中碳非调质钢的高周疲劳性能

来源期刊：钢铁2011年第2期

论文作者：惠卫军 董瀚 翁宇庆

文章页码：1 - 6

关键词：中碳非调质钢； 高周疲劳性能； 微观组织； V元素； 洁净度

Key words：medium-carbon microalloyed forging steel； high-cycle fatigue property； microstructure； vanadium； cleanliness

摘    要：非调质钢常用来代替调质钢制造用于疲劳设计的运动部件,因而改善其疲劳性能十分重要。对于铁素体-珠光体型非调质钢,由于存在软相铁素体,其疲劳裂纹基本上萌生于试样表面的铁素体/珠光体边界,并优先沿着该边界扩展。因此,强化铁素体、改善铁素体的分布状态和组织细化是改善其疲劳性能的关键。研究结果证实,具有粗大网状铁素体-珠光体组织或粗大贝氏体组织的非调质钢的疲劳性能较差,而具有细小、均匀的铁素体-珠光体组织的非调质钢则具有良好的疲劳性能。在热锻态,微合金化元素V因具有明显的析出强化和组织细化作用而能够明显地改善铁素体-珠光体型非调质钢的疲劳性能。与回火马氏体组织不同,氧含量对铁素体-珠光体组织的疲劳性能没有明显的影响。总之,组织精细控制的铁素体-珠光体型非调质钢的疲劳性能可达到调质钢的水平。

Abstract: It is demanded to improve the fatigue properties of medium-carbon microalloyed forging steels which are increasingly used to replace conventional quenched and tempered(QT) medium-carbon steels for the manufacture of fatigue design components.For ferrite-pearlite steel,owing to the existence of soft phase of ferrite,it was revealed that fatigue crack preferentially initiated and propagated along the ferrite/pearlite boundary in the early stage of fatigue crack propagation.Therefore,the fatigue property of ferrite-pearlite microalloyed forging steel could be improved by increasing ferrite strength through precipitation strengthening and controlling the distribution of ferrite and refining microstructure.Further investigation showed that ferrite-pearlite steel with film-like ferrite along coarse prior austenite grain boundary and pearlite microstructure or coarse bainite microstructure had lower fatigue property.However,ferrite-pearlite steel with much fine and uniform ferrite and pearlite microstructure had higher fatigue property.Microalloying element V can significantly improve the fatigue properties of ferrite-pearlite steel mainly through precipitation strengthening and grain refining mechanism in as-forged condition.Unlike that of tempered martensite structure,there was little effect of oxygen content on the fatigue properties of ferrite-pearlite steel.In conclusion,the fatigue properties of microstructure carefully controlled ferrite-pearlite steel could be as high as that of QT steel.