What we have here is a failure to communicate :)


In some past thread our friend Chuck M. educated me to the fact that we are in error when we try to make 4130 and chrome-moly synonamous. They aren't.

Now to some of the points of the thread. Every FAA certified AMT (formerly A&P Mechanic) gets some good old oxy-fuel welding training on 4130 usually on plate and the students that excell get to weld some tube, most of this training is going to be less than 40 hours, I still don't know of an A&P training program that has worked GTAW into its regular curriculum. Believe it or not, this brief introduction to welding gives an AMT mechanic authority to sign off on welded repairs whether they did them or they are signing for somebody else who did. I bet you wish you haddn't asked now eh? If anybody does know of an A&P program that does include GTAW please let me know as I could use them as an example to help persuade several programs I would like to influence on this matter.

Having said that, lots of folks, especially in the experimental classes use oxy-fuel and 4130. There are any number of websites devoted to just this subject. I know many old timers who can make gas welded cluster joints that are just as pretty as any Tig welder can produce. The big debate in this area will always be about post weld stress relief. Some do and some don't. This argument extends from grandpaw down at the local hanger to the major airlines. Some feel that they have enough experience to ignore the ASM metals handbook and the various producers of components and just don't stress relieve material under 0.090 or so. An engineer may of course take that responsibility upon himself, but I will never give such a recomendation, even if the procedure has stood the test of time. Structural hardware, be it a bike frame or an FA/18 is too critical to jettison the council of the folks who originally made the part.

That was the long story. The short story is this; Use fillers recommended by the manufacture of the product when available. When research won't give you the manufacturers recommendations than look to respected sourses such as ASM Materials Handbook Vol 6, which can be found in many libraries and technical colleges. Find a reliable source and find it in annotated (cited) text. No word of mouth.