IAEA Coordinated Research Project on Master Curve Approach to Monitor Fracture Toughness of RPV Steels: Effect of Loading Rate

2009 ◽  
Author(s):  
Hans-Werner Viehrig ◽  
Enrico Lucon ◽  
William L. Server
Keyword(s):  
Static Loading ◽  
Master Curve ◽  
Loading Rate ◽  
Dynamic Testing ◽  
Loading Rates ◽  
Brittle Transition ◽  
Upper Limit ◽  
Rate Effects ◽  
Unloading Compliance ◽  
Ductile To Brittle Transition

The Master Curve (MC) approach procedure standardized in ASTM E1921 is defined for quasi-static loading conditions. However, the extension of the MC method to dynamic testing is still under discussion. The effect of loading rate can be broken down into two distinct aspects: 1) the effect of loading rate on Master Curve To values for loading rates within the loading rate range specified in ASTM E1921 for quasi-static loading, and 2) the effect of loading rate on Master Curve To values for higher loading rates. The IAEA CRP8 includes both aspects, but primarily focuses on the second element of loading rate effects, i.e. loading rate ranges above the upper limit of the E1921 standard and it comprises: - results of a round-robin exercise to validate the application of the Master Curve approach to precracked Charpy (PCC) specimens tested in the ductile-to-brittle transition region using an instrumented pendulum, - Master Curve data obtained at different loading rates on various RPV steels, in order to assess the loading rate dependence of To and compare it with an empirical model proposed by Wallin, and - the comparison of results from unloading compliance and monotonic loading in the quasi-static range.

Relating Structural Loading Rate to Testing Rate for Fracture Mechanics Specimens

2014 ◽  
Author(s):  
Carey L. Walters ◽  
Jan Przydatek
Keyword(s):  
Loading Rate ◽  
Factor Loading ◽  
Transition Curve ◽  
Maritime Industry ◽  
Static Test ◽  
Loading Rates ◽  
Brittle Transition ◽  
Testing Rate ◽  
Ductile To Brittle Transition ◽  
Offshore Industry

It is very well-known that fracture toughness depends on loading rate. Higher strain rates can shift the ductile to brittle transition curve to higher temperatures, resulting in a more brittle structure at the same temperature. However, there is little effort to relate the testing rate to the loading rate within the offshore and maritime industry. For example, BS 7448-1 requires that the stress intensity factor loading rate be 0.5 MPa√m/s to 3.0 MPa√m/s. The loading rates of BS 7448-1 are very far away from the vibrational modes of the specimen, so these limitations are not necessary in order to assure a quasi-static test. In comparison, SSC 275 indicates that normal ship loading rates can be of the order of 220–440MPa√m/s. The results of SSC 275 are consistent with results obtained from a Dutch offshore equipment supplier, who indicates a time to maximum loading of 0.25–1.3 seconds. In general, a conservative loading scenario for the maritime and offshore industry is on the order of 200 times faster than the loading rate that is recommended by BS 7448-1. Testing at the standard rate has the consequence of artificially lowering the ductile to brittle transition temperature by 8–35°C in comparison to a real loading scenario, thus possibly giving a false impression of safety. This means that a CTOD measured as 0.2 mm for static testing conditions could be 0.08–0.15 mm for actual loading. The analysis is shown to be consistent with CTOD test data on a Quenched and Tempered (QT) and a Thermo-Mechanically Controlled Processed (TMCP) S690 grade steel.

Analysing the Notch Effect Within the Ductile-to-Brittle Transition Zone of S275JR Steel

2013 ◽  
Author(s):  
Sergio Cicero ◽  
Tiberio García ◽  
Virginia Madrazo ◽  
Jorge Cuervo ◽  
Estela Ruiz ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Bearing Capacity ◽  
Transition Zone ◽  
Master Curve ◽  
Notch Effect ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Brittle Transition ◽  
Apparent Fracture Toughness ◽  
Ductile To Brittle Transition

This paper analyses the notch effect in ferritic-pearlitic steel S275JR in a range of temperatures within the material Ductile-to-Brittle Transition Zone (DBTZ). The notch effect is evaluated in terms of load-bearing capacity, apparent fracture toughness (modeled here using the Theory of Critical Distances) and fracture micromechanisms. The concept of Master Curve in notched conditions is also presented. To this end, experimental results obtained in S275JR notched specimens are presented, together with Scanning Electron Microscopy (SEM) fractographies. The analysis is performed at −50 °C, −30 °C and −10 °C, the material Transition Temperature (T0) being −26.1 °C, with the notch radii ranging from 0 mm (crack-type defects) up to 2.0 mm. The results show how the lower the temperature the larger the notch effect, and also that the evolution of both the load bearing capacity and the apparent fracture toughness is directly related to the evolution of fracture micromechanisms. Moreover, the proposed Master Curve in notched conditions has provided good predictions of the experimental results.

