High strength steel plate and manufacturing method therefor
AssigneePosco
InventorSoon-Taik Hong
Life of this patent
Estimating the term…
Abstract
A high strength steel plate according to an aspect of the present disclosure includes, by weight: 0.05 to 0.20% of C, 0.15 to 0.55% of Si, 0.9 to 1.75% of Mn, 0.001 to 0.05% of Al, 0.03% or less of P, 0.03% or less of S, 0.05 to 0.3% of Cr, 0.05 to 0.6% of Ni, 0.005 to 0.35% of Cu, 0.05 to 0.2% of Mo, 0.005 to 0.07% of V, 0.005 to 0.04% of Nb, 0.0005 to 0.005% of Ca, 0.005 to 0.025% of Ti, 0.002 to 0.006% of N, less than 0.0005% of B, and a balance of Fe, with inevitable impurities, satisfies relationships of Cu+Ni+Cr+Mo: 1.5% or less, Cr+Mo: 0.4% or less, V+Nb: 0.1% or less, and Ca/S: 1.0 or higher, and includes a combined structure of tempered martensite and tempered bainite as a microstructure.
Claims12
A high strength steel plate comprising, by weight:
- 0.05 to 0.20% of C, 0.15 to 0.55% of Si, 0.9 to 1.75% of Mn, 0.001 to 0.05% of Al, 0.03% or less of P, 0.03% or less of S, 0.05 to 0.3% of Cr, 0.05 to 0.6% of Ni, 0.005 to 0.35% of Cu, 0.05 to 0.2% of Mo, 0.005 to 0.07% of V, 0.005 to 0.04% of Nb, 0.0005 to 0.005% of Ca, 0.005 to 0.025% of Ti, 0.002 to 0.006% of N, less than 0.0005% of B, and a balance of Fe, with inevitable impurities, satisfying relationships of Cu+Ni+Cr+Mo:
- 1.5% or less, Cr+Mo:
- 0.4% or less, V+Nb:
- 0.1% or less, and Ca/S:
- 1.0 or higher, and comprising a combined structure of tempered martensite and tempered bainite as a microstructure.
A method of manufacturing a high strength steel plate, comprising:
- reheating a steel slab at 1050 to 1250° C., the steel slab comprising, by weight:
- 0.05 to 0.20% of C, 0.15 to 0.55% of Si, 0.9 to 1.75% of Mn, 0.001 to 0.05% of Al, 0.03% or less of P, 0.03% or less of S, 0.05 to 0.3% of Cr, 0.05 to 0.6% of Ni, 0.005 to 0.35% of Cu, 0.05 to 0.2% of Mo, 0.005 to 0.07% of V, 0.005 to 0.04% of Nb, 0.0005 to 0.005% of Ca, 0.005 to 0.025% of Ti, 0.002 to 0.006% of N, less than 0.0005% of B, and a balance of Fe, with inevitable impurities, satisfying relationships of Cu+Ni+Cr+Mo:
- 1.5% or less, Cr+Mo:
- 0.4% or less, V+Nb:
- 0.1% or less, and Ca/S:
- 1.0 or higher,
- rolling the slab in a temperature range of Tnr to Tnr+100° C. to provide a steel plate,
- austenizing the steel plate in a temperature range of 870 to 950° C.,
- quenching the austenized steel plate to a temperature range of 300° C. or lower, and
- tempering the quenched steel plate in a temperature range of 595 to 700° C.
Dependencies are inferred from the claim text.