材料期刊网

采用砂型和金属型铸造制备M2高速钢铸锭，研究了冷却速度对共晶M2C碳化物形态和性质的影响。结果表明，冷速加快，促进共晶M2C由平直片层状变为弯曲棒状，并使碳化物中合金元素含量降低，基体合金含量升高。不同形态M2C热分解性质差异较为明显：片层状M2C分解产生的MC多分布在碳化物内部，形成大量M6C+MC复合碳化物；棒状M2C起始分解温度低于片层状M2C，MC多形成于碳化物和基体界面处，高温加热易与M6C分离，使复合碳化物数量减少。共晶M2C热分解性质差异与冷速不同引起的合金元素分布变化有关。

The effect of cooling rate on morphology and property of M2C eutectic carbide in M2 high speed steel was investigated by analysis of cast ingots prepared by sand mould and metal mould. The corresponding mechanism was also explored. The results show that the morphology of M2C carbides transforms from lamellar to rodlike with the increase of cooling rate. Meanwhile, the concentration of alloying elements in M2C decreases while it increases in the matrix. The decomposition process of lamellar and rodlike M2C is significantly different. After decomposition, MC forms inside lamellar M2C while it exists at the interface of rodlike M2C/γ. The DTA curve indicates that rodlike M2C is more unstable and decomposes at lower temperature than lamellar M2C. The property of M2C depends on the distribution of alloying elements, which varies greatly at different cooling rates.