tig welding t1 steel plate.

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I'm building a tree shear that uses 5/8 thick T1 steel plate. I have a precision tig 275 with cold wire feeder setup. What is the best procedure as for preheat/postheat - filler wire? Also may be welding to hot rolled steel.
Reply:Honestly b7100, short of using a wire process(other than your cold-wire set-up), I would use SMAW off of your machine and not use GTAW welding on it. GTAW is too slow and the dilution that naturally comes with the process would likely promote cracking issues, depth to width issues will usually result in centerline cracking. Using 7018 or 8018 stick is a much better choice. Best regards, Allanaevald
Reply:Preheat both sides of the joint to at least 200F, 300F is probably better, for the T1 plate.  The pre-heat will slow the cooling of the joint and reduce chances of cracking.  ER80S-D2 filler.  This is a strength undermatch for the T1 plate, but not a gross overmatch for the hot rolled steel.  T-1 would normally be welded with a 100KSI filler metal, but with the lower strength hot roll on the other side of the joint, you need to compromise.  Too high a strength filler metal, and you can have cracking problems on the low strength side of the joint.you don't say anything about the type of joint or preparation(bevel, position, etc) so that's about all the advice I can offer.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:I'm gotta agree that SMAW, FCAW are the way to go. However I'm also attaching stuff from the original maker of T-1, USS. The weldability section refers to "inert gas shielded metal arc process", which both MIG (GMA) and TIG (GTA) were termed at that time.T-1 is a low alloy, low carbon, boron added material. You get in trouble with hydrogen in the weld, and/or a high restraint in the structure, and/or overheat of the base material.The overheat is what you would worry about with Tig (GTA in old school terms). With 5/8" your limit is about 500° F 1 inch or so from the bead for more than a few minutes. Your also gonna have to adjust your wire feed till things look acceptable while holding that temp at distance. It's hard to make any guess at amps and WFS, (I've run cold wire, but never to join something, only overlay/clad).I have multipass Tigged and you have to clean the oxide well between passes.Matt Attached Images
Reply:Thanks for the information. I like the appearence of the tig weld but I think I'll heed your advise and use the low hydrogen rod. T1 is too expensive to take a chance.