STP 1244 Constraint Effects in Fracture Theory and Applicatons: Second Volume Mark Kirk and Ad Bakker, Editors ASTM Publication Code Number (PCN): 04-012440-30 1916 Race Street Philadelphia, PA 19103 Printed in the U.S.A Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized ISBN: 0-8031-2013-3 ASTM Publication Code Number (PCN): 04-012440-30 Copyright 1995 AMERICAN SOCIETY FOR TESTING AND MATERIALS, Philadelphia, PA All rights reserved This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher Photocopy Rights Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by the AMERICAN SOCIETY FOR TESTING AND MATERIALS for users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $2.50 per copy, plus $0.50 per page is paid directly to CCC, 222 Rosewood Dr., Danvers, MA 01923; 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Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword This publication, Constraint Effects in Fracture: Theory and Applications, contains papers presented at the symposium of the same name, held in Dallas/Forth Worth, TX on 17-18 Nov 1993 The symposium was sponsored by ASTM Committee E-8 on Fatigue and Fracture along with the European Structural Integrity Society Mark Kirk of Edison Welding Institute in Columbus, OH and Ad Bakker of Delft University of Technology Laboratory for Materials Science in the Netherlands presided as symposium chairs and are the editors of the resulting publications Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Terry Ingham The conference chairmen and ASTM Committee E08 on Fatigue and Fracture note with great sorrow and regret the death of our colleague Terry Ingham Terry passed away on January 18, 1994, a short two months after we all enjoyed his presence and discussions at the symposium on which this STP is based He will be remembered not only for the quality of his work, but also for his energy and commitment even in the later stages of his illness Terry graduated from the University of Leeds (United Kingdom) with a degree in Metallurgy in 1965 Subsequently, he joined the United Kingdom Atomic Energy Authority (UKAEA) His work included the development of experimental fracture toughness test methods and their relationship to structural behavior, irradiation damage in pressure vessel steels, the effect of specimen size on the fracture toughness transition regime in ferritic steels, and acoustic emission All of these topics resulted in noteworthy contributions to the literature, particularly his contributions to an international study of irradiation damage in steel, and to the pressure vessel materials section of the UK Light Water Reactor Study Group Report Within the European Structural Integrity Society (ESIS) he was a member of the Working Party on Fracture Mechanics Testing Standards, for which he contributed substantially to the R-curve test procedure, P1-87D In 1985, he joined the UK Nuclear Installations lnspectorate (NII) as a Principal Inspector, where he was involved in the licensing of gas cooled reactors and nuclear fueled processing plants Although this endeavor entailed a departure from his experimental work, his interest in fracture mechanics continued at both national and international levels His work at the Nil was recognized in 1994 by the award of the Order of the British Empire (OBE), an honor for which he was justifiably proud Our sympathy is extended to his wife and two daughters; we will all miss him Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Contents vii Overview TWO PARAMETER CONTRACT THEORIES Cleavage Fracture Q u a n t i f i e d - - Y J CHAO AND W JI Variations of a Global Constraint Factor in Cracked Bodies Under T e n s i o n a n d B e n d i n g L o a d s - - J c NEWMAN, JR., J, H CREWS, JR., C A BIGELOW, AND D, S DAWICKE 21 Limits of J-T Characterization of Elastic-Plastic Crack-Tip Fields u165 WANG 43 AND D, M PARKS CRACK GROWTH MODELING A Numerical Study on the Influence of Geometry Variations on Stable Crack Growth in C T S p e c i m e n s for Different Materials G SHAN,O KOLEDNIK, AND 71 D F FISCHER Numerical Simulation of Stable Crack Growth in Fracture Mechanics S p e c i m e n s - - D KLINGBEIL, G M ZAHED, A EBERLE, S FRICKE, AND W BROCKS 88 Numerical Modeling of Ductile Tearing Effects on Cleavage Fracture T o u g h n e s s - - R H DODDS, JR,, M TANG, AND T L ANDERSON 100 The Role of G e o m e t r y a n d Crack Growth on Constraint and Implications for Ductile/Brittle Fracture N v O'DOWD, C F SHIH, AND R, H DODDS 134 MICROMECHANICAL APPROACHES Modeling Crack Growth Resistance Using Computational Cells with Microstructurally-Based L e n g t h S c a l e s - - c E SHIN AND L XIA 163 Prediction of Cleavage Fracture in the Brittle to Ductile Transition Region of a Ferritic S t e e l - - R w J KOERS, A H M KROM, AND A BAKKER 191 The Second Parameter in J - R Curves: Constraint or T r i a x i a l i t y - - w BROCKS AND W SCHMITT 209 Application of the G u r s o n Model to Ductile Tearing R e s i s t a n c e - - w BROCKS D KLINGBEIL, G KUNECKE, AND D.