High-strength hoop and preparation method thereof

Abstract

The invention relates to the field of cross arm hoops, and provides a high-strength hoop and a preparation method thereof. The high-strength hoop is prepared from the following components in percentage by weight: 0.20 percent to 0.23 percent of C, 0.25 percent to 0.30 percent of Si, 1.4 percent to 1.6 percent of Mn, 0.25 percent to 0.40 percent of Ni, 0.04 percent to 0.08 percent of Ce, 0.02 percent to 0.04 percent of Ca, 0.03 percent to 0.05 percent of Nb, 0.02 percent to 0.03 percent of Sm, 0.15 percent to 0.25 percent of Mo, 0.04 percent to 0.06 percent of V, 0.0015 percent to 0.0025 percent of B, 0.01 percent to 0.03 percent of Ti and the balance of Fe and other inevitable impurities. According to the high-strength hoop provided by the invention, the toughness and impact resistance of the high-strength hoop are improved, the durability and reliability of the hoop in a corrosive environment are improved, the corrosion resistance of the hoop is improved, and performance degradation caused by environmental erosion is effectively delayed.

Description

Technical Field

[0001] The present invention relates to the technical field of cross-arm clamps, and specifically, to a high-strength clamp and a preparation method thereof. Background Art

[0002] As a common connecting and fixing device, the clamp plays a crucial role in many industrial fields and engineering applications. With the continuous development of modern industrial technology and the increasing improvement of engineering requirements, more stringent requirements are put forward for the performance of the clamp, and high-strength clamps emerge as the times require. With its excellent mechanical properties, the high-strength clamp performs well in bearing large loads and ensuring the connection stability and reliability, and is widely used in fields such as bridge construction, mechanical manufacturing, and power facility installation.

[0003] High-strength clamps are usually made of metal materials, and their design purpose is to achieve a firm connection and fixation by tightly holding the connected parts. In bridge engineering, high-strength clamps are often used to fix the pier column steel skeletons of bridges, ensure the accurate position of the steel bars during concrete pouring, and improve the integrity and stability of the bridge structure; in the field of mechanical manufacturing, clamps can be used to connect various mechanical parts, transmit power and bear working loads; in the installation of power facilities, clamps are used to fix utility poles, cable trays, etc., to ensure the safe operation of power facilities.

[0004] Currently, the commonly used high-strength clamp materials are mostly metal materials such as alloy steels. Although the strength of the materials can be improved by means of alloying and heat treatment, it often leads to a decrease in the toughness of the materials. In practical applications, when the clamp is subjected to impact loads or complex stresses, it is prone to brittle fracture, thus triggering safety accidents. For example, in some bridge projects, due to the insufficient toughness of the clamps, when natural disasters such as earthquakes occur, the clamps break, resulting in damage to the bridge structure, seriously affecting the safety and reliability of the bridge. In addition, metal materials are prone to corrosion in corrosive environments, resulting in a decline in the performance of the clamps. Especially in some coastal areas or places with strong corrosion such as chemical enterprises, the corrosion problem of the clamps is more prominent. Corrosion not only reduces the strength and stiffness of the clamps, but also shortens their service life and increases the maintenance cost. Based on this, the present invention proposes a high-strength clamp and a preparation method thereof. Summary of the Invention

[0005] The present invention proposes a high-strength clamp and a preparation method thereof, which improve the toughness and impact resistance of the high-strength clamp, improve the durability and reliability of the clamp in a corrosive environment, enhance its corrosion resistance, and effectively delay the performance degradation caused by environmental erosion.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a high-strength hoop, which is composed of the following components by weight percentage: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities.

[0007] As a further technical solution, the high-strength hoop is composed of the following components by weight percentage: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities, wherein, (Ni + Mo) / (Ce + Sm) = 3.5 - 5.5.

[0008] As a further technical solution, the high-strength hoop is composed of the following components by weight percentage: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities, wherein, (Nb + V) / C = 0.3 - 0.5.

[0009] As a further technical solution, the high-strength hoop is composed of the following components by weight percentage: C 0.20%-0.23%, Si 0.25%-0.30%, Mn 1.4%-1.6%, Ni 0.25%-0.40%, Ce 0.04%-0.08%, Ca 0.02%-0.04%, Nb 0.03%-0.05%, Sm 0.02%-0.03%, Mo 0.15%-0.25%, V 0.04%-0.06%, B 0.0015%-0.0025%, Ti 0.01%-0.03%, and the balance is Fe and other inevitable impurities, where Ti / B≥8.

