Unfortunately Dave it comes with the territory, 20 years over furnaces your bound to be on the wrong end at some stage.
The 4140 we made were generally castings that were designedf or hi stress environments, castings ranging from 1kg to 6-7 tonnes, lots of variety.
We probably produced over 200 different variants of iron and steel ranging from automotive, mining and offshore oil and petrochemical made in anything from 1020 mild steel to super duplex stainless steel.
Unfortunately all these companies no longer exist.
Fingers and hands are pretty common, I still don't have much feeling in my left ring finger after having a glowing hot brass bar go through my glove severing nerves and the main artery in my hand about 3 years ago, boy did that make a mess haha, still finding blood at work.
Your very right about people not understanding what goes into producing the stuff that people take for granted. Everything from household appliances to public transport. It doesn't matter how much you try pretty up a foundry it's still a foundry!
Induction hardening machines actually operate on the same principle as induction furnaces, creating a magnetic field which heats the metal.
Induction hardening relies on dwell time to determine harndness depth followed by a quench of either water or aqua depending upon the material.
I spent 4 years in a heat treatment plant after the last big foundry closed down.
We specialized in flame and induction hardening, honestly probably the most enjoyable job I've ever had. Flame hardening very large castings is definitely a sight to see.
Unfortunately pretty much all this type of manufacturing is gone now, very sad actually.