Prediction of Fracture Toughness Temperature Dependence Over a Wide Temperature Range Using Simplified and Direct Scaling Method

2018 ◽  
Author(s):  
Takashi Inoue ◽  
Toshiyuki Meshii
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Wide Temperature Range ◽  
Fracture Load ◽  
Specimen Thickness ◽  
Temperature Range ◽  
Direct Scaling ◽  
Wide Range ◽  
Mc Method

The fracture toughness KJc of the material in the ductile to brittle transition temperature (DBTT) range exhibits both test specimen thickness (TST) dependence and temperature dependence. Attention has been paid to the master curve (MC) method, which provides an engineering approach to address these two issues. Although MC is intended to be applied to arbitrary ferritic material whose yield stress is within the range of 275 to 825 MPa, the KJc value must be obtained to determine the material dependent reference temperature T0. The applicable range of MC method is restricted to T0 ± 50 °C. Previous studies indicate that additional pre-tests to obtain T0 are necessary; thus, there might be some unwritten requirement to the test temperature for the KJc temperature dependence prediction in MC method to work effectively. If testing must be conducted for the material of interest at some restricted temperature, a more flexible KJc temperature dependence prediction can possibly be obtained for a wide temperature range in the DBTT range, if the simplified and direct scaling (SDS) method, which predicts fracture “load” from yield stress temperature dependence proposed previously is applied. In this study, the SDS method was applied to two different steels: Cr-Mo steel JIS SCM440 and 0.55% carbon steel JIS S55C. Both tensile and fracture toughness tests were performed over a wide range of temperatures, specifically, −166 to 100 °C for SCM440 and −166 to 20 °C for S55C. The SDS method (i.e., fracture load is proportional to 1/(yield stress)) was initially validated for the specimens in the DBTT range. Finally, a simplified method was proposed and initially validated to predict the KJc temperature dependence, by applying the SDS using the EPRI plastic J functional form.

Enabling highly reversible sodium metal cycling across a wide temperature range with dual-salt electrolytes

2021 ◽  
Author(s):  
Akila C. Thenuwara ◽  
Pralav P. Shetty ◽  
Neha Kondekar ◽  
Chuanlong Wang ◽  
Weiyang Li ◽  
...  
Keyword(s):  
Wide Temperature Range ◽  
High Energy ◽  
Liquid Electrolyte ◽  
Metal Cycling ◽  
Temperature Range ◽  
Sodium Metal ◽  
Wide Range

A new dual-salt liquid electrolyte is developed that enables the reversible operation of high-energy sodium-metal-based batteries over a wide range of temperatures down to −50 °C.

Elastic Constants in C-plane of Single Crystal Bi 2Sr 2Ca Cu 208 between 80 K and 260 K

1990 ◽  
Vol 193 ◽  
Author(s):  
Jin Wu ◽  
Yening Wang ◽  
Yifeng Yan ◽  
Zhongxian Zhao
Keyword(s):  
Shear Modulus ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Elastic Constants ◽  
Wide Temperature Range ◽  
Sound Propagation ◽  
Anisotropic Elasticity ◽  
Ultrasonic Velocities ◽  
Temperature Range

ABSTRACTThe temperature dependence of the in-plane C11 C22. C12 and C66 modes between 80 and 260 K of superconducting crystals of Bi2Sr2Ca1Cu208 have been obtained via the measurements of ultrasonic-velocities. The anisotropic elasticity in the a-b plane of single crystal Bi2 Sr2Ca1Cu2O8 is manifest. The shear modulus of sound propagation along the [110] with the polarization has been also calculated and shows an overall trend of softening over a wide temperature range above Tc. The shear modulus C6 6 shows three obvious softening minima around 240–250 K, 150 K and 100 K.

