Mechanical Properties, Oxidation Resistance and Their Interaction for Two Gas Turbine Seal Ring Alloys

1992 ◽  
Author(s):  
S. K. Srivastava
Keyword(s):  
Gas Turbine ◽  
Oxidation Resistance ◽  
Stress Rupture ◽  
High Strength ◽  
Low Thermal Expansion ◽  
Static Oxidation ◽  
Long Time ◽  
Short Time ◽  
Stress Rupture Testing ◽  
Invar Type

HAYNES® 242™ alloy is a recently developed Ni-25Mo-8Cr alloy primarily for gas-turbine components requiring a combination of low-thermal expansion and high strength, such as seal rings. INCOLOY® alloy 909 is an iron-base Invar-type alloy used in similar applications. Alloy 909 exhibits substantial advantages over 242 alloy in RT and 650°C (1200°F) - 0.2% yield strength, although at considerable loss of ductility and toughness. In stress-rupture testing over a range of 540°-760°C (1000–1400°F), the 100-hr rupture strengths of alloy 909 are consistently inferior to those of the 242 alloy. This dichotomy in short-time versus long-time tensile properties is likely due to the poor oxidation resistance of alloy 909. Comparative static oxidation and oxidation data concurrent with stress-rupture testing for the two alloys are presented and discussed.

A New Low-Thermal-Expansion, High-Strength Alloy for Gas Turbines

1989 ◽  
Author(s):  
S. K. Srivastava ◽  
George Y. Lai
Keyword(s):  
Thermal Expansion ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Strength ◽  
Environmental Resistance ◽  
Minor Elements ◽  
Low Thermal Expansion ◽  
Strength Alloy ◽  
Long Range Ordering ◽  
Cr System

HAYNES® alloy No. 242, based on Ni-Mo-Cr system, was developed primarily for turbine seal applications. The key characteristics of the alloy are derived from critical control of Ni, Mo, Cr, and several minor elements. The high strength — about twice that of alloy B — is achieved from a long-range ordering reaction. The paper reviews comparative evaluation of 242™ alloy versus several currently used gas-turbine alloys such as alloys B, S, N and INCOLOY® alloy 909. Environmental resistance is particularly emphasized. It is shown that 242 alloy possesses an excellent combination of low-thermal-expansion, high strength, and environmental resistance for gas turbine service up to 1400°F (760°C).

Comparison of Parameter Methods for Extrapolating High-Temperature Data

1959 ◽  
Vol 81 (4) ◽  
pp. 629-643 ◽  
Author(s):  
R. M. Goldhoff
Keyword(s):  
High Temperature ◽  
Stress Rupture ◽  
High Temperature Stress ◽  
Parameter Method ◽  
Time Data ◽  
Rupture Data ◽  
High Temperature Data ◽  
Long Time ◽  
Nimonic 80A ◽  
Short Time

The use of the controversial and contradictory parameter techniques in correlation of high-temperature stress-rupture data is discussed. They are treated with a view toward their application in extrapolating short-time data to predict working stresses in serviceable heat-resistant alloys. Three parameter methods are compared on a statistical basis for their ability to reproduce the isothermal data on which they are based and in particular the longest time data currently available and usable for this purpose. Comparisons are further made with long-time extrapolations based on direct plotting of test data. The materials chosen for evaluation are alloys S-590, A-286, Nimonic 80A, and 1Cr-1Mo-1/4V steel. It is shown that prediction of long-time working stresses using parameter techniques will generally give better results than can be obtained from long extrapolations on double logarithmic plots. Among the parameters themselves, the Manson-Haferd linear parameter method gave the most reliable extrapolations. However, the results obtained using the Larson-Miller method may be improved considerably if the proper constant is selected for each set of data rather than using C = 20 for all data. For reliable extrapolations all methods require data from tests up to 1000 hr and covering adequate ranges of stress and temperature.

