| 摘要 |
PROBLEM TO BE SOLVED: To provide a ring manufacturing method which enables the omission of heat treatment for softening and the suppression of abnormal grain growth on carburization.SOLUTION: A hollow cylindrical steel material made of case hardening steel is heated to a temperature of a recrystallization temperature of the steel material (T(°C)+50°C or more and 1100°C or less. Next, the heated steel material is rolled by ring roll under the condition of a diameter enlarging ratio of 130% or more and 400% or less, and a processing termination temperature of T(°C) or more and 1000°C or less to obtain a ring. Further, the ring after rolling termination is cooled so that the average cooling rate in a temperature interval of 750°C to 600°C is 0.1°C/s or more and 1.0°C/s or less. The ring may be treated by carburization after cooling. |
