Determination of Eurofer97 Fracture Toughness by Testing Small C(T) Specimens

Abstract The use of small specimen test techniques (SSTT) to determine the mechanical properties of irradiated materials has been studied over the past decades both in fission and fusion programs, but also to characterise and optimise new materials by nuclear and non-nuclear communities. Currently a number of activities are running that focus on the standardisation of SSTT to determine fracture toughness properties for fusion reactor materials (IAEA [1], EUROfusion [2], F4E [3]), and to support the long-term operation of light-water reactors (CRIEPI [4]). The determination of the T0 reference temperature (ASTM E1921 [5]) has been successfully achieved by testing small compact tension (C(T)) specimens (W = 8mm, B = 4mm) of non-irradiated and irradiated pressure vessel materials. However, some concerns exist regarding the use of the Master Curve (MC) on ferritic-martensitic steels, not only with SSTT but also with standard specimens. The main concern is the slope of the MC [6, 7], that seems to be steeper than the standard one. In this paper, the fracture toughness of Eurofer97 has been obtained by testing small C(T) specimens with the geometry selected in IFMIF-DONES (W = 9.2mm, B = 4.6mm) in the transition region. T0 has been determined and compared to the one obtained from 0.5T-C(T) specimens (both normalised to 1T). The scatter of the results has also been assessed to validate the scatter description of the MC.

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Improved Elastic Compliance Equation and its Inverse Solution for Compact Tension Specimens

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2017-65406 ◽

2017 ◽

Author(s):

Xian-Kui Zhu

Keyword(s):

Crack Length ◽

Maximum Error ◽

Compact Tension ◽

Crack Size ◽

Accurate Solution ◽

Elastic Compliance ◽

Load Line Displacement ◽

Standard Specimens ◽

Specimen Test ◽

Toughness Testing

ASTM E1820 is a well-developed fracture test standard and has been used worldwide for fracture toughness testing on ductile materials in terms of the J-integral or J-R curve. This standard recommends the elastic unloading compliance technique for measuring crack length in a single specimen test, and an accurate elastic compliance equation is needed to estimate physical crack length. Compact tension (CT) specimen is one of the most often used standard specimens with crack length ratios of 0.45≤a/W≤0.70 prescribed in E1820 for J-R curve testing. The stress intensity factor K of CT specimens used in E1820 was developed by Srawley (IJF, 1976) and has been commonly accepted as the most accurate solution. The compliance equation of CT specimens was developed by Saxena and Hudak (IJF, 1978) and has been used in ASTM E1820 for decades. However, recent results showed that the load-line displacement (LLD) compliance equation is not consistent with that determined from its K solution, and the maximum error of LLD compliance can be larger than 7% at a/W = 0.32 and ∼ 5% at a/W = 0.45 (E1820 standard crack size). The FEA results confirmed that the K solution in E1820 is indeed very accurate, but its compliance equation is less accurate. Thus, an improved compliance equation with high accuracy is developed from the accurate K solution using the numerical integration technique and shooting method.

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Determination of the Fracture Toughness Parameters for an MDF Cement Composite

MRS Proceedings ◽

10.1557/proc-64-257 ◽

1985 ◽

Vol 64 ◽

Cited By ~ 1

Author(s):

M. Arzamendi ◽

R. L. Sierakowski ◽

W. E. Wolfe

Keyword(s):

Fracture Toughness ◽

Cement Composite ◽

Compact Tension ◽

Test Methods ◽

Standard Test ◽

Elastic Behavior ◽

Hardened Cement ◽

Linear Elastic ◽

Toughness Testing

ABSTRACTThe experimental results of fracture toughness testing of a Macro Defect (MDF) Free cement are presented. The material, a hydraulic cement with hydrolyzed polyvinyl polymers, behaves much like a hardened ceramic with measured maximum compressive and tensile strengths of 380 MN/m2 and 69 MN/m2 respectively. Fracture toughness tests were performed on compact tension (CT) and single edge notched beam (SENB) specimens cut from test panels which were supplied in 3mm, 5mm and 10mm thicknesses. The results were evaluated with respect to the fracture toughness parameter Kic using a modification of standard test methods as determined by observed natural behavior. The MDF material exhibited an essentially linear elastic behavior with a fracture toughness slightly higher than typical values recorded for hardened cement paste.

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Fracture Toughness Evaluation of S355 Steel Using Circumferentially Notched Round Bars

Periodica Polytechnica Transportation Engineering ◽

10.3311/pptr.11560 ◽

2018 ◽

Vol 47 (2) ◽

pp. 91-95 ◽

Cited By ~ 1

Author(s):

Fatih Bozkurt ◽

Eva Schmidová

Keyword(s):

Fracture Toughness ◽

Fracture Mechanics ◽

Compact Tension ◽

Compact Tension Specimen ◽

Fracture Load ◽

Alternative Methods ◽

Test Procedures ◽

Toughness Evaluation ◽

Fracture Toughness Evaluation

In engineering applications, steels are commonly used in various areas. The mechanical members are exposed to different loading conditions and this subject can be investigated in fracture mechanics. Fracture toughness (KIC) is the important material property for fracture mechanics. Determination of this properties is possible using a compact tension specimen, a single edge notched bend or three-point loaded bend specimen, which are standardized by different institutions. Researchers underline that these standardized methods are complex, the manufacturing process is difficult, they require special fixtures for loading during the experiment and the test procedures are time consuming. Alternative methods are always being sought by researchers. In this work, two different approaches are investigated for S355 steels. In the first method, a circumferentially cracked round bar was loaded in tensile mode and pulled till failure. Using suitable equations, fracture toughness can be calculated. In the second method, a circumferentially notched bar specimen without fatigue pre-cracking was loaded in a tensile machine. By means of fracture load values, fracture toughness was determined by the proposed equations. It can be stated that these two different approaches for calculating fracture toughness are simple, fast and economical.