Steam Oxidation Behaviour of Ni-Based Single Crystalline Superalloy for the Advanced Gas Turbine

2007 ◽  
Vol 263 ◽  
pp. 111-116
Author(s):  
Hisao Fujikawa ◽  
Takao Murakumo ◽  
Simon Newcomb ◽  
Hiroshi Harada
Keyword(s):  
Oxide Scale ◽  
Gas Turbine ◽  
Oxidation Resistance ◽  
High Strength ◽  
Steam Oxidation ◽  
Inconel 625 ◽  
Steam Turbines ◽  
Single Crystalline ◽  
Inconel 625 Alloy ◽  
Main Steam

Steam oxidation behavior of a new Ni-based single crystalline superalloy (TMS-75) developed as the high strength material for the advanced gas turbine which would be cooled by steam was studied in comparison with Inconel 625 alloy which is a representative Ni based superalloy and 12Cr ferritic steel which is conventionally used in boiler tubes and main steam pipes and steam turbines. TMS-75 alloy showed worse oxidation resistance in steam than Inconel 625 alloy, but it had much better oxidation resistance in steam than 12Cr steel. Also, the oxide scale of Inconel 625 alloy is very thin and is mainly composed of Cr2O3. However, the outer scale of TMS- 75 alloy was mainly composed of NiO with Co and a little Al and other elements. The Ni/Co ratio in the oxide scale was a little higher in the outer layer than in the inner layer.

scholarly journals Metallurgical Development for Added Reliability of Industrial Gas Turbine Rotating Blades

1968 ◽  
Author(s):  
F. J. Wall
Keyword(s):  
Gas Turbine ◽  
Stress Rupture ◽  
Rotating Blades ◽  
Time Stress ◽  
Corrosion Evaluation ◽  
Long Time ◽  
Industrial Gas Turbine ◽  
Microstructural Studies ◽  
Selection Of

Increased reliability of industrial gas turbine rotating blades in the hot section of turbines has been achieved by utilization of advanced metallurgical techniques. These techniques include vacuum melting master alloy heats, minimizing residual stresses in blades after machining, and increasing the quality of nondestructive inspection of blades during and after fabrication. In addition, long time stress-rupture tests, corrosion evaluation, and microstructural studies on advanced alloys have provided necessary information for selection of turbine blade alloys for future generations of turbines.

The Experimental Study on Sensitivity of Hydrogen Embrittlement of 20Cr2Ni4A High-Strength Steel Cleaned by Ultrasonic and Deruster

2011 ◽  
Vol 291-294 ◽  
pp. 1136-1140
Author(s):  
Ling Dong Meng ◽  
Qing Zhang ◽  
Zhi Jie Liang
Keyword(s):  
Experimental Study ◽  
Hydrogen Embrittlement ◽  
High Strength ◽  
Sem Analysis ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Mechanics Performance ◽  
Long Time ◽  
Short Time ◽  
Rupture Mechanism

In order to test whether there is the change of mechanics performance cleaned by ultrasonic and deruster, the experiments on mechanics performance and sensitivity of hydrogen embrittlement have been conducted. During the experiments, 20Cr2Ni4A steel are selected as the materials, which endure the relatively great concussion load in the bad condition, and the gaps’ long-time permanence experiments and short-time tension and concussion experiments have been done. Through the compare of mechanics performances and the SEM analysis of tensile fracture surface of the samples, it can be proved that the mechanics performances and rupture mechanism are the same, no matter whether the materials are cleaned by ultrasonic and deruster or not. These indicate that it doesn’t bring the change of mechanics performances and hydrogen embrittlement to clean the materialss by ultrasonic and deruster.

scholarly journals High Strength Diffusion Braze Repair for Gas Turbine Components

1996 ◽  
Author(s):  
Roger D. Wustman ◽  
Leonard M. Hampson ◽  
Jeffrey S. Smith ◽  
Marc E. Suneson
Keyword(s):  
Gas Turbine ◽  
Base Metal ◽  
Thermal Cycle ◽  
Low Cycle Fatigue ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Strength ◽  
Size And Shape ◽  
Gamma Prime ◽  
Crack Repair

