Methodology for Estimating Thermal and Neutron Embrittlement of Cast Austenitic Stainless Steels During Service in Light Water Reactors

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
O. K. Chopra ◽  
A. S. Rao
Keyword(s):  
Fracture Toughness ◽  
Chemical Composition ◽  
Impact Energy ◽  
Reactor Core ◽  
Charpy Impact ◽  
Charpy Impact Energy ◽  
Light Water Reactors ◽  
Light Water ◽  
Thermal Embrittlement ◽  
Water Reactors

Cast austenitic stainless steel (CASS) materials, which have a duplex structure consisting of austenite and ferrite phases, are susceptible to thermal embrittlement during reactor service. In addition, the prolonged exposure of these materials, which are used in reactor core internals, to neutron irradiation changes their microstructure and microchemistry, and these changes degrade their fracture properties even further. This paper presents a revision of the procedure and correlations presented in NUREG/CR-4513, Rev. 1 (Aug. 1994) for predicting the change in fracture toughness and tensile properties of CASS components due to thermal aging during service in light water reactors (LWRs) at 280–330 °C (535–625 °F). The methodology is applicable to CF-3, CF-3M, CF-8, and CF-8M materials with a ferrite content of up to 40%. The fracture toughness, tensile strength, and Charpy-impact energy of aged CASS materials are estimated from known material information. Embrittlement is characterized in terms of room-temperature (RT) Charpy-impact energy. The extent or degree of thermal embrittlement at “saturation” (i.e., the minimum impact energy that can be achieved for a material after long-term aging) is determined from the chemical composition of the material. Charpy-impact energy as a function of the time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which are also determined from the chemical composition. The fracture toughness J-R curve for the aged material is then obtained by correlating RT Charpy-impact energy with fracture toughness parameters. A common “predicted lower-bound” J-R curve for CASS materials of unknown chemical composition is also defined for a given grade of material, range of ferrite content, and temperature. In addition, guidance is provided for evaluating the combined effects of thermal and neutron embrittlement of CASS materials used in the reactor core internal components. The correlations for estimating the change in tensile strength, including the Ramberg/Osgood parameters for strain hardening, are also described.

Charpy impact energy correlation with fracture toughness for low alloy structural steel welds

2021 ◽  
Vol 113 ◽  
pp. 102934
Author(s):  
Vitor S. Barbosa ◽  
Lucas A.C. de Godois ◽  
Kleber E. Bianchi ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Structural Steel ◽  
Impact Energy ◽  
Charpy Impact ◽  
Charpy Impact Energy ◽  
Energy Correlation ◽  
Steel Welds

Fracture Toughness Properties of SA540 Steels for Nuclear Bolting Applications

1977 ◽  
Vol 99 (3) ◽  
pp. 419-426
Author(s):  
R. R. Seeley ◽  
W. A. Van Der Sluys ◽  
A. L. Lowe
Keyword(s):  
Fracture Toughness ◽  
Impact Energy ◽  
Nuclear Reactor ◽  
Charpy Impact ◽  
Nuclear Regulatory Commission ◽  
Charpy Impact Energy ◽  
Energy Correlation ◽  
Impact Properties ◽  
Minimum Requirements ◽  
Regulatory Commission

Large bolts manufactured from SA540 Grades B23 and B24 are used on nuclear reactor vessels and require certain minimum mechanical properties. A minimum fracture toughness of 125 ksi in. (137 MPa m) at maximum operating stresses is required by the Nuclear Regulatory Commission for these bolts. This minimum toughness property was determined by a stress analysis of a bolt. Minimum required Charpy impact properties were calculated by a fracture toughness-Charpy impact energy correlation and the minimum calculated fracture toughness. The fracture toughness, yield strength and Charpy V notch impact properties were determined for five commercial heats of SA540 steels. Correlations between the fracture toughness and Charpy impact properties of these materials were evaluated. The toughness-impact energy correlation used to set the minimum required Charpy impact properties was found to be unduly conservative, and a different correlation of these properties is suggested. The SA540 steels investigated exhibited fracture toughness properties in excess of the NRC minimum requirements.

