Main Article Content
Abstract
Low Pressure Turbine (LPT) blade in a typical military aircraft engine gets exposed to a temperature in excess of 1000 K while rotating at 8500 rpm during maximum rating of the engine operation. Creep and fatigue are the major damage mechanisms limiting its life. Non-uniformity in combustion leads to development of hot spot causing local temperature rise in excess of 1200 K. Further, LPT rotor experiences over-speeding due to malfunction of the control system causing Low Cycle Fatigue (LCF) damage to the blade. Hence Stress Rupture Test (SRT) and Low Cycle Fatigue (LCF) are the life limiting tests for evaluation of a turbine blade material. Turbine blades of military aircraft engine are made of nickel base super alloys for their excellent high temperature resistance and its source of strengthening are g’ Ni3 (Al, Ti) and carbides respectively. The size, shape and distribution of the strengthening phases can be modified following different heat-treatment cycle to optimise SRT and LCF life. This paper deals with the effect of two heat-treatment cycles on SRT life of a wrought nickel base alloy having major alloying elements as Co, Cr, W, Mo, Al and Ti etc. The two types of heat-treatment cycles are as follows:Type I, Solutioning - Heating at 1220° C for 4 hours followed by cooling in air. Further heating to 1050°C soaking for 4 hours and cooling in air. Ageing cycle comprises of heating at 950°C for 2 hours followed by cooling in air. Type II, Solutioning - Heating at 1210°C for 5 hours and then transferring to a furnace at 1050°C soaking for 1/2-3/4 hour followed by cooling in air. Ageing cycle consists of heating at 900°C soaking for 12 hours followed by cooling in air. Fractography on the tested samples to arrive at the mode of failure, characterisation of the microstructure in respect of γ’ Ni3 (Al, Ti) and carbides using optical microscopy and SEM have been carried out to relate with the SRT life.
Keywords
Article Details
References
- Donachie Mathew., Donachie, J. and Stephen Mathew., " Superalloys A Technical Guide", ASM International, The Material Information Society, Chapter-12, 2002, pp.211-259.
- Sims, C.T., "The Superalloys Wiley Interscience", 1972.
- Reed, C. Roger., "The Superalloys - Fundamentans and Applications", Cambridge University Press, 2006.
- Russian Specification, Ty:14-1-223-72. 5. Khimishuin, F. F., "High Temperature Steels and Alloys", Foreign Technology Division, Wright Patterson, AFB, Ohio, Chap-1.
- Chakravorty, S., West, D. R. F., "High Temperature Strength of Nickel Alloys Based on g’ Phase", Metals Technology, October, 1980, pp.414-419.
- Hammond, C. and Nutting, J., "The Physical Metallurgy of Super Alloys and Titanium Alloys", Metal Science, October, 1977, p.476
- Youdelis, W.V. and Known, O., "Carbide Phases in Nickelbase Superalloy : Nucleation Properties of MC Type Carbides", Material Science, Vol.17, 1985, pp.385-388.
- Yang, Jinija., and Zheng, Qi, et al., "Relative Stability of Carbides and Their Effect on the Properties of K465 Superalloy", Material Science and Engineering, A429, 2006, pp.341-347.
- Pandey, M. C., Satyanarayan, D. V. V. and Tapline, D. M. R., "Performance Enhancement of Alloy X- 750 During Creep via Optimal Solution Treatment and Control of Morphology of Grain Boundary Carbide", Material Science and Technology, Vol.10, November, 1994, pp.936-939.
- Coyne, J. E., "Microstructure Control in Titanium and Nickel Base Forging", Metals Technology, July, 1977, pp.337-345.
- Blade Manufacturing Technology, 55MP-81.
- Stress Rupture Test Standard, GOST:10145.
- Liu, L. R., Jin, T., Zhao, N. R., San, F. R., Guan, H. R. and Hu, Z. Q., "Formation of Carbides and Their Effect on Stress Rupture of a Ni-base Single Crystal Alloy", Material Science and Engineering, A-361, 2003, pp.191-197.
