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.

FITNET FFS Methodologies for the Assessment of Low Constraint Conditions: Overview, Contents and New Contributions

2008 ◽  
Author(s):  
Sergio Cicero ◽  
Federico Gutie´rrez-Solana ◽  
Mustafa Kocak
Keyword(s):  
Fracture Mechanics ◽  
Bearing Capacity ◽  
Structural Integrity ◽  
Assessment Procedure ◽  
Notch Effect ◽  
Load Bearing Capacity ◽  
Critical Crack ◽  
Load Bearing ◽  
Low Constraint ◽  
First Time

In the last years constraint has represented one of the major issues on fracture mechanics and structural integrity research. The need of more adjusted less conservative (and still safe) assessments requires, in many cases, the consideration of the constraint conditions in the crack tip in order to make better predictions of the load bearing capacity or the critical crack dimensions. The newly developed FITNET FFS Procedure gathers a comprehensive set of methodologies for the assessment of low constraint conditions, from those ones that have their origin on the crack shallowness and/or the type of loading (something that is also treated in other procedures), to those related to the notch effect (included for first time in an assessment procedure). Moreover, one of the biggest difficulties that has been traditionally found when performing constraint assessments, has been the obtainment of the different material and constraint parameters that have to be implemented in the calculations. FITNET FFS has dedicated special efforts in providing values of these parameters for a wide variety of materials and geometries, so that the application of its constraint assessment methodologies is noticeably simplified if compared to other procedures. This paper presents these FITNET FFS constraint methodologies and the advances achieved by the procedure in the constraint field.

Analysis of Notch Effect in Fracture Micromechanisms

2012 ◽  
Author(s):  
Sergio Cicero ◽  
Virginia Madrazo ◽  
Isidro Carrascal ◽  
Roman Cicero
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Critical Radius ◽  
High Strength ◽  
Fracture Mechanisms ◽  
Notch Effect ◽  
Progressive Change ◽  
Load Bearing Capacity ◽  
Notched Specimens ◽  
Apparent Fracture Toughness

This paper presents an analysis of the notch effect in fracture micromechanisms. To this end, experimental results obtained in notched specimens are presented, together with the corresponding stress field at fracture and the SEM fractographies. The specimens comprise three materials (structural steel S275JR, high-strength aluminum alloy Al7075-T651 and Polymethyl methacrylate-PMMA) and notch radii varying from 0 mm (cracks) up to 2.5 mm. The results show how the stress relaxation caused by the notch effect is accompanied by a progressive change in the fracture mechanisms, from basically brittle ones in cracked conditions (for the three materials analyzed) to non-linear mechanisms observed for high notch radii, which explain the increase caused by the notch effect in both the load bearing capacity and the apparent fracture toughness. Also the concept of critical radius, that one below which the notch effect is negligible, is justified by SEM observations.

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 Dealing with the Fracture Ductile-to-Brittle Transition Zone of Ferritic Steels Containing Notches: On the Applicability of the Master Curve

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 691
Author(s):  
Sergio Cicero ◽  
Sergio Arrieta
Keyword(s):  
Transition Zone ◽  
Fracture Resistance ◽  
Master Curve ◽  
Experimental Validation ◽  
Specific Reference ◽  
Ferritic Steels ◽  
Initial Attempt ◽  
Brittle Transition ◽  
Weakest Link ◽  
Ductile To Brittle Transition

Characterizing the fracture resistance of ferritic steels operating within their Ductile-to-Brittle Transition Zone (DBTZ) has been successfully addressed through the development of the well-known Master Curve (MC). This tool assumes that fracture, in the presence of crack-like defects, is controlled by weakest-link statistics and follows a three-parameter Weibull distribution. When dealing with notch-type defects, there is no standardized solution to predict the fracture resistance within the DBTZ, but the authors have published some works demonstrating that the MC can also be applied in different ways to characterize ferritic steels containing notches. One of these ways is the direct application of the MC methodology, providing a specific reference temperature (T0N) for each material and notch radius. This work reviews this initial attempt to apply the MC in notched conditions, assessing the validity of the main MC hypotheses (initially valid for cracked conditions) when analyzing notch-type defects and providing experimental validation on steels S275JR, S355J2, S460M and S690Q.

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