Effect of Precipitation Aging Temperatures on Reheat Treated Microstructures and its Phase Stability after Long-Term Exposure in Cast Nickel Base Superalloy, Grade Inconel 738

2017 ◽  
Vol 891 ◽  
pp. 433-437 ◽  
Author(s):  
Nattapol Kontikame ◽  
Sureerat Polsilapa ◽  
Panyawat Wangyao
Keyword(s):  
Phase Stability ◽  
Power Plants ◽  
Turbine Blades ◽  
Research Work ◽  
Nickel Base Superalloy ◽  
Gamma Prime ◽  
Treatment Conditions ◽  
Nickel Base ◽  
Base Superalloy

This research work has an aim to investigate the effect of precipitation aging temperatures of 845°C, 865°C, 885°C and 905°C for 24 hours after solutioning treatment at temperature of 1145°C for 4 hours on final microstructure of cast nickel base superalloy, grade Inconel 738, which is used as a material for turbine blades in land base gas turbine engines to generate electricity in power plants. Further interesting is also extended to study and evaluate the phase stability of precipitated gamma prime particles after long-term heating at tempeatures of 900°C and 1000°C for 200 hours of all received final microstructures after various reheat treatment conditions. From all obtained results, it was found that the higher precipitation aging temperatures provided the more coarsening size of both coarse and fine gamma prime particles. Furthermore, after long-term exposure at high temperatures, this resulted in an increasing of both area density and size of gamma prime particles.

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 Thermal Exposure on Long-Term Heated Microstructures at 900°C of Nickel Base Superalloy Turbine Blade, Grade Inconel 738

2015 ◽  
Vol 658 ◽  
pp. 19-24
Author(s):  
Panyawat Wangyao ◽  
Sureerat Polsilapa ◽  
Surang Singmaneesakulchai ◽  
Aimamorn Promboopha
Keyword(s):  
Heat Treatment ◽  
Working Conditions ◽  
Turbine Blades ◽  
Thermal Exposure ◽  
Stable Phase ◽  
Nickel Base Superalloy ◽  
Gamma Prime ◽  
Nickel Base ◽  
Base Superalloy

The objectives of this research are to search for the most appropriate heat treatment condition for rejuvenating microstructure of cast nickel base superalloy, grade IN-738, turbine blades after using to prolong its life time service again. The turbine blades that had been used for long term service under load and high temperatures resulted in small gamma prime particles connecting to each other and thus forming into larger particles. This effect generally reduces creep resistance and increases the failure. In this research, 5 IN-738 superalloy samples were reheat-treated under simulation of 2 working conditions. First, they were heated at 900oC. At every 400 hours from the beginning of heat treatment until time reaching 1600 hours, these samples were collected and examined the microstructures, size and area fraction of gamma prime particles. Another heating program, they received an over thermal exposure heating at 1125oC for 1 hour after long-term heated at 900oC after every 400 hours-heating. Then the results were analyzed from working conditions. It was found that the sample passed solutioning at 1125oC for 4 hours and aging at 845oC for 24 hours with the over thermal exposure showed the most stable phase stability with γ’ phase increasing after long-term simulated working conditions .

Development of a Generalized LCF-TMF Lifing Model for a Nickel-Base Superalloy

2012 ◽  
Author(s):  
Björn Buchholz ◽  
Uwe Gampe ◽  
Tilmann Beck
Keyword(s):  
Power Generation ◽  
Life Prediction ◽  
Power Plants ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy

