Steel sheet resistant to delayed cracking and wear resistance, and method for manufacturing the same

Abstract

Steel plate with resistance to delayed fracture and wear resistance, and method for producing the same. The steel plate contains the following chemical elements by wt%: C: 0.17 - 0.22%, Si: 0.1 - 0.3%, Mn: 1.0 - 1.4%, P ≤ 0.015%, S ≤ 0.005%, Al: 0.018 - 0.04%, Cu: 0.15 - 0.60%, Ni: 0.1 - 0.31%, B: 0.001 - 0.003%, N ≤ 0.005%, and one or two of Nb: 0.01 - 0.03% and Ti: 0.01 - 0.03%, with the balance being Fe and inevitable impurities; and the steel plate satisfies: 5.68N ≤ Nb + Ti ≤ 0.044 and Cu / Ni ≤ 2.0. The steel plate of the present application exhibits excellent resistance to delayed fracture characteristics and is suitable for manufacturing pipelines in areas such as landfills and waterway dredging.

Claims

1. A steel sheet comprising, by mass%, the following chemical elements: C: 0.17–0.22%, Si: 0.1–0.3%, Mn: 1.0–1.4%, P ≤ 0.015%, S ≤ 0.005%, Al: 0.018–0.04%, Cu: 0.15–0.60%, Ni: 0.1–0.31%, B: 0.001–0.003%, N ≤ 0.005%, and one or both of Nb: 0.01–0.03% and Ti: 0.01–0.03%, with the remainder being Fe and unavoidable impurities; The content of elements N, Nb, and Ti satisfies the following inequality: 5.68N ≤ Nb + Ti ≤ 0.044; The content of elements Cu and Ni satisfies the following inequality: Cu / Ni ≤ 2.

0.

2. The steel sheet according to claim 1, further comprising one or more of the following: Cr ≤ 2.0%, W: 0.01–0.5%, Mo: 0.01–0.5%, Sb: 0.01–0.2%, REM: 0.01–0.2%, V: 0.01–0.2%, and Ca: 0.001–0.01%.

3. The steel plate according to claim 1, satisfying one or more of the following conditions: Cu: 0.29–0.60%; 6.65N ≤ Nb + Ti ≤ 0.04; 0.7 ≤ Cu / Ni ≤ 2.

0.

4. The steel plate according to claim 1, wherein the thickness of the steel plate is 8 to 20 mm.

5. The steel plate according to claim 1, satisfying one or more of the following characteristics: Yield strength ≥ 1100 MPa; tensile strength ≥ 1300 MPa; elongation ≥ 12%; hardness of 450 ± 30 HBW; impact energy at -40°C ≥ 60 J; crack time ≥ 600 hours.

6. The steel plate according to claim 5, wherein the erosion-corrosion resistance of the steel plate is more than twice that of a normal Q235B steel plate.

7. A method for manufacturing the steel sheet according to claim 1, comprising the following steps: 1) The process of smelting and casting. Molten steel is smelted and cast to obtain a cast slab; 2) Heating the cast slab The heating temperature is 1230°C or higher, and the total heating time in the heating furnace is 2 hours or more, with a holding time of 40 minutes or more in the immersion zone; 3) Rough rolling and finish rolling process In the rough rolling stage, the reduction ratio per pass is 15% or more, and / or the reduction amount per pass is 25 mm or more, and / or the total pass deformation ratio is greater than 80%; In the finish rolling stage, the reduction ratio of the final pass is 16% or more at a finish rolling temperature of ≥880°C; 4) Cooling and coil winding process Cool to 550-680°C, then wind into a coil; 5) The process of quenching and tempering. The quenching temperature is 820–845°C, and the quenching holding time T1 is 1.5–2 hours in minutes, where H is the plate thickness in mm; after being removed from the furnace, the steel plate is water-cooled to room temperature at a cooling rate of ≥50°C / s; The tempering temperature is 200-240°C with a tempering holding time T2 of 2H-3H in minutes, where H is the plate thickness in mm and T2 ≥ 12 minutes; 6) Finishing process Correct distortion and trim the edges.

8. The method according to claim 7, wherein in step 3) the finish rolling temperature is 880 to 898°C; and / or in step 4) the material is cooled to 560 to 680°C and then coiled; and / or in step 5) the tempering temperature is 210 to 240°C.

9. The method according to claim 7, wherein in step 5), the quenching temperature is 828 to 845°C; and / or the tempering temperature is 220 to 240°C.

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