The Fracture Morphology of Nickel-Base Superalloys Tested in Fatigue and Creep-Fatigue at 650 C


Book Description

The fracture surfaces of compact tension specimens from seven nickel-base superalloys fatigue tested at 650 C were studied by scanning electron microscopy and optical metallography to determine the nature and morphology of the crack surface in the region of stable growth. Crack propagation testing was performed as part of an earlier study at 650 C in air using a 0.33 Hz fatigue cycle and a creep-fatigue cycle incorporating a 900 second dwell at maximum load. In fatigue, alloys with a grain size greater than 20 micrometers, HIP Astroloy, Waspaloy, and MERL 76, exhibited transgranular fracture. MERL 76 also displayed numerous fracture sites which were associated with boundaries of prior powder particles. The two high strength, fine grain alloys, IN 100 and NASA IIB-7, exhibited intergranular fracture. Rene 95 and HIP plus forged Astroloy displayed a mixed failure mode that was transgranular in the coarse grains and intergranular in the fine grains. Under creep-fatigue conditions, fracture was found to be predominantly intergranular in all seven alloys. Gayda, J. and Miner, R. V. Glenn Research Center NASA-TM-81740, E-793










Superalloys 2012


Book Description

A superalloy, or high-performance alloy, is an alloy that exhibits excellent mechanical strength at high temperatures. Superalloy development has been driven primarily by the aerospace and power industries. This compilation of papers from the Twelfth International Symposium on Superalloys, held from September 9-13, 2012, offers the most recent technical information on this class of materials.




Engine Structures


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High Temperature Alloys for Gas Turbines 1982


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The European Collaborative Programme on Materials for Gas Turbines known as COST-50 was initiated in 1971 and has been supported since then by the Commission of European Communities. The achievements made during the first phase of COST-50 were reviewed at the Conference held in Liege, September 25-27, 1978 and published by Applied Science Publishers Ltd. Nine European Countries : Austria, Belgium, the Federal Republic of Germany, France, Italy, The Netherlands, Sweden, Switzerland, the United Kingdom, and the Joint Research Center of the Community, agreed to continue their participation in COST-50 and the results of the second phase were presented at the Conference held in Liege, October 4-6, 1982 under the following headings : - Corrosion and Coatings - Fatigue, Creep and Structural Stability - Processing The technical sessions consisted of invited papers reviewing recent progress in the development of high temperature alloys with particular emphasis on the results of the European Collaborative Programme. Furthermore, some areas were reviewed by eminent speakers from the United States of America, due to their expertise in their respective fields. In this context and as a tradition introduced in 1978, the keynote lecture "Superalloys technology : today and tomorrow" was del ivered by Dr. F. L. Versnyder. The Conference was completed with a significant Poster Session comprising about fifty contributions from Europe and elsewhere. This book comprises a total of fifty four contributions representing almost all of the papers delivered at the technical sessions and a large part of the presentations made at the Poster Session.







Embrittlement of Engineering Alloys


Book Description

Treatise on Materials Science and Technology, Volume 25: Embrittlement of Engineering Alloys is an 11-chapter text that describes some situations that produce premature failure of several engineering alloys, including steels and nickel- and aluminum-base alloys. Chapters 1 to 3 consider situations where improper alloy composition, processing, and/or heat treatment can lead to a degradation of mechanical properties, even in the absence of an aggressive environment or an elevated temperature. Chapters 4 and 5 examine the effect of elevated temperatures on the mechanical properties of both ferrous and nonferrous alloys. Chapters 6 and 7 discuss the effects of corrosive environments on both stressed and unstressed materials. In these environments anodic dissolution is the primary step that leads to failure. Chapters 8 to 10 deal with the effects of aggressive environments that lead to enhanced decohesion or embrittlement of the metal, such as hydrogen, liquid metal, and irradiation-induced embrittlement. Chapter 11 looks into the embrittlement phenomena occurring during welding, one of the most common processing conditions to which a material could be subjected. This book will prove useful to materials scientists and researchers.




Superalloys 2024


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Low Cycle Fatigue


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