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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