Hardness T22 after cold bending
Hardness T22 after cold bending
(OP)
Hi everyone,
I want to know if you would apply a Heat Treatment after cold forming a 51mm x 4mm SA-213 t22. The tube is U bend with a radius R = 50mm. I have measured the hardness in 20 bends: Max:201HB and MIN:97HB.
Whe are using asme VIII Div.1.
Thanks.
I want to know if you would apply a Heat Treatment after cold forming a 51mm x 4mm SA-213 t22. The tube is U bend with a radius R = 50mm. I have measured the hardness in 20 bends: Max:201HB and MIN:97HB.
Whe are using asme VIII Div.1.
Thanks.





RE: Hardness T22 after cold bending
RE: Hardness T22 after cold bending
RE: Hardness T22 after cold bending
RE: Hardness T22 after cold bending
RE: Hardness T22 after cold bending
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there is a table (T-1 p.73) that shows a recomended method of heat treatment.
What is better for this material?
Also I have read in this forum about heat treatments of 10-15 sec duration with 100F/sec. But I don't remember where (sorry). Do you know something about this method? What do you think?
RE: Hardness T22 after cold bending
A T22 U-bend does not require a post bend thermal treatment per ASME Section VIII, Div 1. IF you do want to perform a post bend thermal treatment, it should be done following the recommend post weld heat treatment requirements to reduce the hardness. Normalization is NOT necessary or required for this material.
For T22 tube material;
Heat the u-bend region to 1250 deg F min (normally 1250 deg F to 1375 deg F).
Hold at 15 minutes at temperature, air cool.
Induction heating of u-bends is common practice. Also, if you are using a shop for this activity, I would ask them to provide a procedure and make sure this procedure has been qualified for use on T22 tube material.
RE: Hardness T22 after cold bending
why do you recommend such a long holding time ?
What if you adapt the holding time in order to reach the hardness requirements of this grade (85HRB) ?
xgiorg,
what is the application for such a u-bend tube ?
thanks in advance.
RE: Hardness T22 after cold bending
Because using a conventional furance for thermal treatment of u-bends, 15 minutes has been used and was appropiate from a qualification standpoint.
This is acceptable. Induction heating will also shorten the time. As I mentioned, post bend thermal treatment requires a procedure that has been qualified using thermal treating equipment that will be used for the u-bends.
RE: Hardness T22 after cold bending
Tomorrow I will decide what to do, but it seems its not a critical point due to hardness is below the max for this material. Why it can be a stress corrosion cracking? Hydrogen sulphide? in this case it will work with water inside and flue gas outside(no SO2 in the gas, 3.36CO2, 13.41O2, 74.83N2, 7.5H2O, 0.89Ar). Thanks a lot everyone.
RE: Hardness T22 after cold bending
Finally I told to the workshop to make the bends without a post Bend Heat treatment, but amazingly, they make it. They have aplied a 925ºC 30min, with heating rate: 180ºC/h (unrestricted heating rate to 300ºC) and air cooling. I know this is not your recomendation. That's why I want to ask if it's ok, because it's my responsability to accept the material. What do you think? In my opinion the microstructure and the grain size will be ok, but I would like to make a hardness test before to make conclusion. Thanks in advance
RE: Hardness T22 after cold bending
This is a re-heat treatment of the bends based on the temperature you provided. Yes, a hardness should be performed along with dimensional checks on a sampling of the bends for conformance with SA 213 and SA 1016.