HIGH STRENGTH STEEL SHEET HAVING EXCELLENT RESISTANCE TO POST WELD HEAT TREATMENT AND METHOD FOR MANUFACTURING SAME

摘要

The present invention relates to a steel sheet having excellent resistance to a post weld heat treatment (PWHT), in which the strength and toughness of the steel sheet are not degraded even when the PWHT is performed after a long-time rolling process. More particularly, the present invention relates to a steel sheet having excellent resistance to a PWHT and a method for manufacturing the same, wherein the steel sheet comprises, by weight%, C: 0.1 to 0.3%, Si: 0.15 to 0.50%, Mn: 0.6 to 1.2%, P: 0.035% or lower, S: 0.020% or lower, Al: 0.001 to 0.05%, Cr: 0.01 to 0.35%, Mo: 0.005 to 0.2%, V: 0.005 to 0.05%, Nb: 0.001 to 0.05%, Ti: 0.001 to 0.05%, Ca: 0.0005 to 0.005%, Ni: 0.05 to 0.5%, one or more selected from a group consisting of Cu: 0.005 to 0.5%, Co: 0.005 to 0.2% and W; 0.005 to 0.2%, and the balance Fe and unavoidable impurities.