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An X-Specimen Test for Determination of Thin-Walled Tube Fracture Toughness

Fatigue and Fracture Mechanics: 32nd Volume ◽

10.1520/stp11667s ◽

2009 ◽

pp. 214-214-13 ◽

Cited By ~ 6

Author(s):

HH Hsu ◽

KF Chien ◽

HC Chu ◽

RC Kuo ◽

PK Liaw

Keyword(s):

Fracture Toughness ◽

Thin Walled Tube ◽

Specimen Test ◽

Thin Walled

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Acoustic Emission Entropy for Evaluation of Fracture Toughness of HSLA Steel Welded Joint

Volume 1B: Codes and Standards ◽

10.1115/pvp2017-66042 ◽

2017 ◽

Author(s):

Mengyu Chai ◽

Weijie Wu ◽

Zaoxiao Zhang ◽

Guangxu Cheng ◽

Quan Duan

Keyword(s):

Fracture Toughness ◽

Acoustic Emission ◽

Welded Joint ◽

Hsla Steel ◽

Amplitude Distribution ◽

Compact Tension ◽

Compact Tension Specimen ◽

New Approach ◽

Astm Standard

In this investigation, fracture toughness behavior of high strength low alloy (HSLA) steel welded joint was studied using acoustic emission (AE) monitoring. For the design of new structures and for the safety and reliability analyses of operating components, fracture toughness (KIC) values of materials play an essential role. Acoustic emission technique (AET) has been used for determination of fracture toughness based on some observable changes of AE evolutions. However, the occurrence of appreciable plasticity in materials, the friction between the crack surfaces and mechanical noise could generate high emission and may result in some difficulties in precise determination of fracture toughness. Thus, the objective of this study is to propose a new approach to evaluate fracture toughness values and to characterize the fracture process based on AE entropy. Specimens were selected from 2.25Cr-1Mo-0.25V steel welded joint which were thermally aged at 978 K for 8 h. The AE signals generated during fracture processes were recorded and the corresponding AE entropy was calculated based on the probability amplitude distribution from each original AE waveform. The point of crack initiation was identified by the occurrence of sudden rise of AE entropy and the corresponding critical load was used to estimate fracture toughness value. The estimated values obtained from the proposed new approach were compared with those determined by the methodology proposed by compact tension specimen testing according to ASTM standard E399. The results showed that the estimated values were in close agreement with those gained from ASTM standard. It was concluded that AE entropy was an effective parameter to estimate fracture characteristics and fracture toughness values.

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Dynamic J-Integral Evaluation of Three-Point-Bend Beams with Various Geometrical Dimensions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.488-489.630 ◽

2011 ◽

Vol 488-489 ◽

pp. 630-633

Author(s):

Marius Gintalas ◽

Antanas Žiliukas ◽

Kaspars Kalniņš

Keyword(s):

Fracture Toughness ◽

Plastic Material ◽

Rectangular Cross Section ◽

Estimation Method ◽

Displacement Curve ◽

Elastic Plastic ◽

Load Line ◽

Load Line Displacement ◽

Specimen Test

J-Integral is the main effective and commonly used tool for cracked elastic-plastic material resistance assessment. Determination of fracture toughness under impact loading conditions is related with problems of crack length measurement. Nevertheless, current experimental techniques restrict the specimen’s geometry taking into account span and height ratio, which is equal to four. Evaluation of fracture toughness estimation method which requires only experimental load-line displacement curve of single specimen is research object of dynamic fracture mechanics. This article proposes an approach of impact fracture toughness determination of elastic-plastic steel from single any size specimen test. Load-line displacement data obtained from three-point-bending tests of rectangular cross section specimens with V form single edge notch was used for J-integral calculation. Five series of specimens with different geometry were manufactured from ductile steel and tested.

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Inter-Laboratory Results and Analyses of Mini-C(T) Specimen Testing of an Irradiated Linde 80 Weld Metal

Volume 1A: Codes and Standards ◽

10.1115/pvp2018-84950 ◽

2018 ◽

Author(s):

William Server ◽

Mikhail Sokolov ◽

Masato Yamamoto ◽

Robert Carter

Keyword(s):

Fracture Toughness ◽

Weld Metal ◽

Compact Tension ◽

Laboratory Assessment ◽

Preliminary Results ◽

Ductile Crack Growth ◽

Specimen Test ◽

Toughness Evaluation ◽

Initiation Fracture Toughness ◽

Vessel Material

An irradiated low-upper-shelf Linde 80 weld metal has been tested by four laboratories as part of an inter-laboratory assessment of use of the miniature compact tension [mini-C(T)] test specimen for Master Curve fracture toughness evaluation following ASTM E1921. The preliminary results from each of the laboratories have been compiled and evaluated together to assess the validity and use of the mini-C(T) specimen for an irradiated reactor pressure vessel material which can exhibit ductile crack growth at low temperatures relative to cleavage initiation fracture toughness. The preliminary results from this mini-C(T) testing can also be compared to extensive specimen test results from larger C(T) specimens of the same irradiated material. Comparisons of the results from each of the laboratories and some inter-laboratory differences in the fracture testing are assessed. The evaluations indicate reasonable agreement between the mini-C(T) and larger specimen results, but the selection of test temperature and the number of test specimens needed to obtain reliable results are more difficult when testing a low-upper-shelf toughness material.

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