Use of instrumented Charpy impact tests for the determination of fracture toughness values

2002 ◽  
pp. 245-252 ◽  
Author(s):  
H.-W. Viehrig ◽  
J. Boehmert ◽  
J. Dzugan
Keyword(s):  
Fracture Toughness ◽  
Charpy Impact ◽  
Impact Tests

Evaluation of Fracture Toughness From Instrumented Charpy Impact Tests for a Reactor Pressure Vessel Steel

2003 ◽  
Author(s):  
A. Parrot ◽  
P. Forget ◽  
A. Dahl
Keyword(s):  
Fracture Toughness ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Impact Tests ◽  
Reactor Pressure Vessel Steel ◽  
Ductile To Brittle Transition ◽  
Reactor Pressure

The monitoring of neutron induced embrittlement of nuclear power plants is provided using Charpy impact test in the surveillance program. However structural integrity assessments require the fracture toughness. Some empirical formulas have been developed but no direct relationship was found. The aim of our study is to determine the fracture toughness of a Reactor Pressure Vessel steel from instrumented Charpy impact test using local approach to fracture. This non-empirical method has been applied in the brittle domain as well as in the ductile to brittle transition for an A508 C1.3 steel. In the brittle domain, fracture occurs by cleavage and can be modeled with the Beremin model. Fracture toughness has been successfully determined from Charpy impact tests results and the influence of several parameters (mesh design, Beremin model with one or two parameters, number of Charpy impact tests results) on the results was considered. In the ductile to brittle transition, cleavage fracture is preceded by ductile crack growth. Ductile tearing has been accounted for in the simulations with the Rousselier model whereas cleavage fracture is still described with the Beremin model. The determination of fracture toughness from Charpy impact tests gave encouraging results but finite element simulations have to be refined in order to improve predictions.

Experimental Research and Analysis of Non-alloy Structural Steel Response Exposed to High Temperature Conditions

2013 ◽  
Vol 32 (2) ◽  
pp. 163-169
Author(s):  
Josip Brnic ◽  
Goran Turkalj ◽  
Sanjin Krscanski
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Structural Steel ◽  
Impact Energy ◽  
Charpy Impact ◽  
Experimental Results ◽  
Charpy Impact Energy ◽  
Over Time

AbstractThis paper presents and analyzes the responses of non-alloy structural steel (1.0044) subjected to uniaxial stresses at high temperatures. This research has two important determinants. The first one is determination of stress-strain dependence and the second is monitoring the behavior of materials subjected to a constant stress at constant temperature over time. Experimental results refer to mechanical properties, elastic modulus, total elongations, creep resistance and Charpy V-notch impact energy. Experimental results show that the tensile strength and yield strength of the considered material fall when the temperature rises over 523 K. Significant decrease in value is especially noticeable when the temperature rises over 723 K. In addition, engineering assessment of fracture toughness was made on the basis of Charpy impact energy. It is visible that when temperature raises then impact energy increases very slightly.

Determination of Dynamic Fracture Toughness Using Strain Measurement

2004 ◽  
Vol 261-263 ◽  
pp. 313-318 ◽  
Author(s):  
Duck Hoi Kim ◽  
Soon Il Moon ◽  
Jae Hoon Kim
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Strain Measurement ◽  
Charpy Impact ◽  
Dynamic Fracture Toughness ◽  
High Rate ◽  
Energy Methods ◽  
Inertial Effects ◽  
Optimum Response

By contrast with static fracture toughness determination, the methodology for dynamic fracture toughness characterization is not yet standardized and appropriate approaches must be devised. The accurate determination of the dynamic stress intensity factors must take into account inertial effects. Most methods for dynamic fracture toughness measurement are experimentally complex. However, dynamic fracture toughness determination using strain measurement is extremely attractive in terms of experimental simplicity. In this study, dynamic fracture toughness tests using strain measurement are performed. High rate tension and charpy impact tests are carried out for titanium alloy, maraging steel and Al alloys. In the case of evaluating the dynamic fracture toughness using high rate tension and charpy impact tests, load or energy methods are used commonly. The consideration about inertial effects is essential, because load or energy methods are influenced by inertia. In contrast, if the position for optimum response of strain is provided, dynamic fracture toughness evaluation using strain near crack tip is more accurate. To obtain the position for optimum response of strain, a number of gages were attached at angles of 60°. Reliability for experimental results is evaluated by Weibull analysis. The method presented in this paper is easy to implement in a laboratory and it provides accurate results compared to results from load or energy methods influenced by inertia.

