WO2024130968A1 - 400 mpa-grade coating-free hot-rolled wire rod and round rod, and rolling process therefor - Google Patents

400 mpa-grade coating-free hot-rolled wire rod and round rod, and rolling process therefor Download PDF

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Publication number
WO2024130968A1
WO2024130968A1 PCT/CN2023/097478 CN2023097478W WO2024130968A1 WO 2024130968 A1 WO2024130968 A1 WO 2024130968A1 CN 2023097478 W CN2023097478 W CN 2023097478W WO 2024130968 A1 WO2024130968 A1 WO 2024130968A1
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Prior art keywords
heating
temperature
rolling
wire rod
long product
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PCT/CN2023/097478
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French (fr)
Chinese (zh)
Inventor
张帆
夏艳花
任安超
王彦林
贾万军
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武汉钢铁有限公司
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Publication of WO2024130968A1 publication Critical patent/WO2024130968A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper

Definitions

  • the invention belongs to the technical field of metallurgy, and in particular relates to a 400MPa-grade coating-free hot-rolled wire rod, a round bar and a rolling process thereof.
  • CN115110006A discloses a weathering steel with high corrosion resistance and a preparation method, a weathering steel, the chemical composition and its mass percentage are: C: 0.05-0.12%, Si: 0.20-0.60%, Mn: 0.30-0.60%, P: 0.07-0.15%, S: ⁇ 0.015%, Cu: 0.25-0.55%, Ni: ⁇ 0.20%, Cr: 0.30-0.60%, the balance is Fe and inevitable impurities, and the relative corrosion rate of atmospheric corrosion resistance is less than 40% of Q345B.
  • the invention adds certain weathering elements such as P, Cu, Cr to the steel, but its relative corrosion rate is only less than 40%, which cannot meet the requirements of free coating, and the addition of P will inevitably deteriorate the cold working performance of the steel, which is not conducive to the deep processing of wire rods and round bars.
  • CN114959483A discloses a weathering steel resistant to a hot, humid and high-salinity marine atmosphere and a production method thereof, wherein the components of the weathering steel are calculated by mass percentage as follows: C: 0.02% to 0.06%, Si: 0.17% to 0.37%, Mn: 0.8% to 1.2%, P: ⁇ 0.012%, S: ⁇ 0.005%, Cu: 0.8% to 1.2%, Cr: 0.2% to 0.4%, Ni: 1.5% to 2%, Mo: 0.1% to 0.25%, Ti: 0.01% to 0.03%, Sn: 0.05% to 0.2%, and the rest is Fe and unavoidable inclusions.
  • the invention ensures that the steel plate has both excellent economy and corrosion resistance by adding a large amount of precious metal Ni and combining certain weathering elements, but the invention is relatively costly and is not suitable for cold processing of wire rods and round bars, and is only a conventional weathering plate.
  • Wire rods and round bars often have to go through multiple deep processing steps (such as cold drawing, stranding, rolling, etc.), and their application scenarios are quite different from those of plates.
  • coating-free weathering steel in plates is relatively mature, but there are no related reports in the field of wire rods and round bars.
  • According to the application scenario requirements of wire rods and round bars from the perspective of chemical composition and rolling process, how to design a 400MPa-grade coating-free hot-rolled wire rod, round bar and its rolling process to meet the needs of multiple industries to upgrade galvanized materials to coating-free weathering materials has become a technical problem that needs to be solved urgently.
  • the purpose of the present invention is to provide a 400MPa grade coating-free weather-resistant hot-rolled wire rod, round bar and its rolling process, which has excellent toughness, cold heading and weather resistance (relative corrosion rate ⁇ 25%), can meet the requirements of deep drawing and cold heading processing, and can meet the requirements of coating-free and bare use for more than 25 years.
  • a 400MPa grade coating-free hot-rolled wire rod and round bar the chemical composition of which is calculated by mass percentage as follows:
  • wire rods and round bars are long products.
  • long products refer to wire rods, bars, and profiles.
  • the long products of the present invention are mainly hot-rolled wire rods and hot-rolled round bars.
  • the rolling process of the above-mentioned 400MPa-grade coating-free hot-rolled wire rod and round bar comprises the following steps:
  • Billet heating including preheating section, heating section and soaking section;
  • Controlled cooling The wire rod adopts the Stelmor process for controlled cooling; the round bar adopts the upper cooling bed for insulation and slow cooling.
  • the billet in the billet heating step, is a small square billet or a rectangular billet with a cross-section of (140-220mm) ⁇ (140-220mm); the heating temperature of the preheating section is ⁇ 600°C, and the heating time is 15min-20min; the heating section is divided into heating section 1 and heating section 2, the heating temperature of heating section 1 is 600°C-1000°C, and the heating time is 10min-15min, the heating temperature of heating section 2 is 1000°C-1200°C, and the heating time is 20min-30min; the heating temperature of the soaking section is 1150°C-1200°C, and the heating time is 20min-30min.
  • the finishing rolling temperature is 830 ⁇ 10°C
  • the sizing temperature is 840 ⁇ 10°C
  • the final rolling temperature is 850 ⁇ 10°C, which are the main temperature parameters of low-temperature controlled rolling.
  • the cooling control step 9 rollers and 13 fans are used for cooling control.
  • the wire rod is cooled by the Stelmor process.
  • the speed of the 0# roller is 0.2-1m/s, and the speed of the remaining 8 rollers is increased by 3%-5% (extremely
  • the air volume of 13 sets of fans is 210000m3 /h, 1# ⁇ 2# fans are opened by 5% ⁇ 25%, and the insulation cover is opened to ensure that the outlet temperature of 2# fan is 700 ⁇ 20°C, 3# ⁇ 13# fans are all closed, and the insulation cover is closed to ensure that the outlet temperature of 13# fan is greater than 350°C.
  • the temperature of the round bar on the cooling bed is greater than 850°C, and a heat preservation cover is used for slow cooling, and the temperature out of the heat preservation cover is greater than 600°C.
  • Carbon has the most significant effect on the strength and plasticity of the wire rod. With the increase of carbon content, the strength of the wire rod continues to increase and the plasticity decreases sharply. The carbon content also affects the drawability of the final product. Taking all factors into consideration, the carbon content of the present invention is 0.02-0.10wt%.
  • Si Silicon is beneficial to corrosion resistance and can significantly improve the elastic limit of the drawn steel wire, but too high Si content will increase the brittleness of ferrite and is not conducive to cold heading. Taking all factors into consideration, the silicon content of the present invention is less than 0.25wt%.
