Astm stp 496 1971

FRACTURE TOUGHNESS TESTING AT CRYOGENIC TEMPERATURES A symposium presented at the Seventy-third Annual Meeting AMERICAN SOCIETY FOR TESTING AND MATERIALS Toronto, Ontario, Canada, 21-26 June 1970 ASTM SPECIAL TECHNICAL PUBLICATION 496 List price $5.00 04-496000-30 AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street, Philadelphia, Pa 19103 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized BY AMERICAN SOCIETY FOR TESTING AND ~IATERIALS 1971 Library of Congress Catalog Card N u m b e r : 70-163001 NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Printed in Baltimore M d Auguat 1971 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword Committee E-24 on Fracture Testing of Metals sponsored the Symposium on Fracture Toughness Testing at Cryogenic Temperatures at the Seventy-third Annual Meeting of the American Society for Testing and Materials, held in Toronto, Ontario, Canada, 21-26 June 1970 The twosession meeting, given on 24 June, was chairmaned by J G Kaufman of the Alcoa Research Laboratories, who was assisted by J F Boysen of the Boeing Company Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions au Related ASTM Publications Fracture Toughness Testing and Its Applications, STP 381 (1965), $19.50 Plane Strain Crack Toughness Testing of High Strength Metallic Materials, STP 410 (1967), $5.50 Review of Developments in Plane Strain Fracture Toughness Testing, STP 463 (1970), $18.50 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Contents Introduction Plane Strain Fracture Toughness of Some Cryogenic Materials at Room and Subzero Wemperatures c VISHNEVSKY AND E A, STEIGERWALD Plane Strain Fracture Toughness of Aluminum Alloys at Room and Subzero Wemperatures F G NELSON AND J G KAUFMAN Influence of Specimen Design in Plane Strain Fracture Toughness Testing-L R HALL 27 40 Fracture of Thin Sections Containing Through and Part-through Cracks-T W ORANGE~ T L SULLIVAN~ AND F D CALFO 61 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP496-EB/Aug 1971 Introduction This special technical publication consists of four papers presented at the Symposium on Fracture Toughness Testing at Cryogenic Temperatures at the 1970 Annual Meeting of the American Society for Testing and Materials, held in Toronto, Canada The session was conceived by the Low Temperature Panel of the ASTM-ASME Joint Committee on Effect of Temperature on the Properties of Metals and cosponsored and supported by ASTM Committee E-24 on Fracture Testing of Metals and the Aerospace Panel of the Joint Committee The symposium was organized to provide a current picture of the state of the art in fracture toughness testing at cryogenic temperatures Of principal interest was the application of the foundation of fracture toughness testing, based upon modified linear elastic fracture mechanics and built by ASTM Committee E-24, to the field of uttralow temperatures The four papers in this volume are representative of the situation today The Vishnevsky-Steigerwald and Nelson-Kaufman papers describe direct applications of the ASTM plane-strain fracture toughness test method (E 399- 70) to cryogenic evaluations, although the temperature control procedures used in that program (carried out several years ago) are not recommended today The paper by L R Hall presents comparative fracture toughness data for several different specimen designs, including those covered by the ASTM method and surface flawed specimens, at various temperatures The fourth, by Orange et al, moves more strongly into the complex area of surface flaws now being attacked by ASTM Committee E-24 and presents an analytical treatment of cryogenic data The Vishnevsky-Steigerwald paper merits special attention, as it is the result of a program