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采用空冷和水冷不同铸型方式,研究冷却速度对离心铸造高硼高速钢辊环组织的影响,制备出辊环。结果表明:铸态高硼高速钢辊环组织由树枝状基体和硼碳化物组成。快速冷却下,基体组织全部转化为马氏体;硼碳化物的类型没有发生变化,由M2(B,C)、M3(B,C)以及M23(B,C)6组成。随着冷却速率的增加,基体晶粒尺寸减小,硼碳化物数量减少,鱼骨状硼碳化物向筛网状转变,局部出现缩颈和孤立现象。冷却速度的增加影响了合金元素在基体和硬质相中的分布,硬质相的显微硬度不变,基体硬度略有增加。空冷砂型离心铸造时,随着距辊环外边缘距离的增加,出现菊花片状的包晶组织,并且数量也逐渐增加。
Adopting different molds of air-cooling and water-cooling, the influence of cooling rate on the structure of the ring of centrifugal casting high boron steel high speed steel was studied and the roll ring was prepared. The results show that the structure of as-cast high-boron steel ring is composed of dendritic matrix and boron carbide. Under rapid cooling, all the matrix was transformed into martensite. The type of boron carbide did not change and consisted of M2 (B, C), M3 (B, C) and M23 (B, C) 6. With the increase of cooling rate, the matrix grain size decreases, the amount of boron carbide decreases, the fish bone like boron carbide changes to the screen shape, and local necking and isolation occur. The increase of cooling rate affected the distribution of alloying elements in the matrix and the hard phase. The hardness of the hard phase did not change while the hardness of the matrix increased slightly. In the air-cooled sand centrifugal casting, chrysotile plate-like peritectic microstructure appears and increases gradually with the distance from the outer edge of the roll ring.