  • Mn Manganese combines with sulfur to form MnS, thereby reducing the harm of sulfur, and can refine pearlite and improve the strength of steel wire; however, Mn is easy to segregate in steel, thereby causing uneven structure and performance, and too high Mn content will also increase production costs.
  • the manganese content of the present invention is less than 0.4wt%.
  • Phosphorus is one of the most effective alloying elements for improving the atmospheric corrosion resistance of steel. Phosphorus can be evenly dissolved in steel, which helps to form a dense protective film on the steel surface, so that the inside is not corroded by the atmosphere. Usually, when w(P) in steel is 0.08% to 0.15%, the corrosion resistance is the best; but for industrial wires that require deep cold processing, phosphorus is easy to produce cold brittleness, which has a great impact on the quality of steel, especially the cold processing performance, so it needs to be strictly controlled. Taking all factors into consideration, the phosphorus content P of the present invention is less than 0.03wt%.
  • S Sulfur is a harmful element in this steel. Sulfur is easy to cause hot brittleness, which in turn deteriorates the wire drawing and heat treatment processing conditions. If the mass fraction of residual sulfur in the steel is reduced to 0.01%, the weather resistance of carbon steel can be greatly improved. Taking all factors into consideration, the sulfur content S of the present invention is less than 0.02wt%.
  • Cu Copper is a commonly used alloying element in the production of corrosion-resistant steel materials. Cu is a metal element with a slow chemical reaction rate. By adding Cu, the strength of steel can be improved, but if the Cu content is too high, it will directly affect the low-temperature toughness of the steel. It is worth noting that copper has a significant effect in offsetting the harmful effects of sulfur in steel. Its action characteristic is that the higher the sulfur content in the steel, the more significant the relative effect of copper in reducing the corrosion rate. This is because copper and sulfur generate insoluble sulfides. Taking all factors into consideration, the copper content of the present invention is 0.1-1.0wt%.
  • Chromium is the main element that improves the weather resistance of steel. Chromium can form a dense oxide film on the surface of steel, improve the passivation ability of steel, and slow down the growth rate of rust layer. However, chromium will greatly improve the hardenability of steel. Excessive chromium will cause abnormal structures such as bainite and martensite to form in steel, which is not conducive to the cold working performance of steel. Taking all factors into consideration, the chromium content of the present invention is 1.0-4.5wt%.
  • Nb, V Niobium and vanadium are common microalloy strengthening elements, which can prevent the growth of austenite grains, refine the reheated austenite grains, and improve the uniformity of organization and performance, but excessive addition will significantly increase production costs, and the composite microalloying strengthening effect of Nb and V is better than that of a single element.
  • the 400MPa-grade coating-free hot-rolled wire rod and round bar of the present invention have a high alloy content.
  • the heating temperature and time of each area of the heating furnace are limited to ensure that the alloy is fully diffused and uniformed during the heating process without causing coarse grains due to high temperature.
  • low-temperature rolling is adopted to obtain fine grains during the rolling process, and slow cooling is combined to avoid the formation of abnormal bainite and martensite abnormal structures, so that the hot-rolled wire rod and round bar products have good cold processing performance.
  • the present invention has the following beneficial effects:
  • the present invention provides a 400MPa-grade hot-rolled wire rod and round bar without coating or plating and a rolling process thereof, which meet the requirements of downstream users for direct bare use without coating or plating and maintenance-free throughout the entire life cycle, thereby greatly reducing the production investment cost; in addition, the present invention has excellent steel strength and toughness through reasonable component design and coordination with the steel rolling process, which can meet various cold processing requirements of hot-rolled wire rods and round bars, thereby greatly expanding the application scenarios of weathering steel.
  • the production process of each embodiment of the present invention is as follows: molten iron pretreatment ⁇ converter/electric furnace smelting (decarbonization, dephosphorization, etc.) ⁇ argon station (deoxidation, alloying, etc.) ⁇ refining (composition adjustment and removal of inclusions, gases, etc.) ⁇ vacuum treatment (precise control of composition and temperature) ⁇ continuous casting ⁇ heating ⁇ rolling into products ⁇ controlled rolling cooling.
  • the detailed production process including smelting process (i.e., steps (1)-(5)) and rolling process (i.e., steps (6)-(8)) is as follows:
  • the molten steel is vacuum treated, the molten steel is circulated ⁇ 4 times, and the composition is fine-tuned;
  • Heating the steel billet including preheating section, heating section and soaking section;
  • the steel billet is a small square billet or a rectangular billet with a cross section of (140-220 mm) ⁇ (140-220 mm); the preheating temperature is ⁇ 600°C and the heating time is 15 min to 20 min; the heating section is divided into heating section 1 and heating section 2, and heating section 1 is used for heating the steel billet.
  • the heating temperature of the first heating section is 600°C ⁇ 1000°C, and the heating time is 10min ⁇ 15min.
  • the heating temperature of the second heating section is 1000°C ⁇ 1200°C, and the heating time is 20min ⁇ 30min.
  • the heating temperature of the soaking section is 1150°C ⁇ 1200°C, and the heating time is 20min ⁇ 30min.
  • Table 2 The specific process parameters are shown in Table 2.
  • the finishing rolling temperature is 830 ⁇ 10°C
  • the sizing temperature is 840 ⁇ 10°C
  • the final rolling temperature is 850 ⁇ 10°C; the specific process parameters are shown in Table 3;
  • Controlled cooling process The wire rod is cooled by the Stelmor process, and 9 rollers and 13 fans are used for controlled cooling.
  • the speed of the 0# roller is 0.2-1 m/s, and the speed of the remaining 8 rollers is increased by 3%-5% (extreme difference) compared with the previous roller.
  • the air volume of the 13 fans is 210000m3 /h, 1#-2# fans are opened by 5%-25%, and the insulation cover is opened to ensure that the outlet temperature of the 2# fan is 700 ⁇ 20°C, and the 3#-13# fans are all closed and the insulation cover is closed to ensure that the outlet temperature of the 13# fan is greater than 350°C.
  • the specific process parameters are shown in Table 4.
  • the round bar is slowly cooled by the upper cooling bed with the upper cooling bed temperature>850°C, and slowly cooled by the insulation cover with the temperature out of the insulation cover>600°C; the specific process parameters are shown in Table 4.
  • the production process of the comparative example is equivalent to that of the embodiment, and the main differences are the chemical composition, heating process parameters, rolling process parameters, and cooling control process parameters.
