Evaluation of the crystallographic fatigue crack growth rate in a single-crystal nickel-base superalloy

• Published in: International journal of fatigue Vol. 127; pp. 259 - 267
• Main Authors: Busse, C., Palmert, F., Sjödin, B., Almroth, P., Gustafsson, D., Simonsson, K., Leidermark, D.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2019; Elsevier BV
• Subjects: Collapse; Crack propagation; Crystallographic cracking; Crystallography; Data points; Fatigue crack growth rate; Fatigue cracks; Fatigue failure; Finite element analysis; Fracture mechanics; Fracture surfaces; Materials fatigue; Nickel; Nickel base alloys; Single crystals; Single-crystal nickel-base superalloys; Stress intensity factor; Superalloys; Three dimensional models; Fracture mechanics; Stress intensity factor; Single-crystal nickel-base superalloys; Finite element analysis; Fatigue crack growth rate; Crystallographic cracking
• ISSN: 0142-1123; 1879-3452; 1879-3452
• DOI: 10.1016/j.ijfatigue.2019.05.023

•Development of a method to evaluate the fatigue crack growth rate of crystallographic cracks in a single-crystal nickel-base superalloy.•Applicable to 3D models with arbitrary material orientation and crack front shapes.•Prediction of crystallographic fatigue crack growth rate.•Calibrated by laboratory tests.•Modeling of complex 3D crack geometries. Cracks in single-crystal nickel-base superalloys have been observed to switch cracking mode from Mode I to crystallographic cracking. The crack propagation rate is usually higher on the crystallographic planes compared to Mode I, which is important to account for in crack growth life predictions. In this paper, a method to evaluate the crystallographic fatigue crack growth rate, based on a previously developed crystallographic crack driving force parameter, is presented. The crystallographic crack growth rate was determined by evaluating heat tints on the fracture surfaces of the test specimens from the experiments. Complicated crack geometries including multiple crystallographic crack fronts were modelled in a three dimensional finite element context. The data points of the crystallographic fatigue crack growth rate collapse on a narrow scatter band for the crystallographic cracks indicating a correlation with the previously developed crystallographic crack driving force.