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大型锻件普遍采用的预处理工艺的特点是生产周期很长,导致炉子的生产率低和燃料大量消耗。新的预处理工艺是在38xH3φA型钢的等温转变图和热动力学图以及这种处理的整个循环过程中实际温度场所确定的结果的基础上制订的。知道了截面任何地方的冷却速度,就可以按照图确定奥氏体转变的温度范围。也可以在已知的截面上冷却后确定所获得的组织和性能。 38ЖНМФА型钢的转变的图把珠光体转变区和贝氏体转变区分开,且过冷奥氏体在珠光体转变区非常稳定。在珠光体转变区的640～660℃处,过冷奥氏体最不稳定,且其转变量为50％,仍需要12.5小时。而在贝氏体转变区(300～320℃),其转变量
The pre-treatment process commonly used in large forgings is characterized by long production cycles leading to low furnace productivity and heavy fuel consumption. The new pretreatment process was developed on the basis of isothermal transformation diagrams and thermodynamic diagrams of 38xH3φA steel and the results obtained from the actual temperature field during the entire cycle of this treatment. Knowing the cooling rate anywhere in the cross-section, the temperature range for austenite transformation can be determined as shown. The obtained structure and properties can also be determined after cooling on a known cross-section. The diagram of the transformation of the 38ЖНМФА section separates the pearlite transformation from the bainitic transformation and the supercooled austenite is very stable in the pearlite transformation. In the pearlite transformation zone of 640 ~ 660 ℃, the most unstable supercooled austenite, and the amount of change of 50%, still need 12.5 hours. In the bainite transformation zone (300 ~ 320 ℃), the amount of change