Q620D钢板连续冷却相变行为和回火工艺

Continuous cooling transformation behavior and tempering process of Q620D steel plate

以Q620D高强度钢板为研究对象，利用热模拟试验机研究了Q620D钢板连续冷却相变规律，同时对比分析了不同回火工艺对钢板组织和性能的影响，确定了Q620D钢板最佳的轧制和热处理工艺。结果表明，采用控制轧制＋超快冷快速冷却＋回火工艺生产Q620D钢板时，钢板轧制后冷却速率不低于20℃／s，回火温度控制在550～600℃，钢板的强度和韧性匹配最佳。回火过程中位错的回复和消失、M／A岛状组织的分解、马氏体组织的转变和铌、钒等微合金元素的析出强化等共同影响Q620D钢板回火后的强度和低温冲击韧性。

In order to determine the best rolling and heat treatment processes, its phase transition laws in continuous cooling is studied by adopting a thermal simulation test machine, and the effect of different tempering processes on the organization and properties is also compared and analyzed. The results show that when the steel Q620D is made by adopting the process of controlled rolling ＋ ultra fast cooling ＋ tempering, the cooling speed is equal or greanter than 20 ~C/s after rolling, the tempering temperature is controlled within 550-600℃, then the mating of the strength and duc- tility is the best. The recovery and disappearance of dislocations, decomposition of M/A island structure, transition of Martensite structure, and separation of microalloying elements such as Nb and V commonly effect the strength after tem- pering and impact ductility at low temperature.