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PWHT for hastealloy C276

PWHT for hastealloy C276

PWHT for hastealloy C276

Hi Please any one help me with the below.

is it necessary to do PWHT for hastealloy C276 as per NACE.

RE: PWHT for hastealloy C276

what NACE Document Number ? NACE MR0103, NACE MR0175 ?
What type of PWHT do you plan ? what hardness do you aim at? answer is probably into the NACE document you are refering to...
I am not very goot with Ni-alloys but I think PWHT is recommanded only to Ni-alloy 800 in wet H2S service... and not for C276.

RE: PWHT for hastealloy C276

Since this is an austenitic alloy there is typically no PWHT.
Now if you have welded it some material that does require PWHT you need to evaluate what damage the HT may cause to the C276.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: PWHT for hastealloy C276

Usually for this alloy MR-0103 mandates a maximum hardness of 35 HRC, generally after solution annealing. Irrespective of the requirements, formed or cold worked components should be solution annealed for best corrosion resistance.
Similar requirements are imposed by MR-0175/ISO-15156-3
For welds they are supposed to achieve the best corrosion resistance in as welded conditions.The only PWHT mandated for this alloy is solution anneal, whenever welding may involve thicker sections(3/4" & above), subject to design requireemnts.
Search in Haynes Intl webpage(booklet on welding of C-276 alloy) for more detailed guidelines.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist

RE: PWHT for hastealloy C276

Dear Chumpes,

I am looking into document NACE MR0175 and I am not planinig for PWHT, my customer is requesting for compliance to NACE MR0175 only.

we know that PWHT is not required for some materials to comply with NACE MR1075 such as 316 SS which dose not need PWHT, but we are not aware if PWHT is needed for Ni-Alloy compositions to comply with NACE.

Also we do not have a copy of the NACE document we have only referred the online souses.

RE: PWHT for hastealloy C276

The only requirement of NACE is that the hardness shall not be above 45 HRC and that the material shall be supplied solution annealed or annealed and cold worked. Post weld heat treatment is usually not carried out and not necessary, for high thickness and big components welding, the heat treatment may be required for precipitation hardening or stress relieving purposes to avoid stress corrosion cracking. But as soon as the hardness is below 45 HRC in the weldeded area and the HAZ the NACE requirement is satisfied and therefore the PWHT is not necessary.

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