The goal of all repair processes is to return the hardware to a serviceable condition. Diffusion braze repairs utilize metallurgical processes to achieve economical repairs of expensive gas turbine components, especially in the turbine section. Component repairs often require dimensional restoration and crack repair on the same part. To achieve this goal, a new diffusion braze repair alloy was developed that combines high strength crack repair and dimensional build up into one material. This new material has mechanical property strength approaching that of the base metal. The improved mechanical properties result from a homogenous gamma prime strengthened diffusion braze zone. As part of an FAA approved test plan, the Howmet ESR (Effective Structural Repair) diffusion braze material was evaluated by tensile and stress rupture testing at elevated temperature. The test results showed high tensile strengths and long stress rupture life. In addition, the effect of the diffusion braze thermal cycle was evaluated on the base metal. A comparison was made between the gamma prime size and shape of engine run JT8D LPT vane clusters before and after the thermal cycle. The thermal cycle was shown to have a beneficial effect on the gamma prime size and shape relative to overaged engine run nozzles. The low cycle fatigue (LCF) life of MarM247 was also shown to improve with the ESR thermal cycle relative to a typical LPT nozzle heat treatment.

Study of Prolonged Service Degradation of Superheater Tubes and its Effects on Remaining Life Predictions

2013 ◽  
Author(s):  
Khalid A. Al-Obaidi ◽  
Nesar Merah
Keyword(s):  
Stress Rupture ◽  
Petrochemical Plant ◽  
Remaining Life ◽  
Material Degradation ◽  
Long Time ◽  
Service Degradation ◽  
Life Predictions ◽  
Stress Rupture Testing ◽  
Prolonged Service ◽  
Plant Shutdown

This study investigates the degradation of superheater tubes that has been in service for very long time. It also discusses the degradation effects on tube remaining life predictions. The tubes, utilized in this study, belong to an industrial boiler that has been in service for 232 000 h in a petrochemical plant and generate steam at 47 barg and 410 °C. Outcomes of this study will contribute to better understanding and development of scientific procedures to make reasonable estimate of tube remaining life considering the tubes aging while in service. This is beneficial in preventing failures and forced plant shutdown when life is consumed. It also helps industry to avoid capital expenditures on premature replacements of boiler tubes that can still serve longer time. In this study, comparison is made between short-term life predictions and actual properties found after about 26.5 years of service. The tubes condition is assessed by metallographic, mechanical and stress rupture testing. According to the results, it is found that prolonged service degradation has strong effects on remaining life predictions. Both effects that would lead to overestimating or underestimating tube remaining life were found if existing procedures are used without consideration for material degradation during service.

Several Modern Wrought Superalloys for Gas Turbine Applications

1996 ◽  
Author(s):  
George Y. Lai
Keyword(s):  
Oxidation Resistance ◽  
Gas Turbines ◽  
Rupture Strength ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Creep Rupture Strength ◽  
Hastelloy X ◽  
Hot Gas ◽  
Low Thermal Expansion ◽  
Honeycomb Seals

The present paper discusses several modern wrought superalloys that are being used for various hot gas path components in modern gas turbines. HAYNES® 230™ alloy (Ni-22Cr-14W-2Mo) is used for combustors and transition pieces to replace an old combustor alloy, HASTELLOY® X alloy (Ni-22Cr-19Fe-9Mo), because of higher creep-rupture strength, better oxidation resistance, higher low-cycle fatigue resistance, and other improved properties. The alumina forming HAYNES 214™ alloy (Ni-16Cr-3Fe-4.5Al-Y) replaces HASTELLOY X for honeycomb seals because of its superior oxidation resistance. HAYNES 242™ alloy (Ni-8Cr-25Mo), strengthened by a long-range ordered phase Ni2(Cr,Mo) with low thermal expansion and high strength, is used for turbine casings and seal rings. A less expensive, nitride-strengthened Fe-Ni-Cr alloy, HAYNES HR-120™ alloy, offers an attractive upgrade to many stainless steels and some Ni-base alloys for less demanding, hot section components.

Short-Time Tests for Long-Time Endurance

1923 ◽  
Vol 128 (4) ◽  
pp. 264-264
Author(s):  
J. W. Harsch
Keyword(s):  
Long Time ◽  
Short Time
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