Ribbon steel for weather-proof gasket and preparation method of ribbon steel

Abstract

The narrow strip steel comprises the following chemical components in percentage by mass: 0.20% < = C < = 0.40%, 0.10% < = Si < = 0.40%, 0.70% < = Mn < = 1.20%, 0.60% < = Cr < = 1.20%, 0.10% < = Ni < = 0.60%, 0.10% < = Mo < = 0.40%, 0.01% < = Al < = 0.08%, less than or equal to 0.020% of P, less than or equal to 0.015% of S and the balance of Fe and inevitable impurities. Through component design, the use scene requirement of the weather-proof gasket is met, the corrosion resistance of the weather-proof gasket is guaranteed through the design of the content of the elements Cu, Cr and Ni, the strength and hardness of the weather-proof gasket are guaranteed through the design of the content of the elements C, Si and Mn, and the use performance of the weather-proof gasket is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a narrow strip steel for weather-resistant gaskets and a preparation method thereof. Background Art

[0002] Weathering steel, also known as atmospheric corrosion resistant steel, is a low alloy steel series between ordinary steel and stainless steel. It is mainly used for steel structures exposed to the atmosphere for a long time, such as railways, automobiles, bridges, towers, containers, etc. In addition, weathering steel is also used to manufacture structural components containing hydrogen sulfide corrosive media in containers such as oil equipment, oil derricks, port construction, oil production platforms and chemical containers. In recent years, with the enhancement of environmental awareness and the promotion of the concept of sustainable development, the application of weathering steel in landscape wall design and customization has become more and more extensive, becoming a new favorite in modern urban landscape design.

[0003] Considering the purpose of weathering steel, conventional weathering steel is required to have corrosion resistance, high strength and welding performance. At present, the common effect of Cu, P, Cr and Ni elements is generally used to improve the corrosion resistance of weathering steel. There are large differences in the specific content of different steel grades. The atmospheric corrosion resistance index is usually used to characterize the corrosion resistance of the material. The larger the index value, the stronger the corrosion resistance. High strength is mainly considered that some weathering steels are used as structural parts. In the context of lightweight, extremely high strength is required. At present, the microalloying effect of elements such as Nb, V, and Ti is generally used to improve the strength. Combined with the controlled rolling and controlled cooling process, secondary precipitates containing elements such as Nb, V, and Ti are used to achieve the purpose of precipitation strengthening, thereby improving the strength of weathering steel. The welding performance is mainly characterized by the carbon equivalent. It is generally believed that the carbon equivalent is ≤0.45, and the welding performance of the steel plate is good. In order to pursue good welding performance in some use environments, the carbon content is even required to be ≤0.06%.

[0004] Weathering gaskets in the fastener system are also an important component of weathering steel. Weathering gaskets have no welding performance requirements. In addition to strength, they also have high requirements for hardness. Currently, few people are involved in the production process of weathering gaskets, especially the production process of narrow strip steel for weathering gaskets. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a narrow strip steel for weather-resistant gaskets and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows: A narrow strip steel for weather-resistant gaskets, whose chemical composition and mass percentage are: 0.20%≤C≤0.40%, 0.10%≤Si≤0.40%, 0.70%≤Mn≤1.20%, 0.60%≤Cr≤1.20%, 0.10%≤Ni≤0.60%, 0.10%≤Mo≤0.40%, 0.01%≤Al≤0.08%, P≤0.020%, S≤0.015%, and the balance is Fe and unavoidable impurities.

[0007] The present invention also provides a method for preparing narrow strip steel for weather-resistant gaskets, which comprises the following steps in sequence: converter smelting, LF furnace refining, RH furnace refining, continuous casting, heating, rolling, and cooling; Among them, in the converter smelting process, the converter steel-making conditions are: C≥0.08%, P≤0.02%, temperature≥1600°C, Ni element is added in the converter furnace, and Ni≥0.10%.

[0008] As a preferred embodiment of the method for preparing narrow strip steel for weather-resistant gaskets according to the present invention, in the converter smelting process, the order of adding materials in the steel-tapping process is: deoxidizer, alloy, pre-melted slag, lime, the content of the deoxidizer is 1.0-2.5kg / t, the content of the pre-melted slag is 2-4kg / t, the content of the lime is 4-6kg / t, the deoxidizer is aluminum or aluminum-iron alloy, and the alloy includes Si, Mn, Cr, and Mo elements.

[0009] As a preferred embodiment of the method for preparing narrow strip steel for weather-resistant gaskets according to the present invention, in the LF furnace refining process, the initial aluminum content is ≥0.02%, the amount of lime added is 1-3kg / t, and the diffusion deoxidizer is ≤2.0kg / t, and the diffusion deoxidizer is one or more of aluminum wire, silicon carbide, carbon powder, and calcium carbide.

