360MPa-grade microbial corrosion-resistant copper-containing antibacterial hot-rolled coil and preparation method thereof

Abstract

This invention relates to the field of steel production technology and discloses a 360MPa-grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion. The chemical composition by mass percentage is: Si≤0.30%, Mn≤0.50%, P≤0.010%, S≤0.0020%, Cu: 1.00~1.85%, Nb≤0.030%, Ti: 0.010~0.020%, Ca: 0.0015~0.0020%, with the remainder being Fe and unavoidable impurities. This invention also discloses a method for preparing the 360MPa-grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion. The 360MPa-grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion and its preparation method of this invention exhibit good mechanical properties and strong corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of steel production technology, specifically to a 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion and its preparation method. Background Technology

[0002] Microorganisms attach to material surfaces and form biofilms. Bacteria within these biofilms can acquire electrons from the metal through direct or indirect electron transfer, leading to microbial corrosion. Biofilms are a major contributing factor to microbial corrosion. The most prominent hazard of microbial corrosion is that it accelerates the localized corrosion process, increasing the rate of corrosion progression and the severity of the damage. Microbial corrosion exists in the service environment of gathering and transportation pipelines, and traditional pipeline steels based on carbon, manganese, and microalloying elements are not resistant to it. While stainless steel has excellent corrosion resistance, it is expensive. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a 360MPa-grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion and its preparation method, which has good mechanical properties and strong corrosion resistance.

[0004] To achieve the above objectives, the 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion designed in this invention has the following chemical composition by mass percentage: Si≤0.30%, Mn≤0.50%, P≤0.010%, S≤0.0020%, Cu:1.00~1.85%, Nb≤0.030%, Ti:0.010~0.020%, Ca:0.0015~0.0020%, with the remainder being Fe and unavoidable impurities.

[0005] Preferably, no carbon is added, and only the residual carbon introduced during the alloying process is retained, with a mass percentage ≤0.03%.

[0006] Preferably, Ni ≤ 0.10%.

[0007] The design principles of the main alloying elements and their mass percentages in this invention are as follows:

[0008] C (carbon): C is the most economical element to improve the strength of steel. However, excessive C content will deteriorate the weldability of steel and reduce its ductility and toughness. Therefore, carbon is not intentionally added in this invention. Only the residual carbon introduced during the addition of alloys in the smelting process is retained and its mass percentage is controlled to be ≤0.03%.

[0009] Mn (manganese): Mn is one of the important solid solution strengthening elements in steel and an important deoxidizing element in the steelmaking process. Mn can also improve the stability of austenite, expand the austenite phase region, and promote the transformation of bainite structure. However, excessive Mn content will not only increase manufacturing costs, but also deteriorate the weldability and corrosion resistance of steel. Therefore, its content is designed to be ≤0.50%.

[0010] Cu (copper): Cu can significantly improve the atmospheric corrosion resistance of materials, but Cu has a low melting point of only 1083℃. Excessive content can easily lead to leakage in continuous casting and edge cracks during hot rolling. Therefore, the mass percentage of Cu should be controlled at 1.00 to 1.85%.

[0011] Ni (Ni): Ni can increase the self-corrosion potential of materials, reduce corrosion tendency, improve atmospheric corrosion resistance, and react with Cu to form a high-melting-point Cu-Ni binary alloy phase, which effectively prevents copper embrittlement caused by Cu. However, Ni is a precious metal element, and excessive content significantly increases the manufacturing cost of steel. Therefore, the Ni content is controlled at ≤0.10% and is not added intentionally.

[0012] Ti (Titanium): Ti is a strong nitride-forming element that inhibits austenite grain coarsening during heating.

[0013] Ca (calcium): Promotes the spheroidization of non-metallic inclusions, which is beneficial to improving the material's resistance to atmospheric corrosion and low-temperature toughness. Its content should be controlled at 0.0015-0.0020%.

[0014] P (phosphorus): Although P improves the corrosion resistance of steel, it reduces the low-temperature toughness of steel and increases the sensitivity to welding cracks. Therefore, it should be controlled within 0.010%.

[0015] S (sulfur): S is a harmful residual element in steel. It readily reacts with Mn to form MnS nonmetallic inclusions, which reduces the resistance to atmospheric corrosion. Therefore, its content should be controlled within 0.0020%.

[0016] A method for preparing a 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion includes the following steps: hot metal pretreatment → converter smelting → LF ladle refining → RH vacuum degassing → continuous casting → slab heating → controlled rolling → controlled cooling → coiling. The hot metal pretreatment → converter smelting → LF ladle refining → RH vacuum degassing → continuous casting employs clean steel smelting technology, involving LF furnace, RH furnace, and calcium treatment to control the morphology, quantity, and size of non-metallic inclusions, thereby reducing their formation. Controlled rolling includes rough rolling and finish rolling, with the rough rolling stage involving multiple passes in the austenite recrystallization zone.