The growing share of power generation from volatile sources such as wind and photovoltaics requires fossil fuel fired power generation units be available and capable of high load flexibility to adjust to the changing capacity of the electrical grid. Additionally, back-up units with quick start capability and energy storage technologies are needed to fill the power shortfall when volatile sources are not available. Gas turbine and combined-cycle gas and steam turbine power plants are able to meet these demands. However, safe component design for improved cycling capability, combined with optimum utilization of material regarding its mechanical properties, requires design procedures and lifing models for the complex loadings resulting from this increased volatility of power demand. Since hot gas path components like turbine blades and vanes are highly stressed by cyclic thermal and mechanical loadings, resulting Thermo-Mechanical Fatigue (TMF), life prediction models such as the classic strain-life Coffin-Manson-Basquin method do not capture the influences of thermal cycling satisfyingly. Advanced TMF prediction models are thus necessary to accurately predict the durability of hot section components. This paper addresses life prediction of the Nickel-base superalloy René 80 at elevated temperature for various loading conditions. For this purpose, isothermal Low Cycle Fatigue (LCF) and corresponding TMF tests, with various temperature ranges and thermal-mechanical phase shifts, have been performed. On this basis, a systematic approach has been developed which allows assessing the key influences on TMF life. Moreover, a generalized model for fatigue has been derived, which has the potential to predict TMF life on the basis of LCF data. The knowledge gained from the model development allows an improved life prediction and better utilization of the material capabilities. Additionally, the required number of material tests for a general insight in the materials behaviour can be reduced significantly.

Effect of Reheat Treatment on Microstructural Refurbishment and Hardness of the As-cast Inconel 738

2014 ◽  
Vol 33 (5) ◽  
pp. 453-461 ◽  
Author(s):  
Piyanut Wongbunyakul ◽  
Patama Visuttipitukkul ◽  
Panyawat Wangyao ◽  
Gobboon Lothongkum ◽  
Prasonk Sricharoenchai
Keyword(s):  
Turbine Blades ◽  
Area Fraction ◽  
Nickel Base Superalloy ◽  
Continuous Increase ◽  
Gas Turbine Blades ◽  
Gamma Prime ◽  
Treatment Conditions ◽  
Proper Size ◽  
Reheat Treatment ◽  
Nickel Base

AbstractThis work investigates the effect of rejuvenation heat treatment conditions for refurbishment of the long-term serviced gas turbine blades, which were made of as-cast nickel base superalloy grade, Inconel 738. The reheat treatment conditions consist of solutionizing treatments at temperatures of 1,438, 1,458 and 1,478 K for 14.4 ks and aging treatments at temperatures of 1,133, 1,148 and 1,163 K for 43.2, 86.4, 129.6 and 172.8 ks. The results show that increase in aging times results in continuous increase of size and area fraction of gamma prime (γ′) particles. The higher solutionizing temperature leads to the lower area fraction and smaller size of gamma prime particles. Regarding the microstructure characteristics, the most proper reheat treatment condition should be solutionizing at temperature of 1,438 K for 14.4 ks and aging at temperature of 1,133 K for 172.8 ks, which provides the highest area fraction of gamma prime particles in proper size.

Effect of Pre-Weld Heat Treatment Temperatures on TIG Welded Microstructures on Nickel Base Superalloy, GTD-111

2015 ◽  
Vol 658 ◽  
pp. 14-18
Author(s):  
Tanaporn Rojhirunsakool ◽  
Duangkwan Thongpian ◽  
Nutthita Chuankrerkkul ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Tig Welding ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy ◽  
Weld Heat

Nickel-base superalloys have been used as high temperature materials in land-base gas turbine application. When subjected to long term, high temperature service, large crack propagation was observed. Typical refurbishment method of these turbines is carried out by using TIG welding followed by post-weld standard heat treatment. However, new crack initiation is found in the heat-affected zone after TIG welding. Pre-weld heat treatment has been discovered to improves final γ + γ’ microstructure. This study focuses on the effect of pre-weld heat treatment temperature on final γ + γ’ microstructure. Seven different conditions of pre-weld heat treatment temperature were investigated. Scanning electron microscopy studies were carried out after pre-weld and post-weld heat treatments to compare the γ + γ’ microstructure and capture microcracks. The best pre-weld heat treatment temperature produces uniform distribution of finely dispersed γ’ precipitates in the γ matrix without post-weld crack.

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