Astm stp 962 1988

S T P 962 Hydrogen Embrittlement: Prevention and Control Louis Raymond, editor ASTM 1916 Race Street Philadelphia, PA 19103 Library of Congress Cataloging-ln-Publlcation Data Hydrogen embrittlement: prevention and control/[edited by] Louis Raymond (ASTM special technical publication; 962) Papers from the Second National Symposium on Test Methods for Hydrogen Embrittlement: Prevention and Control, sponsored by ASTM Subcommittee F7.4 on Hydrogen Embrittlement and held in Los Angeles, May 24-26, 1985 Includes bibliographies and index "ASTM publication code number (PCN) 04-962000-26." ISBN 0-8031-0959-8 Metals Hydrogen embrittlement Congresses Metals-Testing Congresses I Raymond, Louis, 1934II National Symposium on Test Methods for Hydrogen Embrittlement: Prevention and Control (2nd: 1985: Los Angeles) III ASTM Subcommittee F7.4 on Hydrogen Embrittlement IV Series TA460.H89 1988 620.1'623 dc19 88-3490 CIP Copyright by A M E R I C A N S O C I E T Y FOR T E S T I N G AND M A T E R I A L S 8 NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Peer Review Policy Each paper published in this volume was evaluated by three peer reviewers The authors addressed all of the reviewers' comments to the satisfaction of both the technical editor(s) and the ASTM Committee on Publications The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of these peer reviewers The ASTM Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM Printed in Ann Arbor, MI June 1988 Foreword This publication, Hydrogen Embrittlement: Prevention and Control, contains papers presented at the Second National Symposium on Test Methods for Hydrogen Embrittlement: Prevention and Control, which was held in Los Angeles 24-26 May 1985 The symposium was sponsored by ASTM Subcommittee F7.4 on Hydrogen Embrittlement Louis Raymond, Ph.D., L Raymond & Associates, presided as symposium chairman and was editor of this publication Contents Introduction L RAYMOND SECTION 1" OVERVIEW Opening Remarks c SONNINO Overview: Sections and A A ANCTIL Hydrogen Embrlttlement Test Methods: Current Status and ProjectianS L RAYMOND 10 Electrochemical Aspects of Hydrogen in Metais J J DELUCCIA 17 SECTION 2" CURRENT STANDARDSAND PROJECTIONS Hydrogen Embrittlement Coverage by U.S Government Standardization Documents E T CLEGG 37 Other ASTM Committees and ISO Committees Involved in Hydrogen Embrlttlement Test Methods A w GROBIN, JR 46 Specifications for Hydrogen Control Testing of Materlals D J COATES 55 Accelerated Acceptance Testing [or Hydrogen Embrittlement Control R v DREHER 60 Assessment of the Degree of Hydrogen Embrlttlement Produced in High-Strength 4340 Steel by Plating-and-Baking Processes Using Slow Strain Rate Testing w J POLLOCK 68 Panel Discussion: Sections and 81 SECTION 3: HYDROGEN IN STEEL AND TITANIUM Opening Remarks R FRICIONI 89 Electrochemical Sensor for the Determination of Hydrogen in Metals by Potential Measurements A MACKOR, C W DE KREUK, AND J SCHOONMAN 90 The Barnacle Electrode Method to Determine Diffusible Hydrogen in S t e e l s - - D A BERMAN AND V S AGARWALA 98 The Development of an In-Situ Sensor for Measuring the Hydrogen Content of Liquid I r o n - - T OHTSUBO, H KAWASE, AND S YAMAZAKI 105 A Study of the Effect of Voids on Hydrogen Diffusion Through Electroslag Refined Stql~i M WANG AND P G SHEWMON 117 Panel Discussion: Section 125 Summary: Section R FRICIONI 128 S E C T I O N 4: R E L A T I V E S U S C E P T I B I L I T Y Overview: Section D R McINTYRE 133 Sensitivity of Steels to Degradation in Gaseous Hydrogen H J CIALONE AND 134 151 J H H O L B R O O K Discussion The Present Status of the Disk Pressure Test for Hydrogen Embrittlement J.