developed by the Low Temperature Panel and sponsored by the Metal Properties Council with the specific intent of developing cryogenic fracture toughness data suitable for consideration for handbook use It is the official publication of the final report from that program All of the detailed data, on file in the Metal Properties Council Office in the Engineering Center in New York City, are available for further study as fracture test methods evolve The results of this program will also be of special interest to the novice in fracture toughness testing, cryogenic or otherwise They provide ample evidence of the pitfalls and practical problems that may be encountered in obtaining valid Kxr values l Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed Copyright* 1971 by by ASTM International www.astm.org University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized FRACTURETOUGHNESS TESTING AT CRYOGENIC TEMPERATURES Three other presentations that not appear in this volume were made at the symposium: Fracture Behavior of Three Cryogenic Materials (Aluminum Alloys 2021-T81 and 7007-T6 and a Low Silicon Content 301 Stainless steel); by F R Schwartzberg, R D Keys, and T F Keifer; Martin-Marietta Co., Denver, Colo Extension, Penetration, and Arrest of Cracks in 2014-T6 Aluminum Alloy Welds; by D E Schaub, R A Rawe, and R S Wrath; McDonnellDouglas Corp., Santa Monica, Calif Stress Wave Emissions During Subcritical Crack Growth in Beryllium at - F; by A T Green and C E Hartbower; Aerojet-General Co., Sacramento, Calif These papers are not presented in this volume principally because they are not compatible with ASTM style and concepts They do, however, contain valuable information in certain specialized fields Interested persons are referred to the authors for copies of the original manuscripts It is appropriate here to express, on behalf of the Low Temperature Panel, our gratitude to the Aerospace Panel of the Joint Committee and ASTM Committee E-24 for their support of this symposium and, especially, to the Metal Properties Council for their funding of the program leading to first report in this volume Also, special thanks are due J A Boysen for his assistance in setting up the program and cochairmaning the symposium J G Kaufman Alcoa Research Laboratories New Kensington, Pa Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions aut C Vishnevsky and E A Steigerwald Plane Strain Fracture Toughness of Some Cryogenic Materials at Room and Subzero Temperatures R E F E R E N C E : Vishnevsky, C and Steigerwald, E A., " P l a n e S t r a i n Fracture Toughness of Some Cryogenic Materials at Room and Subzero T e m p e r a t u r e s , " Fracture Toughness Testing at Cryogenic Temperatures, ASTM S T P 496, American Society for Testing and Materials, 1971, pp 3-26 A B S T R A C T : An investigation was conducted to measure the plane strain fracture toughness, K~r of eight potential cryogenic service alloys at 75, - 100, and -321 F The test materials included 7039-T61 and 2021-T81 aluminum alloys, Ti-6AI-4V STA in both alpha+beta and beta processed conditions, and the following steels: ASTM A553-A, PH 13-8Mo (H 1150-M), HP 9-4-20, and 18Ni (200 grade) maraging Results include both fracture toughness and tensile data as a function of test temperature for each alloy, together with overall comparisons in terms of the plane strain crack size factor, (K~/~y,) 2, versus yield strength and yield strength to density ratio In cases where valid K~r data could not be generated, the appropriate aspects of the ASTM Tentative Method of Test for Plane Strain Fracture Toughness of Metallic Materials (E 399 - 70T) are discussed K E Y W O R D S : cryogenics, aluminum alloys, titanium alloys, steels, struc- tural steels, strains, stresses, fractures (materials), toughness, tensile properties, bend properties, notch sensitivity, yield strength, cracking (fracturing), density (mass/volume), design, bend tests, tension tests T h e subject of linear elastic fracture mechanics has been widely studied b y m a n y investigators for over a decade A particularly useful o u t g r o w t h of this effort has been the development of the plane strain fracture t o u g h ness, Kic, as a measure of crack propagation resistance, principally in high strength materials This p a r a m e t e r is a useful design tool because it permits a q u a n t i t a t i v e relationship to be expressed between critical flaw size and applied stress in terms of material properties, KI~, and yield strength Principal engineer and manager, respectively, Materials Research Department, TRW Inc., Equipment Group, Cleveland, Ohio 44117 EST 2015 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 Downloaded/printed Copyright9 1971byby ASTM lntcrnational www.astm.org University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized FRACTURETOUGHNESS TESTING AT CRYOGENIC TEMPERATURES In spite of the fact that considerable information has been published on the fracture toughness of various alloys, there is a dearth of reliable K~r data for many high strength structural alloys This situation has arisen because many of the available data were obtained using techniques now known to introduce significant inaccuracies During the past several years, ASTM Committee E-24 on Fracture Testing of Metals has been developing standard procedures for K~c testing and a tentative test method, E 399- 70T, was recently published [I] In view of the complexity of the subject, some eventual modifications to this procedure are anticipated However, the basic techniques are now sufficiently well developed to enable the systematic generation of reliable K~c data for many materials The work described here was initiated by the Low Temperature Panel of the ASTM-ASME Joint Committee on the Effect of Temperature on the Properties of Metals primarily to obtain design KIo data on potential cyrogenic service alloys Eight alloys representing three widely differing classes of materials were included in the program The results of these tests, together with some observations and comments related to the current test method, are presented in the following sections Materials and Procedure Eight materials representing steel, aluminum, and titanium alloy were evaluated in this investigation These are listed in Table 1, which also shows the vendor, the thickness of the as-received stock, and its chemical analysis With the exception of the HP 9-4-20 and 18Ni (200 grade) maraging steels all alloys were obtained in a fully heat treated condition The HP 9-4-20 steel was quenched and tempered at TRW, while the maraging steel was received in an annealed condition that necessitated aging after machining of the test specimens Table gives a summary of the data available on the processing of the test materials Tensile and notch bend fracture toughness properties were determined at 75 F in an ordinary air environment, at -100 F in either acetone or ethanol-dry ice baths, and at -321 F by submersion in liquid nitrogen The specimens were machined with their longitudinal axes perpendicular to the primary working direction, that is, in the WR orientation For the tension tests, conventional threaded end, unnotched bars having a test section diameter of 0.505 in and a gage length of 2.0 in were tested, with a minimum of two tests conducted at each temperature Fracture toughness tests were performed to determine the plane strain fracture toughness, K~c, using procedures developed by ASTM Committee E-24 as ASTM E 399 The toughness