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.