4130 SAW HAZ Hardness

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We have tried doing this procedure once before with no luck. I understand that preheat is one of the most important factors in lowering the hardness of HAZ. Here are the settings we used initially which failed hardness by 30 points or so. Preheat: 500ºFHot Pass: 200amps/25volts/5IPM GMAWRemainder: SWX 150 Flux     300amps/28volts/14.5IPM Any suggestions on lowers our hardness in the HAZ?
Reply:What size(length width and thickness) are the base metal you're welding?  What's the joint geometry(width, bevel angle, etc)?What size wire are you running for the SAW?What is the upper limit for hardness that you're aiming for?Lacking additional information, I'd guess that you need to run your preheat up even higher.  I've welded 4130 with 600F preheat before.  But I'm not sure this will get to the HAZ hardness you're looking forBenson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector