Welding. General knowledge. I'm sure I'll get someone saying something smart like "just weld it", but I want to know either way. I've been asked for the information by some super technical welders who want to know. Not the backyard or muffler shop kind. The type of guys who help with R&D in the industry. Would really like it if this thread doesn't turn into another rust thread. Maybe if we get someone who knows this information about the early model FJ/Prado frame base metal we will all benefit.
Typically late-model (2000+) truck frames are fabricated from high-strength low-alloy (HSLA) steel.
I needed to drill a few small holes in the side of a frame rail in my '14 FJ, and I was surprised at how hard the material was, and how thin. Drilling with a brand new, premium US made drill bit, the material was extremely hard and "crispy", and generated only tiny individual chips rather than a spiral chip.
Auto manufacturers have just introduced the use of ultra-high strength steel in specific areas of vehicle structure, and yes, welding and repair of vehicles using these high strength steel alloys is different than just welding mild steel.
During fabrication, these ultra-high strength alloys must be stamped at elevated temperature, requiring special forming presses.