  • the chemical composition of each embodiment and comparative example of the present invention is shown in Table 1; the heating process parameters of each embodiment and comparative example are shown in Table 2; the rolling process parameters of each embodiment and comparative example are shown in Table 3; the cooling control process parameters of each embodiment and comparative example are shown in Table 4.
  • the test results (toughness, cold heading performance, weather resistance) of each embodiment and comparative example are shown in Table 5.
  • the comparative example contains certain weather-resistant elements (Cr, Cu), but the ratio and content of the relevant elements are significantly different from those of the embodiment. Under the same process flow and different process control, even at lower C and weather-resistant element contents, the toughness and weather resistance of the final wire rod and round bar products of the embodiment are significantly better than those of the comparative example, demonstrating the advancement and creativity of the present invention.
  • the comparative steel types can meet the 400MPa grade requirements, cracks appear in cold heading and the relative corrosion rate is ⁇ 60%, which cannot meet the requirements of deep processing and free coating and plating of hot-rolled wire rods and round bars; while the 400MPa-grade free coating and plating hot-rolled wire rods, round bars and their rolling process developed by the present invention have excellent strength and toughness, with a strength of 400MPa and a surface reduction rate of ⁇ 70%, a relative corrosion rate of ⁇ 25%, excellent cold workability and can meet the user's requirements for free coating and plating and direct bare use.

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Abstract

Disclosed in the present invention is a 400 MPa-grade coating-free hot-rolled wire rod and round rod, which comprises the following chemical components in percentages by mass: C: 0.02-0.10 wt%, Si <0.25 wt%, Mn <0.4 wt%, P<0.03 wt%, S<0.02 wt%, Cu: 0.1-1.0 wt%, Cr: 1.0-4.5 wt%, with Cr/Cu ＝ 5-11, and the balance of Fe and inevitable impurities. The wire rod and the round rod can also undergo the process of microalloying, and further comprise the following chemical components in percentages by mass: Nb: 0.015-0.035 wt%, V: 0.04-0.07 wt%, and Nb/V = 1/3 to 2/3. The 400 MPa-grade coating-free hot-rolled wire rod and round rod and a rolling process therefor provided in the present invention satisfy the coating-free direct naked use requirements and the maintenance-free requirements of the whole life cycle of downstream users, thereby greatly reducing the production and investment cost; in addition, by means of rational component design and matching with a steel rolling process in the present invention, the steel has good strength and toughness, can satisfy various cold machining requirements of a hot-rolled wire rod and round rod, and the use scenarios of a weathering steel are greatly expanded.

Description

一种400MPa级免涂镀热轧盘条、圆棒及其轧制工艺A 400MPa-grade coating-free hot-rolled wire rod, round bar and rolling process thereof 技术领域Technical Field
本发明属于冶金技术领域，具体涉及一种400MPa级免涂镀热轧盘条、圆棒及其轧制工艺。The invention belongs to the technical field of metallurgy, and in particular relates to a 400MPa-grade coating-free hot-rolled wire rod, a round bar and a rolling process thereof.
背景技术Background technique
随着“双碳”目标推进，具有免涂镀、长寿命的耐候钢正成为当下绿色钢铁产品的发展热点；目前，国内外生产的耐候钢多数为板材，由于盘条、圆棒与板材完全不同的深加工流程和应用场景，对产品组织与性能要求差异较大，对于连轧道次多、组织性能要求高且冷加工变形量大的耐候钢结构用热轧盘条及圆钢，国内鲜有报道。With the advancement of the "dual carbon" goals, weathering steel with no coating and long life is becoming a hot spot for the development of green steel products. At present, most of the weathering steels produced at home and abroad are plates. Due to the completely different deep processing processes and application scenarios of wire rods, round bars and plates, the requirements for product organization and performance vary greatly. There are few reports in China on hot-rolled wire rods and round bars for weathering steel structures with many continuous rolling passes, high requirements for organization and performance, and large cold processing deformation.
CN115110006A公开了一种具有高耐腐蚀性能的耐候钢及制备方法，一种耐候钢，其化学成分及其质量百分含量为：C：0.05～0.12％，Si：0.20～0.60％，Mn：0.30～0.60％，P：0.07～0.15％，S：≤0.015％，Cu：0.25～0.55％，Ni：≤0.20％，Cr：0.30～0.60％，余量为Fe及不可避免的杂质，耐大气腐蚀性的相对腐蚀速率为Q345B的40％以下。该发明为确保钢质耐腐蚀性能，向钢中添加了一定的P、Cu、Cr等耐候元素，但其相对腐蚀率只有40％以下，无法满足免涂镀要求，并且P的加入导致钢质冷加工性能必然恶化，对于盘条、圆棒的深加工不利。CN115110006A discloses a weathering steel with high corrosion resistance and a preparation method, a weathering steel, the chemical composition and its mass percentage are: C: 0.05-0.12%, Si: 0.20-0.60%, Mn: 0.30-0.60%, P: 0.07-0.15%, S: ≤0.015%, Cu: 0.25-0.55%, Ni: ≤0.20%, Cr: 0.30-0.60%, the balance is Fe and inevitable impurities, and the relative corrosion rate of atmospheric corrosion resistance is less than 40% of Q345B. In order to ensure the corrosion resistance of steel, the invention adds certain weathering elements such as P, Cu, Cr to the steel, but its relative corrosion rate is only less than 40%, which cannot meet the requirements of free coating, and the addition of P will inevitably deteriorate the cold working performance of the steel, which is not conducive to the deep processing of wire rods and round bars.
CN114959483A公开了一种耐湿热高盐分海洋大气环境的耐候钢及其生产方法，所述耐候钢的组分按质量百分含量计为：C：0.02％～0.06％，Si：0.17％～0.37％，Mn：0.8％～1.2％，P：≤0.012％，S：≤0.005％，Cu：0.8％～1.2％，Cr：0.2％～0.4％，Ni：1.5％～2％，Mo：0.1％～0.25％，Ti：0.01％～0.03％，Sn：0.05％～0.2％，其余为Fe及不可避免夹杂。该发明通过添加大量贵重金属Ni并配合一定的耐候元素，以确保钢板兼备优异的经济性和耐蚀性，但该发明成本较高且不适用于盘条、圆棒的冷加工，只是常规的耐候板。CN114959483A discloses a weathering steel resistant to a hot, humid and high-salinity marine atmosphere and a production method thereof, wherein the components of the weathering steel are calculated by mass percentage as follows: C: 0.02% to 0.06%, Si: 0.17% to 0.37%, Mn: 0.8% to 1.2%, P: ≤0.012%, S: ≤0.005%, Cu: 0.8% to 1.2%, Cr: 0.2% to 0.4%, Ni: 1.5% to 2%, Mo: 0.1% to 0.25%, Ti: 0.01% to 0.03%, Sn: 0.05% to 0.2%, and the rest is Fe and unavoidable inclusions. The invention ensures that the steel plate has both excellent economy and corrosion resistance by adding a large amount of precious metal Ni and combining certain weathering elements, but the invention is relatively costly and is not suitable for cold processing of wire rods and round bars, and is only a conventional weathering plate.
