A study on fatigue crack growth with loading waveform and analysis method for all loading waveform at elevated temperature in SUS 304 stainless steel

J. Ocean Eng. Technol. 1992;6(1):122-130.

SUS 304강의 하중파형에 따른 고온피로균열전파속도 및 전체하중파형의 평가방법의 연구

이상록,이학주,허정원,임만배

한국기계연구소 재료강도실,동아대학교 기계공학과,동아대학교 기계공학과,동아대학교 기계공학과

Keywords: loading waveform, elevated temperature low cycle fatigue, asymmetrical waveform, trapezoidal waveform, crack growth rate, modified J-integral

핵심용어: 하중파형, 고온저사이클피로, 비대칭파형, 사다리꼴파형, 크랙성장속도, 수정J적분

Abstract

The effect of loading waveform on elevated temperature low-cycle fatigue crack growth behavior in a SUS 304 stainless steel have been investigated under symmetrical trangular (fast-fast), trapezoidal and asymmetrical(fast-slow, slow-fast) waveforms at 650.deg. C. It was found that the crack growth rate in fast-slow loading waveform appeared to be higher a little and the crack growth rate in slow-fast loading waveform much higer than that in fast-fast loading waveform, and difference in crack growth rate between fast-show and slow-fast waveforms nearly didn't appear in the region of da/dN>10/sup -2/ The crack growth rate in the trapezoidal loading waveform with t/sub h/=500sec appeared to be faster than that in slow(500sec)-fast(1sec). In addition, parameter modified J-integral could be considered as useful parameter for fatigue crack growth rate in all waveforms. The result obtained are as follow. da/dN=4.91*10/sup -3/ (.DELTA. J/sub c/)/sup 0.565/.