Research And Application Of Spray-welding Composite Materials On Surface Of Hot-shear

Hot-shear blade is the main tool which is used to cut hot rolling steel billet . Its performance directly affects the quality of continuous metal casting billet. Currently, domestic hot-shear blade is mainly made of integral high-alloy steel . Hardness was lowered in pursuit of high resistance to impact, causing lack of hot strength and poor high-temperature wear performance, and finally resulted to low service life. However, imported hot-shear blade is very expensive, and delivery date is long. Thermal spray welding can be used to produce high temperature wear-resisting coating. By doing this, cutting edge of blade can be strengthened while the resilience of the integral hot-shear blade is not lowered. Therefore, studies on the effect of WC and rare-earth on morphology and performance, especially high temperature wear-resisting behavior the paper have been aimed at. The composition of ingredients powder was changed to enhance high-temperature wear performance, thus to develop outstanding performance surfacing materials and finally find out a lower cost production method of producing new type of hot shears with the outstanding performance, which may lay solid foundations for producing the hot shears domestically.The effects of tungsten and rare-earth on microstructure and performance of spray-welding coating were investigated by means of OM, SEM, X-ray. The spray-welding coating was tough Ni solid solution, on which dispersible hard particles was distributed. The coating was combined with matrix by metallurgical bonding. The obtained coating was characterized by a smooth change of microstructure, element distribution and hardness.High-temperature dry sliding wear behavior of coating was focused on. Studies have shown that temperature has a great influence on wearing resistance. At room temperature, Failure mechanism of Ni60 coating was mainly adhesive wear, while oxidation and spalling wear at elevated temperature. Failure mechanisms of Ni/WC coating at room temperature were oxidation wear and spalling wear of oxides, while at elevated temperature, grinding abrasion was added.High-temperature wear performance was significantly affected by rare-earth alloy and WC addition , and it was increased nearly three times more than that of 5CrW2Si by adding appropriate addition of Rare-earth alloy or WC. Microstructure was refined and purified by Rare-earth alloy. The bond strength and the performance of thermal shock were also increased while they were seriously deteriorated by excessive addition of Rare-earth alloy and WC.Method of analysis of variance was used, because the interaction between material compositions may exist.The result was drawn that high temperature wearing resistance was significant impacted by adding rare earth and WC at the same time. Then the optimal composition ratio was gained as 74.6%Ni+25%WC+0.4%RE.