On the Use of the Notch Master Curve for Apparent Fracture Toughness Predictions of Notched Ferritic Steels Operating Within the Ductile-to-Brittle Transition Zone

2015 ◽  
Author(s):  
Sergio Cicero ◽  
Tiberio Garcia ◽  
Virginia Madrazo
Keyword(s):  
Fracture Toughness ◽  
Transition Zone ◽  
Fracture Resistance ◽  
Master Curve ◽  
Ferritic Steels ◽  
Brittle Transition ◽  
Apparent Fracture Toughness ◽  
Different Temperatures ◽  
Fracture Tests ◽  
Ductile To Brittle Transition

This paper presents the Notch-Master Curve as a model for the prediction of the apparent fracture toughness of ferritic steels in notched conditions and operating at temperatures corresponding to their ductile-to-brittle transition zone. The Notch-Master Curve combines the Master Curve of the material in cracked conditions and the notch corrections provided by the Theory of Critical Distances. In order to validate the model, the fracture resistance results obtained in fracture tests performed on notched CT and SENB specimens are presented. The results gathered here cover four ferritic steels (S275JR, S355J2, S460M and S690Q), three different notch radii (0.25 mm, 0.50 mm and 2.0 mm) and three different temperatures within the corresponding ductile-to-brittle transition zone. The results demonstrate that the Notch Master Curve provides good predictions of the fracture resistance in notched conditions for the four materials analyzed.

Loading Rate Effects during Indentation on Strength of Glass

2018 ◽  
Vol 768 ◽  
pp. 8-12
Author(s):  
Xiu Min Gao ◽  
Yi Wang Bao ◽  
Guang Lin Nie
Keyword(s):  
Acoustic Emission ◽  
Work Stress ◽  
Brittle Material ◽  
Loading Rate ◽  
Time Effect ◽  
Spherical Indentation ◽  
Loading Rates ◽  
Local Strength ◽  
Rate Effects ◽  
Testing Approach

The spherical indentation combined with acoustic emission was used to evaluate the local strength of glass, which is a nondestructive testing approach. However, stress time effect on the local strength of glass during spherical indentation has not been studied before. In the present work, stress time effect was investigated by examining the local strength of unstrengthened and strengthened glass at different loading rates. It is discovered that the local strength of glass increased greatly with the loading rate, which confirmed the time dependence of the fracture on glass. As a typical brittle material, the discreteness of strength date of glass measured by spherical indentation was also analyzed to evaluate the strength of glass correctly.

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.

IAEA Coordinated Research Project on Master Curve Approach to Monitor Fracture Toughness of RPV Steels: Effect of Loading Rate

2007 ◽  
Author(s):  
Hans-Werner Viehrig ◽  
Enrico Lucon
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Loading Rate ◽  
Crack Arrest ◽  
Dynamic Fracture Toughness ◽  
Current Status ◽  
Research Project ◽  
Topic Area ◽  
Loading Rates ◽  
Data Assessment

In the final evaluation for the application of the Master Curve in the IAEA Coordinated Research Project Phase 5 (CRP-5), one of the areas which was identified as needing further work concerned the effects of loading rate on the reference temperature To up to impact loading conditions. This subject represents one of the three topic areas within the current CRP-8. The effect of loading rate can be broken down into two distinct aspects: 1) the effect of loading rate on the Master Curve To values for loading rates within the specified in ASTM E1921-05 for quasi-static loading (0.1–2 MPa√m/s); 2) the effect of loading rate on To values for higher loading rates, including impact conditions using instrumented precracked Charpy (PCC) specimens. The new CRP includes both aspects, but primarily focuses on the second element of loading rate effects, i.e. loading rates above 2 MPa√m/s. These issues are investigated within the topic area #2 of CRP-8 (Loading Rate Effect). The mandatory portion of this topic area required participation in a round-robin exercise (RRE) to validate the application of the Master Curve approach to PCC specimens tested in the ductile-to-brittle transition region using an instrumented pendulum (10 tests per participant on the JRQ material). The current status of the RRE is presented in [1]. The non-mandatory portion of this topic area consists in providing Master Curve data obtained at different loading rates on various RPV steels, in order to assess the loading rate dependence of To and compare it with an empirical model proposed by Wallin. Moreover, additional topics will be addressed, such as: • comparison of results from unloading compliance and monotonic loading in the quasi-static range; • estimation of fracture toughness from Charpy V-notch data; • assessment of crack arrest properties from instrumented Charpy results; • effect of irradiation on the relationship between static and dynamic fracture toughness.

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