Service damage mechanism and interface cracking behavior of Ni-based superalloy turbine blades with aluminized coating

2021 ◽  
pp. 106500
Author(s):  
Lei Han ◽  
Haiqiu Shi ◽  
Min Tao ◽  
Chengwei Fei ◽  
Yan Hu ◽  
...  
Keyword(s):  
Turbine Blades ◽  
Damage Mechanism ◽  
Cracking Behavior ◽  
Interface Cracking

Rejuvenation Heat Treatment of Single Crystal Gas Turbine Blades

2017 ◽  
Author(s):  
J. Kuipers ◽  
K. Wiens ◽  
B. Ruggiero
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Damage Mechanism ◽  
Operating Conditions ◽  
Gas Turbine Blades ◽  
Full Solution ◽  
Fatigue Endurance ◽  
Root Surfaces

Thermal degradation of precipitation-hardened nickel based superalloys has been demonstrated to be reversible through full solution rejuvenation heat treatment processing. The specific concern with full solution rejuvenation heat treatment of single crystal alloys is the formation of recrystallized grains on surfaces with residual stress. The threshold temperature for recrystallization and the effect of heat treatment temperature and time on recrystallization depth were evaluated on service run industrial gas turbine blades comprised of nickel based single crystal alloys René N5 and RR2000. Recrystallization of rejuvenated blades was observed on the root surfaces of blades which had been shot peened at original manufacture and/or during a prior repair. Blades which did not receive peening at manufacture were free of recrystallization in critical areas following full solution rejuvenation heat treatment. Given that gas turbine blade roots operate at relatively low temperatures compared to the airfoil, creep is not considered a life limiting damage mechanism for this region of the blade. Rather, high cycle fatigue is considered the primary damage mechanism of concern. As such, fatigue testing of shot peened and heat treated (recrystallized) René N5 specimens was carried out at 650°C at various stress levels in comparison with baseline (non-recrystallized) specimens to determine the extent to which recrystallization would limit fatigue endurance at blade root operating conditions. It was found that recrystallization did not reduce the fatigue endurance relative to baseline samples at the tested conditions. The findings indicate that repair including full solution rejuvenation heat treatment of previously peened blades comprised of René N5 alloy is feasible provided that recrystallization be limited to root surfaces.

scholarly journals Cracking, Microstructure and Tribological Properties of Laser Formed and Remelted K417G Ni-Based Superalloy

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 71 ◽  
Author(s):  
Shuai Liu ◽  
Haixin Yu ◽  
Yang Wang ◽  
Xue Zhang ◽  
Jinguo Li ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Turbine Blades ◽  
Laser Forming ◽  
Laser Remelting ◽  
Working Process ◽  
Cracking Behavior ◽  
Precipitated Phase ◽  
Before And After ◽  
Cracking Mechanisms

The K417G Ni-based superalloy is widely used in aeroengine turbine blades for its excellent properties. However, the turbine blade root with fir tree geometry experiences early failure frequently, because of the wear problems occurring in the working process. Laser forming repairing (LFR) is a promising technique to repair these damaged blades. Unfortunately, the laser formed Ni-based superalloys with high content of (Al + Ti) have a high cracking sensitivity. In this paper, the crack characterization of the laser forming repaired (LFRed) K417G—the microstructure, microhardness, and tribological properties of the coating before and after laser remelting—is presented. The results show that the microstructure of as-deposited K417G consists of γ phase, γ′ precipitated phase, γ + γ′ eutectic, and carbide. Cracking mechanisms including solidification cracking, liquation cracking, and ductility dip cracking are proposed based on the composition of K417G and processing characteristics to explain the cracking behavior of the K417G superalloy during LFR. After laser remelting, the microstructure of the coating was refined, and the microhardness and tribological properties was improved. Laser remelting can decrease the size of the cracks in the LFRed K417G, but not the number of cracks. Therefore, laser remelting can be applied as an effective method for strengthening coatings and as an auxiliary method for controlling cracking.

scholarly journals Damage Mechanism Based Approach to the Structural Health Monitoring of Wind Turbine Blades

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1223
Author(s):  
Malcolm McGugan ◽  
Leon Mishnaevsky
Keyword(s):  
Structural Health Monitoring ◽  
Wind Turbine ◽  
Health Monitoring ◽  
Turbine Blades ◽  
Leading Edge ◽  
Adhesive Bond ◽  
Damage Mechanism ◽  
Surface Erosion ◽  
Wind Turbine Blades ◽  
Structural Health

