The effect of dwell times and minimum temperature on out-of-phase thermomechanical fatigue crack propagation in a steam turbine steel—Crack closure prediction. (September 2022)

• Record Type: Journal Article
• Authors: Azeez, Ahmed; Eriksson, Robert; Norman, Viktor; Leidermark, Daniel; Moverare, Johan
• Is Part Of: International journal of fatigue. Volume 162(2022)
• Publication Date: 2022-09
• Subjects: Thermomechanical fatigue -- Fatigue crack growth -- High temperature steel -- Crack closure -- Numerical modelling; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2022.106971
• Languages: English
• ISSNs: 0142-1123

Abstract

Abstract: Exploring crack growth behaviour is needed to establish accurate fatigue life predictions. Cracked specimens were tested under strain-controlled out-of-phase thermomechanical fatigue conditions. The tests included dwell times and three different minimum temperatures. Higher minimum temperature gave faster crack growth rates while the additions of dwell times showed no effects. Crack closure was observed in all the tests where the addition of dwell times and change in minimum temperature displayed little to no effect on crack closure stresses. Finite element models with a sharp stationary crack and material parameters switching provided acceptable predictions for the maximum, minimum, and crack closure stresses. Highlights: Strain-control out-of-phase thermomechanical fatigue (OP-TMF) crack growth testing. Crack growth rates increase with higher minimum temperature, no effects from dwell. Crack closure in all OP-TMF tests, no influence from minimum temperature or dwell. Accounting for crack closure collapses crack growth rates on isothermal tests. Crack closure stresses prediction using improved 3D FE model with stationary crack.