盘条、圆棒往往都要经过多道工序的深加工(如：冷拔、捻股、辊压等)，其应用场景与板材有较大差距，当前免涂镀耐候钢在板材中发展较为成熟，但在盘条、圆棒领域则未见相关报道。根据盘条、圆棒应用场景要求，从化学成分、轧制工艺综合考虑，如何设计出一种400MPa级免涂镀热轧盘条、圆棒及其轧制工艺，以满足多个行业将镀锌材升级为免涂镀耐候材的需求，成为亟待解决的技术问题。 Wire rods and round bars often have to go through multiple deep processing steps (such as cold drawing, stranding, rolling, etc.), and their application scenarios are quite different from those of plates. Currently, the development of coating-free weathering steel in plates is relatively mature, but there are no related reports in the field of wire rods and round bars. According to the application scenario requirements of wire rods and round bars, from the perspective of chemical composition and rolling process, how to design a 400MPa-grade coating-free hot-rolled wire rod, round bar and its rolling process to meet the needs of multiple industries to upgrade galvanized materials to coating-free weathering materials has become a technical problem that needs to be solved urgently.
发明内容Summary of the invention
本发明目的在于提供一种400MPa级免涂镀耐候热轧盘条、圆棒及其轧制工艺，具有优异的强韧性、冷镦性以及耐候性能(相对腐蚀率≤25％)，可满足深度拉拔和冷镦加工要求，并且能满足免涂镀、25年以上裸用要求。The purpose of the present invention is to provide a 400MPa grade coating-free weather-resistant hot-rolled wire rod, round bar and its rolling process, which has excellent toughness, cold heading and weather resistance (relative corrosion rate ≤ 25%), can meet the requirements of deep drawing and cold heading processing, and can meet the requirements of coating-free and bare use for more than 25 years.
为达到上述目的，采用技术方案如下：In order to achieve the above purpose, the technical solutions adopted are as follows:
一种400MPa级免涂镀热轧盘条、圆棒，其化学成分按质量百分数计如下：A 400MPa grade coating-free hot-rolled wire rod and round bar, the chemical composition of which is calculated by mass percentage as follows:
C：0.02～0.10wt％、Si：＜0.25wt％、Mn：＜0.4wt％、P＜0.03wt％、S＜0.02wt％、Cu：0.1～1.0wt％、Cr：1.0～4.5wt％、Cr/Cu＝5～11，其余为Fe及不可避免的杂质；盘条和圆棒均为长材。注：钢材的大类中长材指的是线材、棒材、型材，本发明的长材产品主要是热轧盘条和热轧圆棒。C: 0.02-0.10wt%, Si: <0.25wt%, Mn: <0.4wt%, P <0.03wt%, S <0.02wt%, Cu: 0.1-1.0wt%, Cr: 1.0-4.5wt%, Cr/Cu=5-11, the rest is Fe and unavoidable impurities; wire rods and round bars are long products. Note: Among the major categories of steel products, long products refer to wire rods, bars, and profiles. The long products of the present invention are mainly hot-rolled wire rods and hot-rolled round bars.
按上述方案，C：0.04～0.08wt％、Si：＜0.25wt％、Mn：＜0.4wt％、P＜0.03wt％、S＜0.02wt％、Cu：0.3～0.7wt％、Cr：2.0～3.0wt％、Cr/Cu＝6～10，其余为Fe及不可避免的杂质。According to the above scheme, C: 0.04~0.08wt%, Si: <0.25wt%, Mn: <0.4wt%, P <0.03wt%, S <0.02wt%, Cu: 0.3~0.7wt%, Cr: 2.0~3.0wt%, Cr/Cu=6~10, and the rest is Fe and unavoidable impurities.
按上述方案，精炼过程可进行微合金化，其化学成分按质量百分数计还包括Nb：0.015～0.035wt％、V：0.04～0.07wt％、Nb/V＝1/3～2/3。According to the above scheme, microalloying can be performed during the refining process, and the chemical composition thereof includes, by mass percentage, Nb: 0.015-0.035wt%, V: 0.04-0.07wt%, and Nb/V=1/3-2/3.
上述400MPa级免涂镀热轧盘条、圆棒的轧制工艺，包括以下步骤：The rolling process of the above-mentioned 400MPa-grade coating-free hot-rolled wire rod and round bar comprises the following steps:
钢坯加热：包括预热段、加热段和均热段；Billet heating: including preheating section, heating section and soaking section;
轧制：采取低温控轧，全流程采用奥氏体未再结晶轧制；Rolling: Low temperature controlled rolling is adopted, and austenite non-recrystallization rolling is adopted in the whole process;
控冷：盘条采用斯太尔摩工艺控制冷却；圆棒采用上冷床保温缓冷。Controlled cooling: The wire rod adopts the Stelmor process for controlled cooling; the round bar adopts the upper cooling bed for insulation and slow cooling.
按上述方案，钢坯加热步骤中，钢坯为小方坯或矩形坯，断面(140～220mm)×(140～220mm)；预热段加热温度≤600℃、加热时间15min～20min；加热段分加热1段和加热2段，加热1段的加热温度600℃～1000℃、加热时间10min～15min，加热2段的加热温度1000℃～1200℃、加热时间20min～30min；均热段加热温度1150℃～1200℃、加热时间20min～30min。According to the above scheme, in the billet heating step, the billet is a small square billet or a rectangular billet with a cross-section of (140-220mm)×(140-220mm); the heating temperature of the preheating section is ≤600°C, and the heating time is 15min-20min; the heating section is divided into heating section 1 and heating section 2, the heating temperature of heating section 1 is 600°C-1000°C, and the heating time is 10min-15min, the heating temperature of heating section 2 is 1000°C-1200°C, and the heating time is 20min-30min; the heating temperature of the soaking section is 1150°C-1200°C, and the heating time is 20min-30min.