specimens were fatigue preeracked Acetone was used for all tension testing, while ethanol was used for the notch bend tests to avoid possible damage to the dip gage used to monitor crack opening displacement Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized ORANGE ET AL ON FRACTURE OF THIN SECTIONS 67 For the surface crack defined by point C, the plastic zone would surely grow through the thickness prior to failure, and most of the uncracked ligament would undergo plastic deformation Under these conditions, fracture might well be controlled by the stress intensity at or near the major axis of the semiellipse If this crack were in a pressure vessel, elastic theory could not predict whether it would leak or burst Lacking more powerful analytical methods, we might speculate that, if the crack opening displacement were sufficiently large, the ligament might fail by tensile instability (and the vessel would leak) and that this would be most likely for long cracks But the yielded ligament might also act as a plastic hinge, allowing the cracked region to bulge outward in the manner associated with through cracks [13] This would induce a bending stress which would further complicate the problem Under these conditions it would be unwise to expect a cracked tension specimen to simulate the behavior of a cracked pressure vessel The empirical relation developed by Eiber et al ([14], Fig 15) for partthrough V notches in gas line pipe is similar in appearance to Fig of this paper Their burst tests also indicate that failure type (that is, leak or burst) can be correlated with relative fracture stress for through cracks and surface cracks of the same length If the fracture stress for a given surface crack is less than that for a through crack of the same length, that surface crack will result in a leak at failure; if greater, catastrophic fracture will occur I~1 t - \ I k \I I ASSUMED: 'c= K~lT;r0~s SURFACECRACK THROUGHCRACK o o d 1.0 I .- \ - ii x ~- i ~ ~ ~ K I c ~/2c= O.25 ~ I 0"5 Kc; a/t = 0"823 ~ ~ KIc= - = I I I 12 16 NORMALIZEDCRACKLENGTH,2clt 0.4 Kc; aJt : 0.887 I 20 FIG Effect of material toughness on predicted fracture stress for through and partthrough cracks at limiting depth Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 0.02 0.02 C 0.04 Cr 5.85 4.45 Cu 0.19 0.60 0.18 0.18 Fe 0.0005 0.0034 0.0040 tI 0.012 0.57 Mg 0.25 0.69 0.01 0.01 Mn O 0.0005 0.091 0.098 0.0012 0.007 0.007 N Si 0.12 0.92 Chemical composition of materials tested (percent by weight) Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 2219-T87 Muminum balance balance 5.3 Ti-5A1-2.5Sn (0.11 i n ) 2014-T6 aluminum 5.3 A1 Ti-5AI-2.5Sn (0.06 in.) Alloy TABLE 2.5 2.5 Sn 0.09 balance 0.02 a~ce bal- Ti Zn 0.08 0.09 0.05 Zr 0.11 V O O (3 O Oo z I o C Qo o 300 77 20 +70 -320 -423 2219-T87 a l u m i n u m 55.0 64.5 70.7 65.0 75.2 80.3 105 178 211 119 193 228 ksi 379 445 487 448 519 554 727 1230 1450 821 1330 1570 MN/m Yield S t r e n g t h 67,7 84.0 96.3 72.3 86.7 99.7 114 189 223 129 202 247 ksi 467 579 664 499 598 687 785 1300 1540 887 1390 1710 MN/m ' Ultimate Strength Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized a M e a s u r e m e n t considered unreliable b N o t measured 300 77 20 +70 -320 -423 2014-T6 a l u m i n u m 300 77 20 degK 300 77 20 -{-70 -320 -423 deg F Test Temperature -}-70 -320 -423 Ti-5AI-2.5Sn, 0.11 in (2.9 ram) Ti-5A1-2.5Sn, 0.06 in (1.6 ram) Alloy 1 X 106 11 12 10 X 10e 12 12 17 X l0 s 19 ~ 17 X 10e 19 19 psi 74 X 109 79 83 72 X l0 g 79 80 120 X 109 130 - 120 X 10' 130 130 N/re' Elastic M o d u l u s T A B L E Tensile properties of test materials (average: longitudinal direction) ll 12 14 18 19 14 16 13 b b b a Elongation in in (5 cm), % O, ~O i z o z O z O 70 FRACTURETOUGHNESS TESTING AT CRYOGENIC