高强度钢54SiCrV6超高周疲劳研究

介绍了用2万Hz超声波振动疲劳试验机对高强度钢54SiCrV6的超高周（10亿周）疲劳强度研究，结果发现，该种材料的高周直到超高周区间，疲劳强度随材料寿命的加大呈明显减小，即S－N曲线呈明显下降，这一结果与传统的假说完全不同。传统的假说认为该区间的疲劳强度为水平渐近线或为一定值，本文建议该种材料的高周及超高周区间疲劳强度用延长线代替水平渐近线，并给出实际结果与传统假说间差别，借助于电子显微镜对试件微观组织的观察及对引起疲劳破坏起始处进行化学分析，发现这种材料的寿命在10^7周附近疲劳机理出现突变，即小于10^7周的试件的初始疲劳裂纹在表面，达到10^7周附近的 件的初始疲劳裂纹在内部，并发现试件的断裂有些是由于其中心有钙化物等杂质，另一些则是由于材料内部空洞引起。

Gigacycle fatigue of high strength steel 54SiCrV6

An attempt has been made to characterize gigacycle (10 10 cycles) fatigue behavior of high strength spring steel (54SiCrV6) wire by means of an ultrasonic frequency of 20 kHz fatigue test and analytical techniques. The fatigue strength of the steel wires in gigacycle cycles was determined at a load ratio R=-1. The experimental results show that fatigue rupture can occur and the fatigue endurance stress continues to decrease with increasing number of cycles between 10 6 and 10 10 cycles. This result is much different from conventional hypothesis. The differences between conventional hypothesis and test results are presented. The extension line of low-cycle fatigue strength can be used as fatigue strength of gigacycle in stead of horizontal asymptotic. Observations of the fracture section were made by using Scanning Electron Microscopy (SEM) and chemical analyses were made with special instruments. The fatigue rupture mechanism of gigacycle of high strength steel is discussed.