Structure And Properties Of Laser Cladding Fe-based Amorphous Coating Under The Action Of Magnetic Field And The Transition Layer

Surface properties of machine parts need to be promoted increasingly because of the rapid development of modem industry.Most of them must work reliably and continuously under a high speed,high pressure,over loading or corrosion circumstance.Composite coatings developed on common metal benefit for improving surface properties of materials,prolonging the working life of machine parts and decreasing environment pollution.Amorphous—nanocrystalline composite materials are promising in the area of surface modification because of its high microhardness,strength and excellent corrosion resistant property. In this paper, alloy powders are pre—coated on 45 steel and Fe-Ni—Si-B-V amorphous—nanocrystalline composite coatings are developed by laser cladding. Microstructures of the coatings,growth mechanism of the amorphous phase and nanocrystalline phase,influence of microalloying on the alloy system and wear properties of the coatings are investigated in detail.At the same time,factors and rules influencing the coatings are studied.In this paper, the Fe-based amorphous coatings were fabricated on A3 steel by laser cladding under magnetic field. The microstructure, phase, micro-area composition distribution, microhardness and wear resistance of the coatings were analyzed byX-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), microhardness tester, UMT-2 wear tester. The main results are as follows:1. Completely amorphous phase in coating cann’t abtained bu laser cladding. With the increase of magnetic field intensity,the gain size in coatings decreases.2. Magnetic field effect on the hardness of coating is not obvious. But due to the magnetic field to make phase homogenization, make the cladding layer hardness value along the depth direction of coatings under magnetic field more stable.3.When plating a amorphous coating of Ni-P on the surface of the substrate, the coating with amorphous can be obtained. With the increase of magnetic field intensity, the amorphous content of cladding coating also increased accordingly.4. The role of the magnetic field weakening the melt flow in the process of laser cladding.Improved the glass forming ability of cladding coatings.5.In the pre-plating Ni-P amorphous layer of the substrate surface,the friction coefficient of amorphous after laser cladding is significantly smaller and the bending performance and impact toughness is improved.