Hey Guys,
Havent forgotten about you, I have just been out of town. I am currently putting together an article on this subject, from both engineering and practical perspectives. One thing I would like to point out, is that a vast majority of the articles on the internet about weldiung 4130 with tig are written with the intention of selling a welding process, and typically by automovie motorsports persons ( this is important ). They also tend to have little or no engineering test data behind them. Tensile testing is whats mostly talked about since its cheap and easy to perform, however in most cases pointless. A correctly designed weldment in our tubing sizes will never fail in the weld, even with the weakest welding filler ( RG-45 ), it will always fail in the HAZ reguardless of welding process and with similiar strengths. Whats this mean, the correctly designed joint in 3/4" .035 welded with RG-45 and a torch will have the same strength as if it were welded with ER120S series and a the gtaw process. Go up to 3/8 plate and things change a bit, and high strength fillers and electric welding have an advantage. So since strangth is not the issue....what is? Fatigue. Look back at incident reports and some 98% appear to be all fatigue failures. So the auto racing industrys products (cars) tend to use heavier material, typically have a very low useful life, and so they tend to use Gtaw, high strength fillers with little or no reguard for fatigue as they typically destroy a vehicle before the fatigue life of a weldment is surpassed. This is why one should be very careful is chising where to get information from. The auto racing world, while using the same alloys, has a completely different set of operating and lifecycle conditions than aviation. So what about fatigue, well thats the article I am writing.......