500 MPa class hot-rolled steel strip for building structures resistant to corrosion in areas exposed to sea spray, and method for manufacturing hot-rolled steel strip.

Abstract

This disclosure relates to hot-rolled steel strips for building structures and a method for manufacturing the hot-rolled steel strips. The hot-rolled steel strips include a base layer, a corrosion-resistant layer, and an interfacial transition layer disposed between the base layer and the corrosion-resistant layer; the mass percentages of the chemical elements in the base layer are: C: 0.050-0.100%, Si: 0.15-0.30%, Mn: 1.0-1.8%, P: 0.0005-0.0030%, S: 0.0005-0.0100%, Cr: 0.80-1.60%, Ni The composition is: 0.50-1.20%, Cu:0.20-0.40%, Al:0.020-0.050%, Ti:0.010-0.018%, Nb:0.020-0.100%, N:0.0005-0.0050%, Mo:0.20-0.50%, and the remainder being Fe and other unavoidable impurities; the corrosion-resistant layer is prepared from industrial-grade pure titanium. The yield strength of the base layer of the hot-rolled strip steel for building structures in this disclosure is 500 MPa or more, the tensile strength is 640 MPa or more, the yield strength ratio is 0.75-0.85, the impact energy at -40°C is 190 J or more, the corrosion resistance rate of the corrosion-resistant layer to sea spray is 0.006 mm / year or less, the thickness of the interface transition layer is 8 μm or less, and the interface shear strength is 263 MPa or more.

Claims

1. A hot-rolled steel strip for building structures, comprising a base layer, a corrosion-resistant layer, and an interfacial transition layer disposed between the base layer and the corrosion-resistant layer; Here, the base layer contains, in addition to Fe and other unavoidable impurities, the following chemical elements in mass percent: C: 0.050–0.100%, Si: 0.15–0.30%, Mn: 1.0–1.8%, P: 0.0005–0.0030%, S: 0.0005–0.0100%, Cr: 0.80–1.60%, Ni: 0.50–1.20%, Cu: 0.20–0.40%, Al: 0.020–0.050%, Ti: 0.010–0.018%, Nb: 0.020–0.100%, N: 0.0005–0.0050%, and Mo: 0.20–0.50%; The corrosion-resistant layer is made of industrial-grade pure titanium, preferably TA1, TA2, TA3, or TA4. Hot-rolled steel strip.

2. The hot-rolled steel strip for building structures according to claim 1, wherein the chemical composition of the base layer further satisfies the following relationship: 0.9% ≤ Cu + Ni ≤ 1.45%; and 2(C+N)≦Ti+Nb+Cr+Mo≦1.90%.

3. Hot-rolled steel strip for building structures according to claim 1 or 2, wherein the base layer contains the following chemical elements in mass percent: C: 0.050–0.100%, Si: 0.15–0.30%, Mn: 1.0–1.8%, P: 0.0005–0.0030%, S: 0.0005–0.0100%, Cr: 0.80–1.60%, Ni: 0.50–1.20%, Cu: 0.20–0.40%, Al: 0.020–0.050%, Ti: 0.010–0.018%, Nb: 0.020–0.100%, N: 0.0005–0.0050%, and Mo: 0.20–0.50%, with the remainder being Fe and other unavoidable impurities.

4. Hot-rolled steel strip for building structures according to any one of claims 1 to 3, wherein the base layer has a microstructure of granular bainite and / or plate-like bainite, and the effective particle size is ≤10 μm.

5. Hot-rolled steel strip for building structures according to any one of claims 1 to 4, wherein the base layer has a yield strength of ≥500 MPa, a tensile strength of ≥640 MPa, a yield-tensile ratio of 0.75 to 0.85, and an impact energy of ≥190 J at -40°C.

6. Hot-rolled steel strip for building structures according to any one of claims 1 to 5, wherein the corrosion-resistant layer has a single-phase equiaxed α-Ti microstructure.

7. Hot-rolled steel strip for building structures according to any one of claims 1 to 6, wherein the corrosion-resistant layer has a corrosion rate against sea spray of ≤0.006 mm / year.

8. Hot-rolled steel strip for building structures according to any one of claims 1 to 7, wherein the interface transition layer has a thickness of ≤8 μm and an average particle size of 15 to 40 μm, the interface transition layer contains precipitated (Ti,Nb)C particles of less than 120 nm, and the interface transition layer has an interface shear strength of ≥263 MPa.

9. Hot-rolled steel strip for building structures according to any one of claims 1 to 8, wherein the hot-rolled steel strip has a thickness of 3 to 16 mm.

10. A hot-rolled steel strip for building structures according to any one of claims 1 to 9, wherein the base layer of the hot-rolled steel strip has a yield strength of ≥500 MPa, a tensile strength of ≥640 MPa, a yield-tensile ratio of 0.75 to 0.85, and an impact energy of ≥190 J at -40°C; the corrosion-resistant layer has a corrosion rate against sea spray of ≤0.006 mm / year; and the interfacial shear strength is ≥263 MPa.

11. A method for producing hot-rolled steel strip for building structures according to any one of claims 1 to 10, comprising the following steps in order: 1) Smelting and casting Based on the components of the base layer and corrosion-resistant layer as defined in any one of claims 1 to 3, a base layer slab and a corrosion-resistant layer slab are obtained by smelting and casting; 2) Assemble the slab The base layer slab and the corrosion-resistant layer slab surfaces are ground and polished, and peripheral welding sealing is performed along the contact surfaces of the slabs to form a composite slab including the base layer and the corrosion-resistant layer; after welding sealing, a vacuum treatment is performed on the joint interface; 3) The composite slab is heated and rolled to form a steel strip, where: Heat the composite slab to 900-1000°C; Rough rolling is carried out at a temperature of ≥880°C; finish rolling is carried out at a temperature of 760–850°C, preferably 780–850°C; the pass reduction is 5–20%, preferably 10–20%; and the cumulative reduction is ≥88%. 4) Cool After leaving the rolling mill stand, the steel strip is cooled to 300-450°C at a cooling rate of 10-25°C / s, and then coiled at this temperature to produce hot-rolled steel strip.

12. The method according to claim 11, wherein in step 2), the thickness of the corrosion-resistant layer is 1% to 10% of the thickness of the composite slab; and / or in step 3), the interface transition layer formed between the base layer and the corrosion-resistant layer has a thickness of ≤ 8 μm.

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