Kenney, this brings up a question I've had for quite a few years now. A while back a weld like tibadoe is looking at would have been considered risky due to hydrogen embrittlement, high strength steel frame superheated by welding with high voltage, etc, etc, Whats changed? I no longer hear about hydrogen embrittlement or any of these other issues we faced when welding frames or other high carbon steel items.
Back in the day welding a frame (did many frame repairs against the knowledge of those in the know in my Jeepin/Toyota off-roadin days) was a big no no unless you were prepared to lay in lots of gusset and keep an eye on the repair with the mindset it or the metal around it would fracture again. And being I was rough on my machines they always cracked, I have the stop drill experience to back it up.
Through the years, the type of steel used in frame construction, has evolved, like every thing else has. Very hard metal will brake (snap) where a softer steel will bend. If frame steel was very hard, it would brake when you get into a wreck. I am not sure what the grade of steel, frame steel is, but it is a softer steel so it will bend when it is hit in a wreck. Welding like everything else, is always evolving. A 6011 welding rod, properly welded will hold 60 thousand pounds of tensile strength ( pull a part strenght) . A 7018 rod is good for 70 thousand pounds tensile strength. a 7018 weld will hold 3000 pounds for every 1 inch long by 1/4 thick weld. The only down side to 6011 or 6010 rods, it that they are not as pliable as a 7018 rod is. This is all factored in to an ideal weld of course. The main issue with welding anything on any part of a vehicle is if you are in a wreck, or if what you do to change or add any thing to your vehicle that is not within factory specs, and because of this someone get injured, you are liable for injures, and damages. For this reason, many people do not want to do any repairs. As long as you do the proper prep work before welding, and you make a proper weld, then you let the weld cool down on it's own, the weld will be stronger that the metal around it. If the cooling process is done slowly there is no reason it wont hold, but if after welding process, the weld area is cooled to quickly it will crystallize the weld making it brittle. When dealing with thick metal, it has to be pre heated, then wrapped with insulation so it will cool slowly. If the area next to the weld cracks, then that area has cooled down to quickly, or was not heated enough.