-Z SUN 232 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions au EXPERIMENTAL VALIDATION Fracture Toughness Measurements Using Small Cracked Round Bars-J H GIGVANOLA, H HOMMA, M LICHTENBERGER, J E CROCKER, AND R W KLOPP 255 Experimental Investigation of Fracture Toughness Scaling Models R E LINK AND 286 J A JOYCE The Effect of Constraint Due to Out-of-Plane Stress Field on Fracture of Reactor Pressure Vessel An Experimental and Numerical Study D L RUDLAND, R MOHAN, N D GHADIALI, D DETTY, A R ROSENFIELD, AND G M WILKOWSKI 316 T h e Influence of Plasticity and Geometry on the M i x e d M o d e Fracture of P M M A - - J c w DAVENPORT AND D J SMITH 344 Constraint Effects on the Upper Shelf in Cracked Welded Specimens c FRANCO, 363 P GILLES, C ERIPRET, AND S NALLET APPLICATIONS Constraint Effects in Testing Different Curved Geometries of Zr-2.5Nb Pressure T u b e M a t e r i a l - - E H DAVIES, R S W SHEWFELT, AND A K JARVINE 392 A Comparison of J and CTOD as Elastic-Plastic Fracture Characterizing Parameters J R GORDON, B K NEALE, AND Y.-Y WANG 425 Size and Deformation Limits to Maintain Constraint in Klc and Jc Testing of Bend Specimens K c KOPPENHOEFER, M T KIRK, AND R H DODDS, JR 445 Constraint and Statistical Adjustment Models Applied to Transition Fracture Toughness D a t a - - J , D LANDES 461 Interpretation of Constraint Effects Under PTS Conditions Based on J-Q Fracture M e t h o d o l o g y - - D K M SHUM 479 Application of J-Q Fracture Methodology to the Analysis of Thermal-Shock Experiment T S E - S A - - D K M SHUM 501 Validity of Small Specimen Fracture Toughness Estimates Neglecting Constraint Corrections K WALLIN 519 Author Index 539 Subject Index 541 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Overview The Conference On 17-18 November, 1993, the American Society for Testing and Materials (ASTM) and the European Structural Integrity Society (ESIS) co-sponsored the Second Symposium on Constraint Effects in Fracture This symposium was held in Ft Worth, TX; it followed on the success of the first symposium held in May 1991 in Indianapolis, IN (ASTM STP 1171) A total of 24 papers were presented Of these, 13 were submitted from North America and 11 were submitted from Europe Motivation The application of conventional fracture mechanics techniques to assess the integrity of a cracked structure relies on the notion that a single parameter uniquely characterizes the resistance of a material to fracture Material resistance to catastrophic brittle fracture is characterized by a critical value of the stress intensity factor/tic, while resistance to the onset of ductile, or upper-shelf, fracture is characterized by a critical value of the J-integral J~c Testing standards that govern the measurement of Kic and Jlc, ASTM E 399 and ASTM E 813 respectively, require sufficient specimen thickness to produce predominantly plane strain conditions at the crack tip and sufficient crack depth to position the crack tip in a highly constrained bending field These restrictions are designed to insure the existence of severe conditions for fracture as described by the Hutchinson Rice Rosengren (HRR) asymptotic fields The requirements of the testing standards thereby guarantee that Kit and Jic are lower bound, geometry insensitive measures of fracture toughness However, cracks in civil, nuclear, and marine structures are seldom this highly constrained, which makes predictions of structural fracture resistance based on laboratory fracture toughness values overly pessimistic Excessive pessimism in structural assessment can lead to the unwarranted repair or decommissioning of engineering structures to protect the public safety at a great, often unwarranted, cost and inconvenience Many researchers have long advocated a more pragmatic, engineering approach to assess the fracture integrity of cracked structures This approach requires that constraint in the fracture toughness test specimen approximate that of the structure to provide an "appropriate" toughness for use in an assessment of structural integrity The appropriate constraint is achieved by matching thickness and crack depth between specimen and structure Experimental studies demonstrate the validity of this approach These studies show that use of geometry dependent fracture toughness values allows more accurate prediction of the fracture performance of structures than is possible using conventional fracture mechanics However, the task of characterizing fracture toughness becomes more complex than is presently the case using ASTM standard test methods Testing of nonstandard specimens is required, and different fracture toughness data are needed for each geometry of interest Further, this approach cannot be applied economically to thick section structures (e.g., nuclear pressure vessels) This limitation has motivated the development of theories that extend significantly the range of deformation over which fracture mechanics can be applied accurately to predict the performance of structures Many of the research efforts discussed at the Second Constraint Symposium were