WPS without using filler

[AWeld1]

We are going to weld 1.2mm stainless steel plate that will be used in Portable Water Reservoir expansion joints. But our client wouldn't want any heat tint.

Can we make a wps without using any filler wire? we will just melt the metals that are joint together using lap joint?

please see the attached document for reference.

Thank you.

 

[metengr]

Yes, you can qualify this WPS without filler metal (autogenous) using the GTAW or GMAW (MIG) processes. Use welding grade, argon shielding gas.

 

[EdStainless]

Actually it would be GTAW (TIG) without filler, by definition MIG is adding filler.
Yes, you can develop a WPS for this. It is common practice.

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Plymouth Tube

 

[metengr]

Yes, the MIG would be an option with filler metal you can present to the client.

 

[Tmoose]

When I gas weld using no filler there is discoloration well back from the weld on both sides of the joint.

pics of fresh TIG welds by those far more skilled than I show discoloration beyond the weld as well. Maybe wildly excessive gas flow would shield the nether regions and prevent rainbow.

reportedly no fillere

http://i298.photobucket.com/albums/mm280/m_hoover/Welding/IMG_0534.jpg

with filler

http://www.quik-latch.com/images/Evo_Manifold_3.jpg

I'd expect a quick touch with a wire wheel might restore the original stainless color

 

[EdStainless]

I would suggest a larger gas cup, and lower gas flows.
Any turbulence in the shield gas will serve to draw in oxygen.
A trailing shield, like is used on Ti is helpful also.
You need back shielding, plastic, tape, and some Ar should do the trick.
Make sure that it is taped down well away from the heat of the weld.

And all of the surfaces must be very clean. If you use acetone make sure that it comes from a new sealed container, otherwise it will have enough water in it to still discolor the welds.

You and your customer should agree on acceptable color for the welds and HAZ.
There are published scales.
Saying no discoloration is impractical, in that case you let it discolor and then clean with pickling paste.
A golden or yellow tint is usually acceptable, blue or brown is not.

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Plymouth Tube

 

[weldstan]

There are mini-plasma arc welding systems that would be ideal for your purpose as well. Automated pulsed GTAW systems would also be recommended. These systems can be leased.

 

[tbuelna]

Aweld1- As others noted it is indeed possible to write your WPS describing a fusion butt weld that would not use filler metal, and it is commonly done. There are many fusion weld processes that can be used to produce such weld joints, including TIG, EB, laser, etc. However, the fit-up of the mating parts when using this type of butt weld must be extremely precise.

Having said all that, I looked at the sketch you provided and I did not see any butt welds called out. The only welds shown on your sketch were fillet welds, and the fillet welds as shown in your sketch would not be possible to produce without using a filler metal.

 

[metengr]

tbuelna;
Suggest you view this video clip to change your statement regarding autogenous fillet welds using GTAW

https://www.youtube.com/watch?v=wNM6wTeUgyw

 

[tbuelna]

metengr-

Watched the video but I did not see any example of the type of fillet weld shown in Aweld1's sketch that was made without using filler wire. The autogenous fillet welds shown in the video (welding a cap plate to a tube end) were ones where the length of one fillet leg was much shorter than the mating plate thickness, and were continuous. If you were to intermittently fillet weld the parts as shown in the sketch without filler wire, the resulting welds would exhibit significant undercutting and would probably not be acceptable.

Of course, I would agree with you that autogenous fillet welds can be made successfully. In fact I have made many such TIG welds myself to fuse the outside corners of components made from sheet metal, like fuel or oil tanks. But when fillet stitch welding a doubler to the flat surface of a panel as shown in the sketch I would definitely use a filler wire.

 

[weldstan]

Autogenous fillet welds are commonly used in manufacturing LNG membrane type tankage. Automatic pulsed GTAW and pulsed PAW systems are used. Manually made autogenous welds are also made at locations inaccessible for the automated systems.