The Effects of Cooling Holes on the Creep Life in a Modeling Specimen of Single Crystal Air-Cooled Turbine Blade

2011 ◽  
Vol 284-286 ◽  
pp. 1678-1683 ◽  
Author(s):  
Da Shun Liu ◽  
Bai Zhi Wang ◽  
Zhi Xun Wen ◽  
Zhu Feng Yue
Keyword(s):  
Single Crystal ◽  
Turbine Blade ◽  
Damage Model ◽  
Creep Damage ◽  
Creep Life ◽  
Damage Development ◽  
User Subroutine ◽  
Initial Rupture ◽  
Creep Deformations ◽  
Sem Analyses

This paper presents the study of the influences of cooling holes on the creep life behavior in the modeling specimen of single crystal cooling turbine blade at high temperature. Thin-walled cylindrical specimens with holes are tested to model the air-cooled turbine blade. Specimens without holes are also studied to make comparisons. Experimental results show that at 900°C, the creep lives of specimens with holes are longer than those of specimens without holes. Scanning Electron Microscopy (SEM) analyses reveal that creep deformations occur firstly around the cooling holes and finally rupture at the region with low stress and strain. Finite element analyses are used to study the creep damage development by a K-R damage model which has been implemented into the Abaqus user subroutine (UMAT). Simulation results show that stress concentration and redistribution occur around the cooling holes during the creep development. It is also shown that the maximum strain and stress are around the cooling holes which are the initial rupture region in the experiments.

scholarly journals Creep Damage Repair of a Nickel-Based Single Crystal Superalloy Based on Heat Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 623
Author(s):  
Xiaoyan Wang ◽  
Meng Li ◽  
Yuansheng Wang ◽  
Chengjiang Zhang ◽  
Zhixun Wen
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Creep Damage ◽  
Primary Creep ◽  
Single Crystal Superalloy ◽  
Secondary Creep ◽  
Creep Life ◽  
Phase Coarsening ◽  
Damage Repair ◽  
Creep Time

Taking nickel-based single crystal superalloy DD6 as the research object, different degrees of creep damage were prefabricated by creep interruption tests, and then the creep damage was repaired by the restoration heat treatment system of solid solution heat treatment and two-stage aging heat treatment. The results show that with the creep time increasing, the alloy underwent microstructure evolution including γ′ phase coarsening, N-type rafting and de-rafting. After the restoration heat treatment, the coarse rafted γ′ phase of creep damaged specimens dissolved, precipitated, grew up, and became cubic again. Except for the specimens with creep interruption of 100 h, the γ′ phase can basically achieve the same arrangement as the γ′ phase of the original sample. The comparison of the secondary creep test shows that the steady-state creep stage of the test piece after the restoration heat treatment is relatively increased, and the total creep life can reach the same level as the primary creep life. The high temperature creep properties of the tested alloy are basically recovered, and the restoration heat treatment effect is good.

A Novel and Simple Approach for Predicting Creep Life Based on Tertiary Creep Behavior

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Khosrow Zarrabi ◽  
Lawrence Ng
Keyword(s):  
Gas Turbines ◽  
Damage Model ◽  
Creep Damage ◽  
Life Assessment ◽  
Advanced Technology ◽  
Creep Life ◽  
Practical Applications ◽  
Damage Models ◽  
Multiaxial Creep ◽  
Creep Damage Model

The creep of materials is a research topic of major significance in the life assessment and design of many modern engineering components of advanced technology such as power generation plant, chemical plant, gas turbines, jet engines, spacecrafts, and components made of plastics and polymers. To predict the creep life of such components, one necessary ingredient is a creep damage model. The current creep damage models are either too cumbersome to be readily employed and/or not sufficiently accurate for practical applications. This paper describes a new multiaxial creep damage model that alleviates the major shortcomings of the existing models. Yet it is relatively simple and accurate and is readily applicable to industrial cases.

scholarly journals Numerical Simulation of Creep Damage and Life Prediction of Superalloy Turbine Blade

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Donghuan Liu ◽  
Haisheng Li ◽  
Yinghua Liu
Keyword(s):  
Creep Strain ◽  
Turbine Blade ◽  
Life Prediction ◽  
Damage Model ◽  
Prediction Method ◽  
Creep Damage ◽  
Model Material ◽  
Life Assessment ◽  
Damage Effect ◽  
Superalloy Turbine Blade

Creep caused failure is an important failure mode of the turbine blade. A numerical approach of life assessment of the superalloy turbine blade is proposed in the present paper based on the Lemaitre-Chaboche creep damage model. Material damage is introduced into each element based on the ANSYS APDL function, and the creep damage effect is considered through the modification of Young’s modulus. At last, the strength life and stiffness life of the blade can be obtained through the maximum damage and maximum creep strain criterion, respectively. The present method can not only consider the effect of creep damage, but also give the time histories of the element stresses, damage, and creep strain. The above life prediction results based on the proposed method are compared with theθprojection method, and the results suggest that the present life prediction method of turbine blade is feasible and turbine blade’s life in the present study is determined by creep fracture rather than creep deformation.

