| 摘要 |
A process for producing a steel material which includes 30-minute or longer holding at the pearlite nose transformation completion point. In the process for steel material production, process annealing (3) is conducted between preceding-step hot working (1) and subsequent-step hot working. In the process annealing (3), a semi-product steel material (4) after completion of the preceding-step hot working is introduced into a heat-maintaining tank (7) to cause the steel material to recuperate heat and the semi-product steel material is kept for 30 minutes or longer at a temperature in the range of (pearlite nose transformation completion point)Œ20‹C by means of the transformation latent heat thereof to thereby transform the semi-product steel material into pearlite. Preferably, the semi-product steel material introduced into the heat-maintaining tank is kept for 2 hours or longer at a temperature in the range of (pearlite nose transformation completion point)Œ20‹C. The steel material can be regulated so as to have a hardness after the process annealing of 300 HB or lower. ® KIPO & WIPO 2009
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