Mr Azharuudin,
Your client is correct. The established formula for conversion is : % Ferrite= 0.7 x Ferrite No(FN) or FN= 1.4 X % Ferrite.
Please see the highlighted texts in the attached documents of Fisher Ferrito scope for your information. Up to 28-30 abstract values both FN & % Ferrite runs equal. At higher values the FN is more in number that %Ferrite.
If you look at the ferritoscope MP-30 training document, when you plot the lines intersecting the centerline of the curve(Page-4), it’s clearly visible at higher % Ferrite values, the numerical values of Ferrite No(FN) is more.
Also it would be advisable to cross check the Lab reading (computed as per ASTM E-562) with Fisher Ferrito scope also. As claimed in the Ferrito scope catalogue(marked with a arrow) results could be correlated both in % Ferrite 7 Ferite No.
Use these information to straighten out the calculation and get your PQR through.
Also a question, what prompted you use Super Duplex Welding filler wire for DSS UNS-31803?? Appreciate your response.
Thanks.
Pradip Goswami, P.Eng,IWE
Independent Welding & Metallurgical Engineering Specialist ,
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
.
From: Pradip Goswami [mailto:pradip.goswami@gmail.com]
Sent: Wednesday, August 24, 2016 9:49 AM
To: Anasua Goswami
Subject: Fwd: Re: % Ferrite & FN measurements of Duplex Stainless steel welds
---------- Forwarded message ----------
From: "Mohammed Azharuddin" <humaidazhar@gmail.com>
Date: Aug 24, 2016 3:19 AM
Subject: Re: % Ferrite & FN measurements of Duplex Stainless steel welds
To: "Pradip Goswami" <pradip.goswami@gmail.com>
Cc:
Dear Mr. Pradip,
Please see attached client specification.
We reported ferrite in both vol% and FN value.But the correlation what client is asking ( 70% FN VALUE= VOL% FERRITE ) we are unable to get it.Moreover it is a thumb rule I believe.
Thanks
Mohammed Azharuddin
On 23 August 2016 at 19:39, Pradip Goswami <pradip.goswami@gmail.com> wrote:
Could you scan and email the entire spec.Your client is correct asking ferrite to be reported in volume or % ferrite. Thx
On Aug 23, 2016 12:29 AM, "Mohammed Azharuddin" <humaidazhar@gmail.com> wrote:
Reported values and client comments attached
I believe that 70%FN = VOL% FERRITE is a rule of thumb [pgoswami] --- This is not a rule of thumb. This conversion is arrived at after conducting numerous tests and correlations of numerous data on weld ferrite content.
Actual correlation must be established from the measurements during PQR qualification
These readings are wrong. Please see the explanations above.
On 23 August 2016 at 07:25, Mohammed Azharuddin <humaidazhar@gmail.com> wrote:
Dear Experts,
We have performed qualification on Duplex stainless steel BM UNS 31803 welded to itself with filler ER2594. Shielding gas AR+2% nitrogen
Ferrite measurements of welds were carried out as per ASTM E562 and AWS A4.2.
Client has rejected these values as the correlation is not appropriate.See below reported values and client comment.
From client point of view ,It should have been like VOL % FRRITE = 70% FN VALUE.
Your valuable advise will help us to save this WPS from being rejected.
Many Thanks
Regards,
Mohammed Azharuddin
Comments