A Novel and Simple Approach for Predicting Creep Life Based on Tertiary Creep Behaviour

2006 ◽  
Author(s):  
Khosrow Zarrabi ◽  
Lawrence Ng
Keyword(s):  
Gas Turbines ◽  
Creep Behaviour ◽  
Damage Model ◽  
Creep Damage ◽  
Life Assessment ◽  
Creep Life ◽  
Practical Applications ◽  
Damage Models ◽  
Multiaxial Creep ◽  
Creep Damage Model

The creep of materials is a research topic of major significance in the life assessment and design of many modern engineering components of advance technology such as: power generation plant, chemical plant, gas turbines, jet engines, spacecrafts, components made of plastics and polymers, etc. To predict the creep life of such components, one necessary ingredient is a creep damage model. The current creep damage models are either too cumbersome to be readily employed and/or not sufficiently accurate for practical applications. This paper describes a new multiaxial creep damage model that alleviates the major shortcomings of the existing models yet it is simple and accurate enough to be readily applicable to industrial cases.

An Integrated Welding and Damage Model for Practical Prediction of Creep Life in Welded P91 Alloy

2016 ◽  
Author(s):  
Mahyar Asadi ◽  
Jun Zhao ◽  
Leijun Li
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
Damage Model ◽  
Creep Damage ◽  
Operating Conditions ◽  
Welding Residual Stress ◽  
Creep Life ◽  
Wide Range ◽  
Actual Service ◽  
Service Conditions

Loss of creep resistance in post-weld P91 alloy occurs mainly due to the change in microstructure particularly in the heat-affected zone under actual service operating conditions as well as residual stress from the welding process that is not often properly addressed in many damage models. In this paper, a validated deformation mechanisms map (DMM) using low temperature creep strain accommodation processes i.e. GBS, is used for the P91 alloy that predicts the creep rates over a wide range of temperature and stress including those arising under in the actual service conditions. These creep rates are further utilized into a microstructure-based creep damage model for accurate life prediction. A 3D transient computational welding mechanics (CWM) modeling of a pipe in a super-critical water loop, predicts the thermal, microstructure and stress state from welding. It also determines the coarse and fine grain heat affected zone (CGHAZ & FGHAZ). The CWM results are coupled with physics-based creep damage modeling to practically predict the creep life under the actual service conditions considering the welding residual stress and microstructure states.

Reliability Study for Creep Life of Single Crystal Turbine Blade under Random Crystal Orientations and Random Loads

2010 ◽  
Vol 139-141 ◽  
pp. 1005-1009
Author(s):  
Zong Zhan Gao ◽  
Zhu Feng Yue
Keyword(s):  
Single Crystal ◽  
Turbine Blade ◽  
Moment Method ◽  
Creep Life ◽  
Element Analysis ◽  
Random Loads ◽  
Crystal Orientations ◽  
Single Crystal Turbine Blade ◽  
The Finite Element Analysis ◽  
Mean Time

For the single crystal (SC) Ni-based superalloys, it is difficult to avoid orientation variation along airfoil stacking line of the SC turbine blade. At the mean time, the loading of turbine blade is uncertainly during the working. In this work, the creep life of the SC turbine blade is determined by the finite element analysis (FEA) based on the crystal slip theory. The orientation variations are measured based larger numbers commercial turbine blade made of SC superalloys. Furthermore, Monte-Carlo method and the forth moment method are presented to analysis the reliability for creep life of SC turbine blade under random crystal orientations and random loads based on the FEA method. The basic variables sensitivity are comprehensively analyzed by the forth moment method.

Effects of microstructure and lattice misfit on creep life of Ni-based single crystal superalloy during long-term thermal exposure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenyan Gan ◽  
Hangshan Gao ◽  
Haiqing Pei ◽  
Zhixun Wen
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Precipitation Amount ◽  
Lattice Misfit ◽  
Thermal Exposure ◽  
Phase Evolution ◽  
Creep Rupture ◽  
Simultaneous Increase ◽  
Creep Life ◽  
The Matrix

Abstract According to the microstructural evolution during longterm thermal exposure at 1100 °C, the creep rupture life of Ni-based single crystal superalloys at 980 °C/270 MPa was evaluated. The microstructure was characterized by means of scanning electron microscopy, X-ray diffraction and related image processing methods. The size of γ’ precipitates and the precipitation amount of topologically close-packed increased with the increase in thermal exposure time, and coarsening of the γ’ precipitates led to the simultaneous increase of the matrix channel width. The relationship between the creep rupture life and the lattice misfit of γ/γ’, the coarsening of γ’ precipitate and the precipitation of TCP phase are systematically discussed. In addition, according to the correlation between γ’ phase evolution and creep characteristics during thermal exposure, a physical model is established to predict the remaining creep life.

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