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 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 Long-Term Aging on Microstructural Restoration in Cast Nickel Base Superalloy, GTD-111

2017 ◽  
Vol 891 ◽  
pp. 426-432 ◽  
Author(s):  
Chuleeporn Paa-Rai ◽  
J. Norachan ◽  
Panyawat Wangyao ◽  
Sureerat Polsilapa ◽  
Gobboon Lothongkum
Keyword(s):  
Aging Time ◽  
Research Study ◽  
Volume Fraction ◽  
Area Fraction ◽  
Nickel Base Superalloy ◽  
Final Microstructure ◽  
Reheat Treatment ◽  
Nickel Base ◽  
Base Superalloy

In this research study, the effect of long-term aging after various solutioning temperatures on final microstructure was investigated. The cast nickel base superalloy, GTD-111, usually has standard reheat treatment as follows: solutioning treatment at 1448 - 1478 K for 7.2 ‑ 21.6 ks and aging at 1118 K for 86.4 ks. However, from previous research works, the density of γ՛ phase was not reached the optimum value. Therefore, extension of aging time was performed in the study from 90 to 180, 270, 360, 720, 1080 and 1440 ks in order to increase density or volume fraction of precipitating γ՛ particles. From the results, it was found that longer aging time provided higher values of both area fraction and size of γ՛ particles. However, increase in aging time resulted in the hardness decrease.

The effect of EB PVD coatings on structure and properties of nickel-base superalloy for gas turbine blades

1996 ◽  
Vol 78 (1-3) ◽  
pp. 113-123 ◽  
Author(s):  
A.A. Tchizhik ◽  
A.I. Rybnikov ◽  
I.S. Malashenko ◽  
S.A. Leontiev ◽  
A.S. Osyka
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Nickel Base Superalloy ◽  
Structure And Properties ◽  
Pvd Coatings ◽  
Gas Turbine Blades ◽  
Nickel Base ◽  
Base Superalloy

Mechanical Properties and Microstructure of IN738LC Nickel Superalloy Castings

2014 ◽  
Vol 782 ◽  
pp. 437-440
Author(s):  
Jiří Zýka ◽  
Irena Andršová ◽  
Božena Podhorná ◽  
Karel Hrbáček
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Turbine Blades ◽  
High Strength ◽  
Nickel Superalloy ◽  
Nickel Base Superalloy ◽  
Gamma Prime ◽  
Structure Correlations ◽  
Nickel Base ◽  
Precipitate Strengthening

IN738LC is a cast nickel-base superalloy developed for applications requiring high strength at elevated temperatures. Its balanced composition provides a good combination of tensile and creep-rupture properties as a result of gamma prime precipitate strengthening enhanced by solid solution and grain-boundary strengthening. Experimental castings are used in heat treated state. This alloy is used widely, for example, for manufacturing of gas turbine blades. Recently, customers demand different weight of castings hence different conditions during solidifying and cooling of the castings originate, resulting in different castings microstructure. When approving the castings, mechanical values are measured by tensile test on test bars made from the cast blade roots. This work investigates mechanical properties casting structure correlations, particularly grain, casting defects, carbides.

Effect of Precipitation Aging Conditions on Microstructural Refurbishment in Cast Nickel Base Superalloy GTD-111

2015 ◽  
Vol 1127 ◽  
pp. 79-84
Author(s):  
Panyawat Wangyao ◽  
Luksawee Phansri ◽  
Piyalak Hirisatja ◽  
Kritsayanee Saelor ◽  
Jozef Zrník ◽  
...  
Keyword(s):  
Solution Treatment ◽  
Treatment Programs ◽  
Nickel Base Superalloy ◽  
Image Analyzer ◽  
Proper Solution ◽  
Gamma Prime ◽  
The Matrix ◽  
Reheat Treatment ◽  
Nickel Base ◽  
Base Superalloy

This research study has an aim to evaluate and investigate the effect of various rejuvenation heat treatments on microstructure of long-term serviced cast nickel base superalloy grade GTD-111 used as turbine blade material. The evaluated reheat treatment programs consist of solution treatment at 1195°C for 2, 3, 4 and 5 hours then following with primary aging at 1120◦C for 2 hours and secondary aging at 845°C for 25, 50, 75 and 100 hours, respectively. All reheat treated microstructures were examined and analyzed by SEM and image analyzer. From all obtained results, it was found that the most proper solution treatment duration was 5 hours to provide the most uniform microstructural characteristics, which consist of the uniform distribution of very dense gamma prime particles in the matrix as well as its highest hardness value. Furthermore, when increasing the duration at secondary aging at 845◦C over than 25 hours (which is according to standard heat treatment), such microstructure provided the most gamma prime phase stability comparing to those of other reheat treatment programs.

Effect of Thermal Exposure on Long-Term Heated Microstructures at 900°C of Nickel Base Superalloy Turbine Blades, Grade Udimet 500

2015 ◽  
Vol 658 ◽  
pp. 25-30 ◽  
Author(s):  
Panyawat Wangyao ◽  
Sureerat Polsilapa ◽  
Anchalee Srimek ◽  
Aimamorn Promboopha
Keyword(s):  
Working Conditions ◽  
Thermal Exposure ◽  
Area Fraction ◽  
Nickel Base Superalloy ◽  
Heating Cycle ◽  
Heating Condition ◽  
Gamma Prime ◽  
Average Area ◽  
Nickel Base ◽  
Base Superalloy

In this research, 5 superalloys Udimet-500 samples were reheat-treated under simulation of 2 working conditions. First, they were heated at 900oC for 400 hours of each heating cycle from the beginning until accumulated heating time reached 1600 hours, these samples were collected and examined the microstructures for size and shape of gamma prime particles. Another heating condition, they had an additional over thermal exposure heating at 1125oC for 1 hour after heating at 900oC of each 400 hours-heating cycle. Then the results were analyzed from 2 working conditions. It was found that the area fraction, average area of gamma prime particle values of nickel base superalloy turbine blade, grade Udimet-500 happened in the same directions in first heating program. However, with the over thermal exposure heating at 1125oC for 1 hour after every heating at 900oC for 400 hours-heating, the obtained results show rates of the area fraction, average area of gamma prime particle values had changed more slowly because the temperature 1125oC at the end of each 900C heating could solutioning some coarse gamma prime phase back to the matrix in some degree. Therefore, the rate of ripening of gamma particle size was slower due to that the microstructural rejuvenation was always performed after each heating cycle and also allowed the reprecipitation of uniform finer gamma prime particles providing longer service time than those of first heating condition.

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