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Ferritic stainless steel seamless steel tube and preparation method thereof

A technology of seamless steel pipe and stainless steel, which is applied in the field of steel materials, can solve the problems of high price, damage, and reduced heat exchange effect of heat exchangers, and achieve the effects of improved oxidation resistance, low cost, and simple operation

Active Publication Date: 2015-08-26
SUZHOU GOLDEN WAY STEEL TUBE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The temperature of the exhaust gas discharge port is as high as 800~950°C, and the exhaust gas contains a large amount of sulfur dioxide; if an ordinary No. 20 steel pipe is used, although the heat exchange effect is better, it will be damaged soon under the influence of high temperature and corrosive gas; If it is replaced by austenitic stainless steel tubes that are resistant to high temperature and corrosion, the heat exchanger produced will be expensive and the heat transfer effect will be significantly reduced

Method used

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Examples

Experimental program
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Effect test

preparation example Construction

[0020] The method for preparing the above-mentioned ferritic stainless steel seamless steel pipe includes the following steps: (a) hot-rolled piercing: place the tube billet at 1150-1160°C for 30-60 minutes, and control the compression ratio before the plug to 4.5-5.0% for piercing , followed by natural cooling; (b) the first pickling & inspection: the steel pipe prepared in step (a) was pickled with a mixed solution of hydrofluoric acid and nitric acid, and then inspected by endoscope and visual inspection. Crack detection is carried out on its inner and outer surfaces to confirm whether there are cracks on the inner and outer surfaces of the steel pipe; the pickling time is 30-60min, the mass concentration of the hydrofluoric acid is 2-3%, and the mass concentration of the nitric acid is 4-7% respectively. %; (c) Lubrication: After the inspection in step (b), the inner and outer surfaces of the steel pipes without cracks are coated with lubricant, and dried at 200~250°C. The ...

Embodiment 1

[0023] This embodiment provides a ferritic stainless steel seamless steel pipe, its element weight percentage is as follows C: 0.03%, Si: 0.7%, Mn: 1%, P: 0.03%; S: 0.02%, Cr: 17%, Ti: 0.2%, N: 0.025%, Cu: 0.25%, Al: 0.8%, and the balance is Fe; its preparation method includes the following steps:

[0024] (a) Hot-rolled piercing: place the tube billet at 1150°C for 60 minutes, control the compression ratio before the plug to 4.5% to piercing, and then cool naturally;

[0025] (b) The first pickling & inspection: Pickle the steel pipe prepared in step (a) with a mixed solution of hydrofluoric acid and nitric acid, and then crack the inner and outer surfaces respectively by endoscope and visual inspection. Detect to confirm that there are no cracks on the inner and outer surfaces of the steel pipe; the pickling time is 30min, the mass concentration of the hydrofluoric acid is 2%, and the mass concentration of the nitric acid is 4% respectively;

[0026] (c) Lubrication: After ...

Embodiment 2

[0032]This embodiment provides a ferritic stainless steel seamless steel pipe, and its element weight percentages are as follows, C: 0.03%, Si: 1.1%, Mn: 1%, P: 0.03%; S: 0.02%, Cr: 19% , Ti: 0.4%, N: 0.025%, Cu: 0.25%, Al: 1.2%, and the balance is Fe; the preparation method includes the following steps:

[0033] (a) Hot-rolled piercing: first make a centering hole on the end face of the tube blank (to facilitate centering during piercing), then place it in a heating furnace and heat it to 800 °C at a speed of 8 °C / min, and then heat it at 20 °C / min. The speed is heated from 800 ℃ to 1160 ℃, and the temperature is kept for 30 minutes. The compression rate before the plug is controlled to be 5.0%, and the perforation is then naturally cooled;

[0034] (b) The first pickling & inspection: pickling the steel pipe prepared in step (a) with a mixed solution of hydrofluoric acid and nitric acid, and then cracking its inner and outer surfaces by endoscope and visual inspection. Dete...

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Abstract

The invention relates to a ferritic stainless steel seamless steel tube and a preparation method thereof. The ferritic stainless steel seamless steel tube comprises the following elements in mass percentage: C is less than or equal to 0.03 %, Si is 0.7-1.1%, Mn is less than or equal to 1%, P is less than or equal to 0.03%, S is less than or equal to 0.02 %, Cr is 17-19%, Ti is 0.2-0.4%, N is less than or equal to 0.025%, Cu is less than or equal to 0.25%, Al is 0.8-1.2% and the balance of Fe. The preparation method comprises the following steps: (a) hot rolling perforation; (b) first acid pickling and inspection; (c) lubrication; (d) cold drawing / cold rolling; (e) second acid pickling; (f) thermal processing; and (g) third acid pickling and inspection. Since the weight percentages of Si and Al in the component elements are improved, the inoxidizability of stainless steel is greatly improved, and stainless steel with high yield strength, low plasticity and 1.5 times of thermal conductivity of austenitic stainless steel is provided; according to the preparation method of the ferritic stainless steel seamless steel tube, all steps are linked with one another; the operation is relatively simple; and the ferritic stainless steel seamless steel tube is relatively low in cost.

Description

technical field [0001] The invention belongs to the field of iron and steel materials, and relates to a seamless steel pipe, in particular to a ferritic stainless steel seamless steel pipe and a preparation method thereof. Background technique [0002] A blast furnace in a steel plant is a device that smelts ore into pig iron. A large amount of high-temperature waste gas is discharged during the ironmaking process, and making full use of the large amount of energy contained in the high-temperature waste gas is an important part of reducing the cost of ironmaking. Therefore, many iron and steel plants install heat exchangers at the exhaust outlets, and then the heat exchanged by the heat exchangers preheats the wind used for steelmaking. The temperature of the exhaust gas discharge port is as high as 800~950°C, and the exhaust gas contains a large amount of sulfur dioxide; if an ordinary No. 20 steel pipe is used, although the heat exchange effect is better, it will be dama...

Claims

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Application Information

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IPC IPC(8): C22C38/28C21D8/10C23G1/08
Inventor 吴振环钱祥保金仁明刘凯
Owner SUZHOU GOLDEN WAY STEEL TUBE
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