WO2018001043A1

WO2018001043A1 - Improved 09crcusb steel resistant to sulfuric acid dew point corrosion and preparation method therefor

Info

Publication number: WO2018001043A1
Application number: PCT/CN2017/087108
Authority: WO
Inventors: 苗丕峰; 钱刚; 刘观猷; 葛龙桂; 吴小林; 陈亮; 李经涛; 傅金明; 高助忠
Original assignee: 江阴兴澄特种钢铁有限公司
Priority date: 2016-06-30
Filing date: 2017-06-03
Publication date: 2018-01-04
Also published as: CN105937010A; CN105937010B

Abstract

An improved 09CrCuSb steel resistant to sulfuric acid dew point corrosion. The chemical composition of the steel is, by mass percentage, 0.04-0.12% of C, 0.20-0.50% of Si, 0.35-0.90% of Mn, lower than or equal to 0.030% of P, lower than or equal to 0.030% of S, 0.70-1.10% of Cr, 0.25-0.60% of Ni, 0.25-0.50% of Cu, the content ratio of Ni to Cu being greater than or equal to 1, 0.04-0.10% of Sb, lower than or equal to 0.02% of Ti, 0.02-0.04% of Alt, greater than or equal to 0.0005% of Ca, lower than or equal to 0.007% of N and the balance of Fe and impurity elements. The products are in the forms of hot-rolled steel plates and hot-rolled round tube blanks. For the steel plates, the yield strength is greater than or equal to 345 MPa, the tensile strength is greater than or equal to 490 MPa, the ductility is greater than or equal to 25%, the Charpy impact energy is greater than 100 J at -40 °C, the sulfuric acid dew point corrosion resistance is at the same level as that of the traditional 09CrCuSb, and the plate thickness can reach 40 mm. The sulfuric acid dew point corrosion resistance of the round tube blanks prepared according to such composition likewise is at the same level as that of the traditional 09CrCuSb.

Description

一种改进型 09CrCuSb耐硫酸露点腐蚀用钢及其制造方法技术领域 Improved 09CrCuSb steel for sulfuric acid dew point corrosion resistance and manufacturing method thereof

本发明属于耐硫酸露点腐蚀钢技术领域，具体涉及一种改进型的耐硫酸露点腐蚀用钢板、圆管坯材料及制造方法。背景技术 The invention belongs to the technical field of sulfuric acid dew point corrosion resistant steel, and particularly relates to an improved steel plate for corrosion resistant dew point corrosion, a material for a round tube blank and a manufacturing method thereof. Background technique

在石油、化工、电力和冶金等行业，煤和重油常作为主要燃料。这些燃料含硫量较高，燃烧过程中产生的气体含有 so₂, 并进一步氧化生成 so₃。当烟气温度降至露点温度以下（≤130°C )，或烟气与温度较低的烟风道管壁接触时，烟气中的 S0₃与水蒸气作用形成高浓度的硫酸，对烟肉、烟风道管壁产生严重的腐蚀从而对设备造成破坏。这一问题通过使用耐硫酸露点腐蚀的 09CrCuSb钢材来制造相关部件和设备加以解决。 In the petroleum, chemical, power and metallurgical industries, coal and heavy oil are often used as the main fuels. These high sulfur content fuels, the combustion gases generated during comprising SO _2, and further oxidation so _3. When the flue gas temperature falls below the dew point temperature (≤130 °C), or when the flue gas is in contact with the lower temperature flue duct wall, the S0 ₃ in the flue gas forms a high concentration of sulfuric acid with water vapor. The wall of the flue and flue ducts is severely corroded and causes damage to the equipment. This problem is solved by manufacturing related components and equipment using 09CrCuSb steel which is resistant to sulfuric acid dew corrosion.

专利公开号为 1123845 的发明披露了制造 09CrCuSb 钢材的成分 (质量％)： C : <0.14%, Si : 0.17〜0.37%， Mn: 0.35—0.65%, P: 0.035%， S: 0.035%， Cr: 0.70〜 1.10%， Ni : ≤0.15%， Cu: 0.25—0.50%, Sb: 0.04〜0.12%， Ti : 0.10%， B: 0.10%， Mo: 0.15%，余量为 Fe及杂质元素。据此制造的园管坯然后制成无缝钢管的屈服强度≥2801^«¾，抗拉强度≥4201 ?&，延伸率≥36%。专利公开号为 1490427的发明披露了用于无缝钢管制造的 09CrCuSb 钢材的成分 (质量％)： C: 0.12%， Si : 0.20〜 0.40%， Μη: 0.35〜0.65^ο/_ο， Ρ: ^0.035%, S: ^0.035%, Cr: 0.70—1.10%, Cu: 0.25—0.45%, Sb: 0.04—0.10%, Ti : 0.03—0.07% , 余量为 Fe 及杂质元素。据此制造的无缝钢管的屈服强度 295MPa，抗拉强度 410MPa，延伸率 37%。相对应，中国国家标准 GB 150.2 - 2011规定的用于无缝钢管制造的 09CrCuSb钢材的成分 (质量％)为： C: 0.12%， Si: 0.20〜0.40%， Mn: 0.35—0.65%, P: 0.030%， S: 0.020%， Cr: 0.70—1.10%, Cu: 0.25〜0.45%， Sb: 0.04—0.10%, 余量为 Fe及杂质元素。据此制造的壁厚 8mm的无缝钢管，常温（20°C ) 下的屈服强度 245MPa。 The invention of Patent Publication No. 1123845 discloses the composition (% by mass) of the 09CrCuSb steel material: C: <0.14%, Si: 0.17 to 0.37%, Mn: 0.35 to 0.65%, P: 0.035%, S: 0.035%, Cr : 0.70 to 1.10%, Ni: ≤0.15%, Cu: 0.25-0.50%, Sb: 0.04 to 0.12%, Ti: 0.10%, B: 0.10%, Mo: 0.15%, and the balance is Fe and an impurity element. The tube billet thus produced is then made into a seamless steel tube with a yield strength ≥ 2801^«3⁄4, a tensile strength ≥ 4201 Ω, and an elongation ≥ 36%. The invention of Patent Publication No. 1490427 discloses the composition (% by mass) of 09CrCuSb steel for seamless steel pipe production: C: 0.12%, Si: 0.20 to 0.40%, Μη: 0.35 to 0.65 ^ο / _ο , Ρ: ^0.035 %, S: ^0.035%, Cr: 0.70-1.10%, Cu: 0.25-0.45%, Sb: 0.04-0.10%, Ti: 0.03-0.07%, and the balance is Fe and impurity elements. The seamless steel pipe thus produced has a yield strength of 295 MPa, a tensile strength of 410 MPa, and an elongation of 37%. Correspondingly, the composition (% by mass) of 09CrCuSb steel used for seamless steel pipe manufacturing specified in Chinese National Standard GB 150.2-2011 is: C: 0.12%, Si: 0.20~0.40%, Mn: 0.35-0.65%, P: 0.030%, S: 0.020%, Cr: 0.70 to 1.10%, Cu: 0.25 to 0.45%, Sb: 0.04 to 0.10%, and the balance is Fe and an impurity element. According to this, a seamless steel pipe having a wall thickness of 8 mm was produced, and the yield strength at room temperature (20 ° C) was 245 MPa.

