外加磁场对等离子熔覆Fe313合金涂层组织性能的影响

Effect of External Magnetic Field on Microstructure and Properties ofPlasma Cladding Fe313 Alloy Coating

利用外加磁场辅助等离子熔覆技术在45钢表面制备了Fe313合金涂层。利用OM、SEM、EDS和XRD等表征手段对涂层进行了显微组织和物相组成分析。采用维氏硬度计测试了涂层的显微硬度,通过摩擦磨损实验研究了涂层的磨损性能。结果表明:外加磁场后,在电磁搅拌的作用下,涂层中粗大的柱状晶转变为细小的等轴晶,晶粒细化效果明显。涂层显微组织为亚共晶组织,包含初生过饱和(Fe,Cr)固溶体相以及枝间共晶碳化物相(M 7C 3型碳化物),外加磁场使得共晶碳化物更为细小均匀地分布在涂层中。此外,外加磁场后制得的涂层的显微硬度明显大于未外加磁场时制得的涂层的显微硬度,耐磨性也得到明显改善。在载荷为50 N时,外加磁场电流为0 A和5 A制得的涂层的磨损机制为粘着磨损,外加电流为7 A和9 A制得的涂层的磨损机制为磨粒磨损和轻微粘着磨损混合磨损机制;当载荷为100 N和150 N时,外加磁场电流为0 A和5 A制得的涂层粘着磨损加剧,外加电流为7 A和9 A制得的涂层磨损机制由混合磨损机制转变为粘着磨损机制。

Fe313 alloy coating was prepared on the surface of 45 steel by using external magnetic field assisted plasma cladding technology.OM(optical microscope),SEM(scanning electron microscope),EDS(energy disperse spectroscopy)and XRD(X-ray powder diffractometer)were used to analyze the microstructure and phase composition of the coating.The microhardness of the coating was tested using a Vickers hardness tester,and the abrasion performance of the coating was studied by friction and wear experiments.The results show:After applying a magnetic field,under the action of electromagnetic stirring,the coarse columnar crystals in the coating are transformed into fine equiaxed crystals,and the grain refining effect is obvious.The coating presents a hypoeutectic structure,including a primary supersaturated(Fe,Cr)solid solution phase and an inter-dendrites eutectic carbide phase(M 7C 3 type carbide).The external magnetic field makes the eutectic carbide more finely and uniformly distributed on the coating.The microhardness and abrasion resistance of the coatings prepared after the application of a magnetic field were significantly better than those of the coatings prepared without a magnetic field.At a load of 50 N,the wear mechanism of the coating made by the applied magnetic field current of 0 A and 5 A is adhesive wear,and the wear mechanism of the coating made by the applied current of 7 A and 9 A is mixed wear mechanism of abrasive grain wear and slight adhesive wear.When the load is 100 N and 150 N,the adhesive wear of the coating made by the applied magnetic field current of 0 A and 5 A is intensified,and the wear mechanism of the coating made by the applied current of 7 A and 9 A changes from the mixed wear mechanism to the adhesive wear mechanism.