Study On Process Of High Speed Steel Ingots Using Inclined Slope Pre-crystallization Method

High speed steel (HSS) has important position in cutting field for its high particular advantages. Numerous investigations have indicated that interior primary carbide size and distribution of HSS ingots can be affected not only by hot-working deformation, but also by ledeburite eutectic network structure to some extent. Thereby, how to improve metallurgy technology and control the solidified process of HSS ingots, and consequently acquire homogeneous casting structure of steel ingots are important problems at all times in HSS production. Semi-solid forming technology is a new metal forming method. Its unique advantages in acquiring uniform, fine grain structure, shortening manufacturing procedure, energy conservation and so on will provide a new approach for solving this problems and acquiring high quality HSS ingots.In this paper semi-solid M2 HSS ingots were prepared by inclined slope pre-crystallization method. The effects of casting temperature, slope length and angle on the microstructure of HSS ingots have been explored, and the perfect semi-solid non-dendritic uniform and fine network carbide structure of HSS ingots was obtained; moreover, the microstructure was quantitatively assessed and characterized by mean equivalent diameter, shape factor and mean thickness of carbide; at last, the forming mechanism of semi-solid HSS ingots using inclined slope pre-crystallization method was discussed according to the experiment result.The experiments show that by using cold pouring inclined slope pre-crystallization method, and through controlling appropriate pouring temperature, inclined slope length and angle, M2 HSS ingots of globular or approximate globular non-dentritic primary austenite microstructure and definite fine eutectic ledeburite net carbide can be obtained. And the optimum processing parameters in this experiment condition were gained: pouring temperature is about 1480℃, the inclined slope length and angle are 500mm, 60°, mean equivalent diameter of acquired crystal grain is 50.8μm, shape factor is 0.83, mean thickness is 5.21μm.