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  • 4140 Steel Welding_Help

    We are trying to weld several pieces of 4140 Stell togather without much luck. The welds have to Mag. Particle inspection afterwards, and of the 10 sets that we have welded, 7 of them did not pass the Mag. Particle Inpsection. I tried grinding the welds and rewelding and of those only two of the passed the Mag. Particle inspection. There are cracks in the wleds that only show up during the Mag. Particle inspection.

    I have heard heating the parts to 400 F before welding helps. Have not tried it yet. Is there anyway to ensure that the welds will pass the Mar. Particle Inspection (i.e. no cracks) ?

    Any suggestions would be much appreciated.

    Best,
    DWTUSA

  • #2
    Are you Tig welding the 4140. Preheating to 400F - 600F and using 4140 filler is where to start. I have welded a fair amount of 4140 using Cronatig 340T filler (Cronatron Welding Systems from Lawson Products (www.lawsonproducts.com). I haven't had to mag particle test the welds so I can't help you there but I have had no issues with weld failures.

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    • #3
      4130

      i did alot of big stuff with 4130 for offshore oil, i dont think, mayby im incorrect but there is much of a difference in 4130-4140, all our stuff was mag,d x rayed and ut tested. its been 30 years or so since i last welded this stuff and we had to follow strict procedures, so we never had to think for ourself, what i do remember it is critical to prehaet to 500 and keep it there through the weldmont,we would weld 40 ft long pipe, 30 in dia and a 4 in wall thickness. we used some type of 8018 then put the subarc on it, the welding inspecters were always checking for temp, if you got lazy and welded it under 500 the ut test (ultresonic test-soundwaves) would always find small cracks. i would strongly suggest preheat 500 and maintain till finished and find some way to cover your part to slow cooling, if you are really serious a rod heater is something to think about

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      • #4
        Pre heat is the way to go. The whole part does not have to be heated just the weld area. I always heat to about 350 degrees f. I use a non contact thermometer to check & maintain temp. For stick we use Polaris wire by Nassua Research & for innershield flux core the same.
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        • #5
          Thank you very much for your help. I will try preheating to 500 F next week and monitor the temp. with an indirect instrument. I'll report back on the results.

          Best
          dwtusa

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          • #6
            Take your time and bill the customer. They will be Happy

            Originally posted by dwtusa View Post
            Thank you very much for your help. I will try preheating to 500 F next week and monitor the temp. with an indirect instrument. I'll report back on the results.

            Best
            dwtusa
            I weld a part for the M1-A1 Abrams tank made of 4140. Parts are small (benchtop) and range from 1.25" to .500" thick, 3 pc.
            Blueprint calls out ER80 SD2. My research asked for a preheat to a min. 350F and cool down to touch of about 8 hrs in sand, or oven (bought at Home Depot). I use a Tempil stick for checking temp. The drawing calls out a min. 3/16" weld. I make a two pass weld. The first pass with a slight crown or I'm almost guaranteed a centerline crack (remember, the weld cools from the sides to the center). The second pass is while the part is still above 350F. More of a flat, wide weld for the second pass as the weld size helps with the post weld strength, minimizing cracking concern. I have just welded 63 pcs. with a 100% pass on Mag Particle inspection, bettering a former 98% on 180 pcs. and 99% on a 120 pc. order. All work done to WPS where I developed the PQR.

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            • #7
              Originally posted by Stillwelding View Post
              I weld a part for the M1-A1 Abrams tank made of 4140. Parts are small (benchtop) and range from 1.25" to .500" thick, 3 pc.
              Blueprint calls out ER80 SD2. My research asked for a preheat to a min. 350F and cool down to touch of about 8 hrs in sand, or oven (bought at Home Depot). I use a Tempil stick for checking temp. The drawing calls out a min. 3/16" weld. I make a two pass weld. The first pass with a slight crown or I'm almost guaranteed a centerline crack (remember, the weld cools from the sides to the center). The second pass is while the part is still above 350F. More of a flat, wide weld for the second pass as the weld size helps with the post weld strength, minimizing cracking concern. I have just welded 63 pcs. with a 100% pass on Mag Particle inspection, bettering a former 98% on 180 pcs. and 99% on a 120 pc. order. All work done to WPS where I developed the PQR.
              How did you heat the part to 350 deg. F?

              Jabeel

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