冷却速度对高速钢M_2C共晶碳化物的影响

Effect of Cooling Rates on M_2C Eutectic Carbides in High Speed Steel

采用砂型和金属型铸造制备M2高速钢铸锭,研究了冷却速度变化对高速钢M2C共晶碳化物形态及性质的影响,探讨了M2C共晶碳化物形态变化的机理。结果表明,冷却速度增加,莱氏体网细化,铸态偏析得到改善;M2C形态由片层状转变为棒状,碳化物中合金元素含量降低,高温分解产生的MC碳化物和M6C+MC复合碳化物数量减少。共晶反应时,共晶碳化物和奥氏体相之间的生长速度差异决定了M2C共晶碳化物的形态。

The cast ingots prepared using sand mould and metal mould were analyzed to investigate the effect of cooling rates on morphologies and characters of M2C eutectic carbides in M2 high speed steel. The corresponding mechanism was also studied. The results show that the ledeburite network is refined and the segregation is improved with increasing of cooling rate. Meanwhile, the morphology of M2C carbides transforms from lamellar eutectic to rod-like eutectic. Compared with lamellar M2C, the concentration of alloying elements in rod-like M2C is lower and the amount of MC carbides and M6C＋MC mixture carbides after decomposition of M2C is less. The difference of growing rate between M2C carbide and austenite determines the morpholocly of M2C eutectic carbides.