Grade : 20 ( 20 ) Substitute: 15, 25 Classification : High quality structural carbon steel Chemical composition in % for grade 20 ( 20 ) C Si Mn Ni S P Cr Cu As 0.17 – 0.24 0.17 – 0.37 0.35 – 0.65 max 0.3 max 0.04 max 0.035 max 0.25 max 0.3 max 0.08 Temperature of critical points for grade 20 ( 20 ). Ac1 = 724 , Ac3(Acm) = 845 […]