按上述方案，轧制步骤中，精轧温度为830±10℃、入减定径温度840±10℃，终轧温度850±10℃，这就是低温控轧的主要温度参数。According to the above scheme, in the rolling step, the finishing rolling temperature is 830±10℃, the sizing temperature is 840±10℃, and the final rolling temperature is 850±10℃, which are the main temperature parameters of low-temperature controlled rolling.
按上述方案，控冷步骤中，采用9组辊道和13组风机进行控冷，盘条采用斯太尔摩工艺控制冷却，0#辊道速度0.2～1m/s，余下8组辊道速度相对于前一组辊道提升3％～5％(极 差)；13组风机的风量为210000m3/h，1#～2#风机开启5％～25％，保温盖开启，确保出2#风机温度为700±20℃，3#～13#风机全关、保温盖关闭，确保出13#风机温度＞350℃。According to the above scheme, in the cooling control step, 9 rollers and 13 fans are used for cooling control. The wire rod is cooled by the Stelmor process. The speed of the 0# roller is 0.2-1m/s, and the speed of the remaining 8 rollers is increased by 3%-5% (extremely The air volume of 13 sets of fans is 210000m3 /h, 1#~2# fans are opened by 5%~25%, and the insulation cover is opened to ensure that the outlet temperature of 2# fan is 700±20℃, 3#~13# fans are all closed, and the insulation cover is closed to ensure that the outlet temperature of 13# fan is greater than 350℃.
按上述方案，控冷步骤中，圆棒上冷床温度＞850℃，采用保温罩缓冷，出保温罩温度＞600℃。According to the above scheme, in the controlled cooling step, the temperature of the round bar on the cooling bed is greater than 850°C, and a heat preservation cover is used for slow cooling, and the temperature out of the heat preservation cover is greater than 600°C.
本发明中主要强化元素及工艺的作用及机理如下：The functions and mechanisms of the main strengthening elements and processes in the present invention are as follows:
C：碳对盘条的强度和塑性影响最为显著，随着碳含量的增加，盘条强度不断提高、塑性急剧降低，碳含量还影响最终成品可拉拔性能。综合考虑，本发明碳含量为0.02～0.10wt％。C: Carbon has the most significant effect on the strength and plasticity of the wire rod. With the increase of carbon content, the strength of the wire rod continues to increase and the plasticity decreases sharply. The carbon content also affects the drawability of the final product. Taking all factors into consideration, the carbon content of the present invention is 0.02-0.10wt%.
Si：硅元素对耐腐蚀性能有利，并能显著提高拉拔后钢丝的弹性极限，但过高的Si含量将增大铁素体脆性不利于冷镦加工。综合考虑，本发明硅含量＜0.25wt％。Si: Silicon is beneficial to corrosion resistance and can significantly improve the elastic limit of the drawn steel wire, but too high Si content will increase the brittleness of ferrite and is not conducive to cold heading. Taking all factors into consideration, the silicon content of the present invention is less than 0.25wt%.
Mn：锰与硫结合生成MnS进而减轻硫的危害，并能细化珠光体、提高钢丝强度；但Mn在钢中易于偏聚，进而引起组织与性能不均匀，过高的Mn含量还将增加生产成本。综合考虑，本发明锰含量＜0.4wt％。Mn: Manganese combines with sulfur to form MnS, thereby reducing the harm of sulfur, and can refine pearlite and improve the strength of steel wire; however, Mn is easy to segregate in steel, thereby causing uneven structure and performance, and too high Mn content will also increase production costs. Comprehensive consideration, the manganese content of the present invention is less than 0.4wt%.
P：磷是提高钢耐大气腐蚀性能最有效的合金元素之一，磷在钢中能均匀溶解，有助于在钢表面形成致密的保护膜，使其内部不被大气腐蚀，通常钢中w(P)＝0.08％～0.15％时耐蚀性最佳；但对于需深度冷加工的工业线材而言，磷容易产生冷脆，对钢质量尤其是冷加工性能有较大影响，为此需进行严格控制。综合考虑，本发明磷含量P＜0.03wt％。P: Phosphorus is one of the most effective alloying elements for improving the atmospheric corrosion resistance of steel. Phosphorus can be evenly dissolved in steel, which helps to form a dense protective film on the steel surface, so that the inside is not corroded by the atmosphere. Usually, when w(P) in steel is 0.08% to 0.15%, the corrosion resistance is the best; but for industrial wires that require deep cold processing, phosphorus is easy to produce cold brittleness, which has a great impact on the quality of steel, especially the cold processing performance, so it needs to be strictly controlled. Taking all factors into consideration, the phosphorus content P of the present invention is less than 0.03wt%.
S：硫在本钢种属于有害元素，硫容易产生热脆，进而恶化钢丝拉拔和热处理加工条件，并且如果使钢中残余硫的质量分数降至0.01％，则可使碳素钢的耐候性获得大幅度提升。综合考虑，本发明硫含量S＜0.02wt％。S: Sulfur is a harmful element in this steel. Sulfur is easy to cause hot brittleness, which in turn deteriorates the wire drawing and heat treatment processing conditions. If the mass fraction of residual sulfur in the steel is reduced to 0.01%, the weather resistance of carbon steel can be greatly improved. Taking all factors into consideration, the sulfur content S of the present invention is less than 0.02wt%.
Cu：铜是生产耐腐蚀类钢铁材料常用的合金添加元素，Cu是一种化学反应速度较慢的金属元素，通过添加Cu就能够提高钢材的强度，但如果Cu含量过高，会直接影响钢材的低温韧性。值得注意的是，铜抵消钢中硫的有害作用的效果很明显，其作用特点是，钢中硫含量愈高，铜降低腐蚀速率的相对效果愈显著。这是因为铜与硫生成了难溶硫化物。综合考虑，本发明铜含量为0.1～1.0wt％。Cu: Copper is a commonly used alloying element in the production of corrosion-resistant steel materials. Cu is a metal element with a slow chemical reaction rate. By adding Cu, the strength of steel can be improved, but if the Cu content is too high, it will directly affect the low-temperature toughness of the steel. It is worth noting that copper has a significant effect in offsetting the harmful effects of sulfur in steel. Its action characteristic is that the higher the sulfur content in the steel, the more significant the relative effect of copper in reducing the corrosion rate. This is because copper and sulfur generate insoluble sulfides. Taking all factors into consideration, the copper content of the present invention is 0.1-1.0wt%.
