| Best Brazing Practise |
| Silver Soldering Tips |
| Strength of Silver Solder Joints |
| Silver Solder |
| Silver Solder Fluxes |
| Soft Solder Fluxes |
| Flux Cleaning Salts |
| Boiler Fittings/Accessories |
| Cadmium Bearing Silver Solder & Fluxes |
| Cadmium Free Silver Solder & Fluxes |
| Soft Solders |
| Copper Phos Alloys |
| Silver Solders |
| Refrigeration |
| Welding Products |
| Sievert Propane Torches, Burners & Hearths |
| Hallmarking ? |
| Non Hallmarking |
| Joining Aluminium |
| Joining Brass |
| Joining Cast Iron |
| Joining Stainless Steel |
| Joint Cleanliness |
| London Jan 2011 |
| Myford Fair Sep 2010 |
| Harrogate May 2011 |
| Guildford Jul 2010 |
| Bristol Aug 2010 |
| Midlands Oct 10 |
| Society Presentations |
| References |
| What the professionals say |
Joining Stainless Steel
The most common problem associated with brazing or soldering stainless steel is one of getting the alloy to ''stick''. This is probably caused by using the wrong flux. Conventional silver solder fluxes will not remove chromium oxides so the alloy will not ''wet'' onto the steel. The alloy simply melts, forms globules and falls off.Use our HT5 flux with silver solder or our 2207 flux with soft solders. Problem solved.
There are two other aspects to be considered when silver soldering stainless steel. The first is the occurrence of a phenomenon called ''crevice corrosion''. This shows itself by the joint literally falling apart after exposure to water. After failure, the joint appears not to have adhered to the steel. The water does not affect the steel or solder but attacks the molecular bond between the two.
It does not occur if nickel present at the interface.
It is therefore extremely rare among what are called ''austenitic stainless steels'' They form the 300 series. They are non-magnetic. A common and good example is 316. They all contain nickel and hence overcomes the problem.
For added security you could use 456 alloy. It is reasonably fluid, will produce strong leaktight joints and offers a good colour match.
If the steel is of unknown specification, then use a silver solder containing nickel eg 449 or 850N.
449 contains 49% silver and is cadmium free.
850N contains 50% silver and contains cadmium which improves the fluidity of the alloy.
Another option where much lower temperatures or stresses are involved is to use a silver-tin alloy such as 2207. It has a flux core specifically for stainless steel. Use it like any other soft solder.
Both alloys offer an excellent colour match.
A second potential problem is ''weld decay''.
If the steel is not ''stabilized'' then at temperatures just above 800 deg C the chromium in the steel combines with the carbon and ceases to offer protection. In time the stainless steel will rust and fail.
Keep the liquidus temperature of the silver solder below 750 deg C.
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