I have read however about anti-tank rounds that create so much heat that vaporized metal kills the tank occupants. Not sure, I'd like to see the math.
This effect only occurs when the velocity of the projectile exceeds the speed of sound in both the projectile material and the target material, about 5000 fps with steel. The physics are then the same as liquid hitting liquid--at 5000 fps. The projectile does not go that fast, of course, but an internal "shaped charge" accelelerates a portion of the projectile to that speed upon impact. This effect has nothing to do with bullets penetrating steel.
