One of the first times I was working with T-1 steel, I noticed that the sparks made while using a handheld grinder had a different shape than sparks made while grinding on mild steel. Then I observed that cutting T-1 with an acetylene torch was easier to make a clean cut than when cutting regular mild steel.
It was also obvious that when welding equally prepared material that welding T-1 went smoother. Welds on mild steel will occasionally pop and crater, seemingly for no reason, as the electric “arc” melts the tip of the rod and both pieces of steel being welded into one piece. This rarely happens working with T-1 and appropriate welding rods or wire.
The same is noticed when drilling holes in steel. Yes, T-1 is harder and needs a sharp bit, but once the hole is started it generally drills right through without incident. Drilling in mild steel, there are more episodes of hitting a “hard” spot or having the bit jump inside the hole as though it hit a piece of gravel.
When I mentioned this to a friend who had spent his whole life working with steel, he said that it was because T-1 had more of the impurities burned out as it was made. He said that was the main thing, also the alloy mix was just a bit different, but he felt that the removal of impurities was mostly what made T-1 stronger.
While the 60 series of welding rod (6011, 6013, etc.) is suitable for mild steel, 7018 is the preferred rod for T-1. (The “60” and “70” correlate roughly to 60,000 pounds and 70,000 pounds of tensile strength per square inch of material.) For a successful repair or fabrication using a wire feed (mig) welder, the grade of the welding wire also needs to be matched with the grade of steel being used.
Truck frames are another matter. Most come from the factory with multiple warning stickers, “High-tensile steel. Do not cut, drill or weld to.”
Yet they’ve obviously been cut, had holes drilled and welded to at the factory. There is a 11018 welding rod that flows similar to the 7018 but has a much higher tensile strength. This is what the big boys use to repair truck frames when arc or “stick” welders are used.
One problem repair was the curved teeth on a bale grapple, used to pick up a pad of double-compressed hay bales for export, would occasionally break.
Replacements cut from T-1 steel would just bend. Welding the broken teeth back together resulted in almost immediate fresh breaks abutting the weld. Then I tried the 11018 rod. I ground down the broken pieces of the tooth, so I’d get a finished repair that was 100% weld. With the pieces tack welded in place, I followed with multiple layers of weld, judiciously chipped and wire brushed between layers to remove all traces of welding slag.
And the repair held. Same procedure, just a different class of rod. The guys still managed to break them, but the ones I repaired never broke at or near the weld site. I’ve found that the best time spent when attacking a repair job is to determine why the original part broke. One piece of machinery had a “regular” crack to keep welded up. Reinforcing the area didn’t help. Then, it was observed that in the “home” position, one of the hydraulic cylinders that operated it was pulling the framework into a “tweaked” position. A 1-inch cylinder stop around the clevis end of the rod stopped it before it tweaked the frame, and that spot never cracked again.
Society has evolved from the days of “If you can’t hunt, you die” to “OK, I’m a lousy hunter, but I can bake bread. If you, the maestro of the hunters, would rather not bake your own bread, I’ll do it for you if you’ll share some meat with me.”
People are prone to do better working at something they like to do. All the trades (and I’ll include managing people, trading money, making computers do their tricks and shuffling papers as trades) require learning, hands-on experience and making some mistakes to get to being proficient. Learning doesn’t have to be in a formal classroom.
But that learning has to happen. RE: welding. You know all you need to know when you realize that a particular repair is beyond your skills and/or your equipment. RE: pickup AC. Buying the gauges, vacuum pump, parts and supplies is the easy part. Learning how the system works and being able to diagnose and repair from the pressure cycles and the ambient air temperature takes time and concentration. Like much in life, more art (experience?) than science.
