Effect of cooling rates of solution treatment on rejuvenation heat-treated microstructures of a cast nickel-based superalloy

2021 ◽  
Vol 63 (2) ◽  
pp. 105-112
Author(s):  
Chuleeporn Paa-rai ◽  
Gobboon Lothongkum ◽  
Panyawat Wangyao
Keyword(s):  
Solution Treatment ◽  
Spherical Shape ◽  
Irregular Shape ◽  
Air Cooling ◽  
Gamma Prime ◽  
Nickel Based Superalloy ◽  
Heat Treated ◽  
Two Temperatures ◽  
Cooling Media

Abstract IN-738 turbine blade samples, deteriorated after long term service at high temperatures, were solution heat-treated at two temperatures, 1398 K and 1473 K, for 7.2 ks. Subsequently, the samples were cooled down in different atmospheres, in air and in furnace, for the purpose of studying the effects of different cooling media (rates) on the restored microstructures. Following this, the samples were aged at 1118 K for 43.2 ks and 86.4 ks in order to determine the characteristic of re-precipitated gamma prime particles. A scanning electron microscope (SEM) and ImageJ analysis software were used. The results show that the cooling in air provided gamma prime particles re-precipitating in spherical shape while the cooling in a furnace resulted in coarse gamma prime particles re-precipitating in irregular shape. The samples solutionized at 1398 K for 7.2 ks cooled down in air and then aging at 1118 K provided bimodal microstructure, while the sample solutionized at 1473 K for 7.2 ks, followed by air cooling and aging at 1118 K generated unimodal γ’ precipitation in spherical shape. Cooling in a furnace provides coarse γ’ recipitated particles in more irregular shape for the both solutionizing temperatures studied here. Cooling in a furnace provides coarse γ’ precipitated particles in more irregular shape for the both solutionizing temperatures studied here.

Long-Term Gamma Prime Phase Stability after Various Heat Treatment Conditions with Temperature Dropping during Solution Treatment in Cast Nickel Base Superalloy, Grade Inconel-738

2017 ◽  
Vol 891 ◽  
pp. 420-425
Author(s):  
Sureerat Polsilapa ◽  
Aimamorn Promboopha ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
Turbine Blades ◽  
Solution Treatment ◽  
Nickel Base Superalloy ◽  
Gamma Prime ◽  
Nickel Based Superalloy ◽  
Treatment Conditions ◽  
Nickel Base ◽  
Base Superalloy

Cast nickel based superalloy, Grade Inconel 738, is a material for turbine blades. Its rejuvenation heat treatment usually consist of solution treatment condition with temperature range of 1125-1205 oC for 2-6 hours. Then it is following with double aging process including primary aging at 1055oC for 1 hour and secondary aging at 845oC for 24 hours. However, the various selected temperature dropping program were performed during solution treatment to simulate the possible error of heating furnace. The maximum number of temperature dropping during solution treatment is varied from 1-3 times From all obtained results, the various temperature dropping during solution treatment conditions showed extremely the significant effect on the final rejuvenated microstructures and long-term gamma prime stability after heating at temperature of 900oC for 200 hours.

Long term heating effects at 1173 K and 1273 K on microstructural rejuvenation in various modified alloys based on GTD-111

2021 ◽  
Vol 63 (8) ◽  
pp. 691-698
Author(s):  
Vara Vacharatanon ◽  
Napat Kiatwisarnkij ◽  
Gobboon Lothongkum ◽  
Nuthaporn Nuttayasakul ◽  
Jiaqian Qin ◽  
...  
Keyword(s):  
Research Work ◽  
Solution Treatment ◽  
Nickel Base Superalloy ◽  
Air Cooling ◽  
Gamma Prime ◽  
Treatment Conditions ◽  
Heating Effects ◽  
Reheat Treatment ◽  
Nickel Base

