Soldiering stainless?

David Stifle

David Stifle

Joined
Nov 20, 2008
Messages
10,188
Is there a technique for soldiering 416 stainless? I have never tried it until the other day, and was not aware it would be a problem. But, no matter how hard I tried, the soldier would not stick.
 
You must use a flux that states "for stainless steel " and a solder that's about 5 % silver and melts about 400 F.Otherwise it's not a big deal.Max strength for a joint of solder or braze is a .003" gap.start with a clean surface .[Those who don't know how to solder end up using an epoxy ! ]
 
mete is correct.
Use hard, silver bearing, brazing rods. I get then from a local HVAC installer.
 
Brazing rods are not for soldering. They are for silver brazing, which works well on stainless but requires special flux and 1000 degree plus heat.
Soldering stainless is done with soft solder with 4%+ silver content. I use Stay Clean flux for soft soldering.
 
Another vote for Stay Clean flux here it works great for low temp apps. Amazon sells a starter pack for about 10 bucks. This is a pic of it next to a switchblade that I used it on for soldering damascus bolsters on stainless. good stuff! Depending on the application, you can also pound the solder flat and stack your work making a sandwich of sorts, heat it and position it with a nail or something then let cool or mist it with water to set it faster...good luck.:thumbup:
 
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David, I don't see what solder you're using, but I get good results with Harris Stay Brite silver bearing solder.
It flows at a very low temp and sticks well to all the stainless steels I've tried it on, using the flux mentioned above (and good soldering technique, which is another subject).
I'm not a fan of using it to join, for instance, a stainless bolster on a non-stainless blade- there's probably a way to do it but for me it's pretty hit and miss, so I use other techniques.
 
When soldering stainless, also make sure the metal in the joint has been cleaned to bright metal with an abrasive immediately before soldering.
Hard soldering (brazing) is much stronger than soft soldering, but the heat required sometimes can cause other problems.
 
And of course, don't forget to clean everything thoroughly. No oxidation on the surfaces, no dirt, no grease, no fingerprints. Wash with soap and water, then scour it with degreaser of some kind, and degrease your hands & fingers while you're at it (if you're not gonna wear gloves). Water should cascade evenly across the surface when there's no trace of grease/oils left- you may think you're done and have to redo it a couple times.
 
The trick to silver soldering stainless steel is to use Harris Stay-Clean Liquid Flux part number SCLF4, EDP (electronic data processing?) number of 40002. The UPC (bar code) is 6 84032 00013 1. This is their most active soldering flux formulation. You may be disappointed in the performance of a less concentrated flux. I buy this flux at the local welding shop but it is also available on industrial supply websites and on Amazon as: Harris SCLF4 Stay Clean Soldering Flux, 4 oz.

The solder I use is either Alph Fry 62964 4% silver solder or even better is Kester SN95AG05 #66/44 which is 5% silver. If you don't need 1 pound of the 5% solder you can buy small quantities of it on eBay.

You can get detailed technical information and an MSDS for the flux from:

http://www.harrisproductsgroup.com/e...quid-Flux.aspx
(or http://www.harrisproductsgroup.com > alloys > Soldering > Fluxes > Stay-Clean® Liquid Flux)

This flux contains Muriatic Acid which is another name for Hydrochloric acid or hydrogen chloride (HCl) which will produce free chlorine gas when heated.

Wear a respirator mask rated for hydrogen chloride (Hydrochloric acid / HCl) vapor and chlorine gas. The average paint spray mask is probably not rated for these vapors. The 3M 8246 Particulate Respirator available on Amazon and eBay in single quantity is rated for nuisance level acid vapors http://solutions.3m.com > safety and security > personal protective equipment > disposable respiratory protection (picture) > Nuisance Level Acid Gas

Flux residue is corrosive and a post-solder flux removal procedure should be employed. Because of this it is not recommended for use in electrical or electronic applications.

FLUX RESIDUE REMOVAL
Step #1
Thoroughly soak and wash soldered parts in a solution made up of one to two ounces Tri-sodium Phosphate (TSP), Spic and Span (powdered) or Bicarbonate of soda added to one gallon of water heated to 120° F (49° C) to neutralize the acid residue. Rinse these alkaline cleaning solutions off thoroughly because they are almost as corrosive as the hydrochloric acid.

I keep my bottle of this stuff in an old soup can that gets seriously rusting from the vapor of the flux.
 
The name of the game is clean!! And the surname is be prepared. So the nickname is pratice with scraps ;)
Wear nitrile gloves all the time and wash the parts in soap, then rinse, soak into alchool and let dry. Very important being sure you don't have wet alchool residue when applying the flux, or it will run away!
I suggest pre-tinning the 2 parts to be joined. Be prepared to add a bit of flux along the edges of the part while melting the solder (by the way, you don't want to directly melt the solder, the hot parts will). Usually i use a clean brass rod wetted with flux to spread the solder evenly and to knock away the excess when the part is covered.
With a lead pencil you can draw borders, the solder won't stick there. Just be sure you don't bring lead powder where you want the solder!
 
All the washing and gloves is not necessary. Just sand/file the parts to bright metal, apply flux and solder.
I do it all the time.
 
It may be not necessary, depending on the cleanliness of your hands and your equipment.
"sanding" with what? any abrasive/file could be oil contaminate as well as my hands in the shop and leave residues on the pieces, nevertheless i have never had issues with nitrile gloves and a serious degreasing when soldering, etching, and the like ;)
That's why i feel like suggesting a novice to take the "clean" route, to exclude one possible cause of failure while getting the grip with the process.
 
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By the way, also pre-soldering the 2 parts it's not necessary (and is 3x the time), but i never failed a soldering this way, and it prevents recovering a partial sodering job with parts attached but incomplete joint!!
 
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