Cr：铬是提升钢耐候性能的主要元素，铬能在钢表面形成致密的氧化膜，提高钢的钝化能力，使锈层生长速度减慢。但铬会大幅度提升钢的淬透性，过量的铬会导致钢中形成贝氏体、马氏体等异常组织，对钢的冷加工性能不利。综合考虑，本发明铬含量为1.0～4.5wt％。Cr: Chromium is the main element that improves the weather resistance of steel. Chromium can form a dense oxide film on the surface of steel, improve the passivation ability of steel, and slow down the growth rate of rust layer. However, chromium will greatly improve the hardenability of steel. Excessive chromium will cause abnormal structures such as bainite and martensite to form in steel, which is not conducive to the cold working performance of steel. Taking all factors into consideration, the chromium content of the present invention is 1.0-4.5wt%.
Cr/Cu：同为耐候元素铜、铬存在协同强化作用，基于最经济成本考虑，本发明中Cr/Cu＝5～11。 Cr/Cu: Copper and chromium, both weather-resistant elements, have a synergistic strengthening effect. Based on the most economical cost consideration, in the present invention, Cr/Cu=5-11.
Nb、V：铌、钒是常见微合金强化元素，可阻止奥氏体晶粒长大，细化再加热奥氏体晶粒，提高组织与性能的均匀性，但过量加入将显著提升生产成本，并且Nb、V复合微合金化强化效果优于单个元素作用。综合考虑，本发明铌、钒含量分别为0.015～0.035wt％、0.04～0.07wt％，且Nb/V＝1/3～2/3。Nb, V: Niobium and vanadium are common microalloy strengthening elements, which can prevent the growth of austenite grains, refine the reheated austenite grains, and improve the uniformity of organization and performance, but excessive addition will significantly increase production costs, and the composite microalloying strengthening effect of Nb and V is better than that of a single element. Taking all factors into consideration, the contents of niobium and vanadium in the present invention are 0.015-0.035wt% and 0.04-0.07wt%, respectively, and Nb/V=1/3-2/3.
另外，本发明所述400MPa级免涂镀热轧盘条、圆棒的合金含量高，钢坯加热时对加热炉各区域加热温度与时间进行了限制，确保加热过程合金充分扩散均匀化的同时，不至于因高温导致晶粒粗大；轧制过程为获得最终热轧产品良好的强韧性，采取低温轧制获得细小晶粒，并结合采取缓慢冷却避免异常的贝氏体、马氏体异常组织形成，以便热轧盘条、圆棒产品具备良好的冷加工性能。In addition, the 400MPa-grade coating-free hot-rolled wire rod and round bar of the present invention have a high alloy content. When the steel billet is heated, the heating temperature and time of each area of the heating furnace are limited to ensure that the alloy is fully diffused and uniformed during the heating process without causing coarse grains due to high temperature. In order to obtain good strength and toughness of the final hot-rolled product, low-temperature rolling is adopted to obtain fine grains during the rolling process, and slow cooling is combined to avoid the formation of abnormal bainite and martensite abnormal structures, so that the hot-rolled wire rod and round bar products have good cold processing performance.
相对于现有技术，本发明有益效果如下：Compared with the prior art, the present invention has the following beneficial effects:
本发明提供了一种400MPa级免涂镀热轧盘条、圆棒及其轧制工艺，满足下游用户免涂镀直接裸用以及全寿命周期的免维护要求，大幅降低了生产投资成本；另外，本发明通过合理的成分设计以及与轧钢工艺相配合，钢质强韧性优良，能满足热轧盘条、圆棒的各种冷加工要求，大幅度扩展了耐候钢应用场景。The present invention provides a 400MPa-grade hot-rolled wire rod and round bar without coating or plating and a rolling process thereof, which meet the requirements of downstream users for direct bare use without coating or plating and maintenance-free throughout the entire life cycle, thereby greatly reducing the production investment cost; in addition, the present invention has excellent steel strength and toughness through reasonable component design and coordination with the steel rolling process, which can meet various cold processing requirements of hot-rolled wire rods and round bars, thereby greatly expanding the application scenarios of weathering steel.
具体实施方式Detailed ways
以下实施例进一步阐释本发明的技术方案，但不作为对本发明保护范围的限制。The following examples further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.
本发明各实施例的生产工艺流程如下：铁水预处理→转炉/电炉冶炼(脱C、脱P等)→氩站(脱氧、合金化等)→精炼(成分调整以及去除夹杂物、气体等)→真空处理(成分、温度精准调控)→连铸→加热→轧制成材→控轧冷却。详细的生产工艺(包括冶炼工艺(即步骤(1)-(5))和轧制工艺(即步骤(6)-(8))，具体步骤如下：The production process of each embodiment of the present invention is as follows: molten iron pretreatment → converter/electric furnace smelting (decarbonization, dephosphorization, etc.) → argon station (deoxidation, alloying, etc.) → refining (composition adjustment and removal of inclusions, gases, etc.) → vacuum treatment (precise control of composition and temperature) → continuous casting → heating → rolling into products → controlled rolling cooling. The detailed production process (including smelting process (i.e., steps (1)-(5)) and rolling process (i.e., steps (6)-(8)) is as follows:
(1)对铁水进行深脱硫处理，处理后铁水[S]≤0.05％；(1) deep desulfurization treatment is performed on the molten iron, and after the treatment, the molten iron [S] is ≤ 0.05%;
(2)转炉采用大渣量深脱P和高碳出钢工艺，出钢P≤0.008％、出钢C＝0.04-0.08％，出钢过程进行脱氧合金化；(2) The converter adopts a large amount of slag deep dephosphorization and high carbon steelmaking process, with the steelmaking P ≤ 0.008% and the steelmaking C = 0.04-0.08%, and deoxidation and alloying are performed during the steelmaking process;
(3)精炼渣碱度R＝1.0-4.5，精炼结束后进行软吹，软吹周期≥30min；(3) The basicity of the refined slag is R = 1.0-4.5. After the refining is completed, soft blowing is performed, and the soft blowing cycle is ≥ 30 min;
(4)精炼后钢水进行真空处理，钢水循环≥4次，并对成分进行微调；(4) After refining, the molten steel is vacuum treated, the molten steel is circulated ≥ 4 times, and the composition is fine-tuned;
(5)连铸过程全程保护浇注，过热度稳定控制在≤30℃，得到钢坯；(5) The continuous casting process is protected during pouring, and the superheat is stably controlled at ≤30°C to obtain a steel billet;
(6)对钢坯进行加热：包括预热段、加热段和均热段；(6) Heating the steel billet: including preheating section, heating section and soaking section;
该钢坯加热步骤中，钢坯为小方坯或矩形坯，断面(140～220mm)×(140～220mm)；预热段加热温度≤600℃、加热时间15min～20min；加热段分加热1段和加热2段，加热1 段的加热温度600℃～1000℃、加热时间10min～15min，加热2段的加热温度1000℃～1200℃、加热时间20min～30min；均热段加热温度1150℃～1200℃、加热时间20min～30min；具体工艺参数详见表2；In the steel billet heating step, the steel billet is a small square billet or a rectangular billet with a cross section of (140-220 mm)×(140-220 mm); the preheating temperature is ≤600°C and the heating time is 15 min to 20 min; the heating section is divided into heating section 1 and heating section 2, and heating section 1 is used for heating the steel billet. The heating temperature of the first heating section is 600℃～1000℃, and the heating time is 10min～15min. The heating temperature of the second heating section is 1000℃～1200℃, and the heating time is 20min～30min. The heating temperature of the soaking section is 1150℃～1200℃, and the heating time is 20min～30min. The specific process parameters are shown in Table 2.