[0010] In a second aspect, the present invention provides a method for preparing a high-strength hoop, the steps including: obtaining hoop materials after proportioning according to the chemical composition; then performing melting, casting, rolling, quenching, and gradient tempering to obtain a hoop steel strip, and obtaining the high-strength hoop after cutting and forming.

[0011] As a further technical solution, the melting is carried out under argon protection, and the melting temperature is 1600-1650°C.

[0012] As a further technical solution, the casting temperature is 1500-1550°C, and then it is cooled to room temperature at 40-60°C / min.

[0013] As a further technical solution, the rolling includes rough rolling and finish rolling. The rough rolling temperature is 950-1050°C, the finish rolling temperature is 800-900°C, and then water cooling is carried out at a rate of 15-20°C / s.

[0014] As a further technical solution, the quenching is two-stage quenching. The quenching includes holding at a temperature of 900-920°C for 30-40 min, then water cooling to 300°C, and then holding at a temperature of 840-860°C for 15-25 min, and water cooling to room temperature.

[0015] As a further technical solution, the gradient tempering includes holding at a temperature of 340-360°C for 1.5-2.5 h, and then holding at a temperature of 500-600°C for 1-2 h.

[0016] The working principle and beneficial effects of the present invention are: Through the collaborative optimization of composition design and heat treatment process, the present invention realizes the integrated regulation of "composition - microstructure - properties". The synergistic strengthening of rare earth elements and transition metals, the carbide regulation of microalloying elements, and the grain boundary strengthening of boron and titanium jointly construct a multi-scale strengthening mechanism; while two-stage quenching and gradient tempering further improve the toughness and durability of the material through microstructure refinement and stress elimination. This integrated innovation not only breaks through the bottleneck of traditional hoop materials in strength and corrosion resistance, but also provides a new paradigm for the lightweight design of engineering structural components in harsh environments.

[0017] By precisely controlling the ratio of (Ni + Mo) / (Ce + Sm), the present invention realizes the synergistic effect between rare earth elements and transition metals. As strong carbide-forming elements, Ce and Sm can refine grains and inhibit intergranular corrosion, while Ni and Mo enhance the matrix strength through solid solution strengthening. In Example 2, the synergistic solid solution strengthening effect of Ni and Mo and the grain boundary purification effect of Ce and Sm reach the optimal balance, increasing the tensile strength of the material to 895 MPa and reducing the acid corrosion weight loss to 1.2% at the same time. In principle, rare earth elements inhibit sulfide inclusions by forming stable intermetallic compounds (such as CeS, SmS), while Ni and Mo hinder dislocation movement by occupying lattice interstitial dislocations, thereby enhancing strength and corrosion resistance.

[0018] By regulating the ratio of (Nb + V) / C, the present invention realizes the control of the size and distribution of carbide precipitation phases. As strong carbide-forming elements, Nb and V combine with C to form nano-scale MC-type carbides (such as NbC, VC), and these dispersed precipitation phases can pin grain boundaries and hinder dislocation slip. When (Nb + V) / C = 0.4 (Example 3), the yield strength of the material is significantly improved. In principle, excessive C will lead to the precipitation of coarse carbides, while the appropriate addition of Nb and V avoids stress concentration by homogenizing the distribution of precipitation phases, thus taking into account both strength and toughness.

[0019] By setting Ti / B ≥ 8, the present invention promotes the uniform precipitation of TiB2 particles. As a high-melting-point ceramic phase, TiB2 can form a continuous network structure at grain boundaries, effectively hindering grain boundary slip and the penetration of corrosive media. When Ti / B = 12 (Example 2), the alkali resistance retention rate reaches 98%. In principle, the addition of B reduces the activity of Ti and promotes the heterogeneous nucleation of TiB2, while a high Ti / B ratio ensures the full precipitation of TiB2 and avoids grain boundary embrittlement caused by excessive B.

[0020] The present invention adopts two-stage quenching to achieve multi-stage control of martensitic transformation. High-temperature quenching promotes the homogenization of austenite and eliminates coarse carbides; low-temperature quenching refines the width of martensite laths, thereby improving the toughness of the material. Compared with traditional single-stage quenching (Comparative Example 4), two-stage quenching increases the strength retention rate by 5.5%. In principle, multi-stage quenching controls the driving force of martensitic transformation, avoiding the stress concentration in the structure caused by single quenching, thus optimizing the balance between strength and toughness.