上述 09CrCuSb的发明和标准要求中，元素 Cu和 Sb均有利于提高材料的耐硫酸露点腐蚀性能。但是， Cu 易导致钢材产生热脆，使钢坯和热轧钢材表面产生网状裂纹。 Sb 的加入会进一步恶化其热脆性能，导致钢坯和热轧钢材表面产生大量的网状裂纹。这一问题长期困扰着传统 09CrCuSb产品的生产和使用。 In the above-mentioned invention and standard requirements of 09CrCuSb, both elements Cu and Sb are advantageous for improving the sulfuric acid dew point corrosion resistance of the material. However, Cu tends to cause hot brittleness of the steel, causing a network crack on the surface of the billet and the hot-rolled steel. The addition of Sb further deteriorates its hot brittleness, resulting in a large number of network cracks on the billet and hot rolled steel surfaces. This problem has long plagued the production and use of traditional 09CrCuSb products.

09CrCuSb 除了大量用来生产无缝钢管制造用的圆管坯外，近年来也有用于钢板生 09CrCuSb In addition to a large number of round tube blanks used in the production of seamless steel tubes, it has also been used in recent years for steel sheets.

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替换页（细则第 26条) 产的要求。除了 Cu和 Sb导致的表面网状裂纹问题严重困扰着传统 09CrCuSb板坯和钢板的生产与使用外，越来越多的工程应用要求 09CrCuSb钢板具有较无缝钢管更高的机械性能（屈服强度≥345MPa，抗拉强度≥490^«¾ 以及良好的低温冲击性能），而传统的 09CrCuSb材料已不能满足这一要求，因此，限制了它的使用。发明内容 Replacement page (Article 26) Production requirements. In addition to the surface crevice crack caused by Cu and Sb, which seriously plagues the production and use of traditional 09CrCuSb slabs and steel plates, more and more engineering applications require 09CrCuSb steel plates to have higher mechanical properties than seamless steel pipes (yield strength ≥ 345MPa, tensile strength ≥ 490 ^ « 3⁄4 and good low temperature impact properties), and the traditional 09CrCuSb material can not meet this requirement, therefore, its use is limited. Summary of the invention

本发明所要解决的技术问题是针对上述现有技术提供一种改进型 09CrCuSb耐硫酸露点腐蚀用钢及其钢板和圆管坯的制造方法，并消除热轧钢板和圆管坯以及制造它们的连铸坯因热脆导致的表面网状裂纹。据此制造的钢板屈服强度 ReL 345MPa，抗拉强度 Rm 490MPa，延伸率 25%， -40°C下的夏比冲击功 100】，厚度达 40mm; 据此制造的钢板和圆管坯的耐硫酸露点腐蚀性能与传统的 09CrCuSb处于相同水平。 The technical problem to be solved by the present invention is to provide an improved 09CrCuSb steel for sulfuric acid dew point corrosion and a method for manufacturing the same, and to eliminate hot rolled steel sheets and round billets and to manufacture them. The surface reticular crack of the slab due to hot brittleness. According to the steel plate yield strength ReL 345MPa, tensile strength Rm 490MPa, elongation 25%, Charpy impact energy at -40 ° C, thickness: 40mm; The dew point corrosion performance is at the same level as the conventional 09CrCuSb.

本发明解决上述问题所采用的技术方案为：一种改进型 09CrCuSb耐硫酸露点腐蚀用钢，该钢的化学成分按质量百分含量计为 C: 0.04-0.12%, Si: 0.20-0.50%, Mm 0.35〜0.90%， P: 0.030%， S: 0.030%， Cr: 0.70—1.10%, Ni: 0.25〜0.60%， Cu: 0.25—0.50%, Ni/Cu的含量比 1， Sb: 0.04—0.10%, Ti : 0.02%， Alt: 0.02—0.04%, Ca 0.0005%， N^O.007%, 余量为 Fe及杂质元素；产品形式为热轧钢板或热轧圆管坯。 The technical solution adopted by the invention to solve the above problems is as follows: An improved 09CrCuSb steel for sulfuric acid dew point corrosion resistance, the chemical composition of the steel is C: 0.04-0.12% by mass, and Si: 0.20-0.50%, Mm 0.35~0.90%, P: 0.030%, S: 0.030%, Cr: 0.70-1.10%, Ni: 0.25~0.60%, Cu: 0.25-0.50%, Ni/Cu content ratio 1, Sb: 0.04—0.10 %, Ti : 0.02%, Alt: 0.02-0.04%, Ca 0.0005%, N^O.007%, balance Fe and impurity elements; product form is hot rolled steel sheet or hot rolled round billet.

钢板的屈服强度 345MPa，抗拉强度 490^&，延伸率 25%， -40°C下夏比冲击功 >100J，耐硫酸露点腐蚀性能与传统 09CrCuSb处于相同水平，板厚可达 40mm。并且本发明的改进型 09CrCuSb克服了传统 09CrCuSb热脆导致的表面网状裂纹的不足。 The yield strength of the steel plate is 345MPa, the tensile strength is 490^&, the elongation is 25%, the Charpy impact energy at -40°C is >100J, and the sulfuric acid dew point corrosion resistance is at the same level as the traditional 09CrCuSb, and the plate thickness can reach 40mm. Moreover, the improved 09CrCuSb of the present invention overcomes the shortcomings of the surface reticular crack caused by the heat of the conventional 09CrCuSb.