A damage mechanism based approach to the structural health monitoring of wind turbine blades is formulated. Typical physical mechanisms of wind turbine blade degradation, including surface erosion, adhesive fatigue, laminate cracking and in some cases compressive kinking and failure are reviewed. Examples of a local, damage mechanism based approach to the structural health monitoring of wind turbine blades are demonstrated, including the monitoring of leading edge erosion of wind turbine blades, adhesive bond failure, plydrop delamination, static and dynamic plydrop tests, and bolt and laminate fatigue. The examples demonstrate the possibilities of monitoring specific damage mechanisms, and specific localizations of wind turbine blades.

scholarly journals Effect of ERNiFeCr-2 Filler Metal on Solidification Cracking Susceptibility of CM247LC Superalloy Welds

2021 ◽  
Vol 59 (10) ◽  
pp. 698-708
Author(s):  
Kyeong-Min Kim ◽  
Hye-Eun Jeong ◽  
Ye-Seon Jeong ◽  
Uijong Lee ◽  
Hyungsoo Lee ◽  
...  
Keyword(s):  
High Speed ◽  
Filler Metal ◽  
Theoretical Calculations ◽  
Turbine Blades ◽  
Microstructural Characterization ◽  
Solidification Cracking ◽  
Cracking Behavior ◽  
Temperature Range ◽  
Testing Method ◽  
Varestraint Testing

The metallurgical aspects of weld solidification cracking in Ni-based superalloys (with Ti+Al > 5 mass%) have not been widely investigated thus far. Herein, the solidification cracking susceptibility of the CM247LC superalloy and its welds with ERNiFeCr-2 filler wire was quantitatively evaluated using a novel modified Varestraint testing method, for the successful manufacturing of CM247LC superalloy gas turbine blades. It was found that the solidification brittle temperature range (BTR) of the CM247LC superalloy was 400 K. This measurement was obtained with a high-speed thermo-vision camera. The BTR increased to 486 K for the CM247LC/ERNiFeCr-2 welds (dilution ratio: 74%). Theoretical calculations (i.e., the Scheil equation, performed using Thermo-Calc software) were conducted to determine the temperature range in which both solid and liquid phases coexist, together with the microstructural characterization of the solidification cracking surfaces. The greater increase in BTR for the CM247LC/ERNiFeCr-2 welds than that for CM247LC was attributed to the enlargement of the solid–liquid coexistence temperature range. This correlated with the formation of a low-temperature Laves phase during the terminal stage of solidification, and was affected by the diluted Nb and Fe components in the ERNiFeCr-2 filler metal. Based on the experimental and theoretical results, the proposed modified Varestraint testing method for dissimilar welds is expected to be an effective testing process for solidification cracking behavior in the manufacturing of high-soundness CM247LC superalloy welds.

scholarly journals Experimental Research and Simulation Analysis of Lightning Ablation Damage Characteristics of Megawatt Wind Turbine Blades

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1251
Author(s):  
Yang Zhao ◽  
Bin Yang ◽  
Yao Zhang
Keyword(s):  
Glass Fiber ◽  
Simulation Analysis ◽  
Turbine Blades ◽  
Damage Mechanism ◽  
Coupling Model ◽  
Lightning Strike ◽  
Fe Model ◽  
Wind Turbine Blades ◽  
Lightning Current ◽  
Damage Process

In this paper, the damage mechanism of glass fiber reinforced composite (GFRC) under lightning strike by laying and inserting copper wires in the laminate was studied. The ablation characteristics of GFRC under different lightning current components were explored. Scanning electron microscope (SEM) was used to conduct the morphology analysis at the damaged area. The results show that the high temperature induced by lightning striking leads to resin pyrolysis, glass fiber (GF) sublimation, and stress waves, which results in fiber breakage and delamination. Then, a finite element (FE) thermal-electric coupling model for predicting the lightning ablation damage of GFRC was established. The comparison between the simulation and experimental results are in good agreement, which validate the effectiveness of the proposed FE model. The relationship between the lightning ablation area and the lightning current amplitude, charge amount, and specific energy in creeping discharge and through discharge was obtained by data fitting. The whole ablation damage process was revealed by FE simulation.

