Modelling the crack growth behaviour of a single crystal nickel base superalloy under TMF loading with long dwell times. (March 2021)

• Record Type: Journal Article
• Authors: Palmert, Frans; Almroth, Per; Gustafsson, David; Loureiro-Homs, Jordi; Saxena, Ashok; Moverare, Johan
• Is Part Of: International journal of fatigue. Volume 144(2021)
• Publication Date: 2021-03
• Subjects: Single crystal superalloy -- Creep -- Fatigue -- TMF -- Dwell -- Crack growth; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2020.106074
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: The influence of hold time on IP-TMF crack growth is evaluated for an SX superalloy. The creep crack growth rate da/dt displays a strong correlation with Ct . The relationship between da/dt and Ct is temperature independent. A superposition model based on Ct and ΔKeff successfully describes the overall da/dN . The model was fitted to isothermal tests and yields accurate predictions for IP-TMF. Abstract: The influence of hold time on the crack growth behaviour of a single crystal nickel base superalloy under in-phase thermomechanical fatigue is investigated. Two da/dt models were calibrated using creep crack growth tests in the temperature range 750–950 °C: one based on K and the other on ( Ct )avg . The models were applied, in combination with a cycle dependent model, to predict da/dN of in-phase thermomechanical fatigue crack growth tests with 1–6 h hold time. The predictions based on K were inaccurate and generally non-conservative, whereas the predictions based on ( Ct )avg were accurate. da/dt vs ( Ct )avg followed a single trendline for all temperatures.