Wednesday, December 22, 2010

Re: [MW:8863] Duplex S.S - How to reduce ferrite content in HAZ

Hi,
I think The cooling rate leads to high ferrite content.
To reduce the ferrite percentage/Ferrite number,Treating the high FN welds with a wash using the Tig arc, but no wire after the weld is completed, acts like a heat treatment and gets the Ferrite down.

Thanks & Regards,

(Karthik)

Karthikeyan.S
QA/QC Manager
Getabec Energy Co.,Ltd.
379,Moo6,Soi8,Nikhomphatana,
Rayong-21180,
Thailand.
Phone: 0066 38 897035-8 (Off)
Fax: 0066 38 897034
Hand Phone: 0066 892512282


--- On Wed, 12/22/10, Srini <sethu.srini@gmail.com> wrote:

From: Srini <sethu.srini@gmail.com>
Subject: [MW:8862] Duplex S.S - How to reduce ferrite content in HAZ
To: "Materials & Welding" <materials-welding@googlegroups.com>
Date: Wednesday, December 22, 2010, 2:44 AM

Can you please advice some thoughts how to reduce ferrite in HAZ and
bring into range of 60% max. This is an weld procedure development and
ferrite was as high as 71% (E562 - Metallography method) in HAZ.
Ferrite in parent metal 50%, ferrite in weld metal was 50 to 55%. The
details of the processa are as below.

Material Dual S32205/S31803. Thickness 1.25" (32mm). Process- SAW.
Double butt joint. Parameters 450A/30V/20". Heat input was 42Kj/inch.
After each pass i let the part cool naturally to about 80° and then
welded the next pass. i continued the same to keep the cooling rates
consistent. May be i have put too much control and resulted in faster
cooling rate and hence high ferrite in HAZ.
No intermetallic phases found. ASTM 923 C - no corrosion loss, but the
customer would not accept 71% ferrite in HAZ. has to be less than 60%
to avoid pitting corrosion.

Thanks for any help in advance.

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