undertaken to this end vii Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized viii OVERVIEW Overview of the Papers Presented Considerable advancement in both the understanding and characterization of constraint effects occurred during the two and a half years between the first and second symposia Evidence of advancement is available by contrasting the topics of papers presented at the two meetings During the First Symposium, considerable emphasis was placed on the development of appropriate strategies for characterizing constraint effects on initiation fracture toughness, whether by purely brittle (lower shelf) or by purely ductile (upper shelf) mechanisms Both theoretical analysis and experimental investigations focused on the study of fracture in simple laboratory test specimen geometries At the Second Symposium, considerable emphasis was placed on the study of factors whose resolution will ultimately increase the engineering utility of constraint theories In specific, the following topics were addressed The competition between cleavage and ductile fracture in the transition temperature regime Finite element modelling and theoretical parameterization of crack growth processes The effects of bi-axial loading Additionally, a number of papers reflected cooperative efforts between different engineering specialties Several studies combined aspects of both solid mechanics and metallurgy, or addressed both experimentation and numerical analysis These investigations, particularly the former, signal a fundamental shift of focus in the understanding and characterization of fracture processes in metals There was a general recognition among attendees at the symposium that it is necessary, in certain instances, to incorporate variables that characterize a material at a sub-continuum scale into fracture theories that are used to assess the safety and suitability of structures for continued service This is a major philosophical shift from the tenants of single parameter fracture mechanics (SPFM) that have been widely viewed as the most rational approach for the last 40 years This STP is divided topically into the following five categories: 9 9 2-Parameter Fracture Mechanics (2PFM) theories, papers Crack Growth Modelling, papers Micromechanical Modelling, papers Experimental Validation of Constraint Models, papers Application of Constraint Models, papers This distribution of papers indicates that the understanding of constraint effects on fracture is approaching a critical juncture There is nearly an even division between efforts aimed at development of an appropriate and physically defensible characterization of constraint effects (papers in the first three categories) and efforts aimed at applications or codification (papers in the latter two categories) Summary of Major Findings All of the various constraint models presented at the symposium share a common goal: to extend significantly the validity range of SPFM and thereby facilitate more accurate prediction and assessment of the conditions that cause fracture in structures Available constraint models include the mechanics-based approaches of two-parameter fracture mechanics (2PFM) (that is, J-T, J-Q, JA2, J-etg), statistical techniques based on the Weibull model, and micro-mechanical approaches that address fracture by both cleavage and ductile mechanisms At this stage, the following general statements can be made: In the lower transition regime where cleavage fracture occurs before or just after the onset of ductile tearing, all of the 2PFM constraint models can be applied to parameterize the variation of Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions aut OVERVIEW ix critical fracture toughness with constraint Of the various models available, the J-Q approach of O'Dowd and Shih applies rigorously to the highest deformation levels and to the broadest range of materials Experimental evidence is available, which shows the validity of this approach All of the 2PFM approaches, however, suffer from the disadvantage that they complicate considerably the task of characterizing material toughness because the toughness at a given temperature becomes a function of constraint rather than a single value In the lower transition regime it is also possible to predict, without resort to empirical argument, this variation of toughness with constraint using the results of standard fracture toughness tests coupled with the micro-mechanics approach of Dodds and Anderson At this conference the applicability of this model was extended into the upper transition regime where significant stable tearing may precede the onset of cleavage Again, experimental evidence is available which shows the validity of this approach Certain issues remain with respect to the proper treatment of 3D effects; these are currently under investigation A "master curve" approach to the analysis of fracture toughness data in the transition regime has been proposed in a draft ASTM standard on this topic (ASTM Task Group E08.08.03 on ElasticPlastic Fracture Mechanics Technology