Increased Temperature Margins Due to Constraint Loss

2005 ◽  
Vol 127 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Bostjan Bezensek ◽  
John W. Hancock
Keyword(s):  
Temperature Shift ◽  
The Self ◽  
Stress Fields ◽  
Transition Curve ◽  
Pressure Vessel Steel ◽  
Self Similarity ◽  
Vessel Steel ◽  
Temperature Changes ◽  
Brittle Transition ◽  
Crack Tip Constraint

Enhanced levels of toughness due to loss of crack tip constraint have been related to temperature shifts in the ductile–brittle transition curve. An argument to quantify the temperature shift is developed using the self-similarity of near-tip stress fields under contained yielding combined with scaling techniques developed by Dodds and co-workers (12) for cleavage. This allows the temperature changes which give the same stress field at failure in constrained and unconstrained fields to be determined. The procedure is illustrated using the data of Sherry et al. (3) for an A533B pressure vessel steel. The results are consistent with empirical expressions proposed by Wallin (4), and enable a discussion of the micromechanics of cleavage.

Increased Temperature Margins Due to Constraint Loss

2003 ◽  
Author(s):  
Bostjan Bezensek ◽  
John W. Hancock
Keyword(s):  
Temperature Shift ◽  
Stress Fields ◽  
Transition Curve ◽  
Small Scale ◽  
Pressure Vessel Steel ◽  
Self Similarity ◽  
Small Scale Yielding ◽  
Vessel Steel ◽  
Brittle Transition ◽  
Scale Yielding

Enhanced levels of toughness associated with constraint loss are related to temperature shifts in the ductile-brittle transition curve. An argument to quantify the temperature shift is developed using self-similarity of near-tip stress fields under small-scale yielding combined with scaling techniques developed by Dodds and co-workers [1,2] for cleavage. The change in the yield stress and hence temperature that give the same stress field at failure in constrained and unconstrained fields has been determined. The procedure is illustrated using the data of Sherry et al [3] for A533B pressure vessel steel. The results are consistent with the empirical expressions proposed by Wallin [4], and enable a discussion of the physical implications for the micro-mechanics of cleavage.

Evaluation of through-thickness residual stresses and microstructure in SA516 Gr. 70 steel welds

2021 ◽  
pp. 095440542199012
Author(s):  
Pradeeptta Kumar Taraphdar ◽  
Manas Mohan Mahapatra ◽  
Arun Kumar Pradhan ◽  
Pavan Kumar Singh ◽  
Kamal Sharma ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Nuclear Power ◽  
Three Dimensional ◽  
Welding Process ◽  
Influential Factors ◽  
Stress Fields ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Steel Welds

The critical working condition of nuclear power plant equipment necessitates meticulous determination of the welding process and parameters. In this work, some major influential factors of welding were investigated to observe their effects on the through-thickness residual stress distribution in multipass pressure vessel steel welds. In this regard, experiments were conducted to find the characteristics of residual stresses dispersed in SA516 Grade 70 steel welds of different groove geometries with distinct welding conditions. Three-dimensional finite element models of the weldments were developed considering a moving heat source with temperature-dependent material properties to simulate the welding thermal cycles and corresponding residual stress fields. Effects of weld groove geometry, number of weld passes, external constraints, and preheating on the through-thickness residual stress fields were studied. Additional attention was given to the evaluation of the heterogeneous microstructure and microhardness across the weld cross-section associated with their weld thermal history. Finally, the evolution of the through-thickness residual stresses attributed to subsequent weld passes was elaborated.

Effect of Microstructure Degradation on Fracture Toughness of 20MnMoNi55 Steel in DBT Region

2016 ◽  
Vol 6 (3) ◽  
pp. 11-27
Author(s):  
Sumit Bhowmik ◽  
Prasanta Sahoo ◽  
Sanjib Kumar Acharyya ◽  
Sankar Dhar ◽  
Jayanta Chattopadhyay
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Temperature Curve ◽  
Metallic Alloys ◽  
Reference Temperature ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Brittle Transition ◽  
Ductile To Brittle Transition ◽  
Effect Of Microstructure

The paper considers the effect of microstructure degradation on fracture toughness of 20MnMoNi55 pressure vessel steel. This degradation is reflected through the shift of fracture toughness vs. temperature curve along the temperature axis and rise in reference temperature in ductile to brittle transition (DBT) region. Hardness also depends on the microstructure of metallic alloys. The present study explores the correlation between hardness and fracture toughness for different microstructures in order to calibrate loss in toughness from hardness. The master curve reference temperature and microhardness for different microstructures are measured experimentally. It is observed that there exists a fair linear relation between microhardness and reference temperature.

scholarly journals Analysis of Magnetic Nondestructive Measurement Methods for Determination of the Degradation of Reactor Pressure Vessel Steel

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5256
Author(s):  
Gábor Vértesy ◽  
Antal Gasparics ◽  
Ildikó Szenthe ◽  
Madalina Rabung ◽  
Melanie Kopp ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Measurement Methods ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Magnetic Parameters ◽  
Brittle Transition ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition

Nondestructive magnetic measurement methods can be successfully applied to determine the embrittlement of nuclear pressure vessel steel caused by neutron irradiation. It was found in previous works that reasonable correlation could be obtained between the nondestructively measured magnetic parameters and destructively determined ductile-to-brittle transition temperature. However, a large scatter of the measurement points was detected even in the cases of the non-irradiated reference samples. The reason for their scattering was attributed to the local inhomogeneity of material. This conclusion is verified in the present work by applying three different magnetic methods on two sets of Charpy samples made of two different reactor steel materials. It was found that by an optimal magnetic pre-selection of samples, a good, linear correlation can be found between magnetic parameters as well as the ductile-to-brittle transition temperature with low scattering of points. This result shows that neutron irradiation embrittlement depends very much on the local material properties.

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