kimr91•1mo ago

My old boss said to always quench a hot punch in water, but that advice wrecked a good tool

When I was starting out, the guy running the shop told me to dunk a hot center punch in a bucket of water to cool it faster. I did that for years. Last month, I was working on a set of tongs and the punch I was using, a nice H13 steel one, cracked right down the middle after the third quench. A buddy who does tool steel said rapid cooling like that can cause thermal shock and make hard steel brittle. Now I just set hot punches aside to air cool. Has anyone else been given quenching advice that turned out to be bad for the tool?

3 comments

3 Comments

mason_murray81mo ago

Used to dunk them too, learned the hard way.

the_leo1mo ago

Man that's brutal. So was your old boss just totally wrong about quenching all tool steel, or does it only wreck certain types like that H13 punch? I've got some older punches that seem fine after a water dunk, makes me wonder if the steel grade or the hardness from the maker changes everything.

ray5621mo ago

Honestly wonder if we're all overthinking it. Your old punches are fine, so maybe mason_murray8 just got unlucky with a bad heat treat from the start. Some steels can take a quick water splash if they're not super hard already, but going full red hot to dunk is asking for trouble. It's less about the boss being totally wrong and more about playing Russian roulette with your tools.