Thank you for your interesting question! Can you maybe refer to a test standard where you will find this statement? The custumor or product standard will define a test temperature. For CTOD tests preformed at -10°C, due to plastic deformation, the test specimen will heat up during testing for about 2°C. So generally, the "last" temperature reading will be then -8°C. Is this an answer to your question?
Hi How different is this standard to ASTM E399, No similar to your's, i have a 12mm thickness plate to do CTOD test, and i have done pre-cracking at room temperature with 0.4W to 0.7W crack ratio, and i have to do crack open the sample at 0 degree, So i am puzzled why your sample has 2 step of bending. Now the question is why you have 3 step, fatigue pre-crack, bending at colder temperature and bending at normal temperature? and Why the data of bending done at room temperature was not collected?
Thank you for your question. ASTM E399 is for determination of KIc. In this case, we are measuring the fracture toughness as CTOD value. The ISO 12135 and ASTM E1820 are applicable. The following steps are performed: 1) machining 2) pre-cracking at room temperature 3) quasi-static testing at test temperature (e.g. -10°C). In this step the load or force and clip gauge opening will be measured. The test is ended when the test specimen fails. 4) post-fracture at room or lower temperature. In this step you would like to fully break the test specimen. This is preformed in order to be able to measure the initial crack length (a0). 5) Measuring of the initial fatigue crack length 6) calculation of CTOD 7) Reporting.
Hello Sandeep, the graph plotted is Load (kN) versus stroke displacement (mm). CTOD calculation uses a Load (kN) versus notch opening displacement (mm), this plot is not shown in the video but has a similar look.
Fracture toughness test are performed generally according to ISO 12135 (for Base material) and ISO 15653 (welded material). But upon request also possible: BS 7448-1, BS-7448-2, ASTM E 1290, ASTM E 399, ASTM E 1820, ASTM E 647, ...
Thank you for your question. The applied test temperature for the fracture toughness test in the videoclip is -10°C. At the Belgian Welding Institute CTOD test are preformed from -196°C up to room temperature.
Seems to me that the micro crack on the left side is not long enough. The micro crack must be within certain ratio through the whole specimen. This test sample will be invalid. Specimen also looks huge. So, it’s not necessary to cool him down during testing. You just pre-cool te sample and than test him as is. Safe some work and money for yourself. Read the standards carefully.
Jan, thank you for your concerns. However, this specimen is tested according to EN ISO 12135 and fully acceptable. As this is a very thick high strength steel, the mechanical properties of the material in the center and near the surface are different. As a result, the fatigue crack growth rate is different at mid-thickness. If you read the standard very carefully, only the 7 central measuring points and nine-point average value shall not exceed 20% of a0. In this case this requirement was fulfilled. Regarding the cooling of the test specimen, you can before testing cool the specimen down to the desired temperature. However the temperature of the test specimen shall remain within 2 °C of the nominal test temperature throughout the test, to comply with this requirement the specimen is cooled using a clamping device. If you have any more question or remarks please feel free to ask.
What is the "LAST" mean regarding to testing temperature? "Tests shall be performed at LAST or +5ºC, whichever is lower"
Thank you for your interesting question! Can you maybe refer to a test standard where you will find this statement? The custumor or product standard will define a test temperature. For CTOD tests preformed at -10°C, due to plastic deformation, the test specimen will heat up during testing for about 2°C. So generally, the "last" temperature reading will be then -8°C. Is this an answer to your question?
@@bil-ibs2356 API RP 2Z (2005) the Lowest Anticipated Service Temperature (LAST): I found it. Thank you very much for your promt answer.
Hi
How different is this standard to ASTM E399,
No similar to your's, i have a 12mm thickness plate to do CTOD test, and i have done pre-cracking at room temperature with 0.4W to 0.7W crack ratio, and i have to do crack open the sample at 0 degree, So i am puzzled why your sample has 2 step of bending.
Now the question is why you have 3 step, fatigue pre-crack, bending at colder temperature and bending at normal temperature?
and Why the data of bending done at room temperature was not collected?
Thank you for your question. ASTM E399 is for determination of KIc. In this case, we are measuring the fracture toughness as CTOD value. The ISO 12135 and ASTM E1820 are applicable. The following steps are performed: 1) machining 2) pre-cracking at room temperature 3) quasi-static testing at test temperature (e.g. -10°C). In this step the load or force and clip gauge opening will be measured. The test is ended when the test specimen fails. 4) post-fracture at room or lower temperature. In this step you would like to fully break the test specimen. This is preformed in order to be able to measure the initial crack length (a0). 5) Measuring of the initial fatigue crack length 6) calculation of CTOD 7) Reporting.
Very nice...Graph is plotted between which two terms at 1.15
Is it between applied load and displacement
Hello Sandeep, the graph plotted is Load (kN) versus stroke displacement (mm). CTOD calculation uses a Load (kN) versus notch opening displacement (mm), this plot is not shown in the video but has a similar look.
Hello, under what standard do you analyze the results?
Fracture toughness test are performed generally according to ISO 12135 (for Base material) and ISO 15653 (welded material). But upon request also possible: BS 7448-1, BS-7448-2, ASTM E 1290, ASTM E 399, ASTM E 1820, ASTM E 647, ...
What's the temperature which you apply?
Thank you for your question. The applied test temperature for the fracture toughness test in the videoclip is -10°C. At the Belgian Welding Institute CTOD test are preformed from -196°C up to room temperature.
@@bil-ibs2356 Thank you very much.
Very nice! What is the dimension of the specimen?
180 x 180 mm
Seems to me that the micro crack on the left side is not long enough. The micro crack must be within certain ratio through the whole specimen. This test sample will be invalid.
Specimen also looks huge. So, it’s not necessary to cool him down during testing. You just pre-cool te sample and than test him as is. Safe some work and money for yourself. Read the standards carefully.
Jan, thank you for your concerns. However, this specimen is tested according to EN ISO 12135 and fully acceptable. As this is a very thick high strength steel, the mechanical properties of the material in the center and near the surface are different. As a result, the fatigue crack growth rate is different at mid-thickness. If you read the standard very carefully, only the 7 central measuring points and nine-point average value shall not exceed 20% of a0. In this case this requirement was fulfilled. Regarding the cooling of the test specimen, you can before testing cool the specimen down to the desired temperature. However the temperature of the test specimen shall remain within 2 °C of the nominal test temperature throughout the test, to comply with this requirement the specimen is cooled using a clamping device. If you have any more question or remarks please feel free to ask.