Abstract This research work studied and evaluated the effects of reheat treatment conditions, which consisted of solution treatment at a temperature of 1448 K for 14.4 ks, followed by air cooling and precipitate aging at a temperature of 1118 K for 86.4 ks, on the microstructural rejuvenation or refurbishment of various modified alloys based on the cast nickel base superalloy, GTD-111 with aluminum, nickel and/or cobalt additions after long term heating at temperatures of 1173 K and 1273 K for 1440 ks. From the results obtained, it was found that the reheat treatment conditions applied are more suitable for microstructures after long term heating at a temperature of 1173 K. However, such reheat treatment conditions could not fully return reheat treated microstructures to microstructures similar to those of previous research work. It seems that the selected solutioning temperatures and/or times were not sufficient to completely dissolve all coarse gamma prime particles after long term heating for all samples with alloying additions. Typical size and area fractions of the gamma prime particles of the reheat treated microstructures are very similar to those of the original alloyed ones but with lower values, especially those related to the size of the gamma prime particles.

Effect of Double-Step Solution Treatment on Rejuvenation Heat Treated Microstructure of IN-738 Superalloy

2020 ◽  
Vol 856 ◽  
pp. 36-42
Author(s):  
Chuleeporn Paa-Rai
Keyword(s):  
Heat Treatment ◽  
Image Analysis ◽  
Electron Microscope ◽  
Solution Treatment ◽  
Single Step ◽  
Double Step ◽  
Heat Treated ◽  
Cast Superalloy ◽  
Scanning Electron

This work investigates the effect of rejuvenation heat treatment, with double-step solution treatment at the temperature from 1150 °C to 1200 °C, on the recovered microstructure of IN-738 cast superalloy. The superalloy has been long-term exposed as a turbine blade in a gas turbine prior to this study. After double solution treatment and aging at 845 °C for 12 h and 24 h, the recovered microstructures were examined by using a scanning electron microscope. Coarse γ΄ particles, that have presented in damaged microstructures, could not be observed in the samples after the rejuvenation heat treatment. In addition, the image analysis illustrates that the reprecipitated γ΄ particles in the samples with double-step solution treatments increase significantly in sizes during aging than that in the samples with the single-step solution treatment. Furthermore, the measurement of the samples hardness presents that the as-receive sample hardness is improved after rejuvenation heat treatment studied in this work.

Influence of Microstructure of TC4 Titanium Alloy on Ultrasonic Velocity and Attenuation

2011 ◽  
Vol 117-119 ◽  
pp. 1766-1769
Author(s):  
Yun Long Ai ◽  
Li Liu ◽  
Wen He ◽  
Bing Liang Liang ◽  
Ji Lin Xu
Keyword(s):  
Titanium Alloy ◽  
Longitudinal Wave ◽  
Solution Treatment ◽  
Water Quenching ◽  
Air Cooling ◽  
Attenuation Coefficients ◽  
Wave Velocities ◽  
Tc4 Titanium Alloy ◽  
Heat Treated ◽  
Tc4 Alloy

Primeval TC4 titanium alloy was subjected to solution treatment at 1150°C for 1h, followed by water quenching, oil quenching, air cooling and furnace cooling, respectively. The pulse-echo method was carried out to measure ultrasonic longitudinal wave velocities (ν) and attenuation coefficients (α) of these heat-treated samples. The relationship between microstructures of different cooling rates and ultrasonic parameters such as ultrasonic longitudinal wave velocities (ν) and attenuation coefficients (α) was investigated. The results show that the microstructures of heat-treated TC4 alloy were α phase and β boundaries, and the ultrasonic longitudinal velocities and attenuation coefficients of these heat-treated samples, in turn, increased with reducing the cooling rate from water quenching to furnace cooling.

