Silver solder stainless

[muddstopper]

I have a friend that wants to stick some very thin stainless tube together. Sheet metal thin. I thought about trying to tig it for him but since I aint really practiced to much with the tig, we thought we might just try silver soldering instead. Question is, what grade of silver solder to use. The Harris 56% silver is kind of pricey for the amount of soldering he would be doing so what would be an exceptable alternative. Wont see any pressures or loads, art work, just to look at, but doesnt want it to collapse under its own weight either.

 

[nybirdman]

Tig is made for thin Stainless.......don't think the silver solder will stick.

 

[k0ua]

Sure sounds like a job for TIG. Why not get some of the materiel and practice your TIG for a bit before you tackle the art project. I think your results are going to be a lot better.

 

[weldermike]

Just keep practicing on thin with your tig bud. Youll get it in due time. Just dont practice on a project. I had a job coming up doing some thin edge welds. And made sure i was preparred. 1/16. Always stay practiced. It goes a long way.

 

[Gary Fowler]

There is a grade of silver solder that will bond to stainless but has a really high silver content, however 1/16" sheet metal should be easy to TIG weld. Just butt it up and fusion weld it together, little to no filler rods needed.

 

[MH8675309]

Silver solder will stick to stainless. Used to solder stainless brake lines in the shop years ago. We used a paste instead of a powder flux. It was done this way because the right silver solder will suck right down into the joint almost as good as a copper braze - it was better for not leaking than a tig weld would be. When silver soldering the trick is to not get the stainless too hot. Once you scorch the steel you can forget it. You'll have to cool it down and grind off the blackened steel scale as solder will not stick to this. And yes, real silver solder is expensive. If you are careful you can get regular braze to stick to silver with decent results. Start with a low flame and take your time - don't be in a hurry or you'll make a mess out of it.

 

[kenmac]

the 15 % silver I use ,you can get for about $50.00 per lb

 

[muddstopper]

My buddy decided to try stickwelding his project. He borrowed my old ac/dc tombstone. I have welded car fenders with it so it should do alright with the thin stainless. This gives me an excuse to finally do a permanate hookup of the Idealarc machine I bought about a year ago. I can see some tig practice in my future.

 

[Raspy]

Silver soldering stainless with 45-55% silver solder works very well. Use paste flux and a mapp torch. Brush some flux onto the stainless. Heat the stainless to a dull red and feed in the silver after dipping the end in the flux. Done right it will trickle into the smallest of gaps and seal very nicely. It acts like lead free plumbing solder under those conditions.

15% is called silfloss and is designed for use on copper with no flux. It will work on stainless with the paste flux, but it's not the same as using it on copper where no flux is needed. It also is more viscous when melted and doesn't flow like the 45%.

Use 5% or 15% on copper. Use 45-55% on stainless and use the white paste flux designed for silver soldering. Practice with your heat to where the flux is clear and melted and the steel is just beginning to get red. Involve the solder in the flame and get it to alloy with the base metal. Be careful with the heat! Don't just blast one little spot, but heat the area carefully, with patience, and hold the torch back a bit.

 

[muddstopper]

Silver soldering stainless with 45-55% silver solder works very well. Use paste flux and a mapp torch. Brush some flux onto the stainless. Heat the stainless to a dull red and feed in the silver after dipping the end in the flux. Done right it will trickle into the smallest of gaps and seal very nicely. It acts like lead free plumbing solder under those conditions.

15% is called silfloss and is designed for use on copper with no flux. It will work on stainless with the paste flux, but it's not the same as using it on copper where no flux is needed. It also is more viscous when melted and doesn't flow like the 45%.

Use 5% or 15% on copper. Use 45-55% on stainless and use the white paste flux designed for silver soldering. Practice with your heat to where the flux is clear and melted and the steel is just beginning to get red. Involve the solder in the flame and get it to alloy with the base metal. Be careful with the heat! Don't just blast one little spot, but heat the area carefully, with patience, and hold the torch back a bit.

I think you answered my original question, What would the minimal silver content to silver solder stainless to stainless. I find the 45% silver to be much cheaper than the 56% and should work well with the intended project. I was actually considering the 15%, but didnt know how well that would work. From what I have been reading elsewhere, it seems the 15% would work doing stainless to copper, but not so well stainless to stainless. I saw as little as 8% silver being available, (probably more %options are out there as well), but sort of guessed it would only be suitable for copper to copper soldering.

Took welder to buddy yesterday, he also borrowed my plasma cutter, think I will drive over and see how hes doing stickwelding. My buddy used to be a boilermaker, doing xray welding on huge gas storage tanks. Now hes 68 yr old, and has sold most of his welding equipment. I bought the idealarc from him. It might take him some practice to get back into the swing of stick welding, but I aint betting against him getting it done.