摘要
使用砂漏型试样对高碳铬轴承钢的S-N曲线特性和破坏机理进行了研究。通过旋转弯曲疲劳试验获得的S-N曲线按照破坏模式的不同被划分为裂纹萌生位置不同的两组。一组叫做表面破坏模式的S-N曲线,它发生在高应力幅短寿命区,是由试样表面晶体滑移引起的。另一组叫做内部破坏模式的S-N曲线,它发生在低应力幅长寿命区,是由试样内部的非金属夹杂引起的。由于内部破坏模式的疲劳破坏发生在表面破坏模式的疲劳极限上下很宽的应力幅范围,因此,试验材料的S-N曲线的形状与通常报道的阶梯形状的S-N曲线的形状不同,它具有两条S-N曲线的特性。通过对断口上裂纹萌生位置的详细观察和裂纹萌生位置的初期尺寸参数的计算,阐述了内部破坏模式的破坏机理,提出了基于尺寸参数的超长寿命疲劳极限的推定方法。
According to fracture modes, the S-N curve obtained from cantilever-type rotary bending fatigue tests using bourglass shaped specimens of high carbon-chromium beating steel is clearly classified into two groups of different crack origin. One is called the S-N curve of surface fracture mode. It is governed by a crystal slip on the specimen surface, which occurs in the region of short fatigue life and high stress amplitude level. The other is caUed one of internal fracture mode. It is governed by nonmetallic inclusion at subsurface, which occurs in the region of long fatigue life and low stress amplitude. Because fatigue fractures of internal fracture mode occurs in a wide range of stress amplitude not only below the fatigue limit defined as the threshold of tincture due to the slip governed mode but also above the fatigue limit, the shape of the S-N curve for the material used in this study is different from a step-wise one reported in previous literature and is characterized as duplex S-N curves. Through the detailed observation of fatigue crack origin and calculation of crack initial size parameter, mechanisms for internal fracture mode are discussed and fatigue life prediction procedure is indicated based on crack initial size parameter.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2005年第10期143-148,152,共7页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(50471047
50323003)。