in the Ductile-to-Brittle Transition Regime) Combination of this approach with a statistical correction for thickness effects based on the Weibull model appears to provide a powerful tool for the predicting toughness of geometrically similar specimens from one another (e.g thick C(T)s predicted from thin C(T)s) across a wide range of thicknesses 2PFM models can be applied on the upper shelf to parameterize constraint effects on R-curve behavior However, these approaches lack a rigorous theoretical basis in this application as a reference infinite body field solution that is self-similar to the solutions for growing cracks in finite bodies is not available As a consequence, it can be expected that "size effects" on fracture toughness will likely reveal themselves in such an application On the upper shelf the way forward appears to be through application of some form of local approach wherein sub-continuummaterial variables are incorporated into the models to provide a capability to predict accurately structural behavior from smaller scale fracture toughness test results Acknowledgments The chairmen would like to acknowledge Dorothy Savini of ASTM for her professionalism in guiding us through the planning and smooth execution of the symposium Further, Therese Pravitz and Shannon Wainwright of ASTM are to be commended for their assistance during the peer review process We are indebted to our colleagues who assisted us with the abstract review process and with the conduct of the symposium These individuals included Ted Anderson of Texas A&M University, Wolfgang Brocks of the Fraunhofer-Institut fur Werkstoffmechanik, Bob Dodds of the University of Illinois, Steve Garwood of TWI, Phillipe Gilles of Framatome, Ed Hackett of the Nuclear Regulatory Commission, Lee James of Westinghouse, Dietmar Klingbell of BAM, Ronald Koers of Shell Research, Randy Nanstad of the Oak Ridge National Laboratory, MarjorieAnn E Natishan of the University of Maryland, and C Fong Shih of Brown University Others to be thanked include the authors who submitted the papers that comprise this publication Discussions by the authors and attendees energized symposium atmosphere Finally thanks go to the peer reviewers for their critiques and comments, which helped ensure the quality of this STP Mark Kirk Edison WeldingInstitute,Columbus,Ohio, USA; symposium cochairmanand coeditor Ad Bakker Delft Universityof Technology,The Netherlands; symposium cochairman and coeditor Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WALLIN ON SMALL SPECIMEN FRACTURE 529 TOUGHNESS For this data set eq does seem to underestimate the fracture toughness temperature dependence at toughness levels above 400 MPa~/m The deviation is assumed to be caused by a true loss of constraint effect As a whole, the transition temperatures are again within ~ the same, showing no clear dependence upon specimen size A data set, focusing on lower toughness levels has been generated by McCabe 212J.], for A533B CI.1 steel, with CT specimens having thicknesses in the range 12.5-100 mm The results, analyzed by eqs 2-4, are presented graphically in Fig This data set show a reversed specimen size dependence for To, the largest specimens yielding the lowest transition temperature This is, at least in part, due to the large number of specimens tested at a temperature corresponding to the lower shelf, where the statistical size effect seem to diminish If the lower shelf fracture toughness results are omitted from the analysis the T Ofor the 12.5 mm specimens change from -74 ~ to -80 ~ and for the 25 mm specimens from -77 ~ to -79 ~ thus causing the transition temperatures to be equal within ~ Even inclusion of the lower shelf results cause the transition temperatures to be equal within 11 ~ the smallest specimens yielding the most conservative estimate The application of eq on the lower shelf makes the extrapolation to larger specimens conservative, but the conservatism is not very large A533B CI.1 P l a t e 13A 588 I 458 ~ 3so I /,, 12.5 m , !)=38 To = - "C 25 am, n=63 To = - 7 "C V To = - "C • mm, n=6 To = - "C 400 350 I I I [21] I I M , n=Z6 COHBINED To = Bo = 25 n 95 - "C 250 r 208 5t 150 180 - A -160 I I I I I I I I -14~ -129 -1W -lib -6~ -40 -ZB 20 T ['e] FIG.8 The effect of specimen size for A533B CI steel 212.L] Filled symbols refer to non-failed, end of test values Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 530 CONSTRAINTEFFECTS IN FRACTURE THEORY AND APPLICATIONS: SECOND VOLUME Another data set showing the same type of reversed specimen size dependence for To, as above, has been generated by Bicego et al 2[~] The material is a 1CrMoV forging rotor steel The data comprise 10 ram, 25 mm and 100 mm CT specimens The results, analyzed by eqs 2-4, are presented graphically in Fig The 10 mm and 25 mm specimens yield within ~ the same T 0, but the 100 mm specimens differ more Any definitive conclusions regarding the reversed size effect, seen in this data set, cannot be made due to the small number (three) of 100 mm specimens tested 1CrHoV FORGING, BICEGO & a l 450 I I I ~7 B=lO em C1", n=44 1'o = 68 "C ,A, B=Z5 ~ CT, n=-lZ To = 6Z *C D=lOO mm CT, ~ To = 56 ~ COHBINED 1"o = 65 "C Do = 25 mm 400 350 300 ~ I I 95 ~; / / ZSB zeo 150 '~ lO0 5~; 50 O 20 40 6B 80 r ['c] 100 120 140 160 FIG.9 The effect of specimen size for a 1CrMoV rotor steel forging [22] Filled symbols refer to non-failed, censored test values A material with very much different properties, with respect to the other materials examined here, is the ORNL pressurized thermal shock experiment material (PTSE2) The material is a 88 steel with a room temperature yield stress below 300 MPa and a Charpy-V upper shelf energy around 60 J [23] Thus, this is a material where the fracture toughness should be strongest affected by loss of constraint and ductile tearing effects The original data set only contain 25 mm thick CT specimens For comparison, a set of 20 % side-grooved CVNr~ specimens, made from Kx, specimen PI319 [231, were tested at the Technical Research Centre of Finland (VTI') The combined results, analyzed by eqs 2-4, are presented graphically in Fig 10 The 10 mm and 25 mm specimens yield within ~ the same T o Considering the exceptional material the result appears quite good Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WALLIN ON SMALL SPECIMEN FRACTURETOUGHNESS 531 PTSE2 (TL) 300 I I 1B mm, n=18 To = 26 "C ~x J , 250 I 1) 23 To = 33 "C COHBINED To = 30 "C Go = 25 mm 200 A 95 158 A U A 100 -" "-St 511 -40 -20 B 2B ~ 60 80 T ['el FIG.10 The effect of specimen size for PTSE2 material 25 mm thick CT specimen data taken from 2[~2] and 10 CVN~ specimen data generated for this work at VTT Filled symbols refer to non-failed, end of test values Within an IAEA research program, VTT has tested a French A508 CI.3 forging (FFA) and a Japanese A533B CI.I plate (JRQ) intended to be an irradiation monitor material Both materials were characterized with CVNr~, 12.5 mm round compact (RCT), 25 mm CT and 100 mm CT specimens I18] All specimens were 20 % side-grooved The results, for FFA, analyzed by eqs 2-4, are presented graphically in Fig 11 The steel has a comparatively high resistance to ductile tearing causing even the CVNp~ specimen to yield brittle fracture values up to 350 MPa~m Despite this, the transition temperatures are equal within ~ The JRQ plate proved to be macroscopically inhomogeneous, showing a toughness gradient through the plate thickness (thickness 225 ram) Because the specimens were taken from different depths (see 1[!~]), a comparison of the form presented above is not possible Instead To was determined separately, by eqs 2-4, for each specimen type at each specimen depth All 100 mm thick CT specimens had their cleavage initiation site located close to the side-groove on the plate center side of the specimen Thus, they were classified as belonging to that plate depth The results of the analysis are presented graphically in Fig 12 The figure show a clear toughness gradient throughout the plate, but no trend as regarding specimen size or type can be seen Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 532 CONSTRAINT EFFECTS IN FRACTURE THEORY AND APPLICATIONS: SECOND VOLUME A608 CI.3 Fersln9 FFA [181 lggg CVl~c 111an, n=lS ro = - u v "c A l ~ 1Z.5 m, n=21 To = -113 "C C I ' u , n=6 8m to : - l m / "c / ~" CT lW m, n=6 r,:-l.'c CIIMI/~ll To = -114 "C ~Geg / / , / / / / ,/ / / _ / / / "/ / y,x / / V -~ a m 2109 I I I I I I I -12g -198 -88 -68 -49 -28 r I ['c] FIG.11 The effect of specimen size for FFA forging [181 Filled symbols refer to non-failed, end of test values A533B Cl.1 Plate (d-I~) [18] -29 I I I I I I I CVNpc B=lO am I / | V]iCT B=12.5 u -49 _ CT B=II~ nm P t L./ ~ I I ~" -611 -'ill j J 3e M C T l m CORRESPQ~I"0 CLEAVAGEINITIATION SITE 58 68 78 88 98 DISTANCE1"0 PlaTE Sll~P~ (m) lOB llO FIG.12 The effect of specimen size and location for JRQ plate on transition temperature To Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WALLIN ON SMALL SPECIMEN FRACTURETOUGHNESS 533 DISCUSSION The results studied here concentrate on nuclear pressure vessel steels A533B CI and A508 CI.3, but they include also steels with very different properties (Fig and 10) Looking at all the figures, it is practically impossible to distinguish a toughness level where the small specimens would start to deviate from the large specimen toughness The main difference with small and large specimens is that large specimens yield brittle fracture still at temperatures, where small specimens are on the "upper shelf" In order to obtain a more comprehensive view of the results, the transition temperatures To for each specimen size for all materials have been collected into Fig 13 29 EFFECT OF THICKNESSUPONVALIBITuOF To - - T T " ' 'I T I l CONSERVATIVE 15 t le ,c, T, t ~J m -18 b I o r,- - -38 Itl.o SERVA~IVE -25 1B 12.5 L J I 25 38 75 98 J • l 198 289 238 THICKI~SS (m) A533B CI.1 A533B CI.1 4) A533B CI.1 FIG, [17] FIG, [19] FIG [21] ~ A588 CI.3 A~A478 1CrHoV FIG 11 [18] FIG [16] FIG [22] ASf18 C1.3 FIG [16] ~7 2kCr.