以下对本发明中所含组分的作用及用量选择作具体说明： The following is a detailed description of the action and dosage of the components contained in the present invention:

C: 是确保钢材强度必须的元素，但过高的 C 含量对钢的延性、韧性不利，同时也会使耐腐蚀性能变差。另外，过高的 C 含量也会导致严重的中心 C偏析从而影响薄钢板的冲击性能。本发明控制其含量为 0.04〜0.12%。 C: It is an essential element for ensuring the strength of the steel, but an excessively high C content is detrimental to the ductility and toughness of the steel, and also deteriorates the corrosion resistance. In addition, excessive C content can also cause severe center C segregation and affect the impact properties of thin steel sheets. The present invention controls the content to be 0.04 to 0.12%.

Si: 是钢中的脱氧元素，并以固溶强化形式提高钢的强度，而且有利于钢材的耐腐蚀性能。当 Si 含量低于 0.10%时，脱氧效果较差， Si 含量较高时韧性降低。本发明 Si 含量控制为 0.20〜0.50%。 Si: It is a deoxidizing element in steel and improves the strength of steel in a solid solution strengthening form, and is beneficial to the corrosion resistance of steel. When the Si content is less than 0.10%, the deoxidation effect is poor, and the toughness is lowered when the Si content is high. The Si content of the present invention is controlled to be 0.20 to 0.50%.

Mn: 是对钢的强化有效的元素。起固溶强化作用以弥补钢中因 C 含量降低而引起的强度损失。但 Mn 含量过高时耐蚀性变差。因此，本发明 Mn 含量控制为 0.35〜 0.90%。 Mn: It is an effective element for strengthening steel. It acts as a solid solution to compensate for the loss of strength in the steel due to a decrease in C content. However, when the Mn content is too high, the corrosion resistance is deteriorated. Therefore, the Mn content of the present invention is controlled to be 0.35 to 0.90%.

Cu、 Cr和 Ni: Cu 是提高耐腐蚀性的基本元素，可以促进钢产生阳极钝化，从而降低钢的腐蚀速度。 Cu在锈层中富集能极大地改善锈层的保护性能。为达到锈层中 Cu 富集的效果，要求 Cu 0.20%。 Cr和钢中的 Cu、 Si元素配合使用能显著提高钢的耐腐 Cu, Cr and Ni: Cu is an essential element for improving corrosion resistance and promotes anode passivation of steel, thereby reducing the corrosion rate of steel. The enrichment of Cu in the rust layer can greatly improve the protective properties of the rust layer. In order to achieve the effect of Cu enrichment in the rust layer, Cu is required to be 0.20%. The combination of Cu and Si in Cr and steel can significantly improve the corrosion resistance of steel.

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替换页（细则第 26条) 蚀性能。 Cr和 Ni 的电极电位较低，具有钝化倾向，与 Cu配合使用效果更明显，能明显提高钢的耐蚀性能。重要的是，在钢中加入 Ni可以改善 Cu导致的热脆性能，降低甚至消除连铸钢坯和热轧钢材表面由于热脆产生的网状裂纹。因此，本发明 Cu 含量控制为 0.25〜0.50%， Cr含量控制为 0.70〜1.10%， Ni 控制为 0.25〜0.60%，且须保证 Ni (质量％) /Cu (质量％) 1。 Replacement page (Article 26) Corrosion performance. The electrode potentials of Cr and Ni are low, have a tendency to passivate, and are more effective in combination with Cu, which can significantly improve the corrosion resistance of steel. Importantly, the addition of Ni to the steel improves the hot brittleness caused by Cu, and reduces or even eliminates the network cracks on the surface of the continuously cast slab and hot rolled steel due to hot brittleness. Therefore, the Cu content of the present invention is controlled to be 0.25 to 0.50%, the Cr content is controlled to be 0.70 to 1.10%, and the Ni is controlled to be 0.25 to 0.60%, and Ni (% by mass) / Cu (% by mass) 1 must be secured.

Ti: 是形成析出物对强韧化有效的元素。钢中加入元素 Ti有利于细化钢的组织，减少基体组织间的电位差异从而提高钢的耐晶间腐蚀性能。但是，加入过多的 Ti 将有利于粗大的 TiN析出。粗大的 TiN与基体间的电位差异较大，会成为腐蚀源，恶化钢的耐硫酸腐蚀性能，因此，控制其含量 0.02%。 Ti: is an element which forms precipitates effective for strengthening and toughening. The addition of element Ti to steel is beneficial to refining the microstructure of the steel and reducing the potential difference between the matrix structures to improve the intergranular corrosion resistance of the steel. However, adding too much Ti will facilitate coarse TiN precipitation. The large potential difference between the coarse TiN and the substrate is a source of corrosion, which deteriorates the sulfuric acid corrosion resistance of the steel. Therefore, the content is controlled to 0.02%.

A1: 主要起固氮和脱氧作用，同时也有利于在钢材表面形成钝化膜而提高耐硫酸腐蚀性能。 A1与 N接合形成的 A1N可以有效地细化晶粒，但含量过高会损害钢的韧性而且热加工性变差。因此，本发明控制其含量 (Alt)在 0.02〜0.04%的范围。 A1: It mainly plays a role in nitrogen fixation and deoxidation. It also helps to form a passivation film on the surface of steel to improve the resistance to sulfuric acid corrosion. The A1N formed by the bonding of A1 and N can effectively refine the crystal grains, but if the content is too high, the toughness of the steel is impaired and the hot workability is deteriorated. Therefore, the present invention controls the content (Alt) in the range of 0.02 to 0.04%.

Ca: 钢中微量 Ca元素与硫酸作用生成难熔性的硫酸盐 (CaS0₄) 在金属表面沉积，使金属表面的钝化膜易于被修复，起到阻隔金属被表面液态膜进一步腐蚀从而提高耐腐蚀性能。为此，本发明控制钢中的 Ca含量 0.0005%。 Ca: The trace Ca element in steel reacts with sulfuric acid to form refractory sulfate (CaS0 ₄ ) deposited on the metal surface, which makes the passivation film on the metal surface easy to be repaired, which prevents the metal from being further corroded by the surface liquid film to improve the resistance. Corrosion performance. To this end, the present invention controls the Ca content in the steel to be 0.0005%.

