Sachin,
I would like to make some corrections in my earlier email. By default the position of ASME and NACE code on post forming heat treatment is Stress relieving. See the NACE recommendations below.
Some clients are quite specific in their specifications, one sample (see below in indigo) calls for normalizing and tempering as a requirement after forming. However if the hot forming is done in the normalizing range exemption from further normalizing is provided. Note any normalizing would involve simulation coupon plates.
If you're contemplating normalizing , what is the grade of material to be normalized, design code, design temperature, thickness/es. If you could furnish those details , I may provide some additional info.
Thanks
Pradip Goswami,P.Eng.
Welding & Metallurgical Engineer/Specialist
Ontario Power Generation Inc.
Email-pgoswami@sympatico.ca,
MR0103-2007
2.1.7 Cold forming of carbon and alloy steels is acceptable provided the material was in one of the conditions listed in Paragraph 2.1.2 (c) prior to cold forming. Cold-formed material must be thermally stress relieved following any cold deforming by rolling, cold forging, or another manufacturing process that results in a permanent outer fiber deformation greater than 5%. Thermal stress relief shall be performed in accordance with the applicable ASME Codes, except that the minimum stress-relief temperature shall be 593°C (1,100°F). After stress relieving, carbon steels listed as P-No. 1 materials in Section IX of the ASME Boiler and Pressure Vessel Code shall meet a hardness requirement of 200 HBW maximum.
Other carbon and alloy steels shall meet the appropriate hardness requirements in accordance with Paragraph 2.1.4, 2.1.5, or 2.1.6. 2.1.7.1 This requirement
2.1.4 Other carbon steels shall have a maximum hardness of 22 HRC (237 HBW).
2.1.5 Alloy steels included under the ASME Boiler and Pressure Vessel Code Section IX P-Numbers listed in Table 2 are acceptable at the indicated maximum hardness levels.
2.1.6 Other alloy steels shall have a maximum hardness of 22 HRC (237 HBW).
************************************************************************************************************************
5. FABRICATION
5.1 GENERAL REQUIREMENTS
.
5.1.4 All parts which have been cold formed by more than 5 % shall be subjected to an appropriate normalizing treatment and, if necessary, a tempering treatment.
5.1.5 Normalizing of carbon steel components and base materials shall be performed separately and not as part of hot-forming operations, unless the finishing hot-forming temperature is in the normalizing temperature range of 850 °C (1560 °F) to 960 °C (1760 °F).
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of sachin sankhe
Sent: Tuesday, August 17, 2010 1:59 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:6548] RE: 6522] Normalising requirment in code
Dear Pradip,
Thanks for you reply
In that case does NACE MR0175/NACE MR0103/NACE RP0472 either of them specify normalising requirment? I mean holding time and holding period?
Regards
Sachin
On Tue, 17 Aug 2010 08:58:08 +0530 wrote
>
Hello Sachin,
See below the extract from ASME Sec-VIII,DIV-1 on the
requirements of post forming heat treatments. Yes the code mandates only stress
relieving as post forming heat treatment due to the fact that
C.S/LAS can accommodate deformation strains, thus it's safe to perform
post forming heat treatmentswell below the lower critical (AC1)
temperature.
Unless forming is done above upper critical temperature (AC3)
re-normalizing is not required. Some of the rationale as per my thoughts
are as follows:-
C.S and some LAS do not have appreciable changes in mechanical properties following forming below AC1 temperature under normal service
environments.
If the service media is such so as to cause environmental cracking such as SCC, then it would be dictated by process specific specifications such as NACE or appropriate API guidelines or specific requirements from process licensors.
Normalizing causes changes of phases during heating and cooling. The resultant change of microstructure changes mechanical and other properties
Normalizing is done in the mill under due care. Unless shops are well equipped, re-normalize following forming may destroy material properties.
I hope
this clarifies your query.
Thanks
Pradip Goswami,P.Eng.
Welding & Metallurgical
Engineer/Specialist
Ontario Power Generation Inc.
Email-pgoswami@sympatico.ca,
pgoswami@quickclic.net
UCS-79 FORMING SHELL SECTIONS
AND HEADS- Vessel shell sections, heads,
and other pressure boundary parts of carbon and low alloy steel plates
fabricated by cold forming shall be heat treated subsequently(see UCS-56) when
the resulting extreme fiber elongation is more
than 5% from the as-rolled condition. For
P-No.1 Group Nos. 1 and 2 materials the extreme fiber elongation may be as great as 40% when none of the
following conditions
exist:
(1) The vessel will contain lethal substances either liquid or
gaseous (see UW-2).
(2) The material is not exempt from impact testing by the rules of this Division or impact testing is required
by the material specification.
(3) The thickness of the part before cold forming exceeds 5⁄8 in. (16
mm).
(4) The
reduction by cold forming from the as-rolled
thickness is more than 10% at any location where the extreme fiber
elongation exceeds 5%.
(5) The
temperature of the material during forming
is in the range of 250°F to 900°F (120°C to 480°C).
>
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of sachin
sankhe
>Sent: Monday, August 16, 2010 11:22 AM
>To:
materials-welding@googlegroups.com
>Subject: [MW:6522] Normalising
requirment in code
>
>
Hi,
>
>Why ASME sec VIII div.1 is silent of heat treatment above
lower transformation temp.I mean normalising is not mentioned any where.
>As
per ASME sec VIII div.1 if due to cold forming fibre elongation is more that 5%
then it gives reference of UCS-56,where it mention only stress releiving.
>In
which code I can find Normalising requirment(Temp, Holding time,loading
temp)
>I am aware that temp of normalising is about 910 Deg.c & holding
time is 1mm/min.But I need reference of code.
>
>Regards
>Sachin
>
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