-18o FI6 1B [23] 4~ ASB8 C1.3 FIG [29] FIG.13 The effect of specimen size upon the validity of To Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 534 CONSTRAINTEFFECTS IN FRACTURE THEORY AND APPLICATIONS: SECOND VOLUME In Fig 13 the transition temperature has been normalized with the combined To calculated for the whole data set The expected trend would be for small specimens to yield "unconservative" and large specimens to yield "conservative" estimates of T o Such a trend is, however, not visible In the figure, also the theoretical _+l.t~ro confidence limits for the T Oestimate are included For most cases the combined To estimate is within these confidence limits This adds support to the conclusion that no trend with respect to thickness is visible Fig 13 contain the term "validity" Validity is here defined as the capability of producing predictable toughness estimates If it is possible to predict the behavior of the measured fracture toughness, quantitatively, the value is valid The term "size independence" is not used, because the statistical size effect causes the fracture toughness, in the case of brittle fracture, to be size dependent even for "valid" results The fact that Fig 13 does not show any distinguishable effect of specimen size upon To suggests that the small specimen fracture toughness estimates are valid even when neglecting all constraint corrections The issue of constraint does not seem to be of concern for these types of standard geometry specimens, when the results are treated in the way presented here Hence, it appears that the presently used size requirements for brittle fracture toughness testing are unduly strict, at least from the point of constraint It can even be argued that no size criterions are necessary for the standard geometry specimens, when an analysis like the one used here is applied The intention of this work is not to ridicule the issue of constraint effects On the contrary, it is of utmost importance for the successful realization of a fracture mechanical assessment of a real structure This work only tries to point out an undue conservatism, leading to unnecessary costs, in the presently existing and proposed requirements Fracture mechanical assessment will never become a simple standard tool for normal engineering purposes, unless the cost of testing and the need for material is reduced significantly At the same time as computing costs have reduced enormously, no effort to reduce the cost of testing has been attempted This work shows that a more cost efficient small specimen testing is possible, producing "valid" results SUMMARY AND CONCLUSIONS In this work several large brittle fracture toughness data sets, containing large and small specimen data, have been analyzed by a statistical procedure, based upon brittle fracture theory Based upon the analysis the following can be concluded: when the data is used to determine the fracture toughness transition temperature T o, the data only require a statistical size correction in order to yield comprehensive results, the reliability of To estimates based on CVN~ and 12.5 thick RCT specimens appear to be better than ~ constraint criterions can essentially be neglected for these specimen geometries, it is possible to significantly reduce the cost of testing and the need for material, without affecting the reliability of the fracture toughness estimate Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WALLIN ON SMALL SPECIMEN FRACTURETOUGHNESS 535 ACKNOWLEDGMENTS This work is dedicated to Terry Ingham who did so much pioneering work in elastic plastic brittle fracture toughness testing The work presented here is part of the Nuclear Power Plant Structural Integrity Programme performed at the Technical Research Centre of Finland (VTI') and financed by the Ministry of Trade and Industry in Finland and the Finnish Centre for Radiation and Nuclear Safety REFERENCES H.I Anderson, T L and Dodds, R H., "Specimen Size Requirements for Fracture Toughness Testing in the Transition Region", Journal of Testing and Evaluation, JTEVA, American Society for Testing and Materials, Philadelphia, Vol 19, 1991, pp 123-134 [2.] Wallin, K., "The Size Effect in K~c Results", Engineering Fracture Mechanics, Vol 22, No.l, 1985, pp 149-163 Wallin, K., "The Effect of Ligament Size on Cleavage Fracture Toughness", Engineering Fracture Mechanics, Vol 32, No 3, 1989, pp 449-457 Wallin, K., "Statistical Aspects of Constraint with Emphasis on Testing and Analysis of Laboratory Specimens in the Transition Region", Constraint Effects in Fracture, ASTM STP 1171, E M Hackett, et al Eds., American Society for Testing and Materials, Philadelphia, 1993, pp 264-288 Wallin, K., "Maclioscopic Nature of Brittle Fracture", Journal de Physique IV, Colloque C7, suppl6ment au Journal de Physique III, Vol 3, November 1993, pp 575-584 [.fi] Wallin, K., Saario, T and TSrr6nen, K., "A Statistical Model for Carbide Induced Brittle Fracture in Steels", Metal Science, Vol 18, No 1, 1984, pp 13-16 W Wallin, K., "The Scatter in Iqc-Results", Engineering Fracture Mechanics, Vol 19, No 6, 1984, pp 1085-1093 [81 Wallin, K., "Statistical Modelling of Fracture in the Ductile to Brittle Transition Region" Defect Assessment in Components - Fundamentals and Applications, ESIS/EGF9, J G Blauel and K.