S、 P: 为钢中的杂质元素，易形成偏析、夹杂等缺陷。虽然 S和 P对耐硫酸露点腐蚀起到一定的作用，但作为杂质元素会给钢材的韧性以及热加工性带来不利影响。本发明控制 P 0.030%， S 0.030%。 S, P: It is an impurity element in steel, which is easy to form defects such as segregation and inclusion. Although S and P play a role in the resistance to sulfuric acid dew point corrosion, it acts as an impurity element which adversely affects the toughness and hot workability of the steel. The present invention controls P 0.030%, S 0.030%.

N: 钢中对韧性有害的杂质元素，为了得到优良的低温韧性，本发明控制其含量 0.007%。 N: An impurity element harmful to toughness in steel, in order to obtain excellent low temperature toughness, the present invention controls the content of 0.007%.

本发明的另一目的是提供上述改进型 09CrCuSb 耐硫酸露点腐蚀用钢板的制备方法：首先将冶炼原料依次经 KR铁水预处理、转炉冶炼、 LF 精炼、 RH 真空脱气和连铸，连铸出与钢板成品化学成分相符、厚度为 150mm或以上的连铸板坯。在连铸坯缓冷和表面清理后，将板坯在中性或弱氧化性气氛的加热炉内加热至 1180〜1230°C保温 1 - 3小时后出炉。经高压水除鳞处理后轧制：对于成品板厚 15mm的钢板，采用两阶段轧制，其中粗轧开轧温度在 1050±40°C，中间坯待温厚度 2.0 X 板厚，精轧开轧温度在 810〜920°C ; 对于成品板厚 <15mm的钢板，高压水除鳞处理后直接轧制到最终厚度。轧制完成后经矫直、空冷，制得目标钢板产品。 Another object of the present invention is to provide a method for preparing the above-mentioned modified 09CrCuSb steel sheet for sulfuric acid dew point corrosion: First, the smelting raw material is sequentially subjected to KR hot metal pretreatment, converter smelting, LF refining, RH vacuum degassing and continuous casting, and continuous casting. Continuous casting slabs with a thickness of 150 mm or more in accordance with the chemical composition of the finished steel sheet. After the continuous casting billet is slowly cooled and surface cleaned, the slab is heated in a heating furnace of neutral or weak oxidizing atmosphere to 1180 to 1230 ° C for 1 to 3 hours, and then discharged. Rolling after high-pressure water descaling treatment: For the finished steel plate with a thickness of 15mm, two-stage rolling is adopted, in which the rough rolling and rolling temperature is 1050±40°C, the intermediate billet is warmed to a thickness of 2.0 X, and the finish rolling is performed. The rolling temperature is 810~920 °C. For the steel plate with the finished plate thickness <15mm, the high pressure water is descaled and directly rolled to the final thickness. After the rolling is completed, the target steel product is obtained by straightening and air cooling.

上述改进型 09CrCuSb耐硫酸露点腐蚀用圆管坯的制备方法，按所述改进型耐硫酸露点腐蚀用钢化学组成配置冶炼原料，冶炼原料依次经 KR铁水预处理、电炉 /转炉冶炼、 LF精炼、 VD RH真空处理、连铸，得到 300mm X 340mm或以上尺寸的矩形连铸坯。将连铸坯在中性或弱氧化性气氛的加热炉内加热至 1150〜1210°C保温不少于 1小时，并控制连铸坯在加热炉的总加热时间为 2.5〜3.5小时，出炉。出炉后的连铸坯经高压水除 The above-mentioned improved 09CrCuSb method for preparing a round tube blank for sulfuric acid dew point corrosion, according to the chemical composition of the modified sulfuric acid dew point corrosion steel, the smelting raw material is sequentially subjected to KR hot metal pretreatment, electric furnace/converter smelting, LF refining, VD RH vacuum processing, continuous casting, to obtain rectangular continuous casting billet of 300mm X 340mm or more. The continuous casting billet is heated in a heating furnace of neutral or weak oxidizing atmosphere to a temperature of 1150 to 1210 ° C for not less than 1 hour, and the total heating time of the continuous casting billet in the heating furnace is controlled to 2.5 to 3.5 hours, and is discharged. The continuous casting billet after being discharged is removed by high pressure water

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替换页（细则第 26条) 鳞后进入 17架连轧机组进行轧制，开轧温度 1050 ±40°C，终轧温度 950±40°C，轧至目标尺寸，空冷制得圆管坯产品。 Replacement page (Article 26) After the scale, it enters 17 continuous rolling mills for rolling, with a rolling temperature of 1050 ± 40 ° C, a final rolling temperature of 950 ± 40 ° C, rolling to the target size, and air-cooling to produce round tube blank products.

本发明针对冶金、电力、石油和化工等以煤或重油为燃料的烟气处理***对传统 09CrCuSb 耐硫酸露点腐蚀用圆管坯和高强度、高韧性钢板的需求，使用改进的化学成分生产的连铸坯作为坯料，采取控制轧制的方法制造出厚度可达 40mm，屈服强度为 345MPa级的高强度、高韧性的改进型 09CrCuSb耐硫酸露点腐蚀用钢板和用于无缝钢管制造的改进型 09CrCuSb圆管坯。 The invention aims at the demand of the traditional 09CrCuSb sulfuric acid dew point resistant round tube blank and the high strength and high toughness steel sheet for the flue gas treatment system of coal or heavy oil fueled by metallurgy, electric power, petroleum and chemical industry, using the improved chemical composition. Continuous casting billet as blank, improved rolling 09. 09CrCuSb round tube blank.

与现有技术相比，本发明的优点在于： The advantages of the present invention over the prior art are:

(1) 较传统 09CrCuSb耐硫酸露点腐蚀用钢，本发明加入或显著增加了钢中的 Ni含量，并要求钢中的 Ni含量与 Cu含量之比大于等于 1，消除了 09CrCuSb中由于元素 Cu、 Sb导致的钢坯和钢材表面的网状裂纹问题。同时，保持耐硫酸露点腐蚀性能与 09CrCuSb 处于相同水平。 (1) Compared with the conventional 09CrCuSb steel for sulfuric acid dew point corrosion, the present invention adds or significantly increases the Ni content in the steel, and requires that the ratio of the Ni content to the Cu content in the steel is greater than or equal to 1, eliminating the elemental Cu in the 09CrCuSb. The problem of reticulated cracks on the slab and steel surfaces caused by Sb. At the same time, the corrosion resistance of sulfuric acid dew point is kept at the same level as 09CrCuSb.

