A rolling method for hot-rolled H-shaped steel with ultra-high strength and good toughness for marine engineering structures

Abstract

The invention discloses a rolling method for hot-rolled H-shaped steel for marine engineering structures with both ultra-high strength and good toughness. During the rolling process, the heating temperature of the profiled blank is controlled to be 1270-1280°C, the rough rolling temperature is 1150-1200°C, the finishing rolling start temperature is 970-980°C, and the final rolling temperature is 860-900°C. The hot-rolled H-shaped steel for marine engineering structures with both ultra-high strength (yield strength ≥530MPa, tensile strength ≥740MPa) and good toughness (impact energy ≥170J at ‑20°C) can be obtained by rolling, and the hot-rolled H-shaped steel for marine engineering structures can meet the requirements of harsher marine environments.

Description

Technical Field

[0001] The invention belongs to the technical field of hot rolling processes, and in particular relates to a method for rolling hot-rolled H-shaped steel for marine engineering structures having both ultra-high strength and good toughness. Background Art

[0002] H-beam series products are becoming more and more widely used in the fields of construction, electricity, water conservancy, energy, chemical industry, petroleum, etc. Due to the increasing demand for oil, countries around the world are developing offshore oil, and the demand for H-beam for offshore oil platform structures is also increasing. Hot-rolled H-beam replacing steel plate welding will reduce construction labor intensity, engineering costs and operation cycles, which has great practical significance and good market prospects. In addition to strength requirements, there are also high requirements for toughness, fatigue, lamellar tearing resistance, welding performance, etc. Therefore, it is difficult to produce ultra-high strength hot-rolled H-beam for marine engineering structures with both ultra-high strength and good toughness.

[0003] Patent document CN115011869A (hereinafter referred to as document 1) has disclosed an ultra-high strength hot-rolled H-beam for marine engineering structures and a production method thereof. The patent document CN115011869A (hereinafter referred to as document 1) adopts a weak cooling process in the continuous casting process, and reasonably matches the parameters such as the pulling speed, superheat and water inlet temperature according to the molten steel composition characteristics of the hot-rolled H-beam. The yield strength of the H-beam obtained by rolling is greater than 500MPa (up to 519MPa), the tensile strength is greater than 700MPa (up to 725MPa), and the impact energy at -20°C can reach more than 130J (up to 149J in the transverse direction and 197J in the longitudinal direction), showing higher strength and good low-temperature impact toughness. Patent document CN114959458A (hereinafter referred to as document 2) discloses a method for manufacturing DH36 hot-rolled H-shaped steel for marine engineering structures. During the rolling process, the heating temperature of the ingot is controlled to be 1200-1280°C, the rough rolling temperature is 1000-1100°C, the finishing rolling temperature is 920-960°C, and the final rolling temperature is 850-900°C. The H-shaped steel finally obtained not only has a high yield strength (up to 445MPa) and tensile strength (up to 563MPa), but also has good low-temperature impact toughness (impact energy at -20°C can reach more than 130J (up to 158J in the horizontal direction and 195J in the vertical direction)). However, the hot-rolled H-shaped steel for marine engineering structures manufactured in the above documents 1 and 2 (such as strength and low-temperature impact toughness) still cannot meet the more severe marine environment. Summary of the invention

[0004] In view of the problems existing in the prior art, one aspect of the present invention provides a method for rolling a hot-rolled H-shaped steel for marine engineering structures having both ultra-high strength and good toughness, wherein the chemical composition thereof is as follows by mass percentage: C 0.17% to 0.20%, Si 0.45% to 0.55%, Mn 1.60% to 1.70%, P≤0.025%, S≤0.025%, Nb 0.035% to 0.045%, V 0.08% to 0.11%, Al 0.020% to 0.030%, and the remainder is Fe and unavoidable impurities;

[0005] The rolling method comprises the following steps: heating of the profiled blank, rough rolling, finish rolling and cooling, wherein:

[0006] In the heating process of the profiled blank, the heating temperature of the profiled blank is controlled to be 1270-1280° C., and the holding time is 2.5-4 hours;

[0007] In the rough rolling process, the rough rolling temperature is controlled to be 1150-1200° C., water cooling is used for controlled cooling, and the rolling passes are 3-5 times;

[0008] In the finishing rolling process, the starting temperature of the finishing rolling is controlled to be 970-980°C, and the finishing rolling adopts warm rolling and water-cooled controlled rolling, with 5-7 rolling passes; the final rolling temperature of the finishing rolling is controlled to be 860-900°C, and the total reduction of the two-stage rolling is ≥75%;

[0009] In the cooling process, air cooling is adopted, and straightening is performed after the temperature drops below 100°C.

