FATT (fracture appearance transition temperature)
FATT (fracture appearance transition temperature)
(OP)
I have a problem with a turbine disk.(the material).The customer asked the FATT test for the disk material. In fact, my problem is about the minimal/maximal value accepted.If the disk works arround 50 Degrees Celsius, what is FATT value accepted, or the PERCENTAGE DEVIATION?
Any other information on this problem will be very good.
Thanks!
Any other information on this problem will be very good.
Thanks!





RE: FATT (fracture appearance transition temperature)
Usualy you make a S curve by testing at different temperatures to find out where your 50% point is.That point shall be equal or lower than the spec.
RE: FATT (fracture appearance transition temperature)
Thank you for your prompt ansewer.
But the problem still remain because:
1.The customer has no ideea about the acceptance criteria.
2.I have to guarantee the disk will stay in opperation without problems.
The material of this piece is :
34 CrNiMo 6 according to EN 10083-1
or
36 CrNiMo 6 according to ISO 683-1:1987
Thanks again!
RE: FATT (fracture appearance transition temperature)
We used to call FATT "Fracture Arrest Transition Temperature".
We used the Navy explosive bulge test to plot the "S" curve to determine this temperature.
RE: FATT (fracture appearance transition temperature)
RE: FATT (fracture appearance transition temperature)
It is a shrunk fit disk, from a Skoda Low Presure turbine shaft.But as I said, my problem is that I don't have any prescription (ISO, DIN, ASTM,etc)where I can read something precise. I mean a temperature value: It should be 10 or 15, or 5, degrees C below 50 Degrees C. If you have something related with this, an ISO, ASTM, anything, I will be very satisfied.
Thank you,
Vali
RE: FATT (fracture appearance transition temperature)
I can tell you that your FATT should be below 0 deg C (meaning at least -50 deg C below your operating temperature) for this LP turbine disc material. You need to account for stresses during startup of the machine - this is why I would recommend a much lower FATT to prevent lower toughness during unit start conditions.
I can tell you that in my turbine reference book "State-of-the-Art Weld Repair Technology for Rotating Components" from EPRI TR-107021-V1 for the various grades of LP turbine disk materials (A 470 Classes 1-3), the FATT (50%) is normally around 0 deg F (~-18 deg C).
RE: FATT (fracture appearance transition temperature)
RE: FATT (fracture appearance transition temperature)
RE: FATT (fracture appearance transition temperature)
Tanks again for your tips!
I came back to you again with another problem, and maybe you cen help me.
I would like to obtain the book you have mantioned before:
"State-of-the-Art Weld Repair Technology for Rotating Components"
And, if it is possible the ASTM A471, or an extract from it.
If you can halp me, tell me how do I have to proceed in order to obtein those things.
Thanks,
Vali
RE: FATT (fracture appearance transition temperature)
RE: FATT (fracture appearance transition temperature)
http://www.astm.org
Just type A471 in the search window. It costs US$33.
You can order the EPRI document (and any other EPRI document) from EPRI at:
http://www.epri.com
Just type TR-107021-V1 in the Search window and you can view a summary. Beware of the cost: it is US$500.
Regards,
Cory
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