| 摘要 |
<p>PURPOSE:To produce a cast iron part having a high-hardness hardened structure and having relatively excellent toughness by heating the cast iron part to a prescribed temp., then air-cooling the part, and quenching the part at a temp. immediately above the martensitic transformation point. CONSTITUTION:The cast iron part is high-frequency-heated to a prescribed temp. higher than the austenitic transformation point, kept at that temp. for a fixed time, then air-cooled (d) from the temp. P immediately above the martensitic transformation point, and then tempered as shown by the pattern (e). The pearlite and troostite having relatively high toughness are deposited by the air cooling, the untransformed structure is transformed into stabilized martensite by the quenching from the temp. immediately above the martensitic transformation point, retained austenite is not left, and a cast iron part free of grinding cracks can be obtained.</p> |
