Sakae Takeuchi1 and Tsuneo Homma1
1The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai
The initiation and growth processes of fatigue cracks were examined microscopically on the specimens of pure metals at the final stage of fatigue. In the specimens under fatigue in air, many voids along the grain boundaries subjected to the repeated sliding were microscopically detected by means of electrolycal or chemical polishing, while in argon atmosphere, these voids were not observed. Macroscopically, fatigue cracks were nearly along the maximum shear stress direction for the specimen in argon atmosphere, while in air they were found in a direction deviated slightly from that mentioned above. The above mechanism is discussed in connection with the effects of air and argon atmospheres experimented.
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