Cryogenic hardened steel bullet resistant, ballistic plate

Cryogenic hardened steel bullet resistant, ballistic plate

Freeze tempering, cryogenic hardening a steel ballistic plate by bringing it to around -185 degrees celcius.
-Mainly done with liquid nitrogen.

Maybe as an extra tempering method to make it even harder.
Maybe first: Normal tempering. And baking tempering for 1-2 or more hours.

By Jef Koelewijn
From South-Holland, The Netherlands