[0021] In Comparative Example 1 (Ti / B = 4) of the present invention, due to insufficient precipitation of TiB2, grain coarsening led to a 15% decrease in strength and a 30% reduction in corrosion resistance; in Comparative Example 2, due to excessive rare earths forming inclusions, the tensile strength dropped to 805 MPa, and the acid corrosion weight loss increased by 167%. These results verify the necessity of the composition design of the present invention for performance improvement. In Comparative Example 3, due to excessive carbides, the elongation was significantly deteriorated, while in Comparative Example 4, due to inhomogeneous structure, the strength retention rate decreased by 5.5%. These comparisons show that the two-stage quenching and gradient tempering processes of the present invention significantly improve the comprehensive performance of the material by precisely controlling the microstructure evolution.

[0022] Specific Embodiments The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0023] In the present invention, the preparation method of the high-strength hoop comprises the steps of: obtaining the hoop material after proportioning according to the chemical composition; then, under argon protection, melting at a temperature of 1600 - 1650 °C; casting at a temperature of 1500 - 1550 °C, and then cooling to room temperature at a rate of 40 - 60 °C / min; rolling, including rough rolling and finish rolling, the rough rolling temperature is 950 - 1050 °C, the finish rolling temperature is 800 - 900 °C, and then water cooling is carried out at a rate of 15 - 20 °C / s; two-stage quenching, including holding at a temperature of 900 - 920 °C for 30 - 40 min, then water cooling to 300 °C, then holding at a temperature of 840 - 860 °C for 15 - 25 min, and water cooling to room temperature; holding at a temperature of 340 - 360 °C for 1.5 - 2.5 h, and then holding at a temperature of 500 - 600 °C for 1 - 2 h for gradient tempering to obtain the hoop steel strip, which is cut and formed to obtain the high-strength hoop.

[0024] The following uses more detailed embodiments for further illustration.

[0025] Example 1 In this embodiment, a high-strength clamp is provided, which is composed of the following components by weight percentage: C 0.21%, Si 0.28%, Mn 1.5%, Ni 0.32%, Ce 0.06%, Ca 0.03%, Nb 0.04%, Sm 0.025%, Mo 0.20%, V 0.05%, B 0.002%, Ti 0.02%, and the balance is Fe and other inevitable impurities; Among them, (Ni+Mo) / (Ce+Sm)=4.2; (Nb+V) / C=0.43; Ti / B=10; The preparation method of a high-strength clamp comprises the following steps: preparing the clamp material according to the chemical composition; then smelting at a smelting temperature of 1625°C under argon protection; casting at a temperature of 1525°C, and then cooling to room temperature at 50°C / min; rolling, including rough rolling and finish rolling, wherein the rough rolling temperature is 1000°C and the deformation is 60%, and the finish rolling temperature is 850°C and the deformation is 40%, and then water cooling is performed at a rate of 17°C / s; two-stage quenching, comprising maintaining at a temperature of 910°C for 35 minutes, then water cooling to 300°C, then maintaining at a temperature of 850°C for 20 minutes, and then water cooling to room temperature; maintaining at a temperature of 350°C for 2 hours, and then maintaining at a temperature of 550°C for 1.5 hours for gradient tempering to obtain a clamp steel strip, and the high-strength clamp is obtained after cutting and forming.

[0026] Example 2 In the present embodiment, a high-strength clamp is provided, which is composed of the following components by weight percentage: C 0.22%, Si 0.25%, Mn 1.6%, Ni 0.40%, Ce 0.04%, Ca 0.04%, Nb 0.05%, Sm 0.02%, Mo 0.25%, V 0.04%, B 0.0025%, Ti 0.03%, and the balance is Fe and other inevitable impurities; Among them, (Ni+Mo) / (Ce+Sm)=5.4; (Nb+V) / C=0.41; Ti / B=12; Preparation method of high-strength hoop, the steps include: after preparing materials according to the chemical composition, obtaining the hoop material; then, under argon protection, melting at a melting temperature of 1625 °C; casting at a temperature of 1525 °C, and then cooling to room temperature at 50 °C / min; rolling, including rough rolling and finish rolling, the rough rolling temperature is 1000 °C, the deformation amount is 60%, the finish rolling temperature is 850 °C, the deformation amount is 40%, and then water cooling is carried out at a rate of 17 °C / s; two-stage quenching, including holding at a temperature of 910 °C for 35 min, then water cooling to 300 °C, then holding at a temperature of 850 °C for 20 min, and water cooling to room temperature; holding at a temperature of 350 °C for 2 h, and then holding at a temperature of 550 °C for 1.5 h for gradient tempering to obtain the hoop steel strip, and after cutting and forming, the high-strength hoop is obtained.

