| abstract |
Provided is a heat-treatment oil composition that makes it possible to achieve both high quenching hardness and reduced quenching distortion. A heat-treatment oil composition that includes a base oil (A) and a vapor film rupturing agent (B). The heat-treatment oil composition makes it such that, on a cooling curve obtained in accordance with the cooling performance test method in JIS K2242:2012, the time in seconds to 300°C, e.g., the cooling time from 800°C to 300°C, is less than 6 seconds. Component (B) includes a petroleum resin. |