A Modified Weibull Stress Approach to Determine the Reference Temperature in a Pressure Vessel Steel

2016 ◽  
Vol 5 (3) ◽  
pp. MPC20150035
Author(s):  
Claudio Ruggieri ◽  
Robert H. Dodds
Keyword(s):  
Pressure Vessel ◽  
Reference Temperature ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Modified Weibull ◽  
Weibull Stress

A Micromechanics Approach for Assessing the Applicability of Precracked Charpy Specimens to Determine the T0 Reference Temperature

2013 ◽  
Author(s):  
Rafael G. Savioli ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Cleavage Fracture ◽  
Pressure Vessel ◽  
Reference Temperature ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Toughness Testing ◽  
The Relationship ◽  
Resistance Data ◽  
Weibull Stress

This work describes an application of a micromechanics model for cleavage fracture to determine the reference temperature for pressure vessel steels from precracked Charpy (PCVN) specimens. A central objective is evaluate the effectiveness of the Weibull stress (σw) model to correct effects of constraint loss in PCVN specimens which serve to determine the indexing temperature T0 based on the Master Curve methodology. Fracture toughness testing conducted on an A285 Grade C pressure vessel steel provides the cleavage fracture resistance data needed to estimate T0. Very detailed non-linear finite element analyses for 3-D models of plane-sided SE(B) and PCVN specimens provide the evolution of near-tip stress field with increased macroscopic load (in terms of the J-integral) to define the relationship between σw and J from which the variation of fracture toughness across different crack configurations is predicted. For the tested material, the Weibull stress methodology yields estimates for the reference temperature, T0, from small fracture specimens which are in good agreement with the corresponding estimates derived from testing of much larger crack configurations.

Prediction of Cleavage Fracture in the Ductile-to-Brittle Transition Region of Pressure Vessel Steels: A Probabilistic Model

2006 ◽  
Vol 324-325 ◽  
pp. 283-286
Author(s):  
Xiao Sheng Gao ◽  
Gui Hua Zhang ◽  
T.S. Srivatsan
Keyword(s):  
Fracture Toughness ◽  
Cleavage Fracture ◽  
Pressure Vessel ◽  
Stress Triaxiality ◽  
Weibull Model ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Proposed Model ◽  
Modified Weibull ◽  
Weibull Stress

This paper presents a modified Weibull stress model, which accounts for the effects of plastic strain and stress triaxiality at the crack tip region. The proposed model is applied to predict cleavage fracture in a modified A508 pressure vessel steel. It is demonstrated that the Weibull modulus (m) remains constant in the temperature range considered, while the threshold Weibull stress (σw-min) decreases with an increase in temperature due to reduction of the yield stress and the scale parameter of the Weibull model (σu) increases with temperature reflecting the influences of temperature on both material flow properties and toughness. The proposed model accurately predicts the scatter of the measured fracture toughness data and the strong effects of constraint and temperature on cleavage fracture toughness.

Dislocation structures in 16MND5 pressure vessel steel strained in uniaxial tension at −196°C

2005 ◽  
Vol 96 (8) ◽  
pp. 909-912
Author(s):  
Karel Obrtlík ◽  
Christian Robertson ◽  
Bernard Marini
Keyword(s):  
Uniaxial Tension ◽  
Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel

scholarly journals Micromagnetic Characterization of Operation-Induced Damage in Charpy Specimens of RPV Steels

2021 ◽  
Vol 11 (7) ◽  
pp. 2917
Author(s):  
Madalina Rabung ◽  
Melanie Kopp ◽  
Antal Gasparics ◽  
Gábor Vértesy ◽  
Ildikó Szenthe ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Operating Conditions ◽  
Magnetic Characteristics ◽  
Pressure Vessel Steel ◽  
Training Procedure ◽  
Vessel Steel ◽  
Before And After ◽  
The Individual ◽  
Magnetic Adaptive Testing

The embrittlement of two types of nuclear pressure vessel steel, 15Kh2NMFA and A508 Cl.2, was studied using two different methods of magnetic nondestructive testing: micromagnetic multiparameter microstructure and stress analysis (3MA-X8) and magnetic adaptive testing (MAT). The microstructure and mechanical properties of reactor pressure vessel (RPV) materials are modified due to neutron irradiation; this material degradation can be characterized using magnetic methods. For the first time, the progressive change in material properties due to neutron irradiation was investigated on the same specimens, before and after neutron irradiation. A correlation was found between magnetic characteristics and neutron-irradiation-induced damage, regardless of the type of material or the applied measurement technique. The results of the individual micromagnetic measurements proved their suitability for characterizing the degradation of RPV steel caused by simulated operating conditions. A calibration/training procedure was applied on the merged outcome of both testing methods, producing excellent results in predicting transition temperature, yield strength, and mechanical hardness for both materials.

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