| 摘要 |
PROBLEM TO BE SOLVED: To spheroidize a high-C-low-Cr steel stably and reduce the treatment time.SOLUTION: A method of producing a steel material includes a strain imparting step of introducing a true strain of 0.05 or larger and a spheroidization step consisting of a first-stage heat treatment and a subsequent second-stage heat treatment. (1) A programming rate for the first-stage heat treatment condition of lower than 400°C/h, a heating temperature of Apoint+10°C to Apoint+30°C and lower than 780°C, a heating retention time of 0.5-1 h, a cooling rate of 3°C/h or lower in the temperature range of Apoint to Apoint-20°C, and a cooling finishing temperature of Apoint-35°C or lower. (2) A programming rate for the second-stage heat treatment condition of lower than 400°C/h, a heating temperature of Apoint+5°C to Apoint+25°C and lower than 780°C, a heating retention time of 0.5-2 h, and a cooling rate of 5°C/h or lower in the temperature range of Apoint-15°C to Apoint-50°C. |