TEMPERATURES Effects of Material Properlies The limits of applicability of this analysis are also 'tffeeted by the material properties Equation shows that the timiting crack depth (at which the plastic zone just penetrates the thickness) is also a function of the ratio KIc/K~ Figure shows the effect of K~c/Kc at the limiting depth (for this specific thickness) From this figure it appears that leak-beforeburst failures cannot be predicted at all if K~, is greater than about 0.6K~ (for this thickness), and they can be expected over a wider range of crack lengths if KI~/K~ is low Again, a crack with a depth to length ratio (a/2c) of about 0.25 appears to be the one most likely to leak rather than burst at failure Experimental Procedure Materials The titanium alloy was purchased in two thicknesses rolled from the same heat Mill analyses for both are given in Table The 2014-T6 aluminum alloy (unclad) was from the same lot used in an earlier study [6] The analysis given was made by a commercial laboratory The 2219-T87 aluminum alloy (also unclad) was from the same lot studied in Ref 15; its analysis is also given in Table The tensile properties listed in Table were determined on the standard tension specimen shown in Fig 5a with differential transformer extensometers Fracture Specimens Titanium fracture specimen configurations were as shown in Figs 5b to 5d All 2014-T6 specimens were as shown in Fig 5d The 2219-T87 specimens, Figs 5e and 5f, were sized to be directly comparable with the surface crack specimens tested in Ref I5 Natural cracks were grown from crack starters by fatigue cycling the specimens at low stress Crack starters for all through crack and most surface crack specimens were made by electrical discharge machining For a few of the 2014-T6 surface crack specimens, sharp surface grooves were machine scribed All through crack and some surface crack specimens were fatigue sharpened in tension To obtain more elongated cracks, some surface cracks were extended in cyclic unidirectional bending For all specimens the nominal net cyclic stress was less than half the material yield strength Apparatus and Procedure The 2219-T87 through crack fracture specimens were fitted with antibuckling guides and tested in a 400,000-1b (1.8-MN)-capacity, screw powered tension testing machine All other specimens were tested in hydraulic machines having capacities of 20,000, 24,000, and 120,000 lb (89, Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized ORANGE ET AL ON FRACTURE OF THIN SECTIONS Z(7 (76) 2(51) k -~ 3(76) 1125) 1/21121~ ! f 0~] V- (5] 11021 (B) (A) 9 (c) (D) 6.7(170) 5 (1401~ (E) 24(6101 1213o51 0 71 0 iF) FIG Smooth tension and fracture specimens (dimensions in inches or mm) 107, and 535 kN) For smooth tension tests, differential transformer extensometers were used to measure average strain over a 2-in (5-cm) gage length Cryogenic test temperatures were established by immersing the specimen in liquid nitrogen or liquid hydrogen A vacuum jacketed cryostar with multilayer insulation was used to minimize boiloff Cryogenic liquid level was maintained several inches above the upper specimen grip, and carbon resistors were used as level sensors Results Nominal fracture toughness values for through crack specimens were calculated with the finite width correction factor proposed by Feddersen Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductio 76 3.00 -423 20 20 0.0613 0.0622 0.0617 0.1115 0.1122 0.1126 0.1135 0.1128 0.1128 0.1162 0.1157 1.56 1.58 1.57 2.83 2.85 2.86 2.88 2.87 2.87 2.95 2.94 1.58 1.56 1.61 1.62 1.61 1.60 1.63 1.63 1.60 1.63 1.62 0.277 0.278 0.557 0.123 0.129 0.240 0.269 0.360 0.381 0.994 1.051 0.080 0.085 0.141 0.172 0.179 0.414 0.420 0.481 0.793 0.988 0.995 in 7.0 7.1 14.1 3.1 3.3 6.1 