Problem using silver solder with TIG

[Laiky]

I might be way off but i was under the impression you could silver solder with a tig torch. I bought some (really expensive) silver solder to solder stainless bungs into stainless sheet but when i try to use it it starts to melt, then flares up and turns to crud! I was using a .040 lanthanated tungsten with gas lense and #8 cup on my 20 series torch with about 20-25 cfm of argon. Current was set at 40 amps, no pulse.

What's the deal?

[stseely]

I have only silver soldered with a O/A torch but I have done a bunch of it. But I do know its very important that the metal be very clean. I use scotchbrite and rubing alcohol to clean the parts, you could probably use acetone too. And you need to put flux on the parts your soldering along with the silversolder.
When you heat the parts flux will be a past at first then when you apply heat it will start to turn into a white looking powder then with more heat the flux will turn clear when the flux turns clear the parts are about up to temperature and you can touch the solder to the part and the solder should melt. You have to have good heat control because the solder runs like water when it gets hot. And if you get it to hot it will kill the flux then you need to clean the parts very well and start over.

Others may have another way of doing it but this way has worked for me. Hope this helps.

[fun4now]

i dont think you are going to have much luck with TIG and soder. TIG heats the base matereal only and it is to localized to do any good with soder as the melt points are so far apart. when you soder you want to get the surface area just abouve the soder melt point and let the sodder flow in. on ,and around the area to be sodderd. with TIG you only heat a small area with lil to no surounding area so you are trying to get the soder to melt into liquid SS witch melts way hotter than the sodder causing it to basicly boil the soder. best bet would be get some SS filler and TIG it right, or break out the O/A torches and silver sodder it right. at this point you are trying to do 2 things at once and neather one right. TIG is desined for pin point heat and soddering neads a larger heat efected area.
my $.02 is abanden this ideal and pick one or the other and get-r-done.

[burninbriar]

Tig really isnt designed for brazeing and soldering. The arc is designed to melt the base metal , defeating the function of solder or braze whitch is designed to melt onto hot metal. A torch is a much better option. If you are carefull you can braze with tig but it is very difficult and not recomended.

[precisionworks]

under the impression you could silver solder with a tig torch

If you can, you'll be the only person who's ever done it

Use an O/A torch with correct tip size, use the recommended flux, and it will work well.

[wb5jhy]

If you're doing stainless to stainless and you have a tig, why solder it??
Just tack weld with small dia. SS filler to control heat and distortion.

I think you will need some flux for silver to stainless. I've done it before just to see if it would work. Turn down the amps to 15 or 20 and move the torch around constantly to keep from melting the base metal. When it gets hot enough touch the solder to base metal and it should melt on. If you pass the torch over the silver too long it will boil up and pop and make a big mess. It's not easy and doesn't make for a very nice looking job.

I've even turned down to min amps (8) and used the tig torch to silver solder a big ground lug to #6 copper wire. Worked fine (and quick !!). Just remember to never hold the arc at any one spot or it will melt the base metal and make a mess.

[burninbriar]

How thick is the ss sheet you are working on ?

[Laiky]

I was trying to solder a stainless pipe bung into some .035" sheet. I figured i could get a nice neat seal without warping or having to back gas. I was wrong. It's funny how many conlicting opinions i get on the subject of soldering or brazing with the tig. Some say it can't be done, then others say you can do anything with tig you can do with an gas torch. I like silicon bronze, and find it easy to use. Is that considered brazing?? I would swear i've seen tig soldering in some books but i guess i look at a lot of books so it could just be my rapidly aging memory. Anyhow, when i do the silicon bronze, i strike an arc and put the rod between the tungsten and workpiece, then melt the SB until it flows. Then i move and draw the puddle over with the rod. Is this brazing? I figured it would work with silver solder too.

[joebass]

You can TIG weld braze with Silicon Bronze. You have to use half the amps you would normallt use. The bead should look just like a normal bead. Do a search it has been covered here before, I've never tried it with any silver brazing rod.

[fun4now]

in soddering you shouldent be heating the sodder just the base metal and melting the sodder on the heated base metal, as tig is desined to reduce the heat efected area the too just dont go togather verry well. i supose you could make it work but dont see it getting a proper bond.i would stick to TIG'ing with TIG and brazing/soddering with O/A. they are tried and true methouds that will get you the best bond possible, even if you manage to get a sodderd joint with TIG i just dont see it being as strong as you will want do to improper heat placement.

again i would just grab some SS filler and tig it and be done. you will have a good clean solid bond you can relie on.