Residual principal stresses and crack propagation direction on fatigue fractured surface
Kodama Shotaro; Ishizuka Hiromichi; Satoh Yasuo; Akita Koichi; Suzuki Hideji; Saito Takeyuki
Abstract:X-ray fractography is a technique for analyzing the cause of fractures through the information obtained by irradiating X-ray on the fractured surface. The residual stresses or full widths at half maximums are usually used as the information. This technique is a useful tool for fracture analysis, since the quantitative loading condition etc. can be estimated. X-ray fractography is used in various countries alongside the electron-microscope fractography. In the previous paper, X-ray fractography has been applied to actual size four `Shinkansen (bullet train)' axles tested at the railway Technology Research Institute. The axles are about 200 mm in diameters, induction hardened 0.38% carbon steel with semi-elliptical artificial flaw. X-ray stress measurements were carried out on the fractured surface along the line from the bottom of the artificial flaws to the axle center at intervals of 5 mm. All the results showed that the residual stress on the fractured surface were tensile at the initial crack propagation region, increased to tensile maximums, decreased into compression reaching at the compressive maximums then went up toward zero stress near the final fractured surface.