To Determination of the WWER RPV Steels Crack Resistance Characteristics

2013 ◽  
Author(s):  
Igor Orynyak ◽  
Maksym Zarazovskii ◽  
Sergii Radchenko ◽  
Volodymyr Kozlov
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Crack Resistance ◽  
Temperature Shift ◽  
Charpy Impact ◽  
Temperature Range ◽  
Pressurized Thermal Shock ◽  
Reactor Pressure ◽  
15Kh2nmfa Steel

The efficiency of fracture toughness determined by the methodology of normative document PNAE G-7-002-86 has been analyzed. Crack resistance characteristics of WWER-1000 reactor pressure vessel base metal at unirradiated condition are obtained by experimental way. All specimens were made of the RPV support forging (15Kh2NMFA steel) of abandoned Crimean NPP Fracture toughness experiments were carried out on three types of specimens CT 1T, CT 0.5T and SEB over a temperature range from −130°C to −40°C in fully accordance to the ASTM E1921. Charpy impact energy data obtained on twelve specimens over a temperature range from −80°C to 80°C has been used to determine the 47J transition temperature. Comparison of obtained fracture toughness data with normative curve shows that the last one has unreasonably high lower shelf. It has been found that the PNAE G-7-002-86 Code, which uses the ideology of transition temperature shift, is too conservative to estimate WWER-1000 RPVs resistance against brittle fracture for the pressurized thermal shock (over 90 MPa·√m area of stress intensity factor).

Embrittlement Trend Curves for Notch and Fracture Toughness of 15Kh2MFAA Type Steel

2017 ◽  
Author(s):  
Milan Brumovsky ◽  
Radim Kopřiva ◽  
Miloš Kytka
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Pressure Vessel ◽  
Master Curve ◽  
Charpy Impact ◽  
Type Steel ◽  
Impact Tests ◽  
Surveillance Programs ◽  
Vessel Integrity ◽  
Reactor Pressure

Reactor pressure vessel integrity and lifetime evaluation is based on the use of fracture mechanics apparatus but most of the material vessel material data and their degradation during operation are based on results from Charpy V-notch impact tests. Then, empirical correlations between transition shift of temperature dependence of notch toughness and fracture toughness are applied. Elaboration of „Master Curve“ approach for fracture toughness experimental data analysis allows to use fracture toughness data directly to the reactor pressure vessel integrity evaluation. Wider use of this approach is limited by the lack of appropriate database from surveillance specimen test data, as mostly only Charpy impact specimen are included into the Surveillance specimen programs. Fortunately, all WWER Surveillance programs contain also fracture toughness specimens, either pre-cracked Charpy size or CT-0.5. Thus, database of fracture toughness data from Surveillance programs of WWER-440/V-213C type reactor pressure vessels, operated in the Czech Republic, Slovakia and Hungary and manufactured only by one manufacturer - SKODA JS, was collated and analyzed. These vessels were manufactured from 15Kh2MFAA type steel and appropriate weld metal, both of Cr-Mo-V type with low content of detrimental impurities — P and Cu. Analysis of the data in fluence interval up to 6×1024 m−2 (with neutron energies En larger than 0.5 MeV) show that transition temperature shifts in fracture toughness temperature dependence are higher than for Charpy impact tests. Several formulae have been applied for fitting these shift dependencies with chemical composition of materials and finally new Embrittlement Trend Curves for Charpy shifts have been corrected. Additionally, new Embrittlement Trend Curves for fracture toughness shifts based on “Master Curve” approach have been also proposed. Both trends are using simple power law on fluence with exponents around 0.6 and depend on phosphorus and copper contents even though effect of other elements has been also checked.

