1.1 This specification covers steel plates produced by the thermo-mechanical controlled process (TMCP). Five grades are defined by the yield strength: 50 [345], 60 [415], 65 [450], 70 [485], and 80 [550]. The plates are intended primarily f This specification covers high-strength low-alloy structural steel plates that were produced by the thermo-mechanical controlled process (TMCP). This method consists of rolling reductions and cooling rate controls, which result in mechanical properties