Ann: Anti Dumping Investigation - Release of Verification Report, page-9

"One example of how Bisalloy operate, they’re tied up with Rheinmetal and need Z Grade certification from the German Govt to be able to complete supply of steel. Huge contracts! The certification was due before the end of 2020! That’s over one year ago, no news, and this mob tell their shareholders nothing. It’s obviously failed"

Bisalloy Receives First Armour Steel Order from Rheinmetall for LAND400 Phase 2 - Bisalloy
No mention of the Z grade, but it does say "Bisalloy Steels is pleased to announce the receipt of a significant order from Rheinmetall for highly specialised Australian Made BISALLOY® Armour steel."
So whilst Z grade must be of some importance, it would appear that it isn't critical for supply of material to Rheinmetal.