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.

Correlation of Fracture Toughness With Charpy Impact Energy for Low Alloy, Structural Steel Welds

2017 ◽  
Author(s):  
Kleber E. Bianchi ◽  
Vitor Scarabeli Barbosa ◽  
Rafael Savioli ◽  
Paulo Eduardo Alves Fernandes ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Impact Energy ◽  
Welded Joints ◽  
Structural Integrity ◽  
Charpy Impact ◽  
Reference Temperature ◽  
Transition Curve ◽  
Charpy Impact Energy ◽  
Integrity Assessment ◽  
Steel Welds

Correlations between Charpy impact energy and fracture toughness values have continuously been developed because of their applicability in structural integrity assessment methodologies. This also applies to the integrity analysis of welded joints, which represent material discontinuities and potential failure locus in structures. Therefore, in effective FFS methodology applications, the fracture toughness of welded joints located in critical regions should be accurately estimated. This work addresses an estimation procedure of fracture toughness values based on Charpy impact energy for low alloy, steel welds made from an ASTM A572 Gr 50 base plate material. To produce the welded joints, two processes were used: SMAW and FCAW. To ensure valid toughness test values corresponding to high constraint conditions, a strength overmatched, deeply-cracked SE(B) configuration having a weld centerline notch was adopted. The ductile-to-brittle transition curve was established by means of Charpy tests. Direct CVN correlations with fracture toughness, as well as reference temperature based correlations derived from the Master Curve approach, were evaluated. The obtained results indicate that both correlation procedures are suitable for weld metal toughness estimations based on Charpy data. However, slightly different values of correlation constants than those indicated for the base metal should be employed in the case of the reference temperature method.

Correlation of Charpy Impact Energy and Fracture Toughness for Low Alloy Structural Steel Welds

2019 ◽  
Author(s):  
Kleber Eduardo Bianchi ◽  
Vitor Scarabeli Barbosa ◽  
Paulo Fernandes ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Structural Steel ◽  
Impact Energy ◽  
Charpy Impact ◽  
Charpy Impact Energy ◽  
Steel Welds

scholarly journals Consideration of Thermal Embrittlement in Alloy 316H for Advanced Non-Light Water Reactor Applications

2019 ◽  
Author(s):  
Weiju Ren ◽  
Lianshan Lin
Keyword(s):  
Structural Integrity ◽  
Light Water Reactors ◽  
Light Water ◽  
Thermal Embrittlement ◽  
Water Reactors ◽  
American Society ◽  
Integrity Analysis ◽  
Technical Basis ◽  
Nuclear Applications

Abstract To construct advanced non-light water reactors (ANLWRs) operating in the temperature range above that for the traditional light water reactors (LWRs), Alloy 316H is one of the candidate materials because of its inexpensiveness, significant service experience, and qualification for nuclear applications by the American Society of Mechanical Engineers (ASME). However, during the life span at temperatures expected for the ANLWRs, the alloy is likely to experience thermal embrittlement that has not been a concern for the traditional LWRs. To prepare for the development, the possibility of adverse thermal embrittlement effects on Alloy 316H performance in the ANLWRs must be evaluated and a technical basis regarding thermal embrittlement, if necessary, must be established for structural integrity analysis to provide reasonable assurance of adequate nuclear safety protection. In this paper, current technical basis for nuclear applications of Alloy 316H deterioration from thermal aging is briefly introduced. The likelihood of adverse thermal embrittlement effects on Alloy 316H performance is evaluated through historical data on microstructural and mechanical property evolution. Characterization of thermal embrittlement is then discussed, followed by a review of predictive models and trend curves for alloy embrittlement. Based on the review and evaluation, technical gaps for addressing thermal embrittlement issues are identified and gap-filling actions are recommended for establishing a technical basis to enable adequate consideration of thermal embrittlement in Alloy 316H applications to the ANLWRs.

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