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

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.

Trial Study of the Master Curve Fracture Toughness Evaluation by Mini-C(T) Specimens for Low Upper Shelf Weld Metal Linde-80

2018 ◽  
Author(s):  
Masato Yamamoto
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Test Temperature ◽  
Master Curve ◽  
Weld Material ◽  
Ductile Crack Growth ◽  
Toughness Evaluation ◽  
Data Points ◽  
Lower Test ◽  
Mc Method

The Master Curve (MC) method can be used to directly determine fracture toughness of ferritic reactor pressure vessel (RPV) materials. CRIEPI has been working on the development of a testing technique to apply very small C(T) (called Mini-C(T)) specimens for the MC method. The appropriateness of using Mini-C(T) specimens for several materials including un-irradiated plate, forging, weld metal and irradiated plate has been demonstrated. Through a series of investigations, it was determined that more invalid data, due to ductile crack growth (DCG), can occur when using small size specimens. Linde-80 weld metal, used in the fabrication of some RPVs, is known as low upper shelf material, which tends to exhibit more DCG than high upper shelf materials. In the present study, two sets of 15 Mini-C(T) specimens were machined and pre-cracked from irradiated Linde-80 weld metal. Each set of specimens were provided to two different laboratories (A and B). The laboratories separately conducted the MC tests. DCG occurred even in the lower test temperature condition. About half of specimens for lab A showed excessive DCG and were subjected to the censoring. Some of specimens were rejected since the test temperature is outside of the specified range (T-To < −50°C). As a result, lab A could not obtain valid To with 15 specimens. Lab B also experienced DCG, however were able to obtain a sufficient number of valid KJc data points to determine a valid To. The obtained ToQ (lab A) and To (lab B) are sufficiently close to each other and suggests that Mini-C(T) can be used even for the low upper shelf material if the number of available specimens are sufficiently large. The combined dataset from labs A and B estimated To = 31.5°C, which is in the scatter band of To obtained by pre-cracked Chapry (PCCv), 0.5TC(T) or 1TC(T) specimens in a past Heavy-Section Steel Irradiation (HSSI) project. The overall result suggests that To can be estimated using Mini-C(T) specimens for the lower upper shelf weld material, but 15 is a marginal number of specimens for a valid estimation.

Fracture Toughness Evaluation of the Heterogeneous Bond Region in HT80 Steel Weldments

1984 ◽  
Vol 106 (1) ◽  
pp. 16-20
Author(s):  
Y. Mutoh ◽  
M. Toyoda ◽  
K. Satoh ◽  
S. Doi
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Base Metal ◽  
Crack Front ◽  
Zone Width ◽  
Average Value ◽  
Toughness Evaluation ◽  
Fracture Toughness Evaluation ◽  
Bond Region

Fracture toughness tests of specimens in which the crack fronts consist of the weld metal region, the HAZ, and the base metal region have been carried out. It seems that, even in the case of the specimens, the stretched zone width can be a proper parameter of fracture toughness. It is necessary to take note of the stretched zone width in the lower toughness region in estimating the macroscopic and average value of fracture toughness of the specimen. It is satisfactory to consider that the critical COD values of the specimens used here, even though the weld metal region is away from the center of thickness, are roughly equal to those of specimens of which the crack front is completely in the weld metal.

Fracture Mechanics of Conventional and Narrow Groove Pulse Current Gas Metal Arc Welds of HSLA Steel

2012 ◽  
Vol 710 ◽  
pp. 451-456
Author(s):  
Ravi Ranjan Kumar ◽  
P. K. Ghosh
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Tensile Properties ◽  
Arc Welding ◽  
Hsla Steel ◽  
Gas Metal Arc Welding ◽  
High Strength ◽  
Compact Tension ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding

Mechanical and fracture properties of 20MnMoNi55 grade high strength low alloy (HSLA) steel welds have been studied. The weld joints were made using Gas Tungsten Arc Welding (GTAW), Shielded Metal Arc Welding (SMAW) and Pulse Gas Metal Arc Welding (P-GMAW) methods on conventional V-groove (V-Groove) and Narrow groove (NG-13). The base metal and weld metal were characterised in terms of their metallurgical, mechanical and fracture toughness properties by following ASTM procedures. The J-Integral fracture test was carried out using compact tension C(T) specimen for base and weld metal. The fracture toughness and tensile properties of welds have been correlated with microstructure. In conventional V-groove welds prepared by P-GMAW shows the improvement in initiation fracture toughness (JIC) as compared to the weld prepared by SMAW. Similar improvements in tensile properties have also been observed. This is attributed to reduction in co-axial dendrite content due to lower heat input during P-GMAW process as compared to SMAW. In the narrow groove P-GMA weld prepared at f value of 0.15 has shown relative improvement of JIC as compared to that of the weld prepared by SMAW process.

scholarly journals Fracture Toughness Evaluation of S355 Steel Using Circumferentially Notched Round Bars

2018 ◽  
Vol 47 (2) ◽  
pp. 91-95 ◽  
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.