-H Schwalbe, Eds., Mechanical Engineering Publications, London, 1991, pp 415-445 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 536 CONSTRAINT EFFECTS IN FRACTURETHEORY AND APPLICATIONS:SECOND VOLUME Wallin, K., "A Simple Theoretical Charpy-V - K~c Correlation for Irradiation Embrittlement", Innovative Approaches to Irradiation Damage and Fracture Analysis, PVP-Vol.170, D L Marriott, et al Eds., The American Society of Mechanical Engineers, 1989, pp.93-100 Wallin, K., "Fracture Toughness Transition Curve Shape for Ferritic Structural Steels", Fracture of Engineering Materials & Structures, S T Teoh and K H Lee, Eds., Elsevier Applied Science, 1991, pp 83-88 LUd Wallin, K., "Irradiation Damage Effects on the Fracture Toughness Transition Curve Shape for Reactor Pressure Vessel Steels", International Journal of Pressure Vessels and Piping, Vol 55, No 1, 1993, pp 61-79 [121 Moskovic, R., "Statistical Analysis of Censored Fracture Toughness Data in the Ductile to Brittle Transition Temperature Region", Engineering Fracture Mechanics, Vol 44, No 1, 1993, pp 21-41 [13l "Flaw Evaluation Procedures: Background and Application of ASME Section XI Appendix A", EPRI NP-719-SR, T U Marston, Ed., Electric Power Research Institute, Palo Alto, 1978, pp C8-C12 Server, W L and Oldfield, W., "Nuclear Pressure Vessel Steel Data Base", EPRI NP-933, Electric Power Research Institute, Palo Alto, 1978, Appendix 1, pp 1-16 McGowan, J J., Nanstad, R K and Thomas, K R., "Characterization of Irradiated Current-Practice Welds and A533 Grade B Class Plate for Nuclear Pressure Vessel Service", NUREG/CR-4880, Vol 1, 1988, 134 p ]lZfi] Iwadate, T., Tanaka, Y., Ono, S and Watanabe, J., "An Analysis of Elastic-Plastic Fracture Toughness Behavior of Jzc Measurement in the Transition Region" ElasticPlastic, Fracture: Second Symposium, Volume II-Fracture Resistance Curves and Engineering Applications, ASTM STP 803, C F Shih and J P Gudas, Eds., American Society for Testing and Materials, Philadelphia, 1983, pp II-531 - II-561 1LL7J Morland, E., "Fracture Toughness in the Transition Regime for A533C-1 Steel: The Effect of Specimen Sidegrooving", Fracture Mechanics: Twenty-First Symposium, ASTM STp 1074, J P Gudas, J A Joyce and E M Hackett, Eds., American Society for Testing and Materials, Philadelphia, 1990, pp 215-237 Wallin, K., Valo, M., Rintamaa, R., TOrrOnen, K and Ahlstrand, R., "IAEA Coordinated Research Programme on Optimizing of Reactor Pressure Vessel Surveillance Programmes and their Analyses, Phase 3: Results of the Finnish Contribution", 1994, To be published Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WALLIN ON SMALL SPECIMEN FRACTURETOUGHNESS 537 Ingham, T., Knee, N., Milne, I and Morland, E., "Fracture Toughness in the Transition Regime for A533B Steel: Prediction of Large Specimen Results from Small Specimen Tests", Fracture Mechanics: Perspectives and Directions: Twentieth Symposium, ASTM STP 1020, R P Wei and R P Gangloff, Eds., American Society for Testing and Materials, Philadelphia, 1989, pp 369-389 2~ Lidbury, D and Moskovic, R., "Assessment of the Ductile-to-Brittle Transition Toughness Behaviour of an A508 Class PWR Pressure Vessel Steel by a Statistical Approach", Pressure Vessel Integrity, PVP-Vol 250, The American Society of Mechanical Engineers, 1993, pp 283-294 2~ McCabe, D E., "A Comparison of Weibull and 1~c Analysis of Transition Range Fracture Toughness Data", NUREG/CR-5788, January 1992, 24 p 2~ Bicego, V., Elli, A and Rinaldi, C., "A Predictive Approach to Cleavage Fracture Events in the Transition Region", Engineering Fracture Mechanics, Vol 45, No.5, 1993, pp 587-598 [231 Bryan, R H., Bass, B R., Bolt, S E., Bryson, J W., Corwin, W R., Merkle, L G., Nanstad, R K and Robinson, G C., "Pressurized-Thermal-Shock Test of 6-in.Thick Pressure Vessels PTSE-2: Investigation of Low Tearing Resistance and Warm Prestressing", NUREG/CR-4888, December 1987, 277 p Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1244-EB/Nov 1995 Author Index ,I A J/irvine, A K., 392 Ji, W.,3 Joyce, J A., 286 Anderson, T L., 100 B K Bakker, A.,191 Bigelow, C.A.,21 Brocks, W,,88,209,232 Kirk, M T., 445 Klingbeil, D., 88, 232 Klopp, R W., 255 Koers, R W J., 191 Kolednik, O., 71 Koppenhoefer, K C., 445 Krom, A H M., 191 Kiinecke, G., 232 C Chao, Y J., Crews, J H., Jr., 21 Crocker, J E., 255 D L Davenport, J C W., 344 Davies, P H., 392 Dawicke, D S., 2t Detty, D., 316 Dodds, R H., Jr., 100, 134, 445 E Landes, J D., 461 Lichtenberger, M., 255 Link, R E., 286 M Mohan, R.,316 Eberle, A., 88 Eripret, C., 363 N Nallet, S., 363 Neale, B K., 425 Newman, J C., Jr., 21 F Fischer, D F., 71 Franco, C., 363 Fricke, S., 88 O O'Dowd, N P., 134 G P Ghadiali, N D., 316 Gilles, P., 363 Giovanola, J H., 255 Gordon, J R., 425 Parks, D M., 43 R H Rosenfield, A R., 316 Rudland, D L., 316 Homma, H., 255 539 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by Copyright*of1995 by ASTM lntcrnational www.astm.org University Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 540 CONSTRAINT EFFECTS IN FRACTURE Vr S Schmitt, W., 209 Shan, G., 71 Shewfelt, R S W., 392 Shih, C F., 134, 163 Shum, D K M., 479, 501 Smith, D J., 344 Sun, D.