Abstract: Test high speed steel M2 ( % : 0. 85C, 5. 92W. 4. 74Mo, 3. 86Cr, 1. 84V) was melted by 25kg vacuum induction furnace and ingot was cast bv sand mould. The effect of 0 ~ 1. 3% Al on stiucture of as-cast steel has been studied. Results showed that added 0. 6% Al was available to fine the ledeburite network and improve the distribution of carbides in steel ； while added excessive amount of Al (1. 3% ) promoted the formation of a great lot of acicular carbide eutectoid-transformed from δ ferrite in primary grain. Al promoted the  M₂C carbide translbrnied from curved rod-like to straight lamella-like in which the alloy element content increased. Compared with lamellar M₂C, the rod-like M₂C easily decomposed short rod-like and granular carbides favorably to improve the morphology of carbide in steel.

摘要： 试验M2高速钢(%:0.85C、5.92W、4.74Mo、3.86Cr、1.81V)由25 kg真空感应炉熔炼,并用砂型铸造成锭。研究了0～1.3%Al对钢铸态组织的影响。结果表明,加入0.6%Al,可细化共晶莱氏体网,改善碳化物分布;加入过量Al(1.3%),初生晶粒内部出现大量由δ铁素体通过共析转变产生的针状碳化物。Al促进M₂C共晶碳化物形态由弯曲棒状变为平直片层状,并提高其合金元素含量。与片层状M₂C相比,棒状M₂C在高温易分解成短棒状或球状碳化物,有利改善碳化物形态。

关键词: Al, 高速钢M2, 铸态组织, M₂C共晶碳化物