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A Study on Elevated Temperature Fatigue Crack Growth Using Round Bar Specimen with a Surface Crack

표면균열을 갖는 원형봉재 시편을 이용한 고온 피로균열성장 연구

  • Published : 1996.11.01

Abstract

The compact tension specimen geometry has been widely used for measuring fatigue crack growth rates at elevated temperature when the fatigue load is under tension/tension condition. However, most of the elevated temperature components which have significant crack growth life experience fatigue load under tension/compression conditions. Thus test techniques are required since the compact tension specimen cannot be used for tension/compression loading. In this paper, a simplified test procedure for measureing fatigue crack growth rates is proposed, which employs a round bar specimen with a small surface crack. Fatigue crack growth rates under tension/ tension loading conditions at elevated temperature were measured according to the proposed procedure and compared with those previously measured by C/(T) specimens. Since both the measured crack growth rates were comparable, the fatigue crack growth rates under tension/ compression load can be reliably measured by the proposed procedure. For monitoring crack depth. DC electric potential method is employed and an optimal probe location and current input conditions were proposed.

Keywords

Fatigue;Crak Growth;Surface Crack;DC Electric Potential Method;Round Bar Specimen;Cr-Mo Steel