Creep-Fatigue Crack Growth Behavior of Low Alloy Steel under Displacement-Controlled Conditions

Abstract

Abstract:A practical evaluation of crack growth lifetime using nonlinear fracture mechanics is needed for remaininglife assessment of high-temperature structural components after long-term service. In this study, creep-fatigue crack growth behavior under displacement-controlled conditions was examined using CT specimens on 2 1/4Cr-lMo steel. The J-integral estimation method and the crack growth prediction method using the fully plastic solution were also examined.Creep-fatigue crack growth under displacement hold could be separated into fatigue crack growth in the cyclic portion and creep crack growth in the holding portion. These two mechanisms were competitive with each other, and crack growth behavior was determined by the dominant mechanism of fatigue and creep. The f -integral approach using the fully plastic solution was introduced for predicting low cycle fatigue crack growth and creepfatigue crack growth with relaxation.The suitability of this solution was verified by comparing prediction with experimental data obtained via the slope-line-control method.

Prediction of crack growth in CrMoV cast steel after long-term service at high temperature

“…The authors have proposed a simplified prediction method based on fracture mechanics parameters under displacementcontrolled conditions [3,4]. In this method, J-integral and creep J-integral range are predicted by an elastic finites element method analysis and by reference to the stress-strain behavior of the material.…”

“…In this method, J-integral and creep J-integral range are predicted by an elastic finites element method analysis and by reference to the stress-strain behavior of the material. The applicability of this method to the displacement-controlled creep-fatigue condition has been examined using compact tension (CT) specimens, center cracked tension (CCT) specimens and perforated plates made from virgin 2.25Cr-1Mo steel [3,4,5].…”