[0017] Preferably, the slab heating temperature is 1200–1300℃.

[0018] Preferably, the thickness of the rolled part after rough rolling is controlled at 45-60 mm.

[0019] Preferably, the initial rolling temperature of the finishing mill is controlled at 1000–1060℃, and the final rolling temperature of the finishing mill is controlled at 850–890℃.

[0020] Preferably, the winding temperature is controlled at 620–680°C.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. It has good mechanical properties, strong corrosion resistance, and low cost;

[0023] 2. The microstructure is mainly composed of polygonal ferrite and acicular ferrite, with a grain size of 10 to 12.

[0024] 3. Mechanical properties: Rt0.5: 360~500MPa, Rm: 460~600MPa, impact energy at -20℃ ≥150J;

[0025] 4. Resistance to microbial corrosion: After 168 hours of testing in an environment with an SRB concentration of 25,000 cells / ml, the uniform corrosion rate is ≤0.22 mm / a and the maximum pitting depth is ≤2.8 μm. Attached Figure Description

[0026] Figure 1 The image shows the microstructure of the copper-containing antibacterial hot-rolled steel coil with a microbial corrosion resistance of 360MPa grade according to the present invention under an optical microscope. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] A copper-containing antibacterial hot-rolled steel coil with a 360MPa grade resistance to microbial corrosion has the following chemical composition by mass percentage: Si≤0.30%, Mn≤0.50%, P≤0.010%, S≤0.0020%, Cu: 1.00~1.85%, Nb≤0.030%, Ti: 0.010~0.020%, Ca: 0.0015~0.0020%, with the remainder being Fe and unavoidable impurities.

[0029] No carbon is added; only the residual carbon introduced during the alloying process is retained, with a mass percentage ≤0.03%. In addition, Ni ≤0.10%.

[0030] The preparation method of the above-mentioned 360MPa grade copper-containing antibacterial hot-rolled steel coil with microbial corrosion resistance includes the following steps: hot metal pretreatment → converter smelting → LF ladle refining → RH vacuum degassing → continuous casting → slab heating → controlled rolling → controlled cooling → coiling. Among them, the hot metal pretreatment → converter smelting → LF ladle refining → RH vacuum degassing → continuous casting adopts clean steel smelting technology, and calcium treatment is carried out in LF furnace and RH furnace. Controlled rolling includes rough rolling and finish rolling. The rough rolling stage is carried out in the austenite recrystallization zone with multiple rolling passes.

[0031] In addition, the slab heating temperature is 1200-1300℃, the thickness of the rolled piece after rough rolling is controlled at 40-60mm, the initial rolling temperature of finish rolling is controlled at 1000-1060℃, the final rolling temperature of finish rolling is controlled at 850-890℃, and the coiling temperature is controlled at 620-680℃.

[0032] Ten examples are listed to illustrate the implementation of this process, as shown in Table 1, which contains the chemical composition of the ten examples:

[0033] Table 1 Chemical composition (wt%) of each example

[0034] C Si Mn P S Cu Ni Nb Ti Ca Example 1 0.023 0.24 0.37 0.0100 0.0004 1.14 0.10 0.022 0.017 0.0016 Example 2 0.020 0.22 0.42 0.0082 0.0012 1.68 0.08 0.026 0.015 0.0015 Example 3 0.025 0.23 0.50 0.0046 0.0008 1.24 0.06 0.018 0.012 0.0017 Example 4 0.021 0.28 0.32 0.0054 0.0014 1.37 0.07 0.030 0.016 0.0016 Example 5 0.030 0.21 0.41 0.0064 0.0016 1.49 0.06 0.022 0.020 0.0018 Example 6 0.019 0.26 0.29 0.0071 0.0004 1.85 0.09 0.016 0.018 0.0018 Example 7 0.016 0.30 0.35 0.0051 0.0009 1.16 0.05 0.018 0.014 0.0016 Example 8 0.025 0.23 0.41 0.0042 0.0020 1.00 0.04 0.026 0.010 0.0020 Example 9 0.023 0.25 0.35 0.0054 0.0015 1.75 0.06 0.024 0.015 0.0017 Example 10 0.024 0.22 0.31 0.0034 0.0018 1.65 0.04 0.028 0.014 0.0017

[0035] Table 2 shows the rolling process parameters for 10 embodiments:

[0036] Table 2 Main process parameters of rolling process in each embodiment

[0037]

[0038]

[0039] Table 3 shows the mechanical properties of 10 embodiments:

[0040] Table 3 Mechanical properties of each embodiment (I)

[0041]

[0042] Table 4 shows the Charpy impact performance of 10 examples. The impact test specimens for Examples 1-5 were 5×10×55 mm in size, and those for Examples 6-10 were 10×10×55 mm in size. Each example was tested three times, and the average value was taken.