Revised η-Factors for 3P SE(B) Fracture Specimens Incorporating 3-D Effects

2014 ◽  
Author(s):  
Rodolfo F. de Souza ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Mouth Opening ◽  
Estimation Procedure ◽  
Crack Mouth Opening Displacement ◽  
Evaluation Procedure ◽  
Specimen Thickness ◽  
Crack Mouth ◽  
Opening Displacement ◽  
Wide Range ◽  
Fracture Specimens

Standardized procedures to measure cleavage fracture toughness of ferritic steels in the DBT region most commonly employ three-point bend fracture specimens, conventionally termed SE(B) or SENB specimens. The evaluation protocol of fracture toughness for these crack configurations builds upon laboratory records of load and crack mouth opening displacement (CMOD) to relate plastic work with J (or, equivalently, CTOD). The experimental approach employs a plastic η-factor to relate the macroscale crack driving force to the area under the load versus crack mouth opening displacement for cracked configurations. This work provides revised η-factors derived from CMOD records applicable to estimate the J-integral and CTOD in SE(B) specimens with varying crack size and specimen configuration. Non-linear finite element analyses for plane-strain and 3-D models provide the evolution of load with increased CMOD which is required for the estimation procedure. The analysis matrix considers SE(B) specimens with W = 2B and W = B configurations with and without side grooves covering a wide range of specimen thickness, including precracked Charpy (PCVN) specimens. Overall, the present results provide further validation of the J and CTOD evaluation procedure currently adopted by ASTM 1820 while, at the same time, giving improved estimation equations for J incorporating 3-D effects which enter directly into more accurate testing protocols for experimental measurements of fracture toughness values using 3P SE(B) specimens.

Establishment of Unified Correlation of In-Plane and Out-of-Plane Constraints with Ductile Fracture Toughness of Steel

2016 ◽  
Vol 853 ◽  
pp. 22-27 ◽  
Author(s):  
Bo Rui Yan ◽  
G.Z. Wang ◽  
Fu Zhen Xuan ◽  
Shan Tung Tu
Keyword(s):  
Fracture Toughness ◽  
Ductile Fracture ◽  
Structural Integrity ◽  
Damage Model ◽  
Equivalent Plastic Strain ◽  
Specimen Thickness ◽  
Wide Range ◽  
Out Of Plane ◽  
Correlation Line ◽  
Ductile Fracture Toughness

In this paper, the finite element method (FEM) based on GTN damage model was used to obtain ductile fracture toughness and investigate the establishment method of unified correlation of in-plane and out-of-plane constraints with ductile fracture toughness of steels. The unified constraint parameter Ap at different equivalent plastic strain (εp) isolines has been calculated and analyzed for SEN(B) specimens with a wide range of in-plane and out-of-plane constraints. The results show that the average Ap along the specimen thickness (Apave) can well characterize a wide range of in-plane and out-of-plane constraints. The suitable εpisolines range for establishing the unified correlation between Apave and ductile fracture toughness of the steel has been obtained. For the specimens with lower constraint, the higher εp values should be used. The results also show that the correlation line of JC/Jref-Apave1/2is independent of the selections of the suitable εp isolines and the reference specimen. This may bring convenience for the establishment and application of the JC/Jref-Apave1/2correlation lines. Using ductile fracture toughness data of a small number of specimens with different constraints (such as three specimens with different a/W) together with FEM calculations of the parameter Ap, the correlation line of JC/Jref-Apave1/2can be established. The correlation line may be used in structural integrity assessments incorporating both in-plane and out-of-plane constraints.

Observations Arising From Exponential Fitting Methods to a Charpy V-Notch Energy Database From Tata Steel

2011 ◽  
Author(s):  
Anthony J. Horn ◽  
Thomas M. Axe
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Transition Region ◽  
Pressure Vessel ◽  
Mathematical Expression ◽  
Exponential Fitting ◽  
Wide Range ◽  
Pressure Vessel Steels ◽  
Exponential Temperature Dependence ◽  
Region Data

Charpy testing across a range of temperatures is a cost effective way to characterise the ductile-to-brittle transition region. It is often convenient to fit a curve to Charpy data through the transition region: a commonly used method is to use a continuous tan-h fit, a single mathematical expression that links lower shelf, transition region and ductile upper shelf behaviour in one continuous curve. Using this method, the temperature dependence of Charpy energy is a unique feature of each individual steel with some steels exhibiting steep transition curves and some shallow curves. In contrast to Charpy data, fracture toughness data are usually analysed by partitioning upper shelf and transition region data. The transition region data is generally accepted to fit a universal temperature dependence, the Master Curve, as proposed by Wallin [1] and standardised in ASTM E1921 [2]. Recent research on nuclear pressure vessel steels [3, 4] has indicated that when Charpy data is assessed using a similar method to that used for fracture toughness data, a common exponential temperature dependence is observed. This paper presents the current results from an on-going investigation aimed at assessing the effect of exponential curve fitting methods on a large dataset of Charpy V-notch energy data from Tata Steel. The Tata Steel data cover a wide range of parent plate steels. The results are compared to the recent studies on nuclear pressure vessel steels and a similar exponential temperature dependence is observed.

