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I read that there can be problems with embrittlement using TIG to weld chrome-moly if there is no post weld heat treatment. The particular article went on to say that it is better to use mig with a mild steel filler wire because in the normalized state mild steel is similar in tensile strength to chrome-moly.I have been planning to make torque arms for my rear suspension and was initially thinking to use chrome-moly but now I'm not so sure. Does anyone here have any input related to this?Don't talk about it, Just do it!
Reply:Use 70s2 filler, unless you can re-heat treat the part. The weld will be a blend of 4130 and the mild filler; it will be plenty strong, and yet a little more flexible to avoid cracking. Avoid 4340 unless you want to heat treat it. Just get regular normalized material, you don't need annealed material unless you have a lot of complex, tight bends to do. If you do use annealed material, you would have to heat treat it for a torque arm.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Like Rojo said, or some 80S-D2. This thread should get interesting. very controversial subject here...to heat or not to heat.Anything worth doing is worth doing RIGHT
Reply:Why are you considering using chromoly?It's only about 20% stronger than DOM, and it weighs the same. Just go with heaver wall DOM. Or, are you actually trying to save weight by using thinner walled cromoly?
Reply:Try this:http://www.lincolnelectric.com/knowl...hrome-moly.aspor try this board:http://www.millermotorsports.com/mbo...isplay.php?f=3and type in "chromoly" or variations of the spelling and especially a poster by the name of billet benny. You'll get your eyes full and more than you ever wanted to know about chromoly.
Reply:IMO, there's no need to post heat 4130 unless it's heavier than 1/8" wall thickness, and even then, you can do just as much damage by taking an OA torch to it and letting it air cool (I've gone into arguments with phase diagrams before, and I'm really not ready to do it again, it's like beating a dead horse.) There are two ways I go about welding .083 wall and thinner 4130 for racing apps. The first way I use more frequently, which is to set the machine to 65 amps and run with it. The other way I've done it, which interestingly enough McKinney racecars (builds top fuel and funny car chassis) also does it, is to manually pulse the foot pedal. Turn the amperage up, blast the filler in, let off partially, blast the filler in, and keep going. This is VERY tough to do if you're out of position, which is why I do it less often. The penetration is there, and the HAZ is kept the same size or smaller, and the heat banding is usually a clear indicator of this. None of my moly welds have ever cracked to date, and that includes roll cages, wishbones, wheelie bars, etc, between .095 and .058 wall 4130.Here's a handy article that Miller sent out a while back on the subject. http://www.millerwelds.com/education.../story142.html |
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发表于 2021-9-1 00:56:38