25CrMo4钢先共析铁素体转变及其对力学性能的影响

Transformation of Proeutectoid Ferrite and Its Effect on Mechanical Property of 25CrMo4 Steel

通过将奥氏体化后的25CrMo4钢在Ar3下不同温度保温一定的时间,以观察铁素体的析出规律,结果表明:在675～740℃温度区间等温,随着温度的降低,铁素体析出速度加快.在675℃保温时,获得2%～3%,5%～8%,10%～15%铁素体量的保温时间分别是70 s,120 s和240 s.对不同铁素体含量样品进行冲击、拉伸试验进行分析表明,当铁素体量在11%以内,25CrMo4钢的抗拉强度、屈服强度基本相同,冲击韧性在铁素体量少于5%时也基本一致,但当铁素体含量达到11%时则降低.

25CrMo4 is austenitized at 920℃ for 30min and then isothermal transformation below Ar3 at different preserved temperatures for a certain time to observe the regulation of the detachment of ferrite from austenite.The result shows that when preserved between 675～740℃,as the temperature decreases,the speed of the detachment will become faster;when preserved at 675℃,2～3%,5～8% and 10～15vol.% of ferrite are obtained under for the holding time of 70 s,120 s and 240 s respectively.Tensile test shows that when the amount of ferrite is less than 11%,the tensile strength and the yield atrength are basically the same,and the impact ductility is also unchanged when the amount of ferrite is lower than 5%,but it will decrease when the amount of ferrite is 11%.