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An effective method to improve the structure and properties of high-speed steel for rolls
High-speed steel rollers have excellent properties such as long service life, smooth surface of rolled materials, and uniform thickness. At present, the centrifugal casting method is mostly used in industry to prepare the roll rings of high-speed steel rolls. The preparation process is simple and low-cost. However, because the high-speed steel materials used for rolls contain high alloying elements such as Cr, V, W, and Mo, they solidify. During the process, component segregation easily occurs under the action of centrifugal force, making the performance of the outer layer (working layer) of the roller ring lower than that of the inner layer (non-working layer).
Scientific researchers use the electroslag remelting method to prepare high-speed steel roll materials, and use appropriate modifiers to effectively avoid the segregation of inner and outer layers that is easily caused by the usual centrifugal casting method, improve the structure, improve performance, and achieve good results. Effect. They used recycled scrap high-speed steel as raw materials, configured M2 high-speed steel roll materials, used yttrium-based heavy rare earth composite modifier (product model YFB) produced by Ganzhou Longyttrium Rare Earth Materials Co., Ltd., and cast consumable electrode rods through a vacuum medium frequency induction furnace. , add a modifier during the casting process, the weight of the modifier is proportioned to 1% of the weight of high-speed steel, and then the prepared electrode rod is electroslag remelted, using CaF2-Al2O3-CaO ternary slag to prepare Ф110 mm × 300 mm high speed steel roll ingot. The high-speed steel roll ingot is finally heat treated: annealing at 800°C + quenching at 1050°C + tempering at 550°C twice.
High-speed steel materials are prepared by electroslag remelting. During the smelting process, the water-cooled crystallizer circulates and cools away heat, so its cooling rate is much faster than ordinary centrifugal casting. Therefore, the nucleation rate is improved and the primary grains are At the same time, the multiple branching of dendrites and the reduction of dendrite spacing caused some of the eutectic carbide network structures in the high-speed steel samples to break. After the modifier is added, the nucleation particles increase, which can greatly promote the formation of granular MC-type eutectic carbides with high hardness and high temperature stability in the grains; at the same time, the addition of modifier can remove S and O elements in the steel, thereby improving the It can purify the molten steel and inhibit the formation of eutectic carbides at the grain boundaries during the subsequent solidification process, thereby achieving the purpose of refining the eutectic carbides at the grain boundaries. In addition, the coarse M7C3 type eutectic carbides at the grain boundaries in the sample with modifier added decompose to form fine M2C and M6C type eutectic carbides after heat treatment. Therefore, the eutectic carbide network of the sample is reduced after heat treatment. The structure further fractures. The improvement of the above-mentioned structure improves the impact toughness of the material.
