Research On Iron-Based Ceramic Composite Surfacing Alloys With Magnetic Field

Abrasive wear is one of the most important factors of the failure for machine parts by the process of industrial production. In order to improving the wear resistance for machine parts and reducing the economic loss caused by abrasive wear and reducing production costs, the research of iron-based ceramic composite alloy is great practical significance. In addition, longitudinal DC magnetic field was introduced to the welding process to improve the wear resistance of the surfacing layer and technological properties of hardfacing alloy. Study the influence of formability, microstructure and mechanical properties of the surfacing layer under different magnetic field parameters.Titanium-iron power, high-carbon ferrochromium powder, reduced iron powder and graphite was used as raw materials to mixed into hardfacing alloy according to different quality scores of Fe, Cr, Ti, C element in the experiment. The hardfacing alloy powder was coated on the surface of low carbon steel. In order to determine the optimum surfacing current, plasma arc surfacing equipment was used to welding the alloy powder under different surfacing current. Conduct the surfacing test under the optimum surfacing current to in situ synthesis TiC and M₇C₃ ceramic hard phase. The surfacing layer was detected by means of the X-ray diffraction (XRD), Optical Microscope (OM), Scanning Electron Microscope (SEM), Rockwell Hardness Tester, Vickers hardness tester and wet sand abrasion tester. Comprehensive analysis and comparison to the surfacing layer were conducted which based on phase diagrams and thermodynamic theories. Thus, the best wear resistance alloy system was determined. And then introduce longitudinal DC magnetic field to the process of surfacing the best wear resistance Fe-Cr-Ti-C alloy powder on the low carbon steel. Study the influence of different magnetic field current on the surfacing layer.The result shows that the formability is better and the TiC and M₇C₃ were in situ synthesized in the surfacing layer. A large number of M₇C₃ and TiC ceramic hard phase were formed in the surfacing layer when the powder content 19.8% Cr and 4.5% Ti and the hardness of the surfacing layer is 66.4HRC, the weight loss is 0.1284g, and the wear resistance is excellent. The introduction of the longitudinal DC magnetic field can significantly improve the formability of the surfacing layer. The formability is good when the magnetic filed current is above 2A. The dilution of the base metal becomes bigger along with the increase of the magnetic filed current. The thickness of the interlayer between the functional layer and base metal is moderation when the magnetic field current is between 2-4A. At the same time a large number of TiC and M₇C₃ ceramic hard phase are in situ synthesized in the surfacing layer, and the metallurgical combination between the surfacing layer and base metal is good enough. Most of the M₇C₃ ceramic hard phase in the surface of the surfacing layer distribute with a irregular hexagonal shape when the magnetic field current is 4A. The hardness of the surfacing layer is 68.8HRC, and the weight loss is 0.0810g, the wear resistance of the surfacing layer is the best when the magnetic field current is 4A.