_STP_676-1979.pdf

STRESS RELAXATION TESTING A symposium sponsored by ASTM Committee E-28 on Mechanical Testing AMERICAN SOCIETY FOR TESTING AND MATERIALS Kansas City,Mo.,24,25 May 1978 ASTM SPECIAL TECHNICAL PUBLICATION 676 Alfred Fox,Bell Telephone Laboratories,editor List price$23.75 04-676000-23 bAMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street,Philadelphia,Pa.19103 4 Copyright by AMERICAN SOCIETY FOR TESTING AND MATERIALS 1979 Library of Congress Catalog Card Number:78-74563 NOTE The Society is not responsible,as a body,for the statements and opinions advanced in this publication.Printed in Baltimore,Md.June 1979 Foreword The symposium on Stress Relaxation Testing for Improved Material and Product Reliability was presented at Kansas City,Mo.,24,25 May 1978.The symposium was sponsored by the American Society for Testing and Ma-terials through its Committee E-28 on Mechanical Testing.Alfred Fox,Bell Telephone Laboratories,presided as symposium chairman and editor of this publication.Related ASTM Publications Reproducibility and Accuracy of Mechanical Tests,STP 626(1977),$15.00,04-626000-23 Recent Developments in Mechanical Testing,STP 608(1976),$14.50,04-608000-23 Cyclic Stress-Strain and Plastic Deformation Aspects of Fatigue Crack Growth,STP 637(1977)$25.00,04-637000-30 The Influence of State of Stress on Low-Cycle Fatigue of Structural Ma-terials:A Literature Survey and Interpretive Report,STP 549(1974),$5.25,04-549000-30 Cyclic Stress-Strain BehaviorAnalysis,Experimentation,and Failure Prediction,STP 519(1973),$28.00,04-519000-30 A Note of Appreciation to Reviewers This publication is made possible by the authors and,also,the unheralded efforts of the reviewers.This body of technical experts whose dedication,sacrifice of time and effort,and collective wisdom in reviewing the papers must be acknowledged.The quality level of ASTM publications is a direct function of their respected opinions.On behalf of ASTM we acknowledge with appreciation their contribution.ASTM Committee on Publications Editorial Staff Jane B.Wheeler,Managing Editor Helen M.Hoersch,Associate Editor Ellen J.McGlinchey,Senior Assistant Editor Helen Mahy,Assistant Editor Contents Introduction CONSTITUTIVE RELATIONS Load Relaxation Testing and Material Constitutive Relations E.W.HART 5 Discussion 18 Metal Def onnation ModelingStress Relaxation of Aluminum R.W.ROHDE AND J.C.SWEARGENGEN 21 Discussion 34 A Phenomenology of Room-Temperature Stress Relaxation in Cold-Rolled Copper Alloysp.PARIKH AND E.SHAPIRO 36 Stress Relaxation of Steel Tendons Used in Prestressed Concrete Under Condiflons of Changing Applied StressR.I.GLODOWSKI AND G.E.HOFF 42 MATERIAL AND PRODUCT APPLICATION AND TEST METHODS Room-Temperature Stress Relaxation of EBgh-Strengtti Strip and Wire Spring SteelsProcedures and Datas.u.v.IDERMARK AND E.R.JOHANSSON 61 Discussion 77 Stress Relaxation in Bending of AISI 301 Type Corrosion Resistant Steel StripALFRED FOX 78 Discussion 88 Stress Relaxation in Beryllium Copper StripE.W.FILER AND c.R.SCOREY 89 Discussion 108 Report on Bending Stress Relaxation Round RobinP.PARIKH 112 Negative Stress Relaxation in Polyuretfiane Induced by Volume ShrinkageA.Y.C.LOU 126 Discussion 139 HOLD-TIMES CYCLIC EFFECTS AND RESIDUAL STRESS Stress Relaxation of Residual Metalworking StressesF.T.GEYLING AND P.L.KEY 143 In-Reactor Stress Relaxation of Type 348 Stainless Steel in-Pfle Tabej,M.BEESTON AND T.K.BURR 155 Crack Growth Retardation in Two Low-Stren Materials Under Displacement Controlled Cyclic Loadingi.A.KAPP,J.H.UNDERWOOD,AND I.I.ZALINKA 171 Cyclic Relaxation Response Under Creep-Fatigae Conditions J.H.LAFLEN ANDC.E.JASKE 182 SUMMARY Sammary 209 Index 213 STP676-EB/Jun.1979 Introduction Stress relaxation1 is the time and temperature dependent decrease of stress in a solid due to the conversion of elastic into inelastic strain.Stress relaxation data can be used to develop stress-relief heat treatments for reducing residual stresses and for the design of such mechanical elements as joints,gaskets,and springs.Stress relaxation data are also an important tool for evaluating the constitutive relations governing a materials inelastic behavior.Until approximately I960,stress relaxation was primarily of interest only to those concerned with the design and manufacture of steam and power generating equipment and,to a lesser extent those concerned with the design of gaskets,reinforced concrete,and electric motors.Thus we find that a considerable amount of the early work in this field has been done by the ASTM-ASME Joint Committee on the Effect of Temperature on the Proper-ties of Metals and by individuals associated with this committee.Microminiaturization in the computer and electronics industries coupled with the high reliability of the missile and nuclear reactor industries created a need for standard testing techniques for measuring this mechanical prop-erty.This led to the creation of ASTM Subcommittee E28.ll on Stress Relaxation of ASTM Committee E-28 o