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US 2025/0027182 A1Published application
Hot rolled steel sheet for ground reinforcement and steel pipe for ground reinforcement, and manufacturing methods thereof
AssigneePosco
InventorsYun-Ik KWON, Hak-Jun KIM, Kyong-Su PARK, Seok-Jong SEO
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Abstract
The present invention relates to: a hot rolled steel sheet for ground reinforcement and a steel pipe for ground reinforcement, which have excellent strength and formability; and manufacturing methods thereof. An aspect of the present disclosure is to provide a hot-rolled steel sheet for ground reinforcement and a steel pipe for ground reinforcement, having excellent strength and formability, and manufacturing methods thereof.
Claims8
A hot-rolled steel sheet for ground reinforcement, comprising by weight:
- 0.05 to 0.1% of C, 0.1% or less (excluding 0%) of Si, 1.5 to 1.9% of Mn, 0.05 to 0.15% of Ti, 0.03 to 0.1% of Nb, 0.03 to 0.1% of Mo, 0.02% or less (excluding 0%) of P, 0.02% or less (excluding 0%) of S, 0.01% or less (excluding 0%) of N, with a balance of Fe and inevitable impurities, wherein the following Relational expressions 1 and 2 are satisfied,
- wherein the hot-rolled steel sheet for ground reinforcement has a microstructure including by area, 90% or more of ferrite,
- wherein a grain of the ferrite has an average size of 15 μm or less,
- wherein the hot-rolled steel sheet includes by weight, 0.05% or more of a carbide containing Ti, Nb, and Mo alone or in combination thereof,
- wherein the carbide has an average size of 20 nm or less,
- 0.002≤(Ti/48+Mo/96+Nb/93)≤0.004 [Relational expression 1]
- 0.002≤(C/12)−(Ti/48+Mo/96+Nb/93)≤0.006 [Relational expression 2]
- in the above Relational expressions 1 and 2, where a content of each alloy element refers to weight %.
5 more elements
A method for manufacturing a hot-rolled steel sheet for ground reinforcement, comprising:
- reheating a steel slab including, by weight:
- 0.05 to 0.1% of C, 0.1% or less (excluding 0%) of Si, 1.5 to 1.9% of Mn, 0.05 to 0.15% of Ti, 0.03 to 0.1% of Nb, 0.03 to 0.1% of Mo, 0.02% or less (excluding 0%) of P, 0.02% or less (excluding 0%) of S, 0.01% or less (excluding 0%) of N, with a balance of Fe and inevitable impurities, wherein the following Relational expressions 1 and 2 are satisfied, at a temperature within a range of 1150° C. to 1300° C.;
- finish hot rolling the reheated steel slab at a temperature within a range of 800 to 950° C. to obtain a hot-rolled steel sheet;
- and
- coiling the hot-rolled steel sheet at a temperature within a range of 550° C. to 700° C.,
- 0.002≤(Ti/48+Mo/96+Nb/93)≤0.004 [Relational expression 1]
- 0.002≤(C/12)−(Ti/48+Mo/96+Nb/93)≤0.006 [Relational expression 2]
- in the above Relational expressions 1 and 2, where a content of each alloy element refers to weight %.
5 more elements
8-9. (canceled)
Dependencies are inferred from the claim text.