Accelerated Cooling of A517-Gr.B and its Post-heating
kianoosh zarrin naghsh
Dear all,
Can we do accelerated cooling by air a A517-Gr.B weldment from its stress relief temperature (540-590°C)? Is there any necessity for post-heating of A517-Gr.B after welding? Thanks
Kianoush Zarrin naghsh |
hpi001
Because A517-Gr.B is Chromium and Molybdenum alloyed material I should
say don't use accelerated cooling after stress relieving to avoid new
stress arises caused by this method. Better cool down in still air
till below 200°C. Post heating for this material is not really
necessary but you can use an insulation blanket for slowing down the
cooling rate after welding.
Best Regards
Herman Pieper
On 2 nov, 15:27, kianoosh zarrin naghsh <kzarrinnag...@yahoo.com>
wrote:
pgoswami
Dear Mr.. Kianoush,
It's always advisable to specify the design or the code of construction , other details e.g section thickness or design requirements etc... while raising a technical query on welding. It's easy to pinpoint the correct recommendation.
As stated by Mr. Pieper below, SA 517Gr-B is a Q&T and very high tensile steel. In a Q&T steel all the mechanical properties(e.g UTS, Y.S , %El, impact) are finely balanced by Q&T treatment. Any improper heat treatment , such accelerated cooling may destroy the basic properties.In no case the PWHT temperature shall exceed the original tempering temperature.
Sec VIII, DIV-1, UHT-56 provides the comprehensive details on HT requirements of this steel , as follows:-
This steel may be welded without PWHT(UHT-82 g ), provided:-
-
the nominal thickness is 0.58 in. to 11⁄4 in. (15 mm to 32 mm),
-
a minimum preheat of 200°F (95°C) and a maximum interpass of 400°F (205°C) is used while welding
-
after completion of welding and without allowing the weldment to cool below the minimum preheat temperature, the temperature of the weldment is raised to a minimum of 400°F (205°C) and maintained at that temperature for at least 4 hr and cooled under blanket
-
all welds are examined by nondestructive examination , which is MPI or LPI as minimum.
I hope the above details would help you.
Thanks.
Welding & Metallurgical Specialist
Email-p...@sympatico.ca,
pgos...@quickclic.net
mailto:material...@googlegroups.com] On Behalf Of hpi001
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