[0010] Another aspect of the present invention provides a hot-rolled H-shaped steel for marine engineering structures having both ultra-high strength and good toughness, which is obtained by rolling using the above-mentioned rolling method.

[0011] In some embodiments, the mechanical properties of the hot-rolled H-beam for marine engineering structures meet the following requirements: transverse impact energy at -20°C ≥ 170J, longitudinal impact energy at -20°C ≥ 210J, yield strength ≥ 530MPa, tensile strength ≥ 740MPa, and elongation A ≥ 19.5%.

[0012] The rolling method of hot-rolled H-shaped steel for marine engineering structures with ultra-high strength and good toughness provided by the above technical solution can obtain a hot-rolled H-shaped steel for marine engineering structures with ultra-high strength (yield strength ≥530MPa, tensile strength ≥740MPa) and good toughness (impact energy ≥170J at -20°C) by controlling the heating temperature of the special-shaped billet to 1270-1280°C, the rough rolling temperature to 1150-1200°C, the finishing rolling start temperature to 970-980°C, the final rolling temperature to 860-900°C and other parameters during the rolling process. Compared with the above-mentioned documents 1 and 2, the hot-rolled H-shaped steel for marine engineering structures can meet the conditions of more severe marine environment. DETAILED DESCRIPTION

[0013] The present invention aims to provide a method for rolling hot-rolled H-shaped steel for marine engineering structures having both ultra-high strength and good toughness, and to provide hot-rolled H-shaped steel for marine engineering structures obtained by rolling the rolling method.

[0014] The rolling method of hot-rolled H-shaped steel for marine engineering structure provided by the present invention comprises the following steps: heating of profiled blank, rough rolling, finish rolling and cooling, wherein:

[0015] In the profiled blank heating process, the profiled blank is heated at a temperature of 1270-1280° C. for a holding time of 2.5-4 hours, and is descaled by high-pressure water after being taken out of the furnace;

[0016] In the rough rolling process, the rough rolling temperature is controlled to be 1150-1200° C., water cooling is used for controlled cooling, the rolling passes are 3-5 times, and then the rough rolled profile is sent to the finishing mill station for finishing rolling;

[0017] In the finishing rolling process, the starting temperature of the finishing rolling is controlled to be 970-980°C, and the finishing rolling adopts warm rolling and water-cooled controlled rolling, with 5-7 rolling passes; the final rolling temperature of the finishing rolling is controlled to be 860-900°C, and the total reduction of the two-stage rolling is ≥75%;

[0018] In the cooling process, air cooling is adopted for cooling, and straightening is carried out after the temperature drops below 100°C, and finally the steel wire is cut to size and bundled. The finished product size can be H300×300×10×15×12000mm.

[0019] In some embodiments, the hot-rolled H-shaped steel for marine engineering structures comprises, by mass percentage, C 0.17% to 0.20%, Si 0.45% to 0.55%, Mn 1.60% to 1.70%, P≤0.025%, S≤0.025%, Nb 0.035% to 0.045%, V 0.08% to 0.11%, Al 0.020% to 0.030%, and the remainder is Fe and unavoidable impurities; optionally, C 0.18% to 0.19%, Si 0.47% to 0.53%, Mn 1.66% to 1.69%, P≤0.015%, S≤0.008%, Nb0.038% to 0.039%, V 0.083% to 0.10%, Al 0.020%~0.026%, the rest is Fe and inevitable impurities.

[0020] In some embodiments, the mechanical properties of the hot-rolled H-beam for marine engineering structures meet the following requirements: transverse impact energy at -20°C ≥ 170J, longitudinal impact energy at -20°C ≥ 210J, yield strength ≥ 530MPa, tensile strength ≥ 740MPa, and elongation A ≥ 19.5%.

[0021] The present invention is described in detail below through specific examples. The examples are intended to help understand the present invention but are not intended to limit the present invention.

[0022] Embodiment 1:

[0023] This embodiment aims to produce a hot-rolled H-beam for marine engineering structures with ultra-high strength and good toughness, and its chemical composition is shown in Table 1 below. The specific production method includes the following processes: converter smelting, LF refining, continuous casting of profiled billets, heating of profiled billets, rough rolling, finishing rolling, and cooling; wherein the converter smelting, LF refining, and continuous casting of profiled billets can be performed according to the operation of the above-mentioned document 1, and the parameters of the profiled billet heating, rough rolling, and finishing rolling processes are controlled as shown in Table 2 below. The surface quality of the hot-rolled H-beam for marine engineering structures obtained after rolling was inspected, and no obvious surface quality defects of the finished product were found, and the surface quality was good; and the mechanical properties of the hot-rolled H-beam for marine engineering structures obtained after rolling were tested, and the test results are shown in Table 3 below.

