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  • stainless steel weld color

    I know when welding stainless (304) the sought after color is gold which i get on my beads but occasionally i get a blue/purple. What am i doing wrong that i am getting that color? I know gray is too hot (which i dont get) so is blueish/purple too cold?

    The second question i have is i just purchased ER316 filler. Can this filler rod be used on 304 and 316 or is ER308 more versatile and better suited?

  • #2
    i have always used 308 on 304 stainless, 309 if im welding mild steel to 304 stainless, color i have no idea, ive noticed a lot of color variations in my welds as well, is it the length of time the argon is flowing over the material, say at the end of a weld and your letting the postflow run? the amount of heat? im sure someone knows..

    the flange looks like a rainbow, ive always wondered the color variations too..


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    • #3
      Copied from a British Stainless Steel Association publication:

      Here is some information copied from the BSSA (British Stainless Steel Association) publication. It shows approximate post weld colors and the corresponding temperatures in degrees C*

      The table below represents the temper colours that are likely to form on stainless steel type 1.4301 (AISI 304) if heated in air.

      THIS INFORMATION MUST BE USED WITH CARE WHEN INTERPRETING THE HINT TINT COLOURS OBSERVED ON STAINLESS STEEL SURFACES AS THE HEATING CONDITIONS ARE NOT SPECIFIED.

      Colour Formed Approx Temperature C pale yellow 290 straw yellow 340 dark yellow 370 brown 390 purple brown 420 dark purple 450 blue 540 dark blue 600

      The colors of the letters do not reflect the actual colors of the weld bead(s)! These colors are for clear legible viewing only!

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      • #4
        F is equal to (9/5 C) + 32

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        • #5
          Originally posted by regal2800 View Post
          I know when welding stainless (304) the sought after color is gold which i get on my beads but occasionally i get a blue/purple. What am i doing wrong that i am getting that color? I know gray is too hot (which i dont get) so is blueish/purple too cold?

          The second question i have is i just purchased ER316 filler. Can this filler rod be used on 304 and 316 or is ER308 more versatile and better suited?
          The colors on the surface of the weld have NOTHING to do with your welding.
          The colors(oxides) are formed at 975 and below, when contaminants on the surface burn.
          The burning contaminants could be machining oil, or any thing it was in contact with. Even if you cleaned it. Contaminants get into the fabric of the metal.
          Also just to make a comparison. Artists make RAKU pottery that uses copper carbonate as the glaze.
          Right when the red hot ceramic comes out of a kiln it is red hot (about 1600). the artist then removes the ceramic piece from kiln and puts it into sawdust or newspaper or a number of anything that will burn and make smoke. This process produces rainbow colors on the surface of the ceramic piece. The more reduction(more smoke and if the ceramic piece is buried in the sawdust the color produced is green or yellow green.
          If only one side of the ceramic piece is in contact in burnable material, reds and purples are produced.
          The oxides present on the surface help to produce these colors. All metals turn colors when heated and cooled.
          When you just cut a piece of steel with a O/A torch you will see colors.

          You can even control this process for artistic purposes.
          Take a piece of copper or steel and heat a spot on it with a torch (rich flame) , then take a piece of newspaper(crumpled up) or handfull of saw dust and press it against the surface and you will see colors produced. A hand held propane torch works very well.

          In some ceramic kilns the copper oxides in the glaze can be made to turn metallic red if the ceramic piece is left in the kiln and the gas kiln has a rich flame (reduction) will make these beautiful metallic red colors.

          Its all about the temperature, and the oxygen deprived atmosphere .
          Even your argon gas that is shielding the weld from oxygen can have some variation and cause the colors of your weld to be different even though all the welding perimeters are the same.
          BTW...I have welded some parts about 1/8 thickness stainless that look completely chrome after the welding was completed. The thickness of the weldment matters also. Has nothing to do with your welding.

          If you over heat the weldment will look grey.

          304 should be welded with 308 filler wire.
          316 stainless should be welded with 316 filler wire.
          Last edited by Donald Branscom; 05-04-2011, 08:57 AM.

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          • #6
            Blown99gt

            That stainless exhaust manifold(header) looks great!
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            • #7
              consistent color is what you really look for. they say light straw/copper color, but consistent heat stain means consistent penetration, says my welding teacher

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              • #8
                Your Tig job on the manifold looks very good......

                Currently making 4 inch SS exhaust system for diesel fishing boat .. Schedule 5, type 316 ,.030 mig wire A-1025 shielding gas....The welds are dark gray...Just like it's supposed to be for this process...

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                • #9
                  Originally posted by regal2800 View Post
                  I know when welding stainless (304) the sought after color is gold which i get on my beads but occasionally i get a blue/purple. What am i doing wrong that i am getting that color? I know gray is too hot (which i dont get) so is blueish/purple too cold?

                  The second question i have is i just purchased ER316 filler. Can this filler rod be used on 304 and 316 or is ER308 more versatile and better suited?
                  Well actually all those colors are kind of ideal for what you are looking for. i know im only 19 but i have been sanitary welding for two years and i get all those colors along with walking the cup on round tube and anything structural make it perfect.

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