@freemo
"The synthetic fibre Kevlar was introduced in 1971, and most ballistic vests since the 1970s are based on kevlar, optionally with the addition of trauma plates to reduce the risk of blunt trauma injury. Such plates may be made of ceramic, metal (steel or titanium) or synthetic materials. "

According to this article, soldiers still wear minimal steel in their bulletproof vests. But this is no longer plate armor of yesteryear.
https://www.sciencedirect.com/science/article/pii/S2214914718301727