The Temperature Dependence of Yield Stress and Fracture Toughness in Unstabilized Zirconia Crystals

1986 ◽  
Vol 78 ◽  
Author(s):  
T. W. Coyle ◽  
R. P. Ingel ◽  
P. A. Willging
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Test Temperature ◽  
Room Temperature ◽  
Single Edge ◽  
Melting Technique ◽  
Strength Tests ◽  
Edge Notch

ABSTRACTThe flexural strength and the single edge notch beam fracture toughness of undoped ZrO2 crystals, grown by the skull melting technique, were examined from room temperature to 1400°C. On heating the toughness increased with test temperature to a maximum of 4.0 MPajm at 1225°C then gradually decreased to 2.6 MPa/m. Upon cooling after a 20 minute hold at 1250°C an increase in toughness to 5 MPa/m was observed at 1200°C; upon cooling to lower temperatures Kic gradually diminished. The loaddeflection curves for the flexural strength tests showed marked nonlinearity before failure for samples tested on cooling. The temperature dependence of the apparent yield stress suggests that initial yielding occurs by slip above 1200°C but that from 1200°C to 1050°C the observed yielding is due to stress induced tetragonal to monoclinic transformation.

scholarly journals On the Temperature Dependence of Vaporization Enthalpy and its Correlation with Surface Tension.

2021 ◽  
Author(s):  
Amin Alibakhshi ◽  
Bernd Hartke
Keyword(s):  
Surface Tension ◽  
Critical Temperature ◽  
Melting Point ◽  
Temperature Dependence ◽  
Wide Temperature Range ◽  
Thermophysical Properties ◽  
Vaporization Enthalpy ◽  
Temperature Range

Temperature dependence of vaporization enthalpy is one of the most important thermophysical properties of compounds. In the present study, we theoretically developed relationships applicable to evaluation of vaporization enthalpy of compounds from diverse chemical families for a wide temperature range from melting point to the critical temperature. One outcome of the proposed approach is a relationship describing the correlation between the surface tension and vaporization enthalpy which outperforms the extensively applied Kabo method proposed for the same purpose.<br>

scholarly journals Temperature Dependence of Fracture Characteristics of Variously Heat-Treated Grades of Ultra-High-Strength Steel: Experimental and Modelling

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5875
Author(s):  
Jaroslav Pokluda ◽  
Ivo Dlouhý ◽  
Marta Kianicová ◽  
Jan Čupera ◽  
Jana Horníková ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
High Stress ◽  
Stress Triaxiality ◽  
High Strength ◽  
Fracture Mechanisms ◽  
Temperature Range ◽  
Heat Treated ◽  
Shape Ratio ◽  
Standard Steel

The temperature dependence of tensile characteristics and fracture toughness of the standardly heat-treated low-alloyed steel OCHN3MFA along with three additionally heat-treated grades was experimentally studied. In the temperature range of ⟨−196; 22⟩ °C, all the additional heat treatments transferred the standard steel from a high- to ultra-high strength levels even with improved tensile ductility characteristics. This could be explained by a reduction of the inclusion content, refinement of the martensitic blocks, ductile retained austenite content, and homogenization of the shape ratio of martensitic laths as revealed by metallographic, X-ray, and EBSD techniques. On the other hand, the values of the fracture toughness of all grades were found to be comparable in the whole temperature range as the cause of a high stress triaxiality in the pre-cracked Charpy V-notch samples. The values of the fracture toughness of the standard steel grade could be predicted well using the fracture model proposed by Pokluda et al. based on the tensile characteristics. Such a prediction failed in the case of additionally heat-treated grades due to the different temperature dependence of the fracture mechanisms occurring in the tensile and fracture-toughness tests. While the tensile samples fractured in a ductile-dimple mode at all temperatures, the fracture-toughness specimens exhibited a transition from the ductile to quasi-brittle fracture mode with decreasing temperature. This transition could be interpreted in terms of a transfer from the model proposed by Rice and Johnson to the model of Tvergaard and Hutchinson.

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