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TIG is best way to weld Chrome-Moly

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  • TIG is best way to weld Chrome-Moly

    Q. I am interested in purchasing a chassis kit to build a pro street 1970 SS Chevelle. My problem - should I buy Chromoly or mild steel? I am told a Chromoly chassis can only be welded with TIG. Is this true? if so,why? A mild steel chassis is only certified up to 7.49 seconds. That is why I want Chromoly. I want to buy the Miller 130 MIG welder that can plug into a 110 outlet. What are your thoughts? If this will work for Chromoly what wire should I use? The tubing ranges in size from 1-5/8 to 3/4" with wall thicknesses from .058 to .085. (Submitted by: Dennis Wallace from Sunrise, Florida)

    A. The best way to do Chrome-moly is to TIG it. Most drag racing sanctioning bodies require TIG for the Chrome-moly anyway. MIG will have to be stress- relieved after welding. This is done with a temp crayon and each weld is heated slowly to about 900-1000 degF. This is very time consuming and does change the parent metal properties some. If you use TIG and keep your tube fit up nice and tight, you shouldn't need to stress relieve the joint area. The TIG beads are smaller, the metal transfer is less violent and base metal fusion is better. If you are limited by 110 voltage, try a Maxstar 200. It can run on anything from 110v to 460v and you should be able to get at least 110 Amps out of it. Plenty of power for welding up to .085. Hope this helps. Good luck and have fun with your project!