-P FIDELLE Discussion 153 171 Screening Tests for Hydrogen Stress Cracking Susceptibility w R CRUMLY 173 Ranking Materials for Extreme Sour Gas Servlee Using the Slow Strain Rate Method D s McINTYRE 178 A Bent B e a m Test Method for Hydrogen Sulfide Stress Corrosion Cracking Reslstance D O c o x Discussion 190 198 Selection of Petroleum Industry Materials Through Use of Environmental Cracking T e s t s - - s w CIARALDI Discussion 200 212 S E C T I O N 5" H Y D R O G E N IN W E L D I N G Overview: Section J BLACKBURN 217 In Situ Measurement of Hydrogen in Weld Heat Affected Zones Thru Mass Spectrometry and Computer Analysis G M PRESSOUYRE, V LEMOINE, D J M D U B O I S , J - B L E B L O N D , P R SAILLARD, AND F M FAURE Testing of Welding Electrodes for Diffusible Hydrogen and Coating Molsture T A SIEWERT 219 238 Diffusible Hydrogen Testing by Gas Chromatography M A QUINTANAAND I R D A N N E C K E R 247 Panel Discussion: Gas Chromatography 269 The Effect of Weld Metal Diffusible Hydrogen on the Cracking Susceptibility of HY-80 Steel R j WONG 274 In-Process Prediction of the Diffusible Hydrogen Content of G a s - M e t a l AI'C D R WHITE AND W G CHIONIS 287 Panel Discussion: Diffusible Hydrogen 299 SECTION 6: PREVENTION AND CONTROL: CASE HISTORIES Overview: Section w FIELD 303 Prevention of Hydrogen E m b r R t l e m e n t by Surface F i l m s - - G T MURRAY Discussion 304 316 Hydrogen Embrlttlement and Relief T r e a t m e n t Study of Zinc P h o s p h a t e - C o a t e d S u b m u n l f l o n s - - G P VOORHIS Discussion 318 334 Examination of Cadmium-Plated Aircraft Fasteners for Hydrogen E m b r i t t l e m e n t - - M LEVY AND G A BRUGGEMAN Discussion Proof Test Logic for Hydrogen Embrlttlement Control w E Ka.S~S Discussion 335 341 343 349 SECTION 7: RESEARCH IN PROGRESS Quantitative Analysis of Critical Concentrations for Hydrogen-Induced C r a c k l n g - - G M PRESSOUYRE AND F M FAURE 353 Assessment of t h e Degree of Hydrogen Embrittlement Produced in P l a t e d H i g h - S t r e n g t h 4340 Steel by P a i n t S t r i p p e r s U s i n g Slow S t r a i n R a t e T e s t i n g - - w J POLLOCK AND C GREY 372 T h e Hydrogen E m b r i t t l e m e n t Susceptibility of Ferrous Alloys: T h e Influence of Strain o n H y d r o g e n E n t r y a n d T r a n s p o r t - - J R SCULLY AND P J MORAN 387 Hydrogen Transport, Microstructure, and Hydrogen-Induced Cracking in A u s t e n i t i c Stainless Steels T PERNG AND C ALTSTETTER 403 T e m p e r a t u r e D e p e n d e n c e of Fatigue Crack Propagation in Niobium-Hydrogen AHoys N POLVANICH AND K SALAMA 417 Index 429 STP962-EB/Jun 1988 Introduction A proliferation of test methods relative to hydrogen embrittlement prevention and control has been generated since the publication of Hydrogen Embrittlement Testing, A S T M STP 543 As a result, only one voluntary consensus standard, ASTM Method for Mechanical Hydrogen Embrittlement Testing of Plating Processes and Aircraft Maintenance (F 519-77), has been generated since that time Over 30 other standards, either federal, military, international, or industrial, have incorporated variations on this single test standard to provide some semblance of consistency throughout the industry A recent rash of failures due to hydrogen embrittlement, including failures in alloys other than high-strength steels, has caused a revitalized interest in this activity The need for more standard test methods has never been more apparent To this end, it was felt that the time had come to put together a symposium bringing in experts throughout the world to provide ASTM with a state-of-the-art review of the technology, its aplalications, and a focus on how to prevent hydrogen embrittlement failures in the future These failures can be prevented either: (1) by eliminating the sources of hydrogen in the making of alloys (primarily steel); (2) by the manufacturing of hardware; or (3) by the ultimate generation of hydrogen under different environmental conditions generally associated with dissimilar metals producing galvanic couples that are primarily used as sacrificial anodes to prevent corrosion As of this writing, hydrogen embrittlement has now been documented as the cause for failure in high-strength aluminum alloys, specifically aged to avoid stress corrosion cracking, for such critical applications as main rotor fittings for helicopter blades Fractures have occurred, as with steel, simply with time after being exposed to moisture in a storage box that encounters common atmospheric temperatures These failures are found with a prestressed T-73 specifically designed to eliminate susceptibility to stress corrosion cracking overage condition for a 7000 series aluminum alloy The response to the call for papers in 1984 was expansive The papers were divided primarily into seven sections: Overview or state-of-the-art tutorial Existing