(2)传统 09CrCuSb制造的耐硫酸露点腐蚀用钢的屈服强度较低，为 235MPa级。本发明制造的改进型 09CrCuSb耐硫酸露点腐蚀用钢板克服了这一不足，不仅具有高的屈服强度 (≥345MPa)，高的抗拉强度 (≥490MPa)，良好的延伸率 (≥25%)，而且还具有高的韧性 (-40°C下夏比冲击功 >100J)。 (2) The steel with sulfuric acid dew point corrosion produced by the conventional 09CrCuSb has a low yield strength of 235 MPa. The improved 09CrCuSb steel plate for sulfuric acid dew point corrosion manufactured by the invention overcomes this deficiency, and has high yield strength (≥345MPa), high tensile strength (≥490MPa), good elongation (≥25%), It also has high toughness (Charpy impact energy at -40 ° C > 100 J).

(3) 本发明制造的产品形式为热轧钢板和热轧圆管坯，而传统 09CrCuSb的产品形式仅为制造无缝钢管用的热轧圆管坯。因而，本发明扩大了 09CrCuSb钢材的形式，应用范围也更加广泛。附图说明 (3) The product produced by the present invention is in the form of a hot-rolled steel sheet and a hot-rolled round billet, and the conventional 09CrCuSb product form is only a hot-rolled round billet for producing a seamless steel pipe. Thus, the present invention expands the form of the 09CrCuSb steel and has a wider range of applications. DRAWINGS

图 1为本发明实施例 1中连铸坯的表面示意图； Figure 1 is a schematic view showing the surface of a continuous casting blank according to Embodiment 1 of the present invention;

图 2为本发明实施例 1中钢板成品的表面示意图； 2 is a schematic view showing the surface of a finished steel sheet according to Embodiment 1 of the present invention;

图 3为本发明实施例 2中连铸坯的表面示意图； Figure 3 is a schematic view showing the surface of a continuous casting blank in Embodiment 2 of the present invention;

图 4为本发明实施例 2中钢板成品的表面示意图； 4 is a schematic view showing the surface of a finished steel sheet in Embodiment 2 of the present invention;

图 5为本发明实施例 3中圆管坯成品的表面示意图； Figure 5 is a schematic view showing the surface of a finished product of a round tube according to Embodiment 3 of the present invention;

图 6为本发明各实施例与对比例的腐蚀速率变化图。具体实施方式 Figure 6 is a graph showing changes in corrosion rate for various embodiments of the present invention and comparative examples. detailed description

以下结合本发明的较佳实施例对本发明的技术方案作更详细的描述。但该等实施例仅是对本发明较佳实施方式的描述，而不能对本发明的范围产生任何限制。 The technical solutions of the present invention are described in more detail below in conjunction with the preferred embodiments of the present invention. However, the embodiments are merely illustrative of preferred embodiments of the invention, and are not intended to limit the scope of the invention.

实施例 1 Example 1

本实施例涉及的改进型 09CrCuSb耐硫酸露点腐蚀钢板的厚度为 10mm，所包含的 The modified 09CrCuSb sulfuric acid dew point corrosion resistant steel sheet according to the embodiment has a thickness of 10 mm, and the included

4 4

替换页（细则第 26条) 化学成分及其质量百分含量： C: 0.09%， Si: 0.34%， Mn: 0.85%， P: 0.019%， S: 0.014%， Cr: 0.80%, Cu: 0.27%, Ni: 0.34 %, Ni/Cu = 1.26， Sb: 0.042%, Ti: 0.013%, Alt: 0.028%， Ca: 0.0009%， N: 0.0036%，余量为 Fe及杂质元素。 Replacement page (Article 26) Chemical composition and its mass percentage: C: 0.09%, Si: 0.34%, Mn: 0.85%, P: 0.019%, S: 0.014%, Cr: 0.80%, Cu: 0.27%, Ni: 0.34%, Ni /Cu = 1.26, Sb: 0.042%, Ti: 0.013%, Alt: 0.028%, Ca: 0.0009%, N: 0.0036%, and the balance is Fe and impurity elements.

上述钢板的制造工艺如下： The manufacturing process of the above steel plate is as follows:

按上述改进型 09CrCuSb 耐硫酸露点腐蚀用钢的化学组成配置冶炼原料依次进行 KR铁水预处理 -转炉冶炼 - LF 精炼 - RH 真空脱气 -连铸（连铸坯厚 300mm) - 加热 (保温处理) - 高压水除鳞 - 轧制 -矫直 - 空冷至室温 -成品。连铸时钢水的过热度控制在≤30°C，且尽可能缩短连铸坯在高温区的停留时间。 According to the above-mentioned modified 09CrCuSb sulfuric acid dew point corrosion steel chemical composition configuration smelting raw materials in order KR hot metal pretreatment - converter smelting - LF refining - RH vacuum degassing - continuous casting (continuous casting billet thickness 300mm) - heating (insulation treatment) - High pressure water descaling - rolling - straightening - air cooling to room temperature - finished product. The overheating of the molten steel during continuous casting is controlled to ≤ 30 ° C, and the residence time of the continuous casting slab in the high temperature zone is shortened as much as possible.

进一步的讲，上述加热、轧制阶段的具体工艺为：将连铸坯在中性气氛的加热炉内加热至 1190°C保温 2.3小时，出炉后经高压水除鳞处理后直接轧制到最终厚度。轧制完成后再经矫直、空冷，制得目标钢板产品。 Further, the specific process of the above heating and rolling stages is as follows: the continuous casting slab is heated in a heating furnace of a neutral atmosphere to a temperature of 1190 ° C for 2.3 hours, and after being discharged, it is subjected to high-pressure water descaling treatment and directly rolled to the final. thickness. After the rolling is completed, the target steel product is obtained by straightening and air cooling.

经由上述工艺制造的连铸板坯和成品钢板表面均无热脆引起的网状裂纹，见图 1和图 2所示，而且产品钢板具有高的强度、高的韧性，其力学性能如表 1所示。 The surface of continuous casting slab and finished steel plate manufactured through the above process has no mesh crack caused by hot brittleness, as shown in Fig. 1 and Fig. 2, and the steel plate has high strength and high toughness, and its mechanical properties are shown in Table 1. Shown.

