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为探究奥氏体化温度和冷却速率对40Cr钢球化过程的影响,采用双相区球化退火研究了热轧态40Cr钢的球化退火行为和力学性能.奥氏体化温度从760℃提高到800℃,冷却速率从10℃·h-1上升到30℃·h-1,组织硬度随冷却速度呈V形变化,碳化物球化率随冷却速度变化正好与前者相反.奥氏体化温度为760℃,冷却速率为20℃·h-1所得到的球化组织球化率高,且碳化物细小,具有良好的冷成形性能,可大幅度缩短球化退火时间,显著提高生产效率.提出了球化退火过程中离异共析转变机制,控制好球化过程中奥氏体化温度、冷却速率及保温时间有利于离异共析转变的发生.
In order to investigate the effect of austenitizing temperature and cooling rate on the spheroidization of 40Cr steel, the spheroidizing annealing behavior and mechanical properties of hot-rolled 40Cr steel were studied by two-phase zone spheroidizing annealing.The austenitizing temperature ranged from 760 ℃ When the cooling rate increased from 10 ℃ · h-1 to 30 ℃ · h-1, the hardness of the microstructure changed V-shape with the cooling rate, and the rate of carbide spheroidization changed with the cooling rate just as the former. When the temperature is 760 ℃ and the cooling rate is 20 ℃ · h-1, the spheroidization rate of the spheroidized structure is high, and the carbide is fine with good cold formability, which can greatly shorten the spheroidizing annealing time and significantly increase the production Efficiency.It is proposed that the transformation mechanism of eutectic eutectoid transformation during spheroidizing annealing and the control of the austenitizing temperature, the cooling rate and the soaking time in the process of spheroidization are favorable to the occurrence of dissociation eutectoid transformation.