silver with tin

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How do you butt weld .070 thick 1% tin bearing sterling silver  and not end up with a very brittle weld?
Reply:My understanding was that butt joints were always poor choices for brazing/soldering with thin materials. Lap joints were usually the best choice for joining 2 edges like that..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:This material needs to be butt welded for the application.
Reply:This material needs to be butt welded for the application.
Reply:This is production. The material is 96% silver w/ tin. It's long coils that need to be joined. .070 inches thick by 3.25 inches wide. We are useing a Lincoln Precision 375 tig welder with 75& argon/ 25% helium gas. We can not sub out the work. The welds end up very brittle if at all. The best so far have been with lower power. But even these will not survive the stresses of the rest of the process. We do weld 96% silver without tin with no problems.
Reply:First you said the material was silver, 1% tin.  Now you mention 96% silver with tin.  Are there other intentional alloying elements other than tin?  From the equilbrium diagram for Ag-Sn, it appears that up to 11.5% Sn can be held in solid solution FCC Ag, so this indicates the structure should remain ductile regardless of melting and cooling.
Reply:The material is: 96% silver                        2% copper                        1% tin                         .6% zinc                          remainer trace elements
Reply:silver-solder it.that works on bandsaw blades without being brittle.
Reply:Can't use any kind of solder.
Reply:I would guess that maybe the manufacturer could shed some light on the weldabilty of this alloy.I am curious about your weld setup and the possiblilty that maybe your inert shielding is inadequate and you are picking up oxygen and nitrogen in the weld.  Are you clamping close to the joint with heat sinks and using a back purge?You say the welds are brittle if at all, which suggests you are having trouble just getting a uniform weld?How about some pictures of what you are getting?
Reply:What is the final use for the sheet; is it being used as welded, or undergoing more processing? Any chemicals involved? Is this a new process/product, or an old one using different materials than before? How does the brittleness manifest itself; the sheets falling apart? Have you considered the variation of resistance welding called stitch welding which uses pressure and current applied by a moving wheel? With the high conductivity of Silver, I don't know how well that would work, or if the finished  dimensions would be suitable for your purpose but If time at temperature is part of your problem, this might mitigate it.
Reply:The material is rolled after the welding to a much thinner guage. Most times this takes many passes in a rolling mill. Even on the first pass this material will crack at the welds. This is a new product for us. We can not change the make up of the product per customers specs. We only have the one welder. Would a change in gas help? If so, what do you recommend?
Reply:I have not found any info on this particular alloy, but I'm pretty sure this is wholly a solid solution alloy that is not heat treatable to produce increased strenghth and hardness as is steel.  So, it sould not matter if this is welded and then quenched or cooled slowly.I am just guessing that brittleness from welding may be due to inadequate inert shielding and formation of brittle oxide and/nitride intermetallics.  How are you fixtureing this weld and shielding the backside?  An no, changing the gas won't help, unless your present gas in contaminated, or a blend of oxygen or CO2.Again, how about some pics?Last edited by pulser; 06-25-2010 at 05:19 PM.