高温フレッティング疲労強度のショットピーニングによる改善

概要

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Fretting fatigue tests at elevated temperature were carried out using shot-peened specimens of 12Cr-Mo-W-V steam turbine steel. The shot peening process increased the fretting fatigue strengths by a factor of 1.8 at an elevated temperature (773K) as well as at room temperature. This is mainly due to the compressive residual stress induced by shot peening. In order to investigate the effectiveness of shot peening for long-term practical use, the fretting fatigue tests of the specimens shot-peened and subsequently exposed for long periods up to 30000hrs at 773K were carried out. Although the compressive residual stress was reduced by a factor of 3 after this process, the fretting fatigue strength at 773K increased by a factor of 1.8. The effectiveness of the shot peening was found for long-period practical use at 773K. Prediction of fretting fatigue lives was made on the basis of elastic-plastic fracture mechanics, where the compressive residual stress by shot peening and the frictional force between the fretting pad and the specimen were taken into consideration. The predicted lives were in good agreement with the experimental results.
一般社団法人日本機械学会の論文
1990-08-25