[0024] Embodiment 2-4

[0025] Example 2-4 was carried out according to the operation of Example 1, except that the chemical composition of the hot-rolled H-beam for marine engineering structure produced and the control of parameters during rolling were different, as shown in Table 1 and Table 2. The mechanical properties of the hot-rolled H-beam for marine engineering structure obtained after rolling in Example 2-4 were tested, and the test results are shown in Table 3.

[0026] Comparative Example 1

[0027] Comparative Example 1 was carried out in accordance with the operation of Example 1, except that the parameters during rolling were controlled differently, as shown in Tables 1 and 2. The mechanical properties of the hot-rolled H-beam for marine engineering structures obtained after rolling in Comparative Example 1 were tested, and the test results are shown in Table 3.

[0028] Table 1: Chemical composition of hot-rolled H-beams of various examples (wt%)

[0029] Examples C Si Mn P S Nb V Al Example 1 0.18 0.47 1.68 0.015 0.008 0.039 0.083 0.024 Example 2 0.19 0.52 1.67 0.014 0.007 0.038 0.094 0.021 Example 3 0.18 0.53 1.66 0.013 0.007 0.039 0.10 0.026 Example 4 0.19 0.49 1.69 0.015 0.008 0.038 0.085 0.020 Comparative Example 1 0.18 0.47 1.68 0.015 0.008 0.039 0.083 0.024

[0030] Table 2: Rolling process parameters of each example

[0031]

[0032]

[0033] Table 3: Mechanical properties of hot-rolled H-beams of various examples

[0034]

[0035] As shown in Tables 1 to 3 above, it can be seen that the hot-rolled H-shaped steels for marine engineering structures produced in Examples 1 to 4 have both ultra-high strength and good toughness, wherein the mechanical properties of the hot-rolled H-shaped steels for marine engineering structures produced meet the following requirements: transverse impact energy at -20°C ≥170J (preferably ≥177J), longitudinal impact energy at -20°C ≥210J (preferably ≥215J), yield strength ≥530MPa (preferably ≥538MPa), tensile strength ≥740MPa (preferably ≥746MPa), and elongation A ≥19.5%. In contrast, in Comparative Example 1, a lower billet heating temperature, a lower rough rolling temperature, and a lower finishing rolling start temperature are controlled during the rolling process, and the strength and low-temperature impact toughness of the hot-rolled H-shaped steel for marine engineering structures obtained are relatively low.

[0036] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for rolling hot-rolled H-shaped steel for marine engineering structures having both ultra-high strength and good toughness, characterized in that: The chemical composition of the hot-rolled H-shaped steel for marine engineering structure is as follows by mass percentage: C 0.17%-0.20%, Si 0.45%-0.55%, Mn 1.60%-1.70%, P≤0.025%, S≤0.025%, Nb 0.035%-0.045%, V 0.08-0.11%, Al 0.020%-0.030%, and the rest is Fe and unavoidable impurities; The rolling method comprises the following steps: heating of the profiled blank, rough rolling, finish rolling and cooling, wherein: In the profiled blank heating process, the heating temperature of the profiled blank is controlled to be 1270-1280° C., and the holding time is 2.5-4 hours; In the rough rolling process, the rough rolling temperature is controlled to be 1150-1200° C., water cooling is used for controlled cooling, and the rolling passes are 3-5 times; In the finishing rolling process, the starting temperature of the finishing rolling is controlled to be 970-980°C, and the finishing rolling adopts warm rolling and water-cooled controlled rolling, with 5-7 rolling passes; the final rolling temperature of the finishing rolling is controlled to be 860-900°C, and the total reduction of the two-stage rolling is ≥75%; In the cooling process, air cooling is adopted for cooling, and straightening is performed after the temperature drops below 100°C; The mechanical properties of the hot-rolled H-shaped steel for marine engineering structures meet the following requirements: transverse impact energy at -20°C ≥170J, longitudinal impact energy at -20°C ≥210J, yield strength ≥530MPa, tensile strength ≥740MPa, and elongation A ≥19.5%.

2. A hot-rolled H-shaped steel for marine engineering structures having both ultra-high strength and good toughness, which is obtained by rolling the rolling method according to claim 1.

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