Did i harden the steel?
So i've been brazing a rack or two. The other day i was working with a piece of 4130 tube from Aircraft Spruce. I wanted to pinch the end of the tube to form a tab. I heated it with the torch (hot, like yellow hot) then pinched it in the vice. Then i put it in water to cool it.
Later, when it came time to drill a hole in the tab, i drilled through the first wall of the tube (in drill press) and by the time it was punching through the first wall and gettting to the second, it just seemed to stop making any progress. I thought my bit was bad so i threw another one in the press, same thing. Well, they were both old bits. I got a brand new one and still was having a really hard time making any progress! Finally i realized, i must have hardened the steel.
I re-heated it, then let it cool naturally. I tried drilling again and while not buttery soft like mild steel, i did get the hole finished. The other side i pinched in the vise without heating and that side drilled normally (much easier).
So, am i right in assuming that i hardened that steel and that is why i couldn't drill it? It's easier to flatten in the vise when heated. I wonder if i could still drill it alright if i hadn't quenched it in water afterword. I may have to try that next time.