6.8 9.1 9.7 25.2 26.7 2.0 2.2 3.6 4.4 4.5 10.5 10.7 12.2 20.1 25.1 25.3 mm Initial Crack Length, 2c lll0 1090 806 821 623 671 402 381 409 405 321 59.3 58.8 46.5 1010 904 848 796 794 441 540 376 323 334 310 147.1 131.1 123.0 115.5 115.1 63.9 78.3 54.6 46.8 48.5 44.9 161.3 158.3 116.9 119.0 90.3 97.3 58.3 55.2 MN/m Gross Fracture Stress, a ksi Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized aluminum 2014-T6 25 51 25 51 25 51 76 76 1.00 2.00 1.00 2.00 1.00 2.00 3.00 3.00 -423 Ti-5AI-2.5Sn 20 0.0624 0.0616 0.0632 0.0639 0.0632 0.0629 0.0640 0.0640 0.0628 0.0640 0.0639 51 25 51 25 51 25 51 25 51 76 76 2.00 1.00 2.00 1.00 2.00 1.00 2.00 1.00 2.00 3.00 3.00 -423 mm in mm in deg F deg K Specimen Thickness, t Specimen Width, W Test Temperature Ti-5Al-2.5Sn Alloy T A B L E - - T h r o u g h crack frakture test data 46.5 46.0 49.6 86.7 84.6 83.1 86.0 80.4 82.3 80.5 79.1 58.7 52.8 62.9 66.2 65.8 60.1 67.8 57.7 59.1 66.0 61.2 ksiv~ 51.1 50.5 54.5 95.3 93.0 91.3 94.5 88.3 90.4 88.5 86.9 64.5 58.0 69.1 72.7 72.3 66.0 74.5 63.4 64.9 72.5 67.2 MNm-~/z Nominal Fracture Toughness, K c , o o o z o z o" " e- ",4 bo aluminum 300 77 20 470 -320 -423 140 170 170 170 140 170 6.7 6.7 6.7 5.5 6.7 170 6.7 5.5 140 5.5 O 334 O 402 0.515 0.623 0.909 1,004 1.186 0.332 0.420 0.480 0.621 0.884 0.998 1.203 0.297 0,400 0.492 0,610 0.825 0.891 1.027 1.184 1.72 1.71 1.71 1.72 1.70 1.73 1.73 1.74 1.74 1.73 1.72 1.71 1.73 1.74 1,73 1.73 1.71 1,71 1.73 1.72 1.74 1.74 0.0676 0.0672 0.0673 0.0676 0.0670 0.0680 0.0682 0.0685 0.0687 0.0680 0.0676 O.0673 0.0683 0.0686 0.0682 0.0680 0.0672 0.0675 0.0683 0.0676 0.0686 0.0684 8.5 10.2 13.1 15.8 23.1 25.5 30.1 8.4 10.7 12,2 15.8 22.5 25.3 30,6 7.5 10.2 12.5 15.5 21.0 22.6 26.1 30.1 19.7 21.5 26.2 30.1 30.6 35.5 36,4 289 272 236 222 217 196 190 362 354 343 330 326 318 299 436 424 415 394 385 376 352 460 445 432 424 401 396 384 370 41.9 39.5 34.2 32.2 31.5 28.4 27.5 52.5 51.3 49.8 47.9 47.3 46.1 43.4 63.2 61.5 60,2 57.1 55.9 54.6 51.1 66.7 64.6 62.6 61.5 58.2 57.5 55.7 53.6 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 2219-T87 0.775 O 846 1.032 1.187 1.204 1.399 1.432 1.52 1.56 1.55 1,53 1.53 1.54 1.55 0.0600 0.0613 0.0611 0.0604 0.0602 0.0608 0.0611 58.6 57.8 55.9 58.2 57.4 58.2 57.4 58.3 61.6 66.8 69.4 83.5 84.7 85.2 71.3 76.5 79.2 83.0 96.8 99.9 100.8 67.4 74.4 78.6 85.9 92.2 94.4 97.7 100.4 53.3 52.6 50.9 53.0 52.2 53.0 52.2 53.1 56.1 60.8 63.2 76.0 77.1 77.5 64.9 69.6 72.1 75.5 88.1 90.9 91,7 61.3 67.7 71.5 78.2 83.9 85.9 88.9 91.4 ,,q -.4 "1" o O z -9 m rZ O -423 deg F 20 degK Test Temperature 1.00 1.00 1.00 2.00 1.00 2.00 2.00 1.00 2.00 1.00 2.00 1.00 2.00 1.00 2.00 2.00 1.00 2.00 1.00 1.00 1.00 in 25 25 25 51 25 51 51 25 51 25 51 25 51 25 51 51 25 51 25 25 25 mm Specimen Width, W 0.0630 0.0628 0.0631 0.0635 0.0636 0.0643 0.0621 0.0648 0.0635 0.0647 0.0641 0.0650 0.0628 0.0640 0.0646 0.0646 0.0642 0.0631 0.0630 0.0639 0.0640 1.60 1.60 1.60 1.61 1.62 1.63 1.58 1.65 1.61 1.64 1.63 1.65 1.60 1.63 1.64 1.64 1.63 1.60 1.60 1.62 1.63 mm 0.022 0.024 0.027 0.027 0.031 0.033 0.034 0.037 0.038 0.040 0.040 0.041 0.046 0.050 0.051 0.056 0.056 0.031 0.033 0.033 0.034 in 0.56 0.61 0.69 0.69 0.79 0.84 0.86 0.94 0.97 1.02 1.02 1.04 1.17 1.27 1.30 1.42 1.42 0.79 0.84 0.84 0.86 mm a t in Crack Depth, Specimen Thickness, 0.089 0.078 0.065 0.075 0.077 0.099 0.132 0.102 0.122 0.123 0.128 0.147 0.158 0.173 0.175 0.190 0.200 0.297 0.286 0.300 0.391 in 2c 2.26 1.98 1.65 1.91 1.96 2.51 3.35 2.59 3.10 3.12 3.25 3.73 4.01 4.39 4.45 4.83 5.08 7.54 7.26 7.62 9.93 mm Crack Length, 207.6 207.5 213.3 182.7 180.8 169.0 152.3 153.5 152.0 137.9 145.7 130.0 107.4 102.4 98.0 96.7 101.5 138.3 136.9 136.9 143.6 ksi 1430 1430 1470 1260 1250 1170 1050 1060 1050 951 1000 896 741 706 676 667 700 954 944 944 990 MN/m tr Gross Fracture Stress, KQ Apparent Fracture Toughness, 51.8 49.8 47.1 42.8 43.1 45.4 46.0 42.0 45.3 41.3 44.6 42 l 37 ] 37.9 36.6 40.2 43.8 48.2 48.8 49.0 54.2 56.9 54.7 51.8 47.0 47.4 49.9 5O 46.1 49.8 45.4 4.