产品钢板的耐硫酸酸露点腐蚀性能按照 JB/T 7901规定的试验方法，在温度 70°C、硫酸浓度 50%、全浸 24小时条件下，测量其腐蚀速率，测得的结果见表 1。与此相对照，也采用市场上销售的传统 09CrCuSb圆管坯（所包含的成分及其质量百分数为： C: 0.09%, Si: 0.31 %， Mn: 0.49%, P: 0.014%, S: 0.029%, Cr: 0. 90 %, Cu: 0.37%， Ni: 0.04%， Alt: 0.023%, Ti: 0.057%， B: 0.012%, Sb: 0.055%，余量为铁及杂质元素）进行同样的试验，其结果作为对比例也列在了表 1之中。由表 1可见：本发明例所制造的改进型 09CrCuSb钢板的耐硫酸露点腐蚀性能与传统 09CrCuSb处于同一水平，相差仅为 5.1%。 The sulfuric acid resistance of the product steel plate is measured according to the test method specified in JB/T 7901. The corrosion rate is measured at a temperature of 70 ° C, a sulfuric acid concentration of 50%, and a full immersion for 24 hours. The measured results are shown in Table 1. In contrast, the conventional 09CrCuSb round billet sold on the market (the composition and mass percentage thereof are: C: 0.09%, Si: 0.31%, Mn: 0.49%, P: 0.014%, S: 0.029) %, Cr: 0. 90 %, Cu: 0.37%, Ni: 0.04%, Alt: 0.023%, Ti: 0.057%, B: 0.012%, Sb: 0.055%, balance is iron and impurity elements) The results of the tests are also shown in Table 1 as comparative examples. It can be seen from Table 1 that the modified 09CrCuSb steel sheet produced by the present invention has the same resistance to sulfuric acid dew point corrosion as the conventional 09CrCuSb, and the difference is only 5.1%.

为检验本发明所制造的改进型 09CrCuSb钢板产品在不同侵蚀时间下的耐硫酸露点腐蚀性能，使用本发明例制造的钢板与对比例的传统 09CrCuSb在温度 70°C、硫酸浓度 50%、全浸 6— 24小时条件下，测量其腐蚀速率，结果如图 6所示。在实验误差允许范围内，本发明制造的改进型 09CrCuSb钢板的腐蚀速率与传统 09CrCuSb没有差异。实施例 2 In order to test the sulfuric acid dew point corrosion resistance of the improved 09CrCuSb steel sheet product manufactured by the present invention under different etching times, the steel sheet manufactured by the example of the present invention and the conventional 09CrCuSb of the comparative example were at a temperature of 70 ° C, a sulfuric acid concentration of 50%, and a full dip The corrosion rate was measured under 6-24 hours, and the results are shown in Fig. 6. The corrosion rate of the modified 09CrCuSb steel sheet produced by the present invention is not different from the conventional 09CrCuSb within the experimental error tolerance. Example 2

本实施例涉及的改进型 09CrCuSb耐硫酸露点腐蚀钢板厚度为 40mm，所包含的成分及其质量百分数与实施例 1相同。 The modified 09CrCuSb sulfuric acid dew point corrosion resistant steel sheet according to the present embodiment has a thickness of 40 mm, and the components and mass percentages thereof are the same as in the first embodiment.

本实施例钢板的制造工艺与实施例 1 基本相同，仅加热、轧制工艺存在差异，具体如下- 将连铸坯在弱氧化性气氛的加热炉内加热至 1200Ό保温 2.5小时，出炉后经高压水除鳞，然后进行两阶段轧制。第一阶段轧制 (即粗轧)开轧温度为 106CTC，中间坯厚 100mm The manufacturing process of the steel sheet of this embodiment is basically the same as that of the first embodiment, and only the heating and rolling processes are different, as follows - the continuous casting billet is heated to 1200 Torr in a heating furnace of a weak oxidizing atmosphere for 2.5 hours, and is subjected to high pressure after being discharged. The water is descaled and then subjected to two-stage rolling. The first stage rolling (ie rough rolling) rolling temperature is 106 CTC, and the intermediate thickness is 100 mm.

5 5

替换页（细则第 26条) ( = 2.5 x 板厚第二阶段轧制 (即精轧)开轧温度为 830°C，最终板厚 40mm。钢板轧制完成后经矫直并空冷至室温制得目标钢板产品。 Replacement page (Article 26) ( = 2.5 x plate thickness The second stage rolling (ie finish rolling) rolling temperature is 830 ° C, and the final plate thickness is 40 mm. After the steel plate is rolled, it is straightened and air cooled to room temperature to obtain the target steel plate product.

经由上述工艺制造的连铸板坯和成品钢板表面均无热脆引起的网状裂纹，见图 3和图 4所示，而且本实施例制造的成品钢板同样具有高的强度、高的韧性，见表 1所示。 The surface of the continuous casting slab and the finished steel sheet manufactured through the above process are free from the network crack caused by hot brittleness, as shown in FIG. 3 and FIG. 4, and the finished steel sheet manufactured by the embodiment also has high strength and high toughness. See Table 1.

采用与实施例 1相同的耐硫酸酸露点腐蚀性能测试方法，测量其腐蚀速率，结果见表 1所示。由表 1可见：本发明例所制造的改进型 09CrCuSb钢板的耐硫酸露点腐蚀性能与传统 09CrCuSb处于同一水平，相差仅为 2.2%。在全浸 6— 24小时条件下，其腐蚀速率如图 6所示。在实验误差允许范围内，本发明制造的改进型 09CrCuSb钢板的腐蚀速率与传统 09CrCuSb没有差异。实施例 3 The corrosion rate of the sulfuric acid dew point corrosion resistance test was measured in the same manner as in Example 1, and the corrosion rate was measured. The results are shown in Table 1. It can be seen from Table 1 that the modified 09CrCuSb steel sheet produced by the present invention has the same sulfuric acid dew point corrosion resistance as the conventional 09CrCuSb, and the difference is only 2.2%. The corrosion rate is shown in Figure 6 under full immersion for 6-24 hours. The corrosion rate of the modified 09CrCuSb steel sheet produced by the present invention is not different from the conventional 09CrCuSb within the experimental error tolerance. Example 3

本实施例涉及的改进型 09CrCuSb耐硫酸露点腐蚀圆管坯直径为 60mm，所包含的成分及其质量百分含量： C: 0.06%， Si: 0.35%, Mn: 0.48%， P: 0.024%, S: 0.017%, Cr: 0.84%， Cu: 0.29%， Ni: 0.34 %， Ni/Cu = 1.17, Sb: 0.048%， Ti : 0.016%， Alt: 0.020%， Ca: 0.0008%， N: 0.0050%，余量为 Fe及杂质元素。 The improved 09CrCuSb sulfuric acid dew point corrosion-resistant round tube blank of the present embodiment has a diameter of 60 mm, and the composition and mass percentage thereof are: C: 0.06%, Si: 0.35%, Mn: 0.48%, P: 0.024%, S: 0.017%, Cr: 0.84%, Cu: 0.29%, Ni: 0.34%, Ni/Cu = 1.17, Sb: 0.048%, Ti: 0.016%, Alt: 0.020%, Ca: 0.0008%, N: 0.0050% The balance is Fe and impurity elements.

