The Creep Of Steel At High Temperatures

Excerpt from The Creep of Steel at High Temperatures This investigation on the creep resistance of steels was undertaken at the request of the Babcock & Wilcox Co., to provide engineering data at the higher temperatures. The work was carried out in the Department of Physics at the Massachusetts Institute of Technology. The difficulties in the path of accurately determining the creep resistance are evidenced by the wide diversity of values obtained by different experimenters, and there is still much to be done on the development of research apparatus. The type of flow occurring ¡11 steel is not certain, even after the subject has been studied by scores of experimenters. There is need of more fundamental research. In the meantime, however, the designer requires engineering data on a large variety of steels for high temperature use. It has been attempted here to supply this data for a considerable number of materials at the higher temperatures. The author desires to express his indebtedness to Mr. J. B. Romer for the inetallographic examination of the test specimens, and to Prof. Albert Sauveur and Dr. R. S. Williams for examining the manuscript. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Excerpt from The Creep of Steel at High Temperatures Above red heat, steel has yielding characteristics not usually associated with it at ordinary temperatures. We do not, as yet, have sufficient information to indicate definitely into which class of solid or fluid flow hot steel belongs. It may be either a plastic solid or a viscous fluid, or combine the properties of both. A viscous fluid, of which pitch is a good example, has the flow characteristics Shown in curve (a) of Fig. 1. The rate of flow is proportional to the load, even down to the smallest values, and yet a great resistance may be Offered against loads acting for a short time. This class of materials has no true elasticity and therefore no yield point. A plastic solid, such as wet clay, has flow characteristics as shown in curve (b) of Fig. 1. Here we have a more complicated condition. Until the load reaches a certain value there is no flow or extension, but after this point is reached the flow increases regularly in proportion to the load in excess of this value. It will be noted that the flow curve does not reach zero at a definite value of load, but approaches the axis gradually. We do not know the exact cause of this departure from a straight line at low flow rates, but it is probably due to the fact that plastic solids are made up of grains or particles of various sizes and shapes and some are less resistant to pressure than others. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Creep-resistant steels are widely used in the petroleum, chemical and power generation industries. Creep-resistant steels must be reliable over very long periods of time at high temperatures and in severe environments. Understanding and improving long-term creep strength is essential for safe operation of plant and equipment. This book provides an authoritative summary of key research in this important area. The first part of the book describes the specifications and manufacture of creep-resistant steels. Part two covers the behaviour of creep-resistant steels and methods for strengthening them. The final group of chapters analyses applications in such areas as turbines and nuclear reactors. With its distinguished editors and international team of contributors, Creep-resistant steels is a valuable reference for the power generation, petrochemical and other industries which use high strength steels at elevated temperatures. Describes the specifications and manufacture of creep-resistant steels Strengthening methods are discussed in detail Different applications are analysed including turbines and nuclear reactors

Our rationale for the second edition remains the same as for the first edition, which appeared over twenty years ago. This is to offer simplified, useful and easily understood methods for dealing with the creep of components operating under conditions met in practice. When the first edition was written, we could not claim that the methods which were introduced were well-tried. They were somewhat conjectural, although firmly based, but not sufficiently well devel oped. Since that time, the Reference Stress Methods (RSM) introduced in the book have received much scrutiny and development. The best recognition we could have of the original methods is the fact that they are now firmly embedded in codes of practice. Hopefully, we have now gone a long way towards achieving our original objectives. There are major additions to this second edition which should help to justify our claims. These include further clarification regarding Reference Stress Methods in Chapter 4. There are also new topics which depend on RSM in varying degrees: • Creep fracture is covered in Chapter 7, where methods for assessing creep crack initiation and crack growth are fully described. This chapter starts with a review of the basic concepts of fracture mechanics and follows with useful, approximate methods, compatible with the needs of design for creep and the availability of standard data. • Creep/fatigue interactions and environmental effects appear in Chapter 8.

A compendium of European and worldwide research investigating creep, fatigue and failure behaviors in metals under high-temperature and other service stresses. It helps set the standards for coordinating creep data and for maintaining defect-free quality in high-temperature metals and metal-based weldments.