scholarly journals Fracture Toughness of Hollow Glass Microsphere-Filled Iron Matrix Syntactic Foams

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2566
Author(s):  
Dirk Lehmhus ◽  
Jörg Weise ◽  
Attila Szlancsik ◽  
Imre Norbert Orbulov
Keyword(s):  
Fracture Toughness ◽  
Failure Modes ◽  
Bulk Material ◽  
Syntactic Foam ◽  
Charpy Impact ◽  
Notch Sensitivity ◽  
Powder Injection ◽  
Hollow Glass Microsphere ◽  
Hollow Glass ◽  
Impact Tests

In this study, iron-based metal matrix syntactic foam (MMSF) containing hollow glass microspheres as filler was investigated with respect to notch sensitivity aspects. The MMSF was produced by means of metal powder injection molding. The notch sensitivity was studied via (i) elastic-plastic fracture mechanics measurements (determination of R-curves based on three-point bending tests) and (ii) Charpy impact tests. In both cases, the samples were machined with two different (U- and V-shaped) notch geometries. The critical J-integral value was determined for both notch types, which resulted in lower fracture toughness values in the case of the V-shaped notches and thus notch sensitivity of the material. This finding can be connected to the characteristics of the deformation zone and the associated stress concentration at the tip of the machined notches. The results were confirmed by Charpy impact tests showing ~30% higher impact energy in the case of the U-shaped notch. The failure modes were investigated by means of scanning electron microscopy. In contrast to the bulk material, the MMSF showed brittle fracture behavior.

Comparison of Transition Temperature Shifts From Notch Impact and Fracture Toughness (Master Curve) Testing

2015 ◽  
Author(s):  
Milan Brumovsky ◽  
Milos Kytka ◽  
Michal Falcnik
Keyword(s):  
Fracture Toughness ◽  
Charpy Impact ◽  
Pressure Vessels ◽  
Fracture Toughness Test ◽  
Transition Temperatures ◽  
Irradiation Embrittlement ◽  
Fracture Toughness Testing ◽  
Impact Tests ◽  
Static Fracture ◽  
Toughness Testing

Evaluation of integrity and lifetime of reactor pressure vessels is usually based on fracture mechanics approach using empirical correlation between transition temperatures from impact tests and static fracture toughness test results in the form of “design curve”. Moreover, material degradation during operation is also usually monitored by impact surveillance specimen testing under the assumption that shifts in temperature dependencies if impact toughness and static fracture toughness are the same. To verify this assumption, study of the correlation between these two shifts has been performed on WWER steels — 15Kh2MFA (Cr-Mo-V) and 15Kh2NMFA (Ni-Cr-Mo-V) types. Several sources of results have been used : (a) reconstitution of tested remains of Charpy V-notch impact test specimens from irradiated programs was performed to obtain pre-cracked Charpy size specimens for three point bending type fracture toughness testing, (b) comparison of tests results from surveillance programs irradiated by similar fluences, (c) experimental irradiation programs with accelerated irradiation in research reactor. Additionally, some results from the recent study of irradiation embrittlement of high nickel weld are included — its behavior shows to some extraordinary tendency. Thanks to the use of reconstitution, both series of specimen were irradiated under the same conditions — temperature and neutron fluence and comparison is reliable. Results show that transition temperatures from fracture toughness testing are larger than those from Charpy impact tests. Similar results have been obtained also for other two groups of results.

Determination of Transport Packaging Kit Speed before Impact with a Rigid Barrier during Emergency Impact Tests on the Missile Track

2020 ◽  
Vol 34 (1) ◽  
pp. 26-37
Author(s):  
S.I. Gerasimov ◽  
V.I. Erofeev ◽  
V.A. Kikeev ◽  
O.V. Krivosheev ◽  
V.I. Kostin ◽  
...  
Keyword(s):  
Rigid Barrier ◽  
Impact Tests
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