[MW:4149] SAW PROCESS and FCAW backing question

Mr. Asghari,

 

The most influential variable in the SAW process is Arc Voltage (Arc Length). As voltage is increased, flux consumption increases. 

 

If your Procedure utilizes an active flux (one that is relatively high in silicon, manganese or perhaps even chromium), weld chemistry can be influenced detrimentally especially in multipass welding.  For example, the silica tends to break down in the heat of the arc and can introduce adverse amounts of oxygen to the weld metal.  

 

If you are using an alloying flux to recover alloy elements, voltage can significantly affect the amount of elements picked up through the rate of flux consumption.  Follow Manufacturers recommendations closely to obtain desired chemistry.

 

The reason FCAW requires backing is due to the fluidity of the FCAW puddle. 

 

Thanks,

 

Darcy Morin

 

 

 

 

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Ali Asghari
Sent: January-25-10 10:40 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:4147] FW: 4106] essentials about SAW PROCESS

 

Dear Goswami

thank you for reply.

but my intention of question is :when the composition of weld metal is dependent to flux,which welding parameters affect on amount of alloying elements in weld metal?

regards

 

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From: pgoswami <pgoswami@quickclic.net>
To: materials-welding@googlegroups.com
Sent: Sun, February 21, 2010 3:04:18 AM
Subject: [MW:4116] FW: 4106] essentials about SAW PROCESS

 

Mr Asghari,

 

Both QW-404.10 & 404.27 applies to procedure qualification by SAW and are essential variables. In SAW , one can do the alloying through flux only, or though wire or through flux and wire combined.

 

You may be aware that SAW fluxes are manufactured (briefly without going into details) as acidic flux, basic (agglomerated, bonded or fused) or neutral fluxes. Each flux behaves differently during welding. Due to these factors SAW flux is so important and fabricator has to know precisely the AWS classification as mentioned in SFA -5.23 or SFA 5.17 as provided by consumable manufacturer.

 

QW 404.10-  Where the alloy content of the weld metal is very much  dependent upon the composition of the flux used, any change in any part of the welding procedure may result in the important alloying elements in the weld metal being outside of the specification range  given in the Welding Procedure Specification. If  the production welds are not being made in accordance with the procedure specification, the authorized inspector may require that a check be made on the chemical composition of the weld metal on a production weld.

 

QW-404.27— Where the alloy content of the weld metal is largely dependent upon the composition of the supplemental filler metal  or any other form of additive, such as  alloy powder. This changes weld metal chemistry thus deemed as essential variable as per ASME Sec-IX.

 

Regarding your earlier queries:-

 

·         what is effect of filler composition in transfer mode in GMAW?—None, transfer mode is a function of, wire size, shielding gas and Polarity/ Arc Current.

 

·         why backing material is required for FCAW for root pass?—FCAW is not meant to be a full penetration weld , unless some improved and special  power source is used, such as STT.

 

 

Hope I have tried to clear your doubts. I am attaching an e-book on SAW for your reference.

 

Thanks

 

 

Pradip Goswami,P.Eng ,IWE 

Senior Engineer/Specialist(Welding-Metallurgy)

Machine Dynamics & Component Integrity Dept.

Engineering & Training Services Division

ONTARIO POWER GENERATION Inc.

PO Box-2000, RR-55(South)

Nanticoke, Ontario,N0A1L0

Tel:-(519) 587-2201, Ext 3107--in Nanticoke

         (416) 231-4111, Ext 5925--in Kipling,Toronto

Fax: (519) 587-6814

Email-pradip.goswami@opg.com.

 

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of ali asghari
Sent: Wednesday, January 20, 2010 5:35 AM
To: materials-welding@googlegroups.com
Subject: [MW:4106] essentials about SAW PROCESS

Dear all

does anybody have experiences or interpretations about

QW 404.10 & 404.27(the alloy content of the weld metal is largely dependent(how can assess) upon the composition of the flux used, any change in any part of the welding procedure which would result in the important alloying elements in the weld)

 

QW 404.24:10% VOLUME IN TOTAL LENTGH OR NOT?

 

 

1

 

 

REGARD ADVANCES.

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