standards, both on a national and international scale Hydrogen introduced during the making of steel or other alloys Methods for measuring the relative susceptibility of other metals and alloys to hydrogenassisted stress cracking S Hydrogen induced during welding The application of coupon test techniques to the testing of actual hardware Research in progress, which will be the foundation of future research and direct the activities of universities and other research institutes in future research activities This volume meets the purposes for which it was organized, provides the reader with a stateof-the-art review with specific details, and offers many new ideas Section is an overview section that provides a backdrop for topics related to the processing of steel and titanium, service environment, manufacturing and processing, prevention and control, and research in progress Section examines current standards and their significance and identifies qualifying factors in the use and interpretation of their results The main focus is on the introduction of hydrogen Copyright 1988 by ASTM International www.astm.org HYDROGEN EMBRI-I-rLEMENT during manufacturing and processing, about which most of the specifications are written ASTM Standard F 519 clearly illustrates that the standard is written solely to ensure that no hydrogen is introduced into the steel during a plating operation or during the use of maintenance chemicals in the cleaning of high-strength steels Other technical societies have been surveyed to see how they use a variety of hydrogen embrittlement processing and control standards Section focuses on the measurement of the hydrogen introduced during the making of steel, which can be measured as a total or diffusible hydrogen This section summarizes advances in vacuum fusion and electrochemical methods for the measurement of both the total and diffusible hydrogen Section provides a variety of new tests encompassing testing in high-pressure hydrogen gas environments to hydrogen sulfide stress cracking conditions encountered in the petroleum industry The methods appear to focus on accelerated and rapid testing techniques that would be more consistent with the scheduling or time constraints of industry, with a concern about the cost impact to such controls Section is dedicated totally to advances in hydrogen embrittlement prevention and control in welding Real-time monitoring techniques of hydrogen during the weld metal deposition are described in addition to post-weld methods of hydrogen analysis, including mechanical tests that provide constraints that rank or evaluate hydrogen stress cracking susceptibility in welds Section focuses on applying our knowledge of the behavior of hydrogen under sustained loads in production applications, whether these loads are externally induced or through residual stresses from processing, to actual hardware such as submunitions, fasteners, and hydraulic actuators Section identifies research in progress related to a broad range of applications from slow strain rate tension testing to hydrogen-assisted fatigue failures in niobium Methods of measuring hydrogen in fabricated hardware and their precision and accuracy are discussed This STP provides a variety of new proposed test methods, interpretation of data, and use in a variety of fields that include petroleum, nuclear, aircraft, and space, in addition to the more common military applications of high-strength steels The STP serves as a foundation for any manufacturer involved in the plating of parts for corrosion protection and provides an awareness of the sensitivity of these parts to the environment relative to any embrittling factors that might be produced because of conditions for environmentally assisted fracture that are not commonly identified The most prominent experts in the field of hydrogen emhrittlement have contributed to this STP and can be readily identified with regard to any further information or specific details of their work that might support the prevention and control of hydrogen embrittlement failures in any new applications In summary, we are encountering an era where high-strength materials are being selected for applications based on ballistic impact, wear resistance, hardened surfaces for