Dear Mr. Srini,
try to do the following:
- increase the heat input - according to EN 1011-3 Recommendation for welding of ss this steel has to be welded with heat input in the range of 0.5-2.5 kJ/mm (now you have 1.7 kJ/mm);
- increase the bevel angle - the more this angle is, the less the mix between the weld metal and the base metal is and the more the austenite content is;
- use a wire and flux with higher Ni & N content in comparison with the base metal - after solidification the nitrogen will difuse to the HAZ and will increase the austenite/ferrite ratio.
Regards
Parvan Chavdarov
----- Цитат от Srini (sethu.srini@gmail.com), на 22.12.2010 в 18:13 -----
Yes. i am proceeding with G48A to asertain pitting resistance.
However, is there any thing more i can do to fine tune the process
itself to get the ferrite in HAZ down?
Thanks
Srini
On Dec 22, 3:16 am, p_chavda...@mail.bg wrote:
Dear Mr. Srini,
Two things:
1. According to me it is strange that you have measured so high ferrite
content, taking into consideration the weld method and the obtained heat
input. Are you sure that the ferrite content in the HAZ 71% is.
2. From what I am reading I am not convinced that there is no loss in the
resistance to pitting corrosion. ASTM C is a good procedure in terms of
determining the loss in the resistance because of precipitation of
intermetallic phases, but not in general. Take into account, that sometimes
even when there are no intermetallic phases, pitting corrosion could appear
because of local depletion of Cr, Mo or N, i.e. locally the PREn is less
than required. By such high ferrite content, you could expect at least
precipitation of Cr2N (there is no enough austenite to dissolve the
nitrogen), so I suggest you to perform additionally the G 48 test in order
to ascertain that there is no loss.
Regards
Parvan Chavdarov
----- Цитат от Srini (sethu.sr...@gmail.com), на 21.12.2010 в
21:44 ----- 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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P.S. Само да ти кажа - Коледа идва с 30% Хостинг Отстъпка
и Безплатен Домейн като подарък
http://www.icn.bg/default.icn?show=about&status=about-news&news=158
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