Steels for Steam Power Plant

Abstract

A review of the work carried out for the Steels for High Temperature committee of the British Electrical and Allied Industries Research Association between 1930 and 1952.† In this paper the achievements of the J/E committee between the years 1930 and 1952 are reported. Development of steam power plant largely depends on the physical properties of the materials. Realization of the effects of creep in metals has caused creep data to supersede Hooke's law in the determination of design methods for steam power plant. The study of the effects of creep properties in different steels led to the adoption of chromium- molybdenum, and chromium-molybdenum-silicon and, to a less extent, molybdenum-vanadium steel for the high-temperature components; superheater tubes, steam pipes, and superheater headers for plant using temperatures above 900 deg. F. From creep tests made, the stress-time relation for each component was obtained. Methods of creep testing are compared, and abnormally high creep rates are investigated. The testing of the reliability of long-time creep tests deduced from short-time creep tests is described. Relaxation tests carried out enabled a mathematical relation between relaxation time and stress to be derived. Investigations into the effects on the properties of the steel, of the presence of minor elements in the steel, and the method of manufacture, are described, and also the cause and effects of grain growth. The causes of, and means of avoiding, cracking of steel are studied. Future developments are outlined. FOREWORD C. H. Desch, D.Sc, Ph.D., F.R.S. Chairman of the Steels for High Temperature Committee of B.E.A.I.R.A. Since 1930 the Steels for High Temperature committee of the British Electrical and Allied Industries Research Association has fostered work on the properties of steels used in steam power plant. The committee was formed from the committee of the Department of Scientific and Industrial Research on the behaviour of materials at high temperatures, at a time when the importance of the phenomenon of creep in designing high-temperature steam power plant was being realized. The committee has always included in its membership representatives of leading steel makers, tube manufacturers, turbine builders, and boiler makers. The Admiralty has also been well represented and, also since their formation, the British Electricity Authority and the British Iron and Steel Research Association. The views of metallurgists and engineers concerned with the production and use of high-temperature steels have thus been combined in furthering co-operative work which has effectively contributed to advances in the design and efficiency of British steam power plant. The work of this committee has thus formed an integral part of the development of high-temperature steels which has been made by British industry over the last twenty years. The committee has throughout the work had the co-operation of the Engineering and Metallurgy Divisions of the National Physical Laboratory where most of the investigational work has been carried out. This work has been supported financially by the steel-making and the appropriate user industries. Since the inception of the committee in 1930 a number of detailed technical reports have been issued on various problems which it has investigated. The following report has been prepared to provide an overall picture of the major achievements of the committee. Although he has not been concerned with experimental work, Mr. Sage has had access to all reports and papers connected with the research. The value of the contributions of numerous investigators at the National Physical Laboratory is acknowledged, and Dr. Jenkins and Mr. Tapsell should be specially mentioned as having taken a leading part in the investigation since its inception.