- Yulai Xu., Qiumin Jin., Xueshan Xiao., Xiuli Cao., Guoqing Jia., Yuemei Zhu and Huaijin Yin., "Strengthening Mechanisms of Carbon in Modified Nickel-Based Superalloy Nimonic 80A", Material Science and Engineering, A-528, 2011, pp.4600- 4607.
- Yulai Xu., Lei Zhang., Jun Li., Xueshan Xiao., Xiuli Caob., Guoqing Jia and Zhi Shen., "Relationship Between Ti/Al Ratio and stress-Rupture Properties in Nickel-Based Superalloy", Material Science and Engineering, A-544, 2008, pp.48-53.
- Joy Mittra, A. N., Suparna Banerjee., Raghvendra Tewari and Gautam K. Dey., "Fracture Behavior of Alloy 625 with Different Precipitate Microstructures", Material Science and Engineering, A-574, 2013, pp.86-93.
References
Donachie Mathew., Donachie, J. and Stephen Mathew., " Superalloys A Technical Guide", ASM International, The Material Information Society, Chapter-12, 2002, pp.211-259.
Sims, C.T., "The Superalloys Wiley Interscience", 1972.
Reed, C. Roger., "The Superalloys - Fundamentans and Applications", Cambridge University Press, 2006.
Russian Specification, Ty:14-1-223-72. 5. Khimishuin, F. F., "High Temperature Steels and Alloys", Foreign Technology Division, Wright Patterson, AFB, Ohio, Chap-1.
Chakravorty, S., West, D. R. F., "High Temperature Strength of Nickel Alloys Based on g’ Phase", Metals Technology, October, 1980, pp.414-419.
Hammond, C. and Nutting, J., "The Physical Metallurgy of Super Alloys and Titanium Alloys", Metal Science, October, 1977, p.476
Youdelis, W.V. and Known, O., "Carbide Phases in Nickelbase Superalloy : Nucleation Properties of MC Type Carbides", Material Science, Vol.17, 1985, pp.385-388.
Yang, Jinija., and Zheng, Qi, et al., "Relative Stability of Carbides and Their Effect on the Properties of K465 Superalloy", Material Science and Engineering, A429, 2006, pp.341-347.
Pandey, M. C., Satyanarayan, D. V. V. and Tapline, D. M. R., "Performance Enhancement of Alloy X- 750 During Creep via Optimal Solution Treatment and Control of Morphology of Grain Boundary Carbide", Material Science and Technology, Vol.10, November, 1994, pp.936-939.
Coyne, J. E., "Microstructure Control in Titanium and Nickel Base Forging", Metals Technology, July, 1977, pp.337-345.
Blade Manufacturing Technology, 55MP-81.
Stress Rupture Test Standard, GOST:10145.
Liu, L. R., Jin, T., Zhao, N. R., San, F. R., Guan, H. R. and Hu, Z. Q., "Formation of Carbides and Their Effect on Stress Rupture of a Ni-base Single Crystal Alloy", Material Science and Engineering, A-361, 2003, pp.191-197.
Yulai Xu., Qiumin Jin., Xueshan Xiao., Xiuli Cao., Guoqing Jia., Yuemei Zhu and Huaijin Yin., "Strengthening Mechanisms of Carbon in Modified Nickel-Based Superalloy Nimonic 80A", Material Science and Engineering, A-528, 2011, pp.4600- 4607.
Yulai Xu., Lei Zhang., Jun Li., Xueshan Xiao., Xiuli Caob., Guoqing Jia and Zhi Shen., "Relationship Between Ti/Al Ratio and stress-Rupture Properties in Nickel-Based Superalloy", Material Science and Engineering, A-544, 2008, pp.48-53.
Joy Mittra, A. N., Suparna Banerjee., Raghvendra Tewari and Gautam K. Dey., "Fracture Behavior of Alloy 625 with Different Precipitate Microstructures", Material Science and Engineering, A-574, 2013, pp.86-93.