Study On Microstructure And Properties Of NbC-TiC-VC Wear Resistant Surfacing Alloy

Surfacing refers to use some alloy materials with special performance cladding on the surface of metal materials or parts, the formation of metallurgical bonding is to give special material properties or restore the original shape and size of the process of parts. Surfacing welding technology is widely used in the repair and manufacture of mechanical parts, which has important significance for the rational use of materials, the improvement of product design and performance, the reduction of production cost. Therefore, this test chose Fe based alloy with reasonable price and good performance, set Nb, Ti, V, Mo as main alloying elements. The effects of the alloying elements in the surfacing layer had been analyzed. This text is to solve the surface wear of the metal parts.In this paper, the slag resistance of the surfacing layer was studied firstly. The results showed that when the marble was 14%, fluorite was 10%, retile was 12%, titanium dioxide was 4%, and titanium iron ore was 8%, the surfacing layer had good slag removal ability and stability.utile had the greatest impact on the slag removal of the surfacing layer. With the increase of graphite content, the amount of dust in the surfacing electrode increased.The microstructure of surfacing layer was martensite, retained austenite and carbide, and the particle reinforced phase was NbC, TiC, VC and Mo2C.The carbide reinforced phase was successfully synthesized by the chemical reaction. Experiments showed that when the graphite content increased, the matrix structure was composed of a low carbon martensite transformation for high carbon martensite. Surfacing layer hardness increased significantly with increase of the amount of graphite; but when the addition amount of graphite was more than 8%, the hardness of the surfacing layer began a downward trend. At the same time, it was found that the hardness increased with the increase of the amount of Ti and Fe, and the hardness of the surfacing layer decreased slowly when the amount of Ti Fe addition increased more than 9%.And it was found that the hardness of surfacing layer increased with the increase of Nb Fe content, and the hardness of the surfacing layer decreased slowly when the amount of Nb Fe added was more than 6%.The effect of the number of layers on the microstructure and properties of surfacing layer was studied. Research showed that the microstructure and properties of the surfacing layer are not very different from that of the 3 layer when surfacing 4 layer, so the test suggested that the 3 layer was suitable.The crack resistance of the surfacing layer was related to the carbon content, alloying element content and microstructure. The size, shape, quantity and the distribution of carbide reinforcement had great influence on the crack resistance of surfacing layer. When the graphite content increased, the number of cracks in the surfacing layer increased, and the crack resistance decreased significantly. The test on the wear resistance of surfacing layer research found that the surfacing layer of wear mechanism was mainly abrasive wear, and may produce the effect of furrow. High hardness alloy carbide in the wear process played the role of the skeleton, hindered the wear debris on the destruction of the surfacing layer, so it could improve the wear resistance of the surfacing layer. And the wear resistance of the surfacing layer increased significantly with the increase of graphite content, but the wear resistance of the surfacing layer began to decrease when the amount of graphite added more than 6.5%.The effect of niobium iron, titanium iron on the wear resistance of surfacing metal was similar to graphite, when niobium iron, titanium iron addition amount were increased, wear resistance of hardfacing layers was improved; but when niobium iron was over 6% or titanium iron was more than 9%, the wear resistance of hardfacing layers appeared downward trend.According to the test results, it can be known that when adding 6.5% graphite, 9%FeTi,6% FeNb,3% FeV,2% FeMo, the surfacing layer had high hardness and wear resistance. The average hardness of surfacing layer was about 61HRC.