【摘要】 为了利用NbC的高硬度和高热稳定性,并避免其在凝固过程中的过分长大,采用喷射成形快速凝固技术制备了M3型高速钢和以Nb代V的M3型高速钢.利用SEM,EDX和XRD等方法研究了Nb对喷射成形M3型高速钢沉积态组织的影响;利用SRV高温摩擦磨损试验机和三维白光干涉表面形貌仪研究了Nb对喷射成形M3型高速钢摩擦磨损性能的影响.结果表明,用等原子分数的Nb替代V,可大幅增加沉积态中一次MC型碳化物.减少一次M₂C型碳化物,同时由于喷射成形高冷速的作用,使得MC碳化物尺寸减小,分布更弥散:这些MC型碳化物的存在是M3型高速钢的抗磨粒磨损性能提高的主要原因,但其对抗氧化性能并无贡献,在高载荷时抗氧化剥落磨损能力增加不明显;Nb对提高M3高速钢回火稳定性也有明显的作用.更多还原

【Abstract】 Spray forming with a short process chains has been proven to be a powerful tool for the production of high-alloyed materials.Niobium,as a strong former for the carbide,will mainly form primary MC carbides,such as NbC,which can be formed via the reaction between Nb and C atoms at the beginning of solidification,and it can act as the inoculants and refine the cast structure of steel which can mainly form primary MC carbides.M3 high speed steel with or without Nb addition were prepared via spray forming.The effect of Nb on the microstructure of spray formed M3 high speed steel was investigated by SEM,EDX and XRD methods;the friction performances of these two steels were studied by SRV high temperature tribometer and 3D white-light interfering profilometer.The results show that the amount of primary MC carbides can increase sharply while the reduction of the amount of primary M₂C due to the substitution of 2%Nb for 1%V（mass fraction） in M3 high speed steel.For the high cooling rate during the spray forming,the primary MC carbides can be refined and dispersed.Large number of primary MC carbides can improve the abrasive wear resistance of M3 high speed steel,but cannot enhance its oxidation resistance;M3 high speed steels containing Nb possess high tempering resistance.更多还原