Fracture Toughness Evaluation of Reactor Pressure Vessel Steels by Master Curve Method Using Miniature Compact Tension Specimens

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Tohru Tobita ◽  
Yutaka Nishiyama ◽  
Takuyo Ohtsu ◽  
Makoto Udagawa ◽  
Jinya Katsuyama ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Master Curve ◽  
Loading Rate ◽  
Compact Tension ◽  
Master Curve Method ◽  
Toughness Evaluation ◽  
Curve Method ◽  
Fracture Toughness Evaluation ◽  
Reactor Pressure

We conducted fracture toughness testing on five types of commercially manufactured steel with different ductile-to-brittle transition temperatures. This was performed using specimens of different sizes and shapes, including the precracked Charpy-type (PCCv), 0.4T-CT, 1T-CT, and miniature compact tension specimens (0.16T-CT). Our objective was to investigate the applicability of 0.16T-CT specimens to fracture toughness evaluation by the master curve method for reactor pressure vessel (RPV) steels. The reference temperature (To) values determined from the 0.16T-CT specimens were overall in good agreement with those determined from the 1T-CT specimens. The scatter of the 1T-equivalent fracture toughness values obtained from the 0.16T-CT specimens was equivalent to that obtained from the other larger specimens. Furthermore, we examined the loading rate effect on To for the 0.16T-CT specimens within the quasi-static loading range prescribed by ASTM E1921. The higher loading rate gave rise to a slightly higher To, and this dependency was almost the same for the larger specimens. We suggested an optimum test temperature on the basis of the Charpy transition temperature for determining To using the 0.16T-CT specimens.

Applicability of Miniature C(T) Specimens for the Master Curve Evaluation of RPV Weld Metal

2015 ◽  
Author(s):  
Masato Yamamoto ◽  
Naoki Miura
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Master Curve ◽  
Master Curve Method ◽  
Rpv Steel ◽  
Steel Base ◽  
Toughness Evaluation ◽  
Curve Method ◽  
The Difference

The Master Curve approach for the fracture toughness evaluation is expected to be a powerful tool to ensure the reliability of long term used reactor pressure vessel (RPV) steels. In order to get sufficient number of data for the Master Curve approach coexistent with the present surveillance program for RPVs, the utilization of miniature specimens that can be taken from the broken halves of the surveillance Charpy specimens is important. CRIEPI has developed the test technique for the miniature C(T) specimens, whose dimensions are 4 × 10 × 9.6 mm, and has verified the basic applicability of the Master Curve approach by means of the miniature C(T) for the determination of the fracture toughness of typical Japanese RPV steel base metals [1]. A series of round robin tests on RPV steel base metals [2–4] demonstrated that the miniature C(T) specimen can be used for the determination of the reference temperature (To) with no specific difficulties in test techniques. The present paper addresses the applicability of the fracture toughness evaluation by the miniature C(T) specimens on a RPV weld metal with multi-layer weld bead structure. The distribution of the fracture toughness and the trend in fracture toughness change with temperature were confirmed to show a good agreement with the assumption of the Master Curve method [5]. Fracture surface of the specimens were in cleavage fracture mode regardless of the difference in fracture toughness level. The relevance of the specimen size correction in the Master Curve method was confirmed. The difference of To values were only in a few degrees Celsius between the data obtained with 0.5 inch-thickness C(T) specimens and the miniature C(T) specimens. The effect of local loss of constraint nearby the specimen side surface was examined by comparing with the datasets from the specimens with and without side grooves. The difference of To was only 3 degree centigrade and no remarkable effect of side grooving could be seen. From overall examination results, it was concluded that the miniature C(T) specimen can be used for the Master Curve evaluation of tested PRV weld metal.

Finite Element Analysis on the Application of Mini-C(T) Test Specimens for Fracture Toughness Evaluation

2015 ◽  
Author(s):  
Hisashi Takamizawa ◽  
Tohru Tobita ◽  
Takuyo Ohtsu ◽  
Jinya Katsuyama ◽  
Yutaka Nishiyama ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Zone ◽  
Compact Tension ◽  
Distribution Analysis ◽  
Constraint Effect ◽  
Element Analysis ◽  
Toughness Evaluation ◽  
Fracture Toughness Evaluation

Fracture toughness evaluation by the Master Curve method using 4-mm-thick miniature compact tension (mini-C(T)) specimens taken from the broken halves of surveillance Charpy specimens has been proposed. In the present study, we performed finite element analysis (FEA) to examine the difference in the constraint effect of the crack tip for differently sized C(T) and precracked Charpy v-notch specimens. The constraint effect of the mini-C(T) specimens in terms of the T-stress and Q-parameter was similar to that of the larger C(T) specimens. In addition, to optimize the fatigue precracking conditions for the mini-C(T) specimen, plastic zone distribution analysis was performed by FEA. Using plastic zone distribution analysis, we demonstrated that a wider machined notch and shorter fatigue precrack length than that in conventional configurations can be applied for narrow and straight notches. We also obtained the fracture toughness data for two kinds of SA533B-1 steels and one weld metal with different sizes in addition to the data obtained in our previous study. It was shown that the reference temperature To obtained from the mini-C(T) specimens was in good agreement with those from other specimens. We compared the fracture toughness data, including the plane strain fracture toughness value obtained by 4T-C(T) specimens, with T41J-based fracture toughness curves proposed in a recent study. Most of the data, including the 4T-C(T) and irradiated specimens, were enveloped by the proposed lower-bound curve.

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

2021 ◽  
Author(s):  
David Andres ◽  
Marta Serrano ◽  
Rebeca Hernandez ◽  
Yiqiang Wang ◽  
Mark Richardson
Keyword(s):  
Fracture Toughness ◽  
Compact Tension ◽  
Main Concern ◽  
Martensitic Steels ◽  
Term Operation ◽  
Standard Specimens ◽  
Specimen Test ◽  
Water Reactors ◽  
The One

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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