趋势，磨损率呈下降趋势；含量25%时，稀释率最大，为20.80%；含量50%时，熔覆层耐蚀性最佳，腐蚀电流密度最小，为0.39 μA/cm2。

Abstract:

The Ni35 powder with different mass fraction (the contents are 0%, 25%, 50%, 75% and 100% respectively) of high carbon ferrochrome powder was prepared on the surface of 27SiMn steel using laser cladding technology. The microstructure and the phase of the laser cladding layers were studied by the means of OM, SEM, EDS and XRD. Using micro-hardness tester, abrasive wear machine and electrochemical corrosion tester, the mechanical and corrosion properties of the laser cladding layers were studied. The experimental results show that: the phases of the cladding layers without high carbon ferrochrome are γ-Ni、FeNi3 and Cr2Ni3. When the content is 50%, the α-Cr and (Cr, Fe)7C3 are produced while the Cr2Ni3 disappears. With increasing the content of high carbon ferrochrome, the lath microstructures increase and coarsen constantly. When the content is 50%, Cr element enrichment happens in the petal-looking microstructure of the upper cladding layer and the lath microstructure of the middle cladding layer, and the light gray microstructure is γ-Ni. And with the content increasing, the micro-hardness increase while the wear rate reduce. When the content is 25%, the maximum dilution rate is 20.80% and when the content is 50%, the cladding layers have the best corrosion resistance, and the corrosion current density is the least, which is 0.39 μA/cm2.