道次间冷却工艺下EH47船板钢表层往复相变行为的研究

针对表层细晶船板钢的研制，采用热模拟试验模拟道次间冷却工艺下EH47船板钢表层“冷却 返红”过程中的往复相变行为，研究了不同类型低温相变组织在升温过程中的相变行为。结果表明，随低温相变组织中贝氏体体积分数的增大，升温奥氏体化温度逐渐降低；随低温组织中马氏体体积分数的增大，升温奥氏体化温度显著提高且相变时间延长。随冷却速率的提高，升温相变后奥氏体组织细化且均匀性提高。当低温组织为粒状贝氏体时，随升温过程的进行，在相变初始阶段相变较慢，当温度高于770 ℃时，奥氏体相变速度剧烈提高，并在830 ℃完成相变。

Phase transformation behavior in surface layer of EH47 heavy plate in interpass cooling process

In view of development of surface fine grain plate,the cyclic phase transformation behavior in surface layer of EH47 ship plate rolled by using interpass cooling process was studied on the thermal simulator.The results show that austenitizing temperature is decreased with the volume fraction of bainite increasing in the microstructure.Austenitizing temperature is increased and phase transformation time was prolonged with the volume fraction of martensite increasing in the microstructure.As the cooling rate increasing,austenite microstructure become finer and more uniform after the reheating phase transformation.When the low temperature structure is granular bainite,the phase transition is slower in the initial phase of the transformation with the temperature rise process.When the temperature is higher than 770 ℃,the austenite transformation speed increases sharply,and the phase transformation is completed at 830 ℃.