The use of high-strength steel alloys got very popular with manufacturers in the late 1950's and early 60's when the trend to unitized-body cars came along. I grew up in the early 1950's around a shop where we did frame straightening, and it was not uncommon to see our frame alignment man heat up frame rails cherry-red with two big acetyline torches while making a pull with a couple of 20-ton jacks and huge chains. Doing that on one of today's cars or trucks would permanently alter the metallurgy and possibly cause suspension parts to break off somewhere down the road, even if the geometry of the frame was correct. There are very specific procedures for welding high-strength steel which absolutely must be followed to make a safe repair on anything manufactured since the late 1980's or newer. The older stuff is much more forgiving.
In my gunsmithing business, I get pretty deeply involved in heat treating metal, even bought a ceramic kiln recently to have a controlled-atmosphere heat source for annealing, hardening, and tempering metal. One particular alloy I work with requires parts to be heat-soaked for several hours at 1300 degrees F., water-quenched, then tempered at 700 degrees for a couple of hours and air-cooled. To prevent oxidation scale during the process, I must wrap the parts in stainless steel foil, or provide an inert-gas atmosphere such as Argon during the heating process. Doing something like that to a truck wheel might be possible, but it would certainly be expensive! Welding can create stresses due to localized heating that can be relieved by heating a part until it's cherry-red all over and slowly air-cooling, a process called annealing, then the part is heated, quenched, and tempered to the desired hardness after the annealing process is done. With the proper alloy, that's how springs are made.
Jerry