[0027] Example 3 In this example, a high-strength hoop is provided, which is composed of the following components by weight percentage: C 0.23%, Si 0.27%, Mn 1.55%, Ni 0.35%, Ce 0.05%, Ca 0.035%, Nb 0.045%, Sm 0.025%, Mo 0.22%, V 0.055%, B 0.0022%, Ti 0.025%, and the balance is Fe and other inevitable impurities; Among them, (Ni + Mo) / (Ce + Sm) = 4.8; (Nb + V) / C = 0.38; Ti / B = 11.4; Preparation method of high-strength hoop, the steps include: after preparing materials according to the chemical composition, obtaining the hoop material; then, under argon protection, melting at a melting temperature of 1625 °C; casting at a temperature of 1525 °C, and then cooling to room temperature at 50 °C / min; rolling, including rough rolling and finish rolling, the rough rolling temperature is 1000 °C, the deformation amount is 60%, the finish rolling temperature is 850 °C, the deformation amount is 40%, and then water cooling is carried out at a rate of 17 °C / s; two-stage quenching, including holding at a temperature of 910 °C for 35 min, then water cooling to 300 °C, then holding at a temperature of 850 °C for 20 min, and water cooling to room temperature; holding at a temperature of 350 °C for 2 h, and then holding at a temperature of 550 °C for 1.5 h for gradient tempering to obtain the hoop steel strip, and after cutting and forming, the high-strength hoop is obtained.

[0028] Example 4 In this embodiment, a high-strength hoop is provided, which is composed of the following components by weight percentage: C 0.20%, Si 0.30%, Mn 1.4%, Ni 0.25%, Ce 0.08%, Ca 0.02%, Nb 0.03%, Sm 0.03%, Mo 0.15%, V 0.06%, B 0.0015%, Ti 0.01%, and the balance is Fe and other inevitable impurities; Among them, (Ni + Mo) / (Ce + Sm) = 3.6; (Nb + V) / C = 0.45; Ti / B = 6.7; The preparation method of the high-strength hoop includes the following steps: After preparing materials according to the chemical composition, hoop materials are obtained; then, under argon protection, melting is carried out at a melting temperature of 1625 °C; casting is carried out at a temperature of 1525 °C, and then cooled to room temperature at 50 °C / min; rolling, including rough rolling and finish rolling, the rough rolling temperature is 1000 °C, the deformation amount is 60%, the finish rolling temperature is 850 °C, the deformation amount is 40%, and then water cooling is carried out at a rate of 17 °C / s; two-stage quenching, including holding at a temperature of 910 °C for 35 min, then water cooling to 300 °C, then holding at a temperature of 850 °C for 20 min, and water cooling to room temperature; holding at a temperature of 350 °C for 2 h, and then holding at a temperature of 550 °C for 1.5 h for gradient tempering to obtain hoop steel strips, and after cutting and forming, the high-strength hoop is obtained.

[0029] Comparative Example 1 In Comparative Example 1, Ti is reduced to 0.008%, Ti / B = 4, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0030] Comparative Example 2 In Comparative Example 2, Ce is increased to 0.12%, Sm is reduced to 0.01%, (Ni + Mo) / (Ce + Sm) = 2.8, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0031] Comparative Example 3 In Comparative Example 3, V is increased to 0.10%, (Nb + V) / C = 0.67; the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0032] Comparative Example 4 In Comparative Example 4, the quenching is changed to single-stage holding at 920 °C for 30 min and water cooling to room temperature, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0033] Test Example 1: The following tests are carried out on the high-strength hoops prepared in the foregoing Examples 1-4 and Comparative Examples 1-4: Tensile strength: Refer to GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature" to detect the tensile strength of the hoop at room temperature; Acid resistance: Immerse the hoop in a sulfuric acid aqueous solution with a weight concentration of 10% for 30 days, record the corrosion weight loss before and after immersion; and calculate the retention rate of tensile strength after acid treatment; Alkali resistance: Immerse the hoop in a sodium hydroxide aqueous solution with a weight concentration of 10% for 30 days, record the corrosion weight loss before and after immersion; and calculate the retention rate of tensile strength after alkali treatment; The results are shown in Table 1 below: Table 1

