Alternating Magnetic Field Of Laser Cladding Fe-based Coating Quality And Wear Macro

Laser cladding is an advanced of surface process producing coating wit metallurgical bond to the substrate. With the special design circuit and magnet coil of the alternating magnetic field device auxiliarying powder feeding laser cladding process, through which it can generate alternating field acting on the molten pool and to melt non-contact processing, which made the dendrite difficult to grow up, or broken and crushed, and formated a new crystal nucleus during metal solidification. By electromagnetic-assisted laser cladding process, in order to refine the Fe-based solidification structure and improve the coating internal defects, such as cracks and pores. Aimed at improve the quality of the coating and providing a completely process for the refinement solidification structure and improve coating inner defects.In this paper, the effects on the macro-morphology and inner-pores of Fe-based coating under different magnetic field strength conditions were analysized by using somatotype microscope. With AutoCAD software to study the characteristics geometry of the Fe-based coating under different magnetic field strength. Using OM, XRD, SEM and EDS to study the composition and structure of the Fe-based composite coating, on this basis, which to clarify the magnetic field effects on the Fe-based coating structure and to reveal the mechanism of the coating structure from dendrite crystal to equiaxed crystal change. The fiction and ware properties of Fe-based coating under different magnetic field strength were tested by the MMU-5G friction and ware tester. The main reason for the wear resistance of coating can be improved is based on study of the Fe-based microstructure under different magnetic field strength.The macro-morphology of coating under different magnetic field strength shows that the surface of the coating morphology change from smooth to wavy, and with increasing magnetic field strength, the wavy shape become more obviously.The coating characteristics geometry studies have shown that the cladding layer height and cross-section area decrease with the increase of the magnetic field strength, but the cladding layer width changed little.The microstructure by OM shows that the cladding layer height and cross-section area decrease with the increase of the magnetic field current, but the cladding layer width changed little. The electromagnetic force in molten pool internal driven the dendrites ablation and mechanical break, and the free broken dendrites become a new nuclei, increasing the nucleation rate, thus prompting the cladding layer top microstructure from dendrite crystal to equiaxed crystal change. The equiaxed crystal zone become wider with the increase of magnetic field strength, but the bottom microstructure change is small. With the further increase of the magnetic field strength, the coating organization has been roughened trend and even elongated strip was located on the inner Fe-based coating. Therefore, the relationship between magnetic field strength and grain refinement curve are extremal curve.The EDS micro area and line scan analysis shows that, compare with and without magnetic, the Fe element content of the texture eutectic and primary phase the Fe-based coating under magnetic field preparation increased hardly, but the content of Cr element reduced.The SEM and XRD qualitative analysis result confirmed that the phase species of Fe-based coating are mostly unassociated with alternating magnetic field strength, and the coatings under with and without magnetic field are mainly composed of y-(Fe, Cr) solid solution, γ-(Fe, Cr) eutectic and a small amount of Fe3(B, C), Cr7(B, C)3and CrFeB compounds.The ambient dry friction wear tests show that the friction and wear behaviors has been improved significantly. The wear weight loss of the electromagnetic control assisted laser cladding coatings is only50%of the non-magnetic field coatings, and the fluctuation of friction coefficient is lower. The morphology of abrasion surface of the coating under with and without auxiliary magnetic field are investigated by SEM. The results indicate that the wear surface of the coatings are prepared under without magnetic left plough, and the main forms is plough wear. There are plough on the wear surface of Fe-based coatings under with magnetic, but the most wear prints failed throughout the wear surface and local surface distribution of small debris, and this shows the main forms are plough wear and local fatigue loss.