| The effects of static stress and dynamic stress on hardenabilty and grain growth in medium carbon steel were investigated. Carbon steel bars were normalized at 925℃-1hr in order to eliminate the segregation of solute atoms and to relieve the residual stress, and then pre-strained in the range of 0 to 3.3%. Jominy bars were prepared for ø l"×L4". In order to observe pre-structure before quenching, grain growth with time was investigated at 800℃, 850℃, 900℃. Jominy end-quenching test was undertaken at constant cooling velocity. Hardenability was enhanced with increasing static stress. Activation energy for grain growth with static stress and dynamic stress was investigated. Austenite grain growth was much more accelerated with increasing static stress and dynamic stress. Grain growth exponent, ｎ was compared with static stress and dynamic stress. That value under dynamic stress was much more bigger than that under static stress. |
|