Effect of Cooling Rate on Microstructure of Rejuvenated Fe-Ni Based Superalloys

2020 ◽  
Vol 856 ◽  
pp. 76-84
Author(s):  
Kittawat Srimark ◽  
Panyawat Wangyao ◽  
Tanaporn Rojhirunsakool
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Temperature ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Air Cooling ◽  
Gamma Prime ◽  
Microstructural Instability ◽  
Cooling Air

Fe-Ni based superalloys have been widely used in land-base gas turbine application. The turbine blade was in service for 50,000 h at high temperature and stresses. When subjected to long-term exposure at high temperature, the microstructure lost its best mechanical properties due to the microstructural instability. The aim of this research is to understand the effect of cooling rate on gamma (γ) grain size and gamma prime (γ’) particle size, morphology, and its volume fraction in rejuvenated Fe-Ni based superalloys. The alloys were solutionized above the γ’ solvus temperature at 1125 °C for 2 h for homogenization and cooling to room temperature at different cooling rates. The alloys were experienced with furnace cooling, air cooling, oil quenching, and water quenching. Microstructural analyses were investigated. Grain size, morphology, volume fraction of γ’ precipitates were investigated. Preliminary mechanical properties such as microhardness was conducted.

Influence of Long-term Aging on Microstructure and Creep Behaviors of FGH95 Nickel-based Superalloy

2012 ◽  
Vol 31 (6) ◽  
pp. 755-758
Author(s):  
S. G. Tian ◽  
G. L. Xie ◽  
J. Xie ◽  
X. M. Zhou
Keyword(s):  
Stress Concentration ◽  
Grain Boundaries ◽  
Aging Treatment ◽  
Creep Properties ◽  
Nickel Based Superalloy ◽  
Microstructure Observation ◽  
Heat Treated ◽  
Carbide Particles ◽  
Fgh95 Superalloy

AbstractBy means of long-term aging treatment, creep properties measurement and microstructure observation, the influences of long-term aging on the microstructure and creep behaviors of FGH95 Superalloy are investigated. Results show that the fine γ′ particles dispersedly precipitate in the alloy after fully heat treated, and coarser γ′ phase discontinuously distribute along the grain boundaries. After the alloy is long-term aged at 723 K for 500 h, the fine γ′ phase with better cube degree and carbide particles distribute dispersedly in the alloy to enhance the creep resistance of the alloy for possessing a longer creep lifetime at the condition of 923 K and 1034 MPa. The deformed feature of the alloy is that configurations of slipping dislocations and the stacking fault appear in the alloy. As the creep goes on, the cracks initiate and propagate along the boundaries due to dislocations tangling in the grain boundaries for bringing out the stress concentration.

scholarly journals EFFECT OF TREATMENT SOLUTION ON THE MICROSTRUCTURE AND MICROHARDNESS OF TERNARY Ni-Al-Nb ALLOY DOPED WITH TITANIUM

2021 ◽  
Vol 22 (1) ◽  
pp. 1
Author(s):  
Hikmat Nugraha ◽  
Pradoto Ambardi ◽  
Djoko Hadi Prajitno
Keyword(s):  
Solution Treatment ◽  
High Strength ◽  
Optical Microscope ◽  
Titanium Content ◽  
Air Cooling ◽  
Gamma Prime ◽  
Titanium Nickel ◽  
Effect Of Treatment ◽  
Hardness Values

EFFECT OF TREATMENT SOLUTION ON THE MICROSTRUCTURE AND MICROHARDNES OF TERNARY Ni-Al-Nb ALLOY DOPED WITH TITANIUM. Nickel-based superalloys have been widely used in various applications, which require high strength at high temperatures. Most types of these superalloys is age-hardenable because they have γ’ particles' chemical composition Ni3(Al, Ti) in γ’-phase matrix. This research will be used alloy Ni-Al-Nb added alloying elements Ti. This research was conducted to study the mechanical properties, microstructure conditions in some alloys Ni-Al-Nb added distinction Titanium element (0,5% and 1% Ti) using the method of aging temperature variation performed at a temperature of 650 °C,700 °C and 750 °C with a holding time 4 hours and air cooling. Tests were conducted to determine the characterization of the specimen includes testing metallographic optical microscope, Rockwell hardness C and SEM- EDS,XRD. Results obtained from this research that addition of titanium element affecting the hardness values as well as the results of the cast, solution treatment and aging process results. The 1% Titanium content can affect the gamma prime coarsening and make the grain on the microstructure result smooth.

