It relates to a high strength easy cutting cast iron based on MT 200 (HT20-40) with silicon carbon ratio raising from 0.4-0.5 to 0.64-0.9, manganese content reducing from 0.8-1.2% to 0.5-0.8% and inoculation before casting being subjected to the hardness of cast parts on surface is lower than that in the center, the metallographical organization of its surface within 0.5-1.5 mm depth is 30-39% ferrite and point-shaped graphite and at its center part is over 90% of pearlite. Thus it achieves casting hardness dropping to HB 160-210 along with strength increasing. It has good cutting behavior and is suitable for mass prodn. of small cast parts with wall thickness of not over 50 mm. |