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Help with silver brazing question

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  • Help with silver brazing question

    I need to silver braze a stainless 303 plug into a stainless (alloy unknown, it is a 300 series tho) piece I drilled a hole in the wrong place.

    I have some Navy "Grade IV" silver solder which is same as BAg1a (Easy-flow). The Navy recommended silver solder for 300 series stainless is "Grade V", which is about the same alloy with the addition of 3% nickle (supposed to aid flow and wetting of 300 series stainles). Grade V is equilivant to BAg-3 (Easy-flo 3).

    Here is the alloy list: (numbers are percent)NOTE the numbers do not line up in the post
    name AG CU ZN CD NI
    Grade IV 49-51 14.5-16.5 14.5-18.5 17-19
    BAg1a 50 15.5 16.5 18

    Grade V 49-51 14.5-16.5 13.5-17.5 15-17 2.5-3.5
    BAg3 50 15 15 16 3

    Do you think the Grade IV will work OK to do this? THe plug is 0.135 dia, the hole is 0.141 dia, the length of the piece is 0.5. I will be drilling a new hole in the correct place that will intersect the plug about 1/3 of its diameter, so it does have to have some strength, but not a lot. No human life is involved.

    Here is a link to the Handy-Harman list of alloys, I got the alloy list for the commercial alloys from it:

    I am cross posting this in Welding to get added exposure.

    Thanks in advance,


  • #2
    Stainless will take silver braze filler very well, IF, you use flux aggressive enough to life the oxides formed.

    Stainless is a poor conductor of heat.
    So - - If the work is of low thermal mass and you exercise patience using fire brick and such to retain the heat you can do a bang up job with either BAg 1 or 3.
    These days of PC politics some suppliers are offering fluoride free SS flux.
    I have regularly used and insist on fluoride bearing white flux for stainless.
    This also carries responsibility to pay attention to not overexposing anything to the fume, particularly if Cd is involved.
    Not rocket science but requires thinking about what your are doing.

    Do NOT rush the heat or you will kill your flux.

    Fluoride bearing Black flux will last a bit longer and take a bit more heat.
    If you are working high thermal mass parts, seriously consider FB Black flux.

    BAg 7 will be the best color match, and best ductility, also rated for food contact.

    Silver braze has significant strength. 50k - 60k psi kinda stuff.

    Hth Ag
    Last edited by agrip; 11-15-2009, 06:37 PM.


    • #3
      Thanks, agrip

      I went ahead and used it and got acceptable results. Slight silver braze ring at the surface (I faced it off after cutting off the excess plug), the new hole drilled OK, and the tapping went OK, tho I had some tough spots where I think the flutes were intersecting the old hole, mabye some flux there.

      My torch was a bit small, but the lump of silver solder in the bottom of the hole melted and the plug dropped into the hole fine, used lots of flux.

      Thanks for the encouraging words.