`Steel blade demonstration in teaching forge`

Mike Tarkanian's classroom demonstration: heat a steel bar, bend it 180°, quench in water, shatter with a hammer — showing untempered martensite brittleness. Used to anchor the "10× tougher than glass but still brittle" framing.

In fact, I think Mike Tarkanian does that in the forge down there. He'll take a piece of steel and he'll heat it up and quench it and show that before you quench it, it'll be nice and soft, and he can heat it up and bend it 90 degrees or 180 degrees. Then he quenches it in water and he hits it — and he makes sure nobody's looking that direction, everybody's got safety glasses on — he can shatter the bar. Because martensite in the untempered condition is extremely brittle. I would say glass brittle, but it's not really glass brittle, it's about 10 times tougher than glass. In fact, cast iron is about 10 times tougher than glass, even though we think of gray cast iron as a very brittle material, and it is. It's just not as brittle as glass.