The Effect of O2, H2o, and N2 on the Fatigue Crack Growth Behavior of an Alpha + Beta Titanium Alloy at 24 C and 177 C


Book Description

To study the effects of atmospheric species on the fatigue crack growth behavior of an a+B titanium alloy (Ti 6-2-2-2-2) at room temperature and 177 C, fatigue tests were performed in laboratory air, ultrahigh vacuum, and high purity water vapor, oxygen, nitrogen and helium at various partial pressures. Accelerated fatigue crack growth rates in laboratory air compared to ultrahigh vacuum are linked to the damaging effects of both water vapor and oxygen. Observations of the fatigue crack growth behavior in ultrahigh purity environments, along with surface film analysis using X-ray photoelectron spectroscopy (XPS), suggest that multiple crack-tip processes govern the damaging effects of air. Three possible mechanisms are proposed: 1) at low pressure (less than 10(exp -1) Pa), accelerated da/dN is likely due to monolayer adsorption on crack-tip surfaces presumably resulting in decreased bond strengths at the fatigue crack tip, 2) for pressures greater than 10(exp -1) Pa, accelerated da/dN in oxygen may result from oxidation at the crack tip limiting reversible slip, and 3) in water vapor, absorption of atomic hydrogen at the reactive crack tip resulting in process zone embrittlement.Smith, Stephen W. and Piascik, Robert S.Langley Research CenterFATIGUE TESTS; FATIGUE (MATERIALS); CRACK PROPAGATION; TITANIUM ALLOYS; EMBRITTLEMENT; ATMOSPHERIC COMPOSITION; X RAY SPECTROSCOPY; WATER VAPOR; ULTRAHIGH VACUUM; PHOTOELECTRON SPECTROSCOPY




Chemical Abstracts


Book Description




Titanium


Book Description

Designed to support the need of engineering, management, and other professionals for information on titanium by providing an overview of the major topics, this book provides a concise summary of the most useful information required to understand titanium and its alloys. The author provides a review of the significant features of the metallurgy and application of titanium and its alloys. All technical aspects of the use of titanium are covered, with sufficient metals property data for most users. Because of its unique density, corrosion resistance, and relative strength advantages over competing materials such as aluminum, steels, and superalloys, titanium has found a niche in many industries. Much of this use has occurred through military research, and subsequent applications in aircraft, of gas turbine engines, although more recent use features replacement joints, golf clubs, and bicycles.Contents include: A primer on titanium and its alloys, Introduction to selection of titanium alloys, Understanding titanium's metallurgy and mill products, Forging and forming, Castings, Powder metallurgy, Heat treating, Joining technology and practice, Machining, Cleaning and finishing, Structure/processing/property relationships, Corrosion resistance, Advanced alloys and future directions, Appendices: Summary table of titanium alloys, Titanium alloy datasheets, Cross-reference to titanium alloys, Listing of selected specification and standardization organizations, Selected manufacturers, suppliers, services, Corrosion data, Machining data.




Extractive Metallurgy of Niobium


Book Description

The growth and development witnessed today in modern science, engineering, and technology owes a heavy debt to the rare, refractory, and reactive metals group, of which niobium is a member. Extractive Metallurgy of Niobium presents a vivid account of the metal through its comprehensive discussions of properties and applications, resources and resource processing, chemical processing and compound preparation, metal extraction, and refining and consolidation. Typical flow sheets adopted in some leading niobium-producing countries for the beneficiation of various niobium sources are presented, and various chemical processes for producing pure forms of niobium intermediates such as chloride, fluoride, and oxide are discussed. The book also explains how to liberate the metal from its intermediates and describes the physico-chemical principles involved. It is an excellent reference for chemical metallurgists, hydrometallurgists, extraction and process metallurgists, and minerals processors. It is also valuable to a wide variety of scientists, engineers, technologists, and students interested in the topic.




Aerospace Materials and Applications


Book Description

"The present volume is focused on documenting the novel processing, fabrication, characterization, and testing approaches that are unique to aerospace materials/structures/systems"--Preface.




Atlas of Stress-corrosion and Corrosion Fatigue Curves


Book Description

A reference for materials scientists that can be used to find the effects of various corrosive media and processing variables on the stress-corrosion cracking and corrosion fatigue characteristics of ferrous and nonferrous alloys. There are more than 500 stress/cracking-time curves, S/N curves, and




Degradation of Implant Materials


Book Description

This book reviews the current understanding of the mechanical, chemical and biological processes that are responsible for the degradation of a variety of implant materials. All 18 chapters will be written by internationally renowned experts to address both fundamental and practical aspects of research into the field. Different failure mechanisms such as corrosion, fatigue, and wear will be reviewed, together with experimental techniques for monitoring them, either in vitro or in vivo. Procedures for implant retrieval and analysis will be presented. A variety of biomaterials (stainless steels, titanium and its alloys, nitinol, magnesium alloys, polyethylene, biodegradable polymers, silicone gel, hydrogels, calcium phosphates) and medical devices (orthopedic and dental implants, stents, heart valves, breast implants) will be analyzed in detail. The book will serve as a broad reference source for graduate students and researchers studying biomedicine, corrosion, surface science, and electrochemistry.




Nondestructive Materials Characterization


Book Description

With an emphasis on aircraft materials, this book describes techniques for the material characterization to detect and quantify degradation processes such as corrosion and fatigue. It introduces readers to these techniques based on x-ray, ultrasonic, optical and thermal principles and demonstrates the potential of the techniques for a wide variety of applications concerning aircraft materials, especially aluminum and titanium alloys. The advantages and disadvantages of various techniques are evaluated.




Materials and Processes


Book Description

The objective of this book is to assist scientists and engineers select the ideal material or manufacturing process for particular applications; these could cover a wide range of fields, from light-weight structures to electronic hardware. The book will help in problem solving as it also presents more than 100 case studies and failure investigations from the space sector that can, by analogy, be applied to other industries. Difficult-to-find material data is included for reference. The sciences of metallic (primarily) and organic materials presented throughout the book demonstrate how they can be applied as an integral part of spacecraft product assurance schemes, which involve quality, material and processes evaluations, and the selection of mechanical and component parts. In this successor edition, which has been revised and updated, engineering problems associated with critical spacecraft hardware and the space environment are highlighted by over 500 illustrations including micrographs and fractographs. Space hardware captured by astronauts and returned to Earth from long durations in space are examined. Information detailed in the Handbook is applicable to general terrestrial applications including consumer electronics as well as high reliability systems associated with aeronautics, medical equipment and ground transportation. This Handbook is also directed to those involved in maximizing the relia bility of new materials and processes for space technology and space engineering. It will be invaluable to engineers concerned with the construction of advanced structures or mechanical and electronic sub-systems.