| 摘要 |
PROBLEM TO BE SOLVED: To provide a hardening method and hardening device in which uniform rapid cooling is carried out in longitudinal direction and circumferential direction of steel pipe with a simple means to obtain steel pipe having excellent and uniform quality.SOLUTION: There is provided a hardening method for steel pipe, in which a seal member 4 is inserted into inner section of steel pipe over full length of a heated steel pipe 1, and a gap is arranged between the steel pipe and the seal member, from a nozzle 3 arranged with a gap from one end surface 5 of the steel pipe, cooling water 2 is jetted at jet flow rate of V(m/second), while a part of cooling water is leaked from the gap between the nozzle and the steel pipe, remaining cooling water is introduced into the gap between the seal member and the steel pipe to leak it from the other end surface 7 at leakage flow rate of V(m/second) in order to realize V<V.SELECTED DRAWING: Figure 1 |
