This Material Specification applies to the high-strength thermomechanically rolled special steel SECURE MS specialĀ® (ThyssenKrupp security steel for civil use) with a hardness from 350 to 450 HBW and 2.0 to 3.5 mm in thickness. Application: The steels may be used for purposes of ballistic protection for civil use. Information Provided by Thyssen Krupp |