-Z., 232 T Tang, M., 100 Wallin, K., 519 Wang, Y Y., 43, 425 Wilkowski, G M., 316 X Xia, L., 163 Z Zahed, G M., 88 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1244-EB/Nov 1995 Subject Index Crack initiation assessment, weld, 363 Crack opening stress, 191 Crack propagation, 88 Crack tip constraint, 43, 209, 316, 392, 479, 501 Crack tip displacement, 21, 100 Crack tip opening angle, 21 Crack tip opening displacement, 425 Crack tip stress fields, 3, 461 A ASTM standards A 515, 100 A 533B, 100, 286, 425 E 399, 445, 519 proposed practice, fracture toughness in transition, 286 B D Bending loads, 21 Bend specimens, 445 small, 519 Biaxial loading, 316, 501 Biaxial stress effect, Brittle-ductile transition, 3, 191 Brittle fracture, 519 Burst test, 392 Deformation, 255 limits, 445 Deformation theory plasticity, 43 Double-edge cracked tension geometries, 461 Double-edge notch specimen, 316 Ductile/brittle fracture, 134 Ductile crack extension, 100 Ductile failure, micromechanisms of, 209 Ductile fracture, 71, 134, 163, 191,425 Ductile tearing, 100, 134, 363 resistance, 232 Ductile-to-brittle transition region, 100, 134, 286 Ductile to cleavage fracture mode, 255 C Cavity growth modeling, 363 Center cracked specimens, 392 Circumferentially notched round bar specimens, 344 Cleavage fracture, 3, 134, 163, 191, 445 toughness, 100, 519 Compact tension specimens, 71, 88 Constraint elevation, 134 Constraint factor, 21, 134, 209, 255 out-of-plane, 71 Constraint gurson model, 163 Constraint model, 461 Cracked round bars, 255 Cracked welds, 363 Crack growth, 134, 191 resistance, 163 resistance curve, 71, 209, 232, 392 stable, 71, 100 E Elastic-plastic analyses plane strain, 43 finite element analyses, 21, 344, 425 fracture, 3, 425 Elevation, constraint, 134 F Ferritic materials, 100 Ferritic steel, 191, 255, 286 541 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 542 CONSTRAINT EFFECTS IN FRACTURE Finite element analysis, 43, 71, 88, 232 elastic-plastic, 344, 425 round bars, 255 three-dimensional, 316 Finite elements, 21, 100, 134, 163, 191 Flaw, semi-elliptical surface, 88 Four-point-bend specimens, 191 Fracture resistance, 163 Fracture toughness, 425, 461, 479, 501 ASTM E 399, 445, 519 cleavage, 100 ductile/brittle, 134 in transition range, proposed ASTM standard, 286 measurements, 255 G Geometry effects, 344, 461 shallow-flaw, 501 variation effects, 71 Zr-2.5Nb, 392 GURSON model, 232 constraint gurson, 163, 191 L Loads and loading, 43, 363 bending, 21 biaxial, 316, 501 dynamic, 232 effects, 344 static, 232 tension, 21 unloading, 479 M Micromechanical model, 209 Middle tension specimens, 88 Models and modeling cavity growth, 363 constraint, 461 constraint gurson, 163, 191 GURSON, 232 micromechanical, 209 numerical, 100 numerical, stable crack growth, 88 scaling, 286 statistical, 461 three-dimensional, 21 two-dimensional, 21 Molecular weight, 344 N H Hydrostatic field, 479 Numerical model, 100 stable crack growth, 88 P J-A9 methodology, J-co-ncept, modified, 88 J-integral, 3, 286, 425, 445 J-Q approach, 316, 363, 461, 479, 501 J-R curve, 209, 392 J-/? curve, 71, 232 J-T characterization, 43, 363 K Kic, 445 Plane strain conditions, 71, 134 Plane strain elastic-plastic analyses, 43 Plane strain fracture, 445, 519 toughness, 255 Plastic deformation, 134 Plasticity, 21, 344 deformation theory, 43 J2 flow theory, 163 Polymethylmethacrylate,344 Pressure tube material, 392 Pressurized thermal shock, 479 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:22:11 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized INDEX 543 Q Q stress, 209 R R-curves, 425 S Scaling models, 286 Scatter, 100 Short crack bend specimens, 286 Side-grooved specimens, 88 Single-edge notch specimens, 344 Size effect, 344, 461, 519 Small-scale yielding, 445 Stable crack growth, 71, 100 Standards ASTM A515, 100 ASTM A533B, 100, 286, 425 ASTM E 399, 445, 519 ASTM proposed, fracture toughness, 286 BS4360, 425 Statistical model, 461 Steel, 100, 191, 255, 286, 316, 425, 461 Stress, out of plane, 316 Stress strain curves, 425 Stress triaxiality, 100, 134, 363 Surface tension, part-through, specimens, 88 T Tension loads, 21 Tension specimens, 286 Thermal shock, 501 pressurized, 479 Three-dimensional model, 21, 88 Titanium, 255 Transition fracture toughness, 461 Triaxiality, 88, 209 stress, 100, 134 Tridimensional analysis, 71 TSE-5A, 501 Two-dimensional model, 21 Two-parameter characterization, 43, 134, 316, 363 T-stress, 43 V Validity, 519 Void coalescence, 163 Void growth, 163 Void nucleation, 191 W Weibull analysis, 286 Weibull model, 461 Welds, cracked, 363 Work hardening, 425 Y Yielding, 100 small scale, 445 Yield strength, 425 W Warm prestress, 479 Z Zr-2.5Nb, 392 ILl ! 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