(7)轧制：采取低温控轧，全流程采用奥氏体未再结晶轧制；(7) Rolling: Low temperature controlled rolling is adopted, and austenite non-recrystallization rolling is adopted in the whole process;
该轧制步骤中，精轧温度为830±10℃、入减定径温度840±10℃，终轧温度850±10℃；具体工艺参数详见表3；In this rolling step, the finishing rolling temperature is 830±10°C, the sizing temperature is 840±10°C, and the final rolling temperature is 850±10°C; the specific process parameters are shown in Table 3;
(8)控冷工艺：盘条采用斯太尔摩工艺控制冷却，采用9组辊道和13组风机进行控冷，0#辊道速度0.2～1m/s，余下8组辊道速度相对于前一组辊道提升3％～5％(极差)；13组风机的风量为210000m3/h，1#～2#风机开启5％～25％，保温盖开启，确保出2#风机温度为700±20℃，3#～13#风机全关、保温盖关闭，确保出13#风机温度＞350℃；具体工艺参数详见表4；(8) Controlled cooling process: The wire rod is cooled by the Stelmor process, and 9 rollers and 13 fans are used for controlled cooling. The speed of the 0# roller is 0.2-1 m/s, and the speed of the remaining 8 rollers is increased by 3%-5% (extreme difference) compared with the previous roller. The air volume of the 13 fans is 210000m3 /h, 1#-2# fans are opened by 5%-25%, and the insulation cover is opened to ensure that the outlet temperature of the 2# fan is 700±20℃, and the 3#-13# fans are all closed and the insulation cover is closed to ensure that the outlet temperature of the 13# fan is greater than 350℃. The specific process parameters are shown in Table 4.
圆棒采用上冷床保温缓冷，上冷床温度＞850℃，采用保温罩缓冷，出保温罩温度＞600℃；具体工艺参数详见表4。The round bar is slowly cooled by the upper cooling bed with the upper cooling bed temperature>850℃, and slowly cooled by the insulation cover with the temperature out of the insulation cover>600℃; the specific process parameters are shown in Table 4.
对比例的生产工艺与实施例相当，主要是化学成分以及加热工艺参数、轧制过程的工艺参数以及控冷工艺参数存在不同之处。本发明各实施例和对比例的化学成分见表1；各实施例和对比例的加热工艺参数见表2；各实施例和对比例轧制过程的工艺参数见表3；各实施例和对比例的控冷工艺参数见表4。各实施例和对比例试验效果(强韧性、冷镦性能、耐候性)见表5。The production process of the comparative example is equivalent to that of the embodiment, and the main differences are the chemical composition, heating process parameters, rolling process parameters, and cooling control process parameters. The chemical composition of each embodiment and comparative example of the present invention is shown in Table 1; the heating process parameters of each embodiment and comparative example are shown in Table 2; the rolling process parameters of each embodiment and comparative example are shown in Table 3; the cooling control process parameters of each embodiment and comparative example are shown in Table 4. The test results (toughness, cold heading performance, weather resistance) of each embodiment and comparative example are shown in Table 5.
表1化学成分

Table 1 Chemical composition

表2加热工艺参数
Table 2 Heating process parameters
表3轧制工艺参数
Table 3 Rolling process parameters
表4控冷工艺参数
Table 4 Controlled cooling process parameters
表5试验效果
Table 5 Test results
从表5可知，对比例中含有一定的耐候元素(Cr、Cu)，但相关元素配比与含量与实施例存在明显差别，在经过相同工艺流程和不同工艺控制下，实施例即使在更低C与耐候元素含量下，最终盘条和圆棒产品的强韧性、耐候性也均显著优于对比例，展现出本发明的先进性与创造性。It can be seen from Table 5 that the comparative example contains certain weather-resistant elements (Cr, Cu), but the ratio and content of the relevant elements are significantly different from those of the embodiment. Under the same process flow and different process control, even at lower C and weather-resistant element contents, the toughness and weather resistance of the final wire rod and round bar products of the embodiment are significantly better than those of the comparative example, demonstrating the advancement and creativity of the present invention.
而且，从表5还可知，对比例钢种虽然能达到400MPa级要求，但冷镦出现开裂并且相对腐蚀率≥60％，不能满足热轧盘条、圆棒深加工和免涂镀要求；而本发明开发的400MPa级免涂镀热轧盘条、圆棒及其轧制工艺，具有优异的强韧性，强度达到400MPa级且面缩率≥70％、相对腐蚀率≤25％，具备优良的冷加工性并可满足用户免涂镀、直接裸用要求。Moreover, it can be seen from Table 5 that although the comparative steel types can meet the 400MPa grade requirements, cracks appear in cold heading and the relative corrosion rate is ≥60%, which cannot meet the requirements of deep processing and free coating and plating of hot-rolled wire rods and round bars; while the 400MPa-grade free coating and plating hot-rolled wire rods, round bars and their rolling process developed by the present invention have excellent strength and toughness, with a strength of 400MPa and a surface reduction rate of ≥70%, a relative corrosion rate of ≤25%, excellent cold workability and can meet the user's requirements for free coating and plating and direct bare use.
以上所述仅是本发明的优选实施方式，应当指出，对于本领域的普通技术人员来说，在不脱离本发明创造构思的前提下，还可以做出若干改进和变换，这些都属于本发明的保护范围。 The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and changes without departing from the creative concept of the present invention, and these all fall within the protection scope of the present invention.

