STEEL MATERIAL EXCELLENT IN TOUGHNESS OF WELD HEAT AFFECTED ZONE

PURPOSE: A steel material with superior toughness of a welding heat-affected zone is provided, in which inclusion of 2μm or greater is properly distributed to prevent the production of coarse TiN. CONSTITUTION: A steel material with superior toughness of a welding heat-affected zone comprises C 0.02~0.15 weight%, Si 0.03~1.0 weight%, Mn 1.0~2.0 weight%, P 0.02weight% or less, S 0.0002~0.01 weight%, Al 0.005~0.08 weight%, Ti 0.003~0.03 weight%, Ca 0.0003~0.005 weight%, N 0.001~0.01 weight%, O 0.004 weight% or less, and the rest Fe and other inevitable impurities. The steel material comprises inclusion of 2μm or greater where the size of the inclusion is the longest width in the vertical direction to the maximum reflection length.