[0043] Table 4 Charpy impact energy performance of each embodiment

[0044]

[0045] The steel plates of this invention were subjected to microbial corrosion resistance studies in an environment containing sulfate-reducing bacteria (SRB). The shape of corrosion pits and the uniform corrosion rate were observed. The embodiments achieved the target performance at a relatively low cost.

[0046] Table 5 shows the antibacterial performance of 10 embodiments:

[0047] Table 5 Antibacterial properties of each example

[0048]

[0049] As can be seen from the examples in the table above, the 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion of the present invention has the following mechanical properties: Rt0.5: 360~500MPa, Rm: 460~600MPa, impact energy at -20℃ ≥150J (where the impact energy sample size of Examples 1~5 is 5×10×55, and the impact energy conversion needs to be multiplied by 2); at an SRB concentration of 25000 / ml, its uniform corrosion rate is ≤0.22mm / a, and the maximum pitting depth is ≤2.8μm. It has good mechanical properties, strong corrosion resistance, and low cost. In addition, as... Figure 1 As shown, the microstructure consists of acicular ferrite and quasi-polygonal ferrite, with a grain size ranging from 10 to 12.

[0050] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims.

[0051] The aspects disclosed in this specification and claims are merely examples, and therefore, this specification and claims are not limited to the details shown. In the foregoing description, detailed descriptions of relevant known functions or configurations have been omitted where it would unnecessarily obscure the focus of this specification and claims.

[0052] When using the terms “comprising,” “having,” and “including” as described in this specification, there may be another part or other part unless used, and the terms used are generally singular but may also be plural.

[0053] Finally, it should be noted that the above description is a further detailed explanation of the invention in conjunction with specific embodiments. It should not be considered that the specific implementation of the invention is limited to these descriptions. For those skilled in the art, any simple substitutions made without departing from the concept of the invention should be considered within the scope of protection of this invention. The above embodiments are merely representative examples of the invention. Obviously, the invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the invention should be considered within the scope of protection of this invention.

[0054] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of this specification to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims. Features of various embodiments of this invention may be combined or spliced ​​together in part or in whole, and may be implemented in various different configurations as will be fully understood by those skilled in the art. Embodiments of this invention may be implemented independently of each other or may be implemented together in an interdependent relationship.

[0055] For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and the above structures should all be considered to fall within the protection scope of the present invention.

Claims

1. A copper-containing antibacterial hot-rolled steel coil with a 360MPa-grade resistance to microbial corrosion, characterized in that: Its chemical composition by mass percentage is as follows: Si≤0.30%, Mn≤0.50%, P≤0.010%, S≤0.0020%, Cu:1.00~1.85%, Nb≤0.030%, Ti:0.010~0.020%, Ca:0.0015~0.0020%, with the remainder being Fe and unavoidable impurities.

2. The 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 1, characterized in that: No carbon is added; only the residual carbon introduced during the alloying process is retained, with a mass percentage ≤0.03%.

3. The 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 1, characterized in that: Ni ≤ 0.10%.

4. A method for preparing a 360MPa-grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 1, characterized in that: The process includes the following steps: hot metal pretreatment → converter smelting → LF ladle refining → RH vacuum degassing → continuous casting → slab heating → controlled rolling → controlled cooling → coiling. Among these, the hot metal pretreatment → converter smelting → LF ladle refining → RH vacuum degassing → continuous casting adopts clean steel smelting technology, and calcium treatment is carried out in the LF furnace and RH furnace. Controlled rolling includes rough rolling and finish rolling. The rough rolling stage is carried out in the austenite recrystallization zone through multiple rolling passes.

5. The preparation method of the 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 4, characterized in that: The slab heating temperature is 1200~1300℃.

6. The preparation method of the 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 4, characterized in that: The thickness of the rolled piece after rough rolling is controlled between 40 and 60 mm.

7. The preparation method of the 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 4, characterized in that: The initial rolling temperature of the finishing mill is controlled at 1000-1060℃, and the final rolling temperature of the finishing mill is controlled at 850-890℃.

8. The preparation method of the 360MPa grade copper-containing antibacterial hot-rolled steel coil resistant to microbial corrosion as described in claim 4, characterized in that: The winding temperature is controlled at 620-680℃.

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