fracture toughness
fracture toughness
(OP)
I have the results of compact tension tests and charpy v-notch tests for some steels.
I need to know how to calculate the fracture toughness
corresponding to each of these measurements?
I understand that the results of these tests are affected by the temperature of the test specimens.
I also have tensile test results for some of the steels.
I need to know how to calculate the fracture toughness
corresponding to each of these measurements?
I understand that the results of these tests are affected by the temperature of the test specimens.
I also have tensile test results for some of the steels.





RE: fracture toughness
A while back[1978?], the French CODAP Code gave a Charpy conversion for different temperatures of 0.66J/degC, to covert to different test temps.
RE: fracture toughness
I am no expert in this field, however my understanding of your problem is that in order to get the fracture toughness
values you require you need to relate the energy values you obtained from the Charpy impact tests in the following formula:-
Kc=(ExGc)^0.5
where Gc = toughness measured in kJ/m^2 (these are the values you should have from your impact test)
E= Modulus of Elasticity of the material which you can get from your tensile tests.
Finally Kc = fracture toughness (which is the thing your after)
hope this helps
RE: fracture toughness
the several formula also are for estimation sauch as Buttelle Columbus :
CVN=0.0108 S^2 R^(1/2) t^(1/3)
S= Hoop Stress (ksi) R=Cylinderical Radius (in) t=thickness (in)
RE: fracture toughness
perhaps no way of calculating the fracture toughness from practical test results exists? or if there is then it is not public knowledge? surely such important information must be made public for us all to see and judge?
RE: fracture toughness
It should be noted that these methods generally give you a lower bound result. If you wish to produce a more accurate figure you need to conduct actual fracture toughness tests.
Another issue if you are examining flaws in welds you will need the HAZ weld toughness properties.
RE: fracture toughness
Another consideration that affects fracture toughness is heat treatment applied after fabrication ( bending, welding), and if these were not applied in a uniform manner ( eg, temperature variations throughout the stress relieving furnace)then the fracture toughness might not be uniform thru the vessel. And of course, if the hydrotest is conducted at too low a temperature, some cracking may occur during this testing that is not predicted based on normal operations.
RE: fracture toughness