Has russia imptoved its armor quality?

Tuccy: Steel is steel, unless it isn't :) Often even in same nation, same period steel for various purposes (armor-wise) differed. Case in point: KV-1 vs. T-34. T-34 had intentionally rather hard but brittle steel - it gave good protection about non-overmatching projectiles (or slightly overmatching), thus in Yugoslavian trials it fared better than M4A3 armor vs. 57mm guns. It was made to provide great frontal protection against guns of 37mm-45mm caliber. Downside was that overmatching hits often resulted in cracking and large caliber high velocity hits could be devastating.   KV, on the other hand, was designed to generally same requirements as Tiger - frontal immunity and side protection vs. 37mm/45mm guns and against AP and HE from field guns. By its role, heavy tanks were expected to be hit more often and by larger calbers, and armor was intentionally softer than on T-34 (not by much though - Soviets used pretty hard steel) to reduce spalling.   Taken to the extreme, US used very soft steel (armor-wise) - again, to reduce spalling and reduce crew losses from penetrations (as they reasoned that spalling from smaller hits is a problem and if tank is hit by a high penetration AT gun, Medium tank won¨t be able to resist anyway).   As for Cast vs. RHA, cast armor in best conditions is rated as providing ca. 90% protection of RHA. It can be clearly seen in soviet practice, for example on T-34 turrets - RHA turret sides were 45mm, cast 52mm. similar for cast vs. RHS IS hull front etc.   Now of course it is more complicated with composite armor - and there is a lot of wild ass guesses and so on around it. For example the ideas of "cavities filled with ceramics" seems to be not fully true for modern composite armor, be it Eastern or Western... and any numbers out there for stuff newer than T-72A is just guesstimate.