Skip to main content

[MW:2755] Re: 2735] RE: 2733] RE: 2729] Ferrite Number (FN) for the deposited weld metal

By Materials & Welding
Hi

I would also like to share my similar past experience on ferrite.

Higher cooling rate reduces the ferrite.
Also if the welder uses higher currents, there is slight loss of Cr and depletes the ferrite number.
If the welder welds with a long arc gap there is pickup of Nitrogen and thus the Nieq. increases,and ferrite number reduces.
This we had encountered with the same batch of electrodes in one particular ASS job.
Hence jobs requiring ferrite control have to be welded with correct paramteres like current,Interpass,short arc gap,etc.. as per WPS

Normally a ferrite level of 4FN min. is recommended to avoid hot cracking.This can be achieved by adjusting the composition of base metal and filler material to obtain a microstructure with a small amount of ferrite in the austenite matrix.

Ferrite can be best determined with a magnetic instrument like Ferritescope, the Magne gage, calibrated to AWS A4.2 or ISO 8249 OR the WRC 1992 diagram.
Also note that ferrite has to be measured after welding and not after PWHT if any.

Regards

Prem Nautiyal
Godrej,Mumbai.

On Tue, 21 Jul 2009 19:45:55 +0530 wrote
>Yes higher heat input, Higher current, cleanliness of joint, will increase
>Ferrite no ,Generally use short arc
>
>
>
>From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of Singh Rishi (TIPO -
>QA/QC)
>Sent: Tuesday, July 21, 2009 4:49 PM
>To: materials-welding@googlegroups.com
>Subject: [MW:2735] RE: 2733] RE: 2729] Ferrite Number (FN) for the deposited
>weld metal
>
>
>
>Thanks  Mr. Hegde,
>
>Can heat input , be a variable for erratic ferrite no ?
>
>For example I'm using filler wire of the same batch no ( packet ) & welder ,
>but in one joint I get Ferrite no. less than 8 % and in other joint I get
>over 10%.
>
>
>
>Best Regards,
>
>Rishi Raj Singh
>
>  _____  
>
>From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of PB HEGDE
>Sent: Tuesday, July 21, 2009 1:57 PM
>To: materials-welding@googlegroups.com
>Subject: [MW:2733] RE: 2729] Ferrite Number (FN) for the deposited weld
>metal
>
>
>
>
>
>
>
>Austenetic SS used in chemical /petrochemical plant require  good Corrosion
>resistance. For which delta ferrite plays the major role.
>
>i)Increase in Delta Ferrite will reduce the corrosion resistance . Therefore
>in severe corrosion resistance requirement  , ferrite to be kept below 8%
>(Generally it is kept between  3-7 %)However  very low ferrite  causes
>defect like hot crack, fissures ,There is no code requirement but Ferrite
>requirement is decided by process licenser ,depending upon the service
>condition
>
>ii)You can check ferrite No by Instrument called Ferrite Meter where you can
>get Ferrite No directly ,Some time You can check with respect to Delong
>Diagram ( Given in ASME Sec 2C ) by calculating /plotting the Cr , and Ni
>equivalent from actual chemical analysis of weld  
>
>iii)My experience -some time Ferrite no increases due to work hardening of
>material If you measure by Ferrite meter
>
>Regards
>
>
>
>Hegde P.B.
>
>09714714803
>
>
>
>From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of tong tong
>Sent: Monday, July 20, 2009 9:31 AM
>To: materials-welding@googlegroups.com
>Subject: [MW:2729] Ferrite Number (FN) for the deposited weld metal
>
>
>
>Dear All,
>
>Regarding above mentioned subject, i would like to know in detail about
>ferrite number. I have a few questions to ask such as What is the ferrite
>number? Why it is so important? Materials subjected to ferrite number?
>Permissible limit of ferrite number? Code and standard that we refer to
>requirement of ferrite number? Procedure to perform ferrite number?..If
>anybody have experience or information regarding this subject hopefully you
>can share with me. Thank in advance for your kind cooperation
>
>
>Regards
>tong2
>
>
>
>
>
>
>
>
>>
>

PREM S NAUTIYAL

CELL : 9820313278
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
-~----------~----~----~----~------~----~------~--~---

Comments

Post a Comment

Popular posts from this blog

Re: [MW:10788] ON PLOT PIPING & OFF PLOT PIPING

By Materials & Welding
Piping systems involved for the flow lines and gathering lines from the well head isolation valve to the production facility or processing plant isolation valve are determined as OFF PLOT. ON PLOT defines piping system in the processing plant and production platform. ANSI/ASME B31.4 applies for off plot piping system. B31.4 allows the use of either API 1104 or ASME section IX (as appropriate). However, occasionally, a very small system such as piping within 500 feet of a processing plant (some client also said 400 feet) may be declared B31.3 rather than B31.4. When B31.3 is invoked, only ASME Section IX is used. before you decide which code to use for welding procedure and/or welder qualification for pipe welding, you have to know the design and construction code applicable to the system. Please read far enough into scope and diagram illustrating the application of either B31.3 and B31.4 hope this helps rgds 2011/4/21 pradip kumar sil < pradipsil@gmail.com > Dear all, ...
Post a Comment
Read more

Materails FAQs

By Materials & Welding
Q: What are equivalents for standard Q 235 B (and Q 235 A) for U-channels? (asked by: boris.vielhaber@vait.com) A: DIN Nr. = 2393 T.2, 2394 T.2, EN 10025 W. Nr. DIN 17007 = 1.0038 Design DIN 17006 = RSt 37-2, S235JRG2 (Fe 360 B) Q: What is St DIN 2391 BK material? (asked by: dmcandrews@automaticstamp.com) A: Precision steel tubes, cold-finished/hard. Q: What is C.D.W. Boiler Tube? (asked by: montydude123@yahoo.com) A: Cold Drawn Welded Boiler Tube. Q: WHAT IS W.Nr. 1.4301? PLS TELL US IN EASY LANGUAGUE (asked...
21 comments
Read more

Heat tint (temper) colours on stainless steel surfaces heated in air // Heat tint

By Materials & Welding
Introduction The colour formed when stainless steel is heated, either in a furnace application or in the heat affected zone of welds, is dependent on several factors that are related to the oxidation resistance of the steel. The heat tint or temper colour formed is caused by the progressive thickening of the surface oxide layer and so, as temperature is increased, the colours change.   Oxidation resistance of stainless steels However, there are several factors that affect the degree of colour change and so there is no a single table of colour and temperature that represents all cases. The colours formed can only be used as an indication of the temperature to which the steel has been heated. Factors affecting the heat tint colours formed Steel composition The chromium content is the most important single factor affecting oxidation resistance. The higher the chromium, the more heat resistant the steel and so the development of the heat tint colou...
Post a Comment
Read more