[0034] Combined with the foregoing content, it can be seen that Examples 1-4 are comprehensively superior to the comparative examples in terms of strength (850-895 MPa), corrosion resistance (acid weight loss ≤ 1.8%), and low-temperature toughness (impact energy ≥ 50 J); among them, Example 2 achieves the highest strength and the best acid resistance through (Ni+Mo) / (Ce+Sm)=5.4 and Ti / B=12; in addition, Examples 1-4 reduce the residual stress through low-temperature + high-temperature tempering, and the retention rate of alkali resistance is > 95%. In Comparative Example 1 (Ti / B=4), due to insufficient precipitation of TiB2 and grain coarsening, the strength decreased by 15% and the corrosion resistance decreased by 30%; in Comparative Example 2 (ratio 2.8), excessive rare earths formed inclusions, and the tensile strength dropped to 805 MPa, and the acid corrosion weight loss increased by 167%; in Comparative Example 3 (ratio 0.67), there were too many carbides, and the elongation was significantly deteriorated. In Comparative Example 4, single-stage quenching resulted in uneven structure, and the strength retention rate was 5.5% lower than that of Example 1.

[0035] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, 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 high-strength hoop, characterized in that, By weight percentage, it consists of the following components: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities.

2. The high-strength hoop according to claim 1, wherein The high-strength hoop, by weight percentage, consists of the following components: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities, where (Ni + Mo) / (Ce + Sm) = 3.5 - 5.

5.

3. The high-strength hoop according to claim 1, characterized in that, The high-strength hoop, by weight percentage, consists of the following components: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities, where (Nb + V) / C = 0.3 - 0.

5.

4. A high-strength hoop according to claim 1, characterized in that, The high-strength hoop, by weight percentage, consists of the following components: C 0.20% - 0.23%, Si 0.25% - 0.30%, Mn 1.4% - 1.6%, Ni 0.25% - 0.40%, Ce 0.04% - 0.08%, Ca 0.02% - 0.04%, Nb 0.03% - 0.05%, Sm 0.02% - 0.03%, Mo 0.15% - 0.25%, V 0.04% - 0.06%, B 0.0015% - 0.0025%, Ti 0.01% - 0.03%, and the balance is Fe and other inevitable impurities, where Ti / B ≥ 8.

5. A preparation method of the high-strength hoop as described in any one of claims 1-4, characterized in that the steps It includes: After batching according to the chemical composition, hoop materials are obtained; Subsequently, through melting, casting, rolling, quenching, and gradient tempering, hoop steel strips are obtained, and after cutting and forming, the high-strength hoops are obtained.

6. The preparation method of a high-strength hoop according to claim 5, characterized in that, The smelting is carried out under argon protection at a smelting temperature of 1600 - 1650 °C.

7. The preparation method of a high-strength hoop according to claim 5, characterized in that, The casting temperature is 1500 - 1550 °C, and then it is cooled to room temperature at 40 - 60 °C / min.

8. The preparation method of a high-strength hoop according to claim 5, characterized in that The rolling includes rough rolling and finish rolling. The rough rolling temperature is 950 - 1050 °C, and the finish rolling temperature is 800 - 900 °C. Then water cooling is carried out at a rate of 15 - 20 °C / s.

9. The preparation method of a high-strength hoop according to claim 5, characterized in that, The quenching is two-stage quenching. The quenching includes holding at a temperature of 900 - 920 °C for 30 - 40 min, then water cooling to 300 °C, and then holding at a temperature of 840 - 860 °C for 15 - 25 min, and finally water cooling to room temperature.

10. The preparation method of a high-strength hoop according to claim 5, characterized in that, The gradient tempering includes holding at a temperature of 340 - 360 °C for 1.5 - 2.5 h, and then holding at a temperature of 500 - 600 °C for 1 - 2 h.

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