(} 46.3 40.8 41.6 40.2 44.2 48.1 53.0 53.6 53.8 59.6 ksi~v/in M N / m 3/2 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Ti-5AI-2.5Sn, 0.06-in (1.6-mm) Alloy T A B L E Surface crack fracture test data ~' 0I Z c m ",4 -423 2014-T6 aluminum 20 20 3.00 2.99 2.99 2.99 3.01 3.00 2.99 2.99 3.00 3.01 3.00 3.O0 1.00 2.00 1.00 1.00 1.00 2.00 1.00 2.00 1.00 2.00 76 76 76 76 76 76 76 76 76 76 76 76 25 51 25 25 25 51 25 51 25 51 51 25 51 51 51 51 0.0622 O.O62O 0.0615 0.0615 0.0600 0.0613 0.0605 0.0612 0.0603 0.0600 0.0603 0.0619 0.1157 0.1122 0.1133 0.1129 0.1128 0.1147 0.1111 0.1143 0.1161 0.1119 0.0637 0.0622 0.O639 0.0633 0.0638 0.0627 1.58 1.57 1.56 1.56 1.52 1.56 1.54 1.55 1.53 1.52 1.53 1.57 2.94 2.85 2.88 2.87 2.87 2.91 2.82 2.90 2.95 2.84 1.62 1.58 1.62 1.61 1.62 1.59 0.034 0.035 0.038 0.042 0.044 0.044 0.046 0.051 0.054 0.055 0.055 0.058 0.023 0.037 0.043 0.056 0.068 0.073 0.O77 0.084 0.097 0.101 0.035 0.037 0.043 0.045 0.048 0.049 0.86 0.89 0.97 1.07 1.12 1.12 1.]7 1.30 1.37 1.40 1.40 1.47 0.58 0.94 1.09 1.42 1.73 1.85 1.96 2.13 2.46 2.57 0.89 0.94 1.09 1.14 1.22 1.24 0.206 0.213 0.3ll 0.403 0.232 0.265 0.457 0.609 1.275 1.115 1.363 0.198 0.118 0.129 0.153 0.179 0.227 0.247 0.290 0.291 0.342 0.337 0.399 0.393 0.590 0.351 0.782 0.820 5.23 5.41 7.90 10.24 5.89 6.73 11.61 15.47 32.39 28.32 34.62 5.03 3.00 3.28 3.89 4.55 5.77 6.27 7.37 7.39 8.69 8.56 10.13 9.98 14.99 8.92 19.86 20.83 72.1 70.8 63.4 55.1 66.2 63.1 51.7 47.8 31.4 33.6 29.6 66.7 207.6 195.5 184.9 162.I 144.0 139.9 118.9 129.0 105.4 110.4 138.0 120.4 111.7 106.1 85.1 80.6 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 11:06:37 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized -423 Ti,SAI-2.5Sn, 0.11-in (2.9-mm) 2.00 1.00 2.00 2.00 2.00 2.00 497 488 437 380 456 435 356 330 217 232 204 460 1430 1350 1270 1120 993 965 820 889 727 761 952 830 770 732 587 556 25.7 25.6 25.4 24.1 27.4 26.8 24.7 26.6 21.5 24.9 21.7 34.2 56.9 59.8 61.3 58.4 58.6 59.6 54.8 61.2 57.1 65.3 52.9 47.3 50.0 45.6 42.4 41.5 28.2 28.1 27.9 26.5 30.1 29.4 27.1 29.2 23.6 27.4 23.8 37.6 62.5 65.7 67.4 64.2 64.4 65.5 60.2 67.2 62.7 71.8 58.1 52.0 54.9 50.1 46.6 45.6 "4 O Z {gt O (b z O -9 m Z O O 76 FRACTURETOUGHNESS TESTING AT CRYOGENIC TEMPERATURES ([1], pp 77-79) With this correction Eq becomes Kr = ax,/WO sece where = ~ + 2-W kay, / Apparent fracture toughness (KQ) values for surface crack specimens were calculated from Eq lb (rearranged) and the free surface correction factor of Ref 11 Fracture test results and some calculated quantities are listed in Tables and Titanium Alloy Figure presents fracture stresses for through cracks and surface cracks in the thinner (0.06-in.) titanium sheet at - F (20 K) The surface crack tests are grouped according to depth to thickness ratio The experimental trends are generally in good agreement with the predicted trends of Fig Nominal fracture toughness (Kr for the through crack specimens was essentially constant (62 ksi~Zm-~ (68 M N / m 3/*) avg) Apparent fracture toughness KQ for the surface crack tests was reasonably constant (47 ksi%/~-~ (52 M N / m 3/2) avg) for all but the seven specimens with cracks deeper than 70 percent of the thickness Note (Fig 6) that for the five of these with short cracks (2c ,-, 0.18 in.) fracture stresses are within the scatterband for through crack tests Using the average KQ value (47 ksivq-~.), Irwin's plastic zone size is between 14 and 29 percent of the uncracked ligament depth for the seven deviant tests However, as discussed O Q) 1.0- ~) ~, \Ok ~xxA~ THROUGHCRACK SURFACECRACK, 0.34