Abstract: The test M2 steel (/%: 0. 81C, 0. 31 Si, 0. 33Mn, 4. 01 Cr, 4.57Mo, 5. 71W, 1. 77V) is melted by a 25 kg high-frequency induction furnace and cast to cross section 50 mm X 100 mm ingots in laboratory. The macro-structure, grain size and distribution of carbides of M2 steel ingot casting by water-cooling copper mould and cast-iron mould are studied. Results show that higher cooling rate is available to control and eliminate the columnar crystal in ingot of M2 steel; with increasing the cooling rate the partial bubbles in M2 steel ingot float off incompletely but the central shrinkage of ingot decreases significantly, the grains are fine and uniform distribution, and the carbides in steel are more dispersed and fine ； the grain size at edge and center of ingot with cast iron mould process are respectively 40 ~ 57 μm and 55 ~ 62 μm and that with water-cooling copper mould process are respectively 30-40 μm and 50 μm.

摘要： 试验M2钢(/%:0.81C,0.31Si,0.33Mn,4.01Cr,4.57Mo,5.71W,1.77V)由实验室25 kg高频真空感应炉熔炼,并浇铸成横截面50 mm×100 mm钢锭。研究了水冷铜模和铸铁模浇铸的M2钢的低倍组织、晶粒尺寸和碳化物分布。结果表明,快速冷却可有效控制和消除M2钢铸锭中的柱状晶,随着冷却速率增大,M2钢铸锭部分气泡上浮不完全,但中心缩孔显著减小,晶粒更细小且分布更均匀,碳化物更加弥散且细小;铸铁模锭边缘和中心部分的晶粒尺寸分别为40~57μm用和55~62μm,而水冷铜模锭边缘和中心部分的晶粒尺寸分别为30~40μm和50μm。

关键词: M2高速工具钢, 冷却速率, 凝固, 低倍, 晶粒尺寸, 碳化物