Fractography and Fracture Toughness Measurement

2009 ◽  
Vol 409 ◽  
pp. 17-27 ◽  
Author(s):  
Roger Morrell
Keyword(s):  
Fracture Toughness ◽  
Surface Crack ◽  
Ceramic Materials ◽  
Test Methods ◽  
Fracture Toughness Test ◽  
Single Edge ◽  
Fracture Toughness Measurement ◽  
Beam Method ◽  
Toughness Measurement ◽  
Good Agreement

Using a variety of advanced ceramic materials, a comparison has been conducted of fracture toughness test methods using the single edge vee-notch beam method and the surface crack in flexure method, the latter restricted to optical fractography. Good agreement has been found between the two methods on materials which were amenable to the SCF method. It has further been shown that the SEVNB method can produce reliable results on materials to which the SCF method is not readily applicable.

Assessing Low-Constraint Fracture Toughness Test Methods Using Clamped SENT Specimens

2019 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Tom McGaughy
Keyword(s):  
Fracture Toughness ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Test Methods ◽  
Fracture Toughness Test ◽  
Single Edge ◽  
Gas Industry ◽  
End Conditions ◽  
The Difference ◽  
Low Constraint

Abstract The low-constraint fracture toughness can be measured using a single edge-notched tension (SENT) specimen in the clamped-end conditions. The SENT specimen has been used in the oil and gas industry in the strain-based design and the crack assessment for transmission pipelines. Since 2006 when DNV published the first SENT test practice, many investigations have been done, and various SENT test methods were developed, including CANMET and ExxonMobil methods in terms of the J-integral and CTOD. The effort led to the first SENT test standard BS 8571 being published in 2014. However, the experimental evaluation methods remain in developing, and different methods may determine inconsistent results. For this reason, the present paper gives a brief review on SENT fracture testing and assesses the available test methods, including progresses on study of stress intensity factor, geometric eta factors, elastic compliance equation, and constraint m factor as well. The difference between J-converted CTOD and double clip gage measured CTOD is also discussed. On those bases, agreements and challenges in SENT testing are identified. The results provide a direction for further investigation to improve the current SENT test methods.

Error Analysis of Ceramic Materials Fracture Toughness Measured by the Single Edge Notched Beam Method

2014 ◽  
Vol 1004-1005 ◽  
pp. 434-437 ◽  
Author(s):  
Jia Liang Wang ◽  
Xian Feng Shen ◽  
Meng Liang Bai ◽  
Gang Zhou ◽  
Mian Jiang
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Error Analysis ◽  
Ceramic Materials ◽  
Single Edge ◽  
Notch Width ◽  
Beam Method

In this study, the fracture toughness of ceramic materials such as Al2O3, SiC, Si3N4, ZrO2 were measured by the SENB method and IF method respectively. The results shown that the value of fracture toughness obtained from the SENB method is significantly higher than the IF method. When the notch width is fixed, with the flexural strength of ceramic materials increasing, the error of fracture toughness from the SENB method compared to the IF method is increased. For example, the flexural strength of ZrO2 is about 847MPa and the error of fracture toughness from the SENB method compared to the IF method is 50.14%, the flexural strength of Al2O3 is about 338MPa and the error of fracture toughness from the SENB method compared to the IF method is only 4.52%.

scholarly journals Standardization of the Laser Notching Method for Measuring Fracture Toughness in Structural Ceramics

2021 ◽  
Author(s):  
Anzhe Wang ◽  
Xinyuan Zhao ◽  
Mingxu Huang ◽  
Yehong Cheng ◽  
Dongyang Zhang
Keyword(s):  
Fracture Toughness ◽  
Structural Ceramics ◽  
Single Edge ◽  
Important Data ◽  
Laser Method ◽  
Notch Angle ◽  
Fracture Toughness Measurement ◽  
Research Objects ◽  
Near Future ◽  
Toughness Measurement

Abstract The single-edge V-notched beam (SEVNB) method based on the laser notching approach can effectively overcome the shortcoming of time-consuming and avoid large errors in traditional fracture toughness measurement ways, nevertheless the laser notching method has not yet been standardized. Taking oxide (ZrO2 and Al2O3), carbide (SiC), nitride (Si3N4) and boride (ZrB2-based) ceramics as the research objects, this paper systematically discussed the effects of notch tip sharpness, notch depth and equivalent notch angle on the measured value of fracture toughness, thereby clearly defined the range of these parameters that required for measuring the fracture toughness accurately. Furthermore, in order to give full play to the advantages of the laser notching method, the feasibility of sample miniaturization was also discussed. This study could provide important data reference and theoretical basis for the standardization of laser method in the near future.

scholarly journals Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 244 ◽  
Author(s):  
Byeong Seo Kong ◽  
Ji Ho Shin ◽  
Changheui Jang ◽  
Hyoung Chan Kim
Keyword(s):  
Fracture Toughness ◽  
Structural Integrity ◽  
Compact Tension ◽  
Fracture Toughness Test ◽  
Pure Tungsten ◽  
Test Environment ◽  
Toughness Test ◽  
Fracture Toughness Measurement ◽  
Ar Gas ◽  
Toughness Measurement

The evaluation of fracture toughness of pure tungsten is essential for the structural integrity analysis in a fusion reactor. Therefore, the accurate quantification of fracture toughness of tungsten alloys is needed. However, due to the inherent brittleness of tungsten, it is difficult to introduce a sharp fatigue pre-crack needed for the fracture toughness test. In this study, a novel fatigue pre-cracking method was developed and applied to the small-sized disc-type compact tension (DCT) specimens of double-forged pure tungsten. To overcome the brittleness and poor oxidation resistance, a low-frequency tensile fatigue pre-cracking was performed at 600 °C in Ar environment, which resulted in the introduction of a sharp pre-crack to DCT specimens. Then, fracture toughness tests were conducted at room temperature (RT), 400 °C, and 700 °C in air and Ar gas environments using as-machined and pre-cracked DCT specimens. At RT and 400 °C, the test environment and crack tip radius did not affect the fracture toughness measurement. However, at 700 °C, the Ar gas environment and the presence of a sharp fatigue pre-crack resulted in a decrease in the measured fracture toughness. Thus, it was suggested that, for the conservative fracture toughness measurement of pure tungsten, fatigue pre-cracking and fracture toughness test should be performed in an inert environment, especially for high-temperature tests.

Fracture toughness measurement of plasma sprayed ceramic coatings

1989 ◽  
Vol 181 (1-2) ◽  
pp. 407-415 ◽  
Author(s):  
F Beltzung ◽  
G Zambelli ◽  
E Lopez ◽  
A.R Nicoll
Keyword(s):  
Fracture Toughness ◽  
Ceramic Coatings ◽  
Fracture Toughness Measurement ◽  
Plasma Sprayed ◽  
Toughness Measurement
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