On the effect of long service exposure: changes in microstructure and mechanical properties of Ni-based superalloy

2020 ◽  
Vol 117 (6) ◽  
pp. 624
Author(s):  
Hassan Keyvanlou ◽  
Reza Soleimani Gilakjani ◽  
Majid Nezakat
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
Nickel Based Superalloy ◽  
Rotating Blade ◽  
Two Temperatures ◽  
Service Exposure ◽  
Scanning Electron

In the present study, the microstructure and the mechanical properties of GTD-111 nickel-based superalloy were investigated. The alloy was in service as the GE-MS9001 gas turbine 1st stage rotating blade for 105,000 hours at a temperature between 950 to 1000 °C. Two sets of samples were extracted from the airfoil and the root of the blade. Then, they were compared for the microstructural and the mechanical properties changes after the high temperature service. Stress-rupture and Charpy V-notch (CVN) tests were conducted on the samples at 871 °C and two temperatures of 25 and 900 °C, respectively. The microstructure and the fracture surface of the samples were analyzed using a scanning electron microscope (SEM). The results showed degradation in the microstructure and the mechanical properties of the airfoil compared to those of the root due to the long-term service at elevated temperatures. The loss in mechanical properties was due to the coarsening of γ’ precipitates and the formation of brittle phases in the grain boundaries.

Effect of Temperature Dropping During Reheat Treatments on GTD-111 Microstructure

2012 ◽  
Vol 31 (2) ◽  
Author(s):  
Piyapat Wongnawapreechachai ◽  
Weerasak Hormkrajai ◽  
Gobboon Lothongkum ◽  
Panyawat Wangyao
Keyword(s):  
Turbine Blades ◽  
Solution Treatment ◽  
Heat Treating ◽  
Effect Of Temperature ◽  
Solution Temperature ◽  
Nickel Based Superalloy ◽  
Reheat Treatment ◽  
Temperature Levels ◽  
General Standard

AbstractThe general standard reheat treatment condition to refurbishment long-term serviced turbine blades, which are made of cast nickel based superalloy, GTD-111, is usually following by solution treatment at 1438 K, 1458 K and 1478 K for 10.8 to 14.4 ks, combination with primary aging at 1328 K for 3.6 ks, and secondary aging at 1118 K for 86.4 ks. However, in practical reheat treatment process, the change of temperature during any heat treating could occur accidentally any time. To simulate this effect, the droppings of temperatures during solution treatment were chosen and carried out to temperature level of 1118 K then heating again to the solution temperature levels. The temperature droppings (according to various programs) were performed during solution treatment. From the results, it was found that effect of temperature dropping during solution treatment greatly influenced the final rejuvenated microstructures.

Effects of adding Ni and Co on microstructure and gamma prime phase stability in Ni superalloy Inconel 738 with 1 wt.-% Al

2020 ◽  
Vol 62 (5) ◽  
pp. 448-453
Author(s):  
Panyawat Wangyao ◽  
Tanaporn Rojhirunsakool ◽  
Witchawet Korthamniwet ◽  
Nithi Saenarjhan ◽  
Gobboon Lothonkum
Keyword(s):  
Nickel Content ◽  
Solution Treatment ◽  
Cobalt Content ◽  
Melting Process ◽  
Vacuum Arc ◽  
Gamma Prime ◽  
Arc Melting ◽  
Heat Treated ◽  
The Stability ◽  
Prime Phase

Abstract The effects of adding nickel and cobalt to Inconel 738 along with adding 1 wt.-% of aluminum were investigated in this study. The alloys, with various amounts of nickel and cobalt, were prepared using a vacuum arc melting process. The alloys were heat treated using a standard heat treatment procedure which consisted of solution treatment at 1448 K for 14.4 ks and precipitation aging at 1118 K for 86.4 ks. Increased nickel content was shown to enhance the stability of gamma prime particles and the gamma matrix as well as assist the formation of gamma prime particles. In the case of the addition of cobalt, the coarsening rate of gamma prime particles decreased with increasing cobalt content. Furthermore, a further addition of aluminum to Inconel 738 resulted in an increase in the area fraction of the gamma prime phase and more rapid growth of gamma prime particles during long-term heating compared to standard Inconel 738.

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