implementation of accelerated manufacturing techniques (as with self-drilling fasteners), and even hard-facing for improved wear resistance All these methods in one way or another eventually require corrosion protection systems or the introduction of dissimilar metals Because of the types of fabrication employed to produce hard surfaces or high-strength materials, residual stresses are inherent to the manufactured hardware All of these factors in combination provide a potential for hydrogen embrittlement failure which cannot be ignored Routine, conventional 3-h to 23-h baking treatments at 375~ (190.5~ are no longer sufficient to prevent embrittlement failures with hydrogen, especially in-service The articles in this STP provide us with an awareness of the problems and the tools with which to address the prevention and control of any hydrogen stress assisted failures Only by implementing this knowledge and properly interpreting test results can unanticipated hydrogen embrittlement failures of fracture critical parts be avoided Therefore, this STP is not the com- INTRODUCTION pletion or summary of a large amount of work that puts the problem of hydrogen embrittlement prevention and control to rest, but instead should be considered as the foundation for developing standards that will help us avoid costly life-threatening catastrophic failures in the future Louis Raymond, Ph.D., L Raymond & Associates, P.O Box 7925, Newport Beach, CA 92658-7925; symposium chairman and editor 420 HYDROGEN EMBRITTLEMENT TABLE Hydrogen content in niobium-hydrogen alloys in ppm weight 273K 400K 13 103 213 361 508 787 1108 60 86 296 445 742 1181 Fatigue tests were performed in tension-tension loading in a closed-loop electrohydraulic machine using a sinusoidal loading cycle of frequency Hz In these tests, the specimen was mounted in the machine with two Teflon side plates to prevent out-of-plane displacements at the crack tip The tests were performed at a load ratio R (equals minimum load divided by maximum load) of approximately 0.05 and at test temperatures of 273 and 400 K A temperature control system with an accuracy of + K was used to control and measure the temperature of the specimen Tests were usually terminated when the crack length was about 60% of the specimen width The stress intensity range AK was determined using the expression Ap A K _ 1/ ~ (1) f(a/W) ~ W where AP : the load range, b and W : the thickness and the width of the specimen, respectively, and f ( a / W ) = the compliance function, given by f(a/W) = (2 + a / W ) (1 a / W ) 3/2 • [0.866 + -a L W + 14.72 5.62 (2) Crack extension was determined by measuring changes in the electrical potential at two points across the crack where a constant alternate current was applied This is based on the principle that electrical resistance in specimens increases with crack extension A schematic diagram for the a-c potential difference system used in this work is illustrated in Fig The system consists of a lock-in amplifier, a bipolar operational power supply (BOP), a strip chart recorder, and a resistance circuit box The resistance box was designed to supply, in conjunction with BOP, a constant current (Io) of approximately A to the specimen Initially, a calibration between the potential difference across the crack and the actual crack extension was made using a traveling microscope to measure the actual crack length The change in electrical potential was recorded on the strip chart recorder that allowed continuous monitoring of the crack growth Copyright by ASTM Int'l (all rights reserved); Mon Dec 13:12:58 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproduction POLVANICH AND SALAMA ON NIOBIUM-HYDROGEN ALLOYS Lock in l Amplifier 01 Input A Re.,f / 421 Strip Chart Recorder 1K ei =IV[ 707rms/Ib = ImA Shielded Wire ,oo I~ I /~3_ ~0.1~ Rs Common BOP I CTS Transformer I'i~176 FIG Schematic for a-c potential difference system Results Figure shows the crack growth rate d a / d N as a function of stress intensity range AK for all specimens tested in this investigation at 273 K The crack growth rate d a / d N was calculated using the increase in the crack length during the number of cycles N between successive crack tip readings Results obtained at T = 400 K are shown in Fig The