Creep-fatigue behavior of turbine disc of superalloy GH720Li at 650 °C and probabilistic creep-fatigue modeling

Abstract Creep-fatigue experiments have been conducted in nickel-based superalloy GH720Li at an elevated temperature of 650 °C with a stress ratio of 0.1, based on which, different dwell times at the maximum loading were applied to investigate the effect of dwell time on the creep-fatigue behaviors. The tested specimens were cut from the rim region of an actual turbine disc in the hoop direction. The grain size and precipitates of the GH720Li superalloy were examined through scanning electronic microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses. Experimental data shows creep-fatigue lifetime decreases as the dwell time prolongs. Further, different scattering was observed in the creep-fatigue lifetime at different dwell times. Then a probabilistic model based on the applied mechanical work density (AMWD), with a linear heteroscedastic function that evaluates the non-constant deviation in the creep-fatigue lifetime, was formulated to describe the dependence of creep-fatigue lifetime on the dwell time. Finally, the possible microscopic mechanism of the creep-fatigue behavior has been discussed by SEM with EDS on the fracture surfaces.

[1]  C. Jaske.  Life Prediction in High-Temperature Structural Materials , 1995 .

[2]  J. Mendez,et al.  Creep–fatigue behavior at high temperature of a UDIMET 720 nickel-base superalloy , 2010 .

[3]  Sankaran Mahadevan,et al.  Reliability analysis of creep-fatigue failure , 2000 .

[4]  Dianyin Hu,et al.  Experimental Investigation of Fatigue Crack Growth Behavior of GH2036 Under Combined High and Low Cycle Fatigue , 2016 .

[5]  Dianyin Hu,et al.  Probabilistic design for turbine disk at high temperature , 2011 .

[6]  J. Cormier,et al.  Relationships between Microstructural Parameters and Time-Dependent Mechanical Properties of a New Nickel-Based Superalloy AD730™ , 2015 .

[7]  L. Rémy,et al.  Oxidation-assisted creep damage in a wrought nickel-based superalloy: Experiments and modelling , 2010 .

[8]  Vikas Kumar,et al.  Simultaneous creep–fatigue damage accumulation of forged turbine disc of IN 718 superalloy , 2013 .

[9]  Jiang Fan,et al.  Probabilistic damage tolerance analysis on turbine disk through experimental data , 2012 .

[10]  Tarun Goswami,et al.  Development of generic creep–fatigue life prediction models , 2004 .

[11]  Yiu-Wing Mai,et al.  A unified equation for creep-fatigue , 2014 .

[12]  Vikas Kumar,et al.  A novel test method to study the simultaneous creep–fatigue interaction , 2012 .

[13]  Zhenzhou Lu,et al.  Reliability analysis for low cycle fatigue life of the aeronautical engine turbine disc structure under random environment , 2005 .

[14]  W. Nelson.  Statistical Methods for Reliability Data , 1998 .

[15]  A. Nussbaumer,et al.  Microstructural influence on the scatter in the fatigue life of steel reinforcement bars , 2015 .

[16]  E. Silveira,et al.  Influence of the level of damage on the high temperature fatigue life of an aircraft turbine disc , 2009 .

[17]  M. Fu,et al.  Competition between work-hardening effect and dynamic-softening behavior for processing as-cast GH4720Li superalloys with original dendrite microstructure during moderate-speed hot compression , 2015 .

[18]  Kamran Nikbin,et al.  Deterministic and probabilistic creep–fatigue–oxidation crack growth modeling , 2013 .

[19]  Tarun Goswami,et al.  Low cycle fatigue life prediction—a new model , 1997 .

[20]  Hong-Zhong Huang,et al.  An efficient life prediction methodology for low cycle fatigue–creep based on ductility exhaustion theory , 2013 .

[21]  M. Shen,et al.  Creep-Fatigue Life Prediction and Reliability Analysis of P91 Steel Based on Applied Mechanical Work Density , 2014, Journal of Materials Engineering and Performance.

[22]  R. Reed,et al.  Heat treatment of UDIMET 720Li: the effect of microstructure on properties , 1999 .

[23]  Rongqiao Wang,et al.  Experimental study on creep–fatigue interaction behavior of GH4133B superalloy , 2009 .

[24]  Jian-xin Dong,et al.  The hot deformation behaviors of coarse, fine and mixed grain for Udimet 720Li superalloy , 2016 .

[25]  Z. Jiao,et al.  Effect of dwell time on creep-fatigue life of a high-Nb TiAl alloy at 750 °C , 2015 .

[26]  Xiaoyong Zhang,et al.  Probabilistic analysis for the functional and structural fatigue of NiTi wires , 2016 .

[27]  Dianyin Hu,et al.  Life Assessment of Turbine Components Through Experimental and Numerical Investigations , 2013 .

[28]  Sayan Gupta,et al.  Probabilistic damage estimation in piping components against thermal creep and fatigue , 2014 .

[29]  Hong-Zhong Huang,et al.  A generalized energy-based fatigue–creep damage parameter for life prediction of turbine disk alloys , 2012 .