上述圆管坯的制造工艺如下： The manufacturing process of the above round tube blank is as follows:

按上述改进型 09CrCuSb耐硫酸露点腐蚀用圆管坯的化学组成配置冶炼原料依次进行 KR铁水预处理 -电炉冶炼 - LF 精炼 - VD真空处理-连铸 -加热 (保温处理） - 高压水除鳞 - 轧制 - 空冷至室温 -成品。 According to the above-mentioned modified 09CrCuSb sulfuric acid dew point corrosion-resistant round tube blank chemical composition configuration smelting raw materials in sequence KR hot metal pretreatment - electric furnace smelting - LF refining - VD vacuum processing - continuous casting - heating (insulation treatment) - high pressure water descaling - Rolling - air cooling to room temperature - finished product.

进一步讲，上述炼钢、连铸流程工艺为：首先经电炉冶炼，然后 LF 精炼， LF精炼过程中要加强脱氧，保持脱氧良好的炉渣时间大于 15分钟且有好的流动性。精炼结束后钢包转入 VD 炉进行高真空脱气处理，在高真空压力下（1.33mbar) 保持时间 15 分钟以上。 VD破空后必须先喂铝线等进行调整，再加 Sb锭。全部合金加完后再进行钢包软吹氩 10分钟以上以保证脱气效果及夹杂物能充分上浮。连铸时钢水的过热度控制在≤30 ，且尽可能缩短铸坯在高温区的停留时间。制得的连铸坯为 300mm X 340mm的矩形连铸坯。 Further, the above-mentioned steelmaking and continuous casting process is as follows: First, smelting by electric furnace, then LF refining, and deoxidation should be strengthened during the LF refining process, and the slag having good deoxidation time is more than 15 minutes and has good fluidity. After refining, the ladle is transferred to a VD furnace for high vacuum degassing and maintained at high vacuum pressure (1.33 mbar) for more than 15 minutes. After the VD is broken, it is necessary to feed the aluminum wire and so on, and then add the Sb ingot. After all the alloys have been added, the ladle is softly blown with argon for more than 10 minutes to ensure the degassing effect and the inclusions can fully float. The superheat of the molten steel during continuous casting is controlled to ≤ 30, and the residence time of the slab in the high temperature zone is shortened as much as possible. The obtained continuous casting billet is a rectangular continuous casting billet of 300 mm X 340 mm.

铸坯加热、轧制阶段的具体工艺为：将连铸坯在中性气氛的加热炉内加热至 1180 °C保温 1小时，总在炉时间 3小时，出炉后经高压水除鳞处理后直接进入 17架连轧机组进行轧制，开轧温度 1070°C，终轧温度 940°C。轧制完成后空冷，制得直径为 60mm 的圆管坯产品。 The specific process of the slab heating and rolling stage is as follows: The slab is heated in a neutral atmosphere heating furnace to 1180 ° C for 1 hour, always in the furnace time for 3 hours, after dewatering by high pressure water after discharging It was put into 17 continuous rolling mills for rolling, the rolling temperature was 1070 °C, and the finishing temperature was 940 °C. After the rolling is completed, air cooling is performed to obtain a round tube blank product having a diameter of 60 mm.

经由上述制造工艺制成的连铸坯和成品圆管坯表面均无热脆引起的网状裂纹。其轧制后的圆管坯产品的表面情况如图 5所示。 The surface of the continuous casting blank and the finished round billet produced through the above manufacturing process are free from network cracks caused by hot brittleness. The surface condition of the rolled round billet product is shown in Fig. 5.

圆管坯的耐硫酸酸露点腐蚀性能测试采用与实施例 1相同的方法，结果见表 1所示。 The sulfuric acid dew point corrosion resistance test of the round billet was carried out in the same manner as in Example 1, and the results are shown in Table 1.

6 6

替换页（细则第 26条) 由表 1可见：本发明例所制造的改进型 09CrCuSb圆管坯的耐硫酸露点腐蚀性能与传统 09CrCuSb处于同一水平，相差仅 4.9%。在全浸 6— 24小时的条件下，其腐蚀速率如图 6所示。在实验误差允许范围内，本发明制造的改进型 09CrCuSb圆管坯的腐蚀速率与传统 09CrCuSb没有差异。表 1 实施例所制造的钢板、圆管坯的力学性能和耐硫酸露点腐蚀性能 Replacement page (Article 26) It can be seen from Table 1 that the modified 09CrCuSb round billet produced by the inventive example has the same resistance to sulfuric acid dew point corrosion as the conventional 09CrCuSb, with a difference of only 4.9%. The corrosion rate is shown in Figure 6 under full immersion for 6-24 hours. The corrosion rate of the improved 09CrCuSb round billet manufactured by the present invention is not different from the conventional 09CrCuSb within the experimental error tolerance. Table 1 Mechanical properties and sulfuric acid dew point corrosion resistance of steel sheets and round billets produced in the examples

* 腐蚀速率差别 = (本例的腐蚀速率 -对比例的腐蚀速率） /本例的腐蚀速率 X 100% * Corrosion rate difference = (Corrosion rate of this example - Corrosion rate of the comparative example) / Corrosion rate of this example X 100%

** 实施例 1 的夏比冲击性能测试采用了 7.5mmxl 0mmx55mm的 V型缺口冲击试样，表中所列冲击功值为转换到 10mmx l 0mmx55mm的标准 V型缺口冲击试样的冲击功值。 ** The Charpy impact test of Example 1 used a V-notch impact test of 7.5 mm x l 0 mm x 55 mm. The impact energy values listed in the table were the impact energy values of the standard V-notch impact specimens converted to 10 mm x 10 mm x 55 mm.

