SAW Twin wire versus single wire 1

[bmoorthy]

Item 1 is being welded with SAW (Longitudinal Seam)using Single Wire technique.

Speed is x mm/min, Current is y amps, voltage is z volts.

Item 2 is being welded with twing wire technique

Speed is x mm/min, Current is y amps for wire "A" and y1 amps for wire "B" and voltage is z volts for wire A and z1 volts for wire B. (both wires are DC).

Question 1: What is the heat in put for item "B"

Question 2: If one takes a cross section from item 1 and and item 2 and did a macro examination which would have had the Higher HAZ

Question 3: If one conducts Impact testing which one might have lower impact as compared to the other (On a theoritical level).

Question 4: In the twin wire technique, if the second wire is given AC and the first wire is given DC, what would be the effect on heat input as compared to both wire being DC.

 

[metengr]

I would suggest you visit the web site below and take the time to review the SAW process. Come back and formulate your questions

http://www.weldprocedures.com/subarc.html

 

[bmoorthy]

Metengr:

The link did not help to find out the heat input. I have visited this sites many times before.

All

The set up of the item 2 (Where twing wire technique is employed)

The two-wire tandem electrode position with individual power sources is used where extreme penetration is required. The leading electrode is positive with the trailing electrode negative. The first electrode creates a digging action and the second electrode fills the weld joint. When two dc arcs are in close proximity, there is a tendency for arc interference between them. In some cases, the second electrode is connected to alternating current to avoid the interaction of the arc.

 

[metengr]

Heat input =

Voltage x amperage x 60/travel speed

 

[bmoorthy]

That is for single wire.

What for twin Wire Tandem technique? Shoul we add up.

If the distance between the wire (Point of deposition is say 25 mm away), then what is the heat input.

My original question was for Twin wire.

 

[metengr]

Here is a paper that might be of interest to understand what is involved with multiple wire welding in pipe fabrication. It is more than just heat input, it is wire formulation, flux/slag and dissolved gases brought on by added heat input.

http://www.journalarchive.jst.go.jp...national1966&cdvol=26&noissue=5&startpage=379

[PDF] Prediction of Heat-Affected Zone Characteristics in Submerged Arc ...File Format: PDF/Adobe Acrobat - View as HTML
(SAW), selecting appropriate values for. process variables is essential in ... study revealed: 1) heat input and wire. feed rate have a positive effect, ...

http://www.aws.org/wj/supplement/Gunaraj2-02.pdf

Regarding dual wire heat input, I would suggest you contact Lincoln Electric for information. Their product brochure gives good information on deposition rate and total heat input, etc., for dual wire SAW.

[PDF] Process: AC/DC Submerged Arc WeldingFile Format: PDF/Adobe Acrobat - View as HTML
The AC/DC SAW process is the ideal choice for. high-deposition, high-speed welds that .... changing heat input levels. Communications between ArcLink and ...
content.lincolnelectric.com/pdfs/products/literature/nx230.pdf

 

[bmoorthy]

Thanks, i think i will make some head way

 

[HgTX]

For what it's worth, the fabricators I deal with just add up all the heat inputs with multiple-wire procedures. But maybe they've been doing it wrong all these years...

Have you tried the AWS Forum?

http://www.aws.org/cgi-bin/mwf/forum_search.pl

Hg

Eng-Tips policies: faq731-376

 

[weldtek]

Use the formula metengr provided and apply it to both wires.

 

[metengr]

Just a side note, you need to be careful about simple addition of heat input per wire. Using two weld wires, one could collectively average the voltage and amperage, but you must use the measured travel speed while using both wires. The travel speed input is critical because as you add more electrodes, the travel speed will increase AND result in lower heat input, instead of higher input.

 

[metengr]

Please note

could collectively average the voltage and amperage

should be deleted.

This sentence was not to be added to my post. I hit the submit button a little too quick.

 

[weldtek]

Agreed, if you look at the travel speeds attained by the folks who wrote the paper metengr referenced they approach 60 ipm with three wires.

 

[metengr]

The paper below might be of interest

[PDF] IMPROVEMENT OF ENERGYAND MATERIALS EFFICIENCIES BY INTRODUCING ...File Format: PDF/Adobe Acrobat - View as HTML
arc welding can be obtained also by calculations using dif-. ferent mathematical models [19, 20, ..... heat-energy input in multiple-wire welding, the wires ...
public.carnet.hr/metalurg/Metalurgija/2007_vol_46/No_1/MET_46_1_047_052_Bajcar.pdf -

 

[HgTX]

Won't both wires have the same travel speed?

Hg

Eng-Tips policies: faq731-376

 

[metengr]

Yes. In some cases I have seen use of individual wire feed speeds versus travel speed of the workpiece. So, one needs to check and doublecheck.