4130 Chrome Moly - What fillers?

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What fillers are normally used for welding chrome moly (4130) tubing?This is just for practice but I want to try welding it with both oxy-acetylene and TIG.What filler for O/A/?What filler for TIG?BTW, if anyone else is interested in learning, you can buy drops of 4130 tubing here:http://www.aircraftspruce.com/catalo...bargainbag.php
Reply:For parts that aren't heat treated: -70S-6 for OAW-70S-2 with TIG.But, if it's just practice it doesn't really matter what filler you use. 70S-6 may be a little easier due to the fact that is has more fluidity.Use 4130 filler with TIG exclusively if parts are going to be heat treated afterwards. Last edited by Joshfromsaltlake; 07-24-2012 at 06:40 AM.
Reply:Thanks for your reply, Josh. I know that it doesn't matter for practice, but I figure if I want to practice for the "real thing," I should use the same filler I would use for the "real thing."I guess that raises a question – Is it even worth buying chrome-moly tubing to practice on? Does it weld up any different from any other tubing?
Reply:It welds no differently than any other carbon or low alloy steel.
Reply:Originally Posted by KelvinThanks for your reply, Josh. I know that it doesn't matter for practice, but I figure if I want to practice for the "real thing," I should use the same filler I would use for the "real thing."I guess that raises a question – Is it even worth buying chrome-moly tubing to practice on? Does it weld up any different from any other tubing?
Reply:Originally Posted by JoshfromsaltlakeIf you have access to TIG I fail to understand why you would choose to use OAW, which is pretty much an obsolete process. Spend you free time perfecting your TIG skills.If you want to mess with OAW just for fun, use mild steel scraps.  It would be idiotic to use OAW on an actual chromoly project, when you had a TIG welder at your disposal.[/FONT]
Reply:Kelvin, you're absolutely correct. Josh is talking out his a$$ as I've seen him do on a few other posts. There are still many parts in the aircraft industry that specify they must be OAW.  Sure they could be TIG'd, but if they were and an accident resulted, lawsuits would be all over the place. There have been studies where the parts have been Tig'd and one part was normalized whereas the other wasn't and both parts exhibited the same characteristics. The key with TIG welding 4130 is to proceed a little bit slower than you normally would to heat the are evenly. PANGEA may be able to shed a little more light on this, I believe he's been welding in the aerospace world for a while if he's still on the forum
Reply:Pangea has probably welded more than his fair share of 4130 but IIRC the area of aerospace he works in won't have much call for planes made from tubular steel. Makoman is probably one of the best guys to speak to in that he's involved with the EAA. I don't think he posts much, if at all, these days. Probably tired with all the BS that goes on but searching the forum for 4130 and Makoman will get you a bunch of posts on the subject (it used to be a weekly occurance with people spouting all sorts of crap about using stainless wires )As Supe said weldpool behaviour etc is no different to other common flavours of steel. The differences are that it's 'fussier' than mild steel with regards to cooling rate i.e. you can screw up the microstructure and get a brittle mess. Probably the best article i've come across (that's written in simple English rather than  'metallurgy') regarding TIG welding 4130... http://www.netwelding.com/Welding%204130.htm Originally Posted by JoshfromsaltlakeIt would be idiotic to use OAW on an actual chromoly project, when you had a TIG welder at your disposal.
Reply:In all ny NHRA, USAC, amd IRL welding jobs, I've always ran ER80S-D2.It's debatable sure, but in all my years and all the parts that have been crashed, I haven't had a failure.Miller Dynasty 200DXMiller Spectrum 250DMiller Millermatic 200Bunch of old blue dinosaurs....
Reply:ER80S-D2 is acceptable (and arguably preferred in joints that are in pure tension due to a closer strength match), but the ER70S-2 and ER70S-6 wires will have greater ductility (less prone to cracking), better impact properties, and the slight difference in strength after dilution with the 4130 can be overcome with a slightly oversized fillet weld, which will also slow the rate of cooling.
Reply:Hey Guys, Standard practice for aviation is ER70S-2 for Tig , and RG-45 for O/A. With a standard tubular joint design the tensile strength for both processes is the same, with the O/A weldment having higher fatigue life. On the flip side O/A is slower and can cause more distortion in the hands of a beginner. Latest FAA handbook for A&P mechanics also lays out the need for PWHT using the Tig process in repair or one-of applications. Either method is perfectly acceptable provided the correct process is used.