Steel Material Showing Excellent Hydrogen-Induced Cracking Resistance and Method for Preparing Same
AssigneePosco
InventorDae-Woo Kim
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Abstract
A steel material showing excellent hydrogen-induced cracking resistance according to an aspect of the present invention comprises, in weight %, 0.10-0.25% of C, 0.05-0.50% of Si, 1.0-2.0% of Mn, 0.005-0.1% of Al, 0.010% or less of P, 0.0015% or less of S, 0.001-0.03% of Nb, 0.001-0.03% of V, 0.01-0.15% of Mo, 0.01-0.50% of Cu, 0.05-0.50% of Ni, and the remainder being Fe and unavoidable impurities, and has a thickness of 100-300 mm. The maximum size of pores formed inside can be 1 μm or less.
Claims15
A steel material having excellent hydrogen-induced cracking resistance, the steel material comprising, by weight percentage (wt %):
- 0.10 to 0.25% of carbon (C), 0.05 to 0.50% of silicon (Si), 1.0 to 2.0% of manganese (Mn), 0.005 to 0.1% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0015% or less of sulfur (S), 0.001 to 0.03% of niobium (Nb), 0.001 to 0.03% of vanadium (V), 0.01 to 0.15% of molybdenum (Mo), 0.01 to 0.50% of copper (Cu), 0.05 to 0.50% of nickel (Ni), and a remainder of iron (Fe) and unavoidable impurities, the steel material having a thickness of 100 to 300 mm,
- wherein a maximum size of a pore, formed in the steel material, is 1 μm or less.
A method for manufacturing a steel material having excellent hydrogen-induced cracking resistance, the method comprising:
- primarily heating a slab including, by weight percentage (wt %), 0.10 to 0.25% of carbon (C), 0.05 to 0.50% of silicon (Si), 1.0 to 2.0% of manganese (Mn), 0.005 to 0.1% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0015% or less of sulfur (S), 0.001 to 0.03% of niobium (Nb), 0.001 to 0.03% of vanadium (V), 0.01 to 0.15% of molybdenum (Mo), 0.01 to 0.50% of copper (Cu), 0.05 to 0.50% of nickel (Ni), and a remainder of iron (Fe) and unavoidable impurities;
- reducing the primarily heated slab in a length direction and a width direction;
- selectively secondarily heating the slab reduced in the length direction and the width direction to be reduced in the thickness direction;
- tertiarily heating the slab reduced in the thickness direction to be hot rolled and air-cooling the hot-rolled slab to provide a steel material;
- and
- quaternarily heating the steel material to be heat-treated and air-cooling the heat-treated steel material to room temperature,
- wherein a maximum size of a pore in the slab reduced in the thickness direction is 1 μm or less.
Dependencies are inferred from the claim text.