majority of the curves in both figures represents the crack growth rates in Stages I and II From both Figs and 4, it can be seen that, at low growth rates (near threshold), there is a strong influence of hydrogen on AKIh This region is followed by Region II where d a / d N linearly increases with AK, and the slope of d a / d N versus AK does not change much with hydrogen The near threshold stress intensity range, Agth, as a function of hydrogen concentration for both 273 and 400 K, is plotted in Fig Also shown in this figure are the results obtained by Fariabi et al at room temperature [22] From Fig 5, one can see that, at constant temperature, AKth of hydrogen-free niobium is the greatest, but decreases rather sharply as hydrogen is increased The decrease of AKth with increased hydrogen is almost linear until it reaches a minimum value at a concentration of approximately 600 ppm weight at the test temperature of 273 K, 400 ppm weight at 296 K, and 280 ppm weight at 400 K Above these hydrogen concentrations, AKth increases as the amount of hydrogen dissolved is increased and levels off as the amount of hydrogen is further increased Also observed in Fig is that the values of AKth at 273 K are less than those obtained at 296 K The latter values are also less than those at 400 K Discussion From Fig 5, one can see that for all temperatures AKth decreases as the amount of hydrogen in the specimen is increased until AKth reaches a minimum value, (Agth)mln This value represents the maximum embrittlement in the material at a given temperature The hydrogen concentration at this maximum embrittlement may be considered as the critical concentration of Copyright by ASTM Int'l (all rights reserved); Mon Dec 13:12:58 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions a 422 HYDROGENEMBRITTLEMENT 508 787 1108 R = 05 Nb-H 273 K 10 i f o 10- f / 10- 9o 10-'~ 10 AK I 14 (MN/m3/2) I 18 22 F I G Fatigue crack propagation rate, d a / d N , versus stress intensity range, A K , in niobium-hydrogen alloys at stress ratio R : 0.05 and 273 K Numbers above curves represent the amount of hydrogen dissolved in ppm weight Nb-H R = 05 400 K -7 10 1181 ~ $ -~ 10-8 >, o E z r "o 60 86 / 10-9 10 -1~ I I I 12 16 AK (MN/m3/2) I 20 24 F I G Fatigue crack propagation rate, d a / d N , versus stress intensity range, A K , in niobium-hydrogen alloys at stress ratio R : O.05 and 400 K Numbers at curves represent the amount of hydrogen dissolved in p p m weight Copyright by ASTM Int'l (all rights reserved); Mon Dec 13:12:58 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions aut POLVANICH AND SALAMA ON NIOBIUM-HYDROGEN ALLOYS 423 14 Nb-H R = 05 [] K 12 10 ix o h ' I I I I 400 800 1200 H y d r o g e n Dissolved ( p p m w t ) FIG S Dependence of threshold stress intensity range, AKth, on hydrogen concentration in niobiumhydrogen alloys Stress ratio R = 0.05 The stress-free solubility of hydrogen in niobium at 273, 296, and 400 K are, respectively, 230, 350, and l l 70 ppm weight hydrogen, Cr, required for embrittlement As the amount of hydrogen dissolved exceeds Cr, AKth increases as a function of hydrogen concentration and seems to reach a steady state value at very high concentrations This behavior suggests that two mechanisms are responsible for the embrittlement of niobium with hydrogen One causes the sharp decrease in ductility when the amount of hydrogen is less than C , while the other mechanism, which partially offsets the embrittlement occurring at lower concentrations, operates when the hydrogen concentration is greater than Cr The effects of the two mechanisms become equal at Cr There is a possibility, however, that under plane stress conditions the effects of closure can be large and can account for or perhaps exceed the observed increase in AKth at high hydrogen concentrations In this case, AKth would either remain constant or continue decreasing after the hydrogen concentration in the specimen exceeds C~, and only one mechanism would be responsible for the behavior of AKthwith hydrogen concentration At present, results to examine the extent of closure contributions to AKth are not available, and we are in the process of developing the experimental capability to perform these measurements Figure indicates that the maximum