Claims (8)

  1. 一种400MPa级免涂镀热轧长材，其特征在于化学成分按质量百分数计如下：A 400MPa grade coating-free hot-rolled long product, characterized in that the chemical composition is as follows by mass percentage:
    C：0.02～0.10wt％、Si：＜0.25wt％、Mn：＜0.4wt％、P＜0.03wt％、S＜0.02wt％、Cu：0.1～1.0wt％、Cr：1.0～4.5wt％、Cr/Cu＝5～11，其余为Fe及不可避免的杂质；所述的长材是盘条或圆棒。C: 0.02-0.10wt%, Si: <0.25wt%, Mn: <0.4wt%, P <0.03wt%, S <0.02wt%, Cu: 0.1-1.0wt%, Cr: 1.0-4.5wt%, Cr/Cu=5-11, and the rest is Fe and unavoidable impurities; the long product is a wire rod or a round bar.
  2. 如权利要求1所述400MPa级免涂镀热轧长材，其特征在于化学成分按质量百分数计如下：C：0.04～0.08wt％、Si：＜0.25wt％、Mn：＜0.4wt％、P＜0.03wt％、S＜0.02wt％、Cu：0.3～0.7wt％、Cr：2.0～3.0wt％、Cr/Cu＝6～10，其余为Fe及不可避免的杂质。The 400 MPa grade coating-free hot-rolled long product as described in claim 1 is characterized in that the chemical composition is as follows in percentage by mass: C: 0.04-0.08wt%, Si: <0.25wt%, Mn: <0.4wt%, P <0.03wt%, S <0.02wt%, Cu: 0.3-0.7wt%, Cr: 2.0-3.0wt%, Cr/Cu=6-10, and the rest is Fe and unavoidable impurities.
  3. 如权利要求1所述400MPa级免涂镀热轧长材，其特征在于可进行微合金化，其化学成分按质量百分数计还包括Nb：0.015～0.035wt％、V：0.04～0.07wt％、Nb/V＝1/3～2/3。The 400MPa grade coating-free hot-rolled long product as claimed in claim 1 is characterized in that it can be micro-alloyed, and its chemical composition, calculated by mass percentage, also includes Nb: 0.015~0.035wt%, V: 0.04~0.07wt%, Nb/V=1/3~2/3.
  4. 权利要求1所述400MPa级免涂镀热轧长材的轧制工艺，其特征在于包括以下步骤：The rolling process of the 400MPa-grade coating-free hot-rolled long product according to claim 1 is characterized in that it comprises the following steps:
    钢坯加热：包括预热段、加热段和均热段；Billet heating: including preheating section, heating section and soaking section;
    轧制：采取低温控轧，全流程采用奥氏体未再结晶轧制；Rolling: Low temperature controlled rolling is adopted, and austenite non-recrystallization rolling is adopted in the whole process;
    控冷：所述长材为盘条时，采用斯太尔摩工艺控制冷却；所述长材为圆棒时，采用上冷床保温缓冷。Controlled cooling: When the long product is a wire rod, the Stelmor process is used for controlled cooling; when the long product is a round bar, an upper cooling bed is used for heat preservation and slow cooling.
  5. 如权利要求4所述400MPa级免涂镀热轧长材的轧制工艺，其特征在于钢坯加热工艺中钢坯为小方坯或矩形坯，断面(140～220mm)×(140～220mm)；预热段加热温度≤600℃、加热时间15min～20min；加热段分加热1段和加热2段，加热1段的加热温度600℃～1000℃、加热时间10min～15min，加热2段的加热温度1000℃～1200℃、加热时间20min～30min；均热段加热温度1150℃～1200℃、加热时间20min～30min。The rolling process of 400MPa grade coating-free hot-rolled long products as described in claim 4 is characterized in that the billet in the billet heating process is a small square billet or a rectangular billet with a cross-section of (140-220mm)×(140-220mm); the heating temperature of the preheating section is ≤600°C and the heating time is 15min-20min; the heating section is divided into heating section 1 and heating section 2, the heating temperature of heating section 1 is 600°C-1000°C and the heating time is 10min-15min, the heating temperature of heating section 2 is 1000°C-1200°C and the heating time is 20min-30min; the heating temperature of the soaking section is 1150°C-1200°C and the heating time is 20min-30min.
  6. 如权利要求4所述400MPa级免涂镀热轧长材的轧制工艺，其特征在于轧制工艺中精轧温度为830±10℃、入减定径温度840±10℃，终轧温度850±10℃。The rolling process of the 400MPa grade coating-free hot-rolled long product as described in claim 4 is characterized in that the finishing rolling temperature in the rolling process is 830±10℃, the sizing temperature is 840±10℃, and the final rolling temperature is 850±10℃.
  7. 如权利要求4所述400MPa级免涂镀热轧长材的轧制工艺，其特征在于控冷工艺中，所述长材为盘条时，采用斯太尔摩工艺控制冷却，9组辊道中0#辊道速度0.2～1m/s，余下8组辊道速度相对于前一组辊道提升3％；全部1#～13#组风机的风量均为210000m3/h，1#～2#风机开启5％～25％，保温盖开启，确保出2#风机温度为700±20℃，3#～13#风机全关、保温盖关闭，确保出13#风机温度＞350℃。The rolling process of 400MPa-grade coating-free hot-rolled long products as claimed in claim 4 is characterized in that in the controlled cooling process, when the long product is a wire rod, the Stelmor process is used to control the cooling, the speed of the 0# roller in the 9 groups of rollers is 0.2-1m/s, and the speed of the remaining 8 groups of rollers is increased by 3% relative to the previous group of rollers; the air volume of all 1# to 13# groups of fans is 210,000m3 /h, 1# to 2# fans are opened by 5% to 25%, and the insulation cover is opened to ensure that the temperature of the 2# fan is 700±20℃, and the 3# to 13# fans are all closed and the insulation cover is closed to ensure that the temperature of the 13# fan is greater than 350℃.
  8. 如权利要求4所述400MPa级免涂镀热轧长材的轧制工艺，其特征在于控冷工艺中，所述长材为圆棒时，圆棒上冷床温度＞850℃，采用保温罩缓冷，出保温罩温度＞600℃。 The rolling process of the 400MPa grade coating-free hot-rolled long product as described in claim 4 is characterized in that in the controlled cooling process, when the long product is a round bar, the temperature of the cooling bed on the round bar is greater than 850°C, and a heat preservation cover is used for slow cooling, and the temperature out of the heat preservation cover is greater than 600°C.
PCT/CN2023/097478 2022-12-22 2023-05-31 400 mpa-grade coating-free hot-rolled wire rod and round rod, and rolling process therefor WO2024130968A1 (en)

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