除上述实施例外，本发明还包括有其他实施方式，凡采用等同变换或者等效替换方式形成的技术方案，均应落入本发明权利要求的保护范围之内。 In addition to the above-described embodiments, the present invention includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement are intended to fall within the scope of the claims of the present invention.

替换页（细则第 26条) Replacement page (Article 26)

Claims

权利要求书 Claim

[权利要求 1] 一种改进型 09CrCuSb耐硫酸露点腐蚀用钢，其特征在于：该钢的化学成分按质量百分含量计为 C: 0.04—0.12% , Si: 0.20—0.50% , Mn ： 0.35〜0.90<¾， P: <0.030% , S: <0.030% , Cr: 0.70〜1.10<¾， Cu ： 0.25—0.50% , Ni: 0.25—0.60% , Ni/Cu的含量比≥1， Sb: 0.04〜0. 10% , Ti: <0.02% , Alt: 0.02〜0.04<¾， Ca >0.0005% , N<0.007% , 余量为 Fe及杂质元素；产品形式为热轧钢板或热轧圆管坯。 [Claim 1] A modified 09CrCuSb steel for sulfuric acid dew point corrosion, characterized in that: the chemical composition of the steel is C: 0.04 - 0.12% by mass percentage, Si: 0.20 - 0.50%, Mn: 0.35 ~0.90<3⁄4, P: <0.030%, S: <0.030%, Cr: 0.70~1.10<3⁄4, Cu: 0.25-0.50%, Ni: 0.25-0.60%, Ni/Cu content ratio ≥1, Sb: 0.04~0. 10% , Ti: <0.02% , Alt: 0.02~0.04<3⁄4, Ca >0.0005%, N<0.007%, balance Fe and impurity elements; product form is hot rolled steel plate or hot rolled round tube Billet.

[权利要求 2] 根据权利要求 1所述的改进型 09CrCuSb耐硫酸露点腐蚀用钢，其特征在于：所述钢板的屈服强度≥345MPa，抗拉强度≥490MPa，延伸率≥ 25% , -40°C下夏比冲击功 [Claim 2] The improved 09CrCuSb steel for sulfuric acid dew point corrosion according to claim 1, characterized in that: the yield strength of the steel plate is ≥ 345 MPa, the tensile strength is ≥ 490 MPa, the elongation is ≥ 25%, - 40 ° C Xia Mi Mi Gong Gong

>100J，耐硫酸露点腐蚀性能与传统 09CrCuSb处于相同水平，板厚可达 40mm° >100J, the sulfuric acid dew point corrosion resistance is at the same level as the traditional 09CrCuSb, and the plate thickness can reach 40mm°

[权利要求 3] —种制造权利要求 1所述改进型 09CrCuSb耐硫酸露点腐蚀用钢板的方法，其特征在于：首先将冶炼原料依次经 KR铁水预处理、转炉冶炼、 LF精炼、 RH真空脱气和连铸，连铸出与钢板成品化学成分相符、厚度为 150mm或以上的连铸板坯；在连铸坯缓冷和表面清理后，将板坯在中性或弱氧化性气氛的加热炉内加热至 1180〜1230°C保温 1 - 3小吋后出炉，经高压水除鳞处理后轧制：对于成品板厚≥15mm的钢板，采用两阶段轧制，其中粗轧幵轧温度在 1050±40°C，中间坯待温厚度≥2.0 板厚，精轧幵轧温度在 810〜920°C; 对于成品板厚 <15mm的钢板，高压水除鳞处理后直接轧制到最终厚度；轧制完成后经矫直、空冷，制得目标钢板产品。 [Claim 3] A method for producing a modified 09CrCuSb steel sheet for sulfuric acid dew point corrosion according to claim 1, characterized in that: first, the smelting raw material is sequentially subjected to KR hot metal pretreatment, converter smelting, LF refining, and RH vacuum degassing. Continuous casting, continuous casting of continuous casting slabs with a thickness of 150mm or more in accordance with the chemical composition of the finished steel sheet; in the furnace of neutral or weak oxidizing atmosphere after slow cooling and surface cleaning of the continuous casting billet The inner heating is heated to 1180~1230 °C for 1 - 3 hours, and then discharged. After high-pressure water descaling treatment, rolling: For the steel plate with finished plate thickness ≥15mm, two-stage rolling is adopted, wherein the rough rolling rolling temperature is 1050. ±40°C, intermediate blank temperature to be ≥2.0 plate thickness, finishing rolling temperature is 810~920°C; for steel plate with finished plate thickness <15mm, high pressure water is descaled and directly rolled to final thickness; After the completion of the system, the target steel products are obtained by straightening and air cooling.

[权利要求 4] 一种制造权利要求 1所述改进型 09CrCuSb耐硫酸露点腐蚀用圆管坯的方法，其特征在于：按所述改进型耐硫酸露点腐蚀用钢化学组成配置冶炼原料，冶炼原料依次经 KR铁水预处理、电炉 /转炉冶炼、 LF精炼、 VD/RH真空处理、连铸，得到 300mmx340mm或以上尺寸的矩形连铸坯；将连铸坯在中性或弱氧化性气氛的加热炉内加热至 1150〜1210 °C保温不少于 1小吋，并控制连铸坯在加热炉的总加热吋间为 2.5〜3.5 小吋，出炉；出炉后的连铸坯经高压水除鳞后进入 17架连轧机组进行轧制，幵轧温度 1050±40°C，终轧温度 950±40°C, 轧至目标尺寸，空冷制得圆管坯产品。 [Claim 4] A method for producing a modified 09CrCuSb round pipe blank resistant to sulfuric acid dew point corrosion according to claim 1, characterized by: smelting raw materials, smelting raw materials according to the chemical composition of the modified sulfuric acid dew point corrosion resistant steel It is sequentially subjected to KR hot metal pretreatment, electric furnace/converter smelting, LF refining, VD/RH vacuum treatment, continuous casting to obtain a rectangular continuous casting billet of 300 mm×340 mm or more; and the continuous casting billet is heated in a neutral or weak oxidizing atmosphere. Heated to 1150~1210 °C for not less than 1 hour, and control the continuous casting billet in the total heating time of the heating furnace is 2.5~3.5 After the furnace is discharged, the continuous casting billet is descaled by high-pressure water and then rolled into 17 continuous rolling mills for rolling. The rolling temperature is 1050±40°C, the final rolling temperature is 950±40°C, and the target size is rolled. A hollow tube blank product is produced by air cooling.