embrittlement occurs at approximately 600 ppm weight at 273 K, 400 ppm weight at 296 K, and 280 ppm weight hydrogen at 400 K The stress-free solubility of hydrogen in niobium at these temperatures are, respectively, 230, 350, and 1170 ppm weight and indicates no correlation between Cr and the formation of stress-free hydride as reported earlier [22] The possibility of stress-induced hydrides formed at the crack tip also seems to be remote since the differences between Cr and the solubility limit at some tempera- Copyright by ASTM Int'l (all rights reserved); Mon Dec 13:12:58 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproduc 424 HYDROGEN EMBRITTLEMENT tures are very great Using the calculations of Grossbeek and Birnbaum [23] for the effects of external stress on the precipitation of hydrides, one finds that a biaxial stress of 0.2/z (# is the shear modulus) is needed to shift the solubility limit 1170 ppm weight at 400 K to the value 6", = 280 ppm weight Such stress (0.2 #) is greater than that likely to be generated at the crack tip Accordingly, it may then be concluded that stress-induced hydrides cannot be also formed and that the decrease of AKth with hydrogen will not be due to the presence of hydrides If hydride, rather than some more mobile form of hydrogen, was responsible for embrittlement, AKth would have reached a minimum value when the hydride phase began to form and then decreased precipitously after that This argument also suggests that the two embrittlement mechanisms are operative when the hydrogen is in solid solution as well as in the hydride phase Also from Fig 5, one can see that the minimum values of threshold stress intensity range for the three test temperatures follow the general behavior of fatigue fracture toughness of most materials where AK decreases as the test temperature decreases Figure is a plot of (AKth)mi n as a function of Temperature T and indicates a linear relationship between the two quantities with a slope of 0.024 MN/m 3/2 The solute concentration buildup in a stress field, Cr, at a distance r has been given by Liu as [24] C~ : C~ exp[ 2(12x/~rr+V) Vx~K]3RT (3) where Co = Vtt = = R = the solute concentration in the bulk, the partial molal volume, Poisson's ratio, and the gas constant From microhardness measurements at room temperature, Fariabi et al [25] determined the plastic zone size, ry in niobium specimens containing various amounts of hydrogen and found that ry does not change much as a function of dissolved hydrogen Co, and is in the order of approximately ram Those authors also found that the calculated hydrogen concentration C, in the stress field around the crack increases linearly as a function of the amount of dissolved hydrogen Co If these results are valid at all temperatures, then A K / T will be constant and agrees with the plot in Fig Using the values for (Agth)mln/T : 0.024 MN/m3/2/K, r : mm, v = 0.37, V~ = 1.7 • 10 -6 m 3, and R = 8.3 • 107 erg/mol K, the quantity between brackets in Eq 3, is equal to 0.056 The ratio of the hydrogen concentrations at a distance r from the crack tip Cr and in the bulk Co will then be equal to 1.06 This indicates that at (Agth)min, there will be no migration of hydrogen from the bulk to the crack tip stress field, and Cr represents the critical hydrogen concentration required for maximum embrittlement This result supports the quantitative correlation obtained by Gerberich and Chen [19], who suggest the existence of AKth, defined as the stress intensity below which no cracking will occur under hydrogen-assisted conditions The agreement, however, is for the minimum values of AKth or for maximum embrittlement at specific temperatures Figure is a plot of the natural logarithm of hydrogen concentration (in percentage of atomic ratio) for maximum embrittlement, 6",, as a function of the inverse absolute temperature As seen, a straight line passes through the data and can be described by Cr = A exp[Q/RT] (4) where A is a constant The value of the activation energy, Q, calculated from Fig 7, is 1400 cal/ tool Copyright by ASTM Int'l (all rights reserved); Mon Dec 13:12:58 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions au POLVANICH A N D S A L A M A ON NIOBIUM-HYDROGEN ALLOYS 425 Nb-H R = 05 oJ r E z _= E J~