Dynamic fatigue reliability analysis of turbine blades under combined high and low cycle loadings

2021 ◽  
pp. 105678952098685
Author(s):  
Peng Yue ◽  
Juan Ma ◽  
Changhu Zhou ◽  
Jean W Zu ◽  
Baoquan Shi
Keyword(s):  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Prediction Method ◽  
Damage Mechanism ◽  
Operational Reliability ◽  
Reliability Model ◽  
Fatigue Reliability ◽  
Dynamic Reliability

Establishment of damage accumulation models for reflecting the combined damage mechanism on the fatigue behavior of aero-engine turbine blades is crucial for their safety. In this work, a novel combined high and low cycle fatigue (CCF) life prediction methodology is presented as a basis of that to consider the interaction between low and high cycle fatigues. Accordingly, a dynamic reliability model is proposed to study the operational reliability of turbine blades under CCF loadings. Moreover, experimental data of materials along with the collected field data from the actual turbine blades are applied to validate the CCF life prediction model and the dynamic reliability model. The validation of the results is conducted by a comparison analysis, which indicates that the proposed life prediction method yields better accuracy, while the dynamic reliability model is proved to be more in line with the outcomes derived by the Monte Carlo simulation.

Numerical Simulation of Rubber-to-Steel Bimaterial Bonded Interface Cracking Based on Cohesive Element

2010 ◽  
Vol 452-453 ◽  
pp. 865-868
Author(s):  
Xiao Ying Liu ◽  
Xiao Xiang Yang ◽  
Xiu Rong Wang
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Crack Formation ◽  
Damage Mechanism ◽  
Interface Strength ◽  
Cohesive Element ◽  
Bonded Interface ◽  
Initiation And Propagation ◽  
Interface Cracking ◽  
Simulation Results

Presented herein is a finite element investigation into the damage mechanism of the adhesive interface of the rubber-steel bimaterial. The cohesive element layer is used at the interface to simulate the initial loading, initiation and propagation of the damage. From the simulation results, it is found that interface strength exert significant effects on the crack formation in the interface. Smaller interface strength could lead to crack initiation more easily.

scholarly journals Lifing the Effects of Crystallographic Orientation on the Thermo-Mechanical Fatigue Behaviour of a Single-Crystal Superalloy

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 998
Author(s):  
Richard Smith ◽  
Robert Lancaster ◽  
Jonathan Jones ◽  
Julian Mason-Flucke
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Damage Mechanism ◽  
Fatigue Behaviour ◽  
Limiting Factors ◽  
Mechanical Fatigue ◽  
Design Engineers ◽  
Service Environments ◽  
Nozzle Guide

Thermo-mechanical fatigue (TMF) is a complex damage mechanism that is considered to be one of the most dominant life limiting factors in hot-section components. Turbine blades and nozzle guide vanes are particularly susceptible to this form of material degradation, which result from the simultaneous cycling of mechanical and thermal loads. The realisation of TMF conditions in a laboratory environment is a significant challenge for design engineers and materials scientists. Effort has been made to replicate the in-service environments of single crystal (SX) materials where a lifing methodology that encompasses all of the arduous conditions and interactions present through a typical TMF cycle has been proposed. Traditional procedures for the estimation of TMF life typically adopt empirical correlative approaches with isothermal low cycle fatigue data. However, these methods are largely restricted to polycrystalline alloys, and a more innovative approach is now required for single-crystal superalloys, to accommodate the alternative crystallographic orientations in which these alloys can be solidified.

Failure Assessment of the First Stage High Pressure Turbine Blades

2016 ◽  
Vol 853 ◽  
pp. 498-502 ◽  
Author(s):  
Chan Wang ◽  
Duo Qi Shi ◽  
Xiao Guang Yang
Keyword(s):  
High Pressure ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Microstructural Characterization ◽  
Damage Mechanism ◽  
High Pressure Turbine ◽  
Element Analysis ◽  
Failure Assessment ◽  
Creep Fatigue ◽  
Simulation And Experiment

Ni-based superalloys are used as turbine blade material in which creep-fatigue is an important damage mechanism. Simulation and experiment methods are used to investigate and predicte the failure mechanism of the first stage high pressure turbine blades of an aeroengine after 600 hours service. The high pressure turbine blades were made of Ni-base superalloy DZ4, fabricated by DS investment casting. The largest stress point was obtained by finite element analysis. During the fatigue test, the high temperature and low cycle fatigue/creep load simulating the real working condition were applied on the blades until they fractured. And then several examinations were carried out to identify the fracture’s main cause, such as visual examination, SEM fractography and microstructural characterization. In conclusion, the fracture of the high pressure turbine blades was mainly caused by the interaction of the fatigue and creep. Besides, the oxidation accelerated the blades fracture.

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