[0010] As a preferred embodiment of the method for preparing narrow strip steel for weather-resistant gaskets according to the present invention, in the RH furnace refining process, the ultimate vacuum time is ≥8 min, the static stirring time is ≥20 min, the aluminum wire is fed first, and then the calcium wire is fed, and the aluminum wire is ≤50 m, and the calcium wire is ≤200 m.

[0011] As a preferred scheme of the preparation method of narrow strip steel for weather-resistant gaskets described in the present invention, the heating furnace used in the heating process is a walking-beam heating furnace, which is divided into a preheating section, a heating section, a heating section, a heating section and a soaking section. The furnace temperature of the preheating section is ≤700°C, the furnace temperature of the heating section is 700-950°C, the furnace temperature of the heating section is 850-1050°C, the furnace temperature of the heating section is 1000-1200°C, the furnace temperature of the soaking section is 1050-1250°C, and the time in the furnace is ≥120min.

[0012] As a preferred solution of the method for preparing the narrow strip steel for weather-resistant gaskets of the present invention, the final rolling temperature of the rolling process is 850-980°C, and the coiling temperature is ≤720°C.

[0013] As a preferred embodiment of the method for preparing the narrow steel strip for weather-resistant gaskets of the present invention, the thickness of the narrow steel strip for weather-resistant gaskets is 1.5-12 mm, and the width is 150-450 mm.

[0014] The beneficial effects of the present invention are: (1) The present invention meets the requirements of the use scenarios of weather-resistant gaskets through component design. The design of the content of Cu, Cr, and Ni elements ensures the corrosion resistance of the weather-resistant gasket. Combined with the content design of C, Si, and Mn elements, the strength and hardness of the weather-resistant gasket are ensured, thereby ensuring its performance.

[0015] (2) The present invention reduces the O and S contents in the molten steel by controlling the steel-making system, deoxidation system and slag-making system, further improving the corrosion resistance and cleanliness of the molten steel. Finally, the content of harmful gas elements is reduced by controlling the pressure and time of the vacuum process.

[0016] (3) The present invention realizes the size and surface quality control of narrow strip steel through high temperature heating and controlled rolling and cooling during the steel rolling process. DETAILED DESCRIPTION

[0017] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation methods.

[0018] An embodiment of the present application provides a narrow strip steel for weather-resistant gaskets, whose chemical composition and mass percentage are: C: 0.30%, Si: 0.25%, Mn: 0.86%, Cr: 0.77%, Ni: 0.29%, Mo: 0.16%, Al: 0.035%, P: 0.015%, S: 0.0015%, and the remainder is Fe and unavoidable impurities.

[0019] It should be noted that the elements Cu, Cr and Ni are mainly used to ensure that the corrosion resistance of weathering steel meets the user's requirements. The element S is harmful to corrosion resistance, so the content of O in the molten steel is reduced by controlling the Al content, and then the S content is controlled as low as possible in combination with high-basicity refined slag. The elements C, Si and Mn are mainly used to ensure that the weathering gasket has high hardness and strength and will not deform during use.

[0020] The embodiment of the present application also provides a method for preparing narrow strip steel for weather-resistant gaskets, which comprises the following steps in sequence: converter smelting, LF furnace refining, RH furnace refining, continuous casting, heating, rolling, and cooling.

[0021] Among them, in the converter smelting process, the steel tapping conditions of the converter are: C: 0.10%, P: 0.01%, temperature T: 1630℃, Ni element is added in the converter, and Ni: 0.20%. Adding Ni element in the converter can effectively reduce the amount of alloy added in the steel tapping process or refining process, improve the cleanliness of molten steel, and accelerate the temperature rise of molten steel. The requirement of steel tapping temperature is mainly to promote the rapid melting of refined slag and alloy, so as to achieve the purpose of improving the cleanliness of molten steel. The requirement of C element is mainly to stabilize the oxygen potential of molten steel and reduce the formation of inclusions.

[0022] The order of adding materials in the converter steelmaking process is: deoxidizer → alloy → pre-melted slag → lime. Among them, the content of deoxidizer is 1.0-2.5kg / t, the content of pre-melted slag is 2-4kg / t, and the content of lime is 4-6kg / t. The deoxidizer is aluminum or aluminum-iron alloy, and the alloy includes Si, Mn, Cr, and Mo elements. The strict regulations on the order of adding materials are mainly to prevent the oxidation of alloys such as Si, Mn, Cr, and Mo, thereby increasing the yield of the alloy. The regulations on the amount of deoxidizer, pre-melted slag, and lime added are mainly to create a suitable refining slag system. The choice of deoxidizer is mainly determined by the actual working conditions. The addition of alloy types after the converter also needs to be determined in combination with the actual number of silos after the furnace.

[0023] In the LF furnace refining process, the initial aluminum content is 0.03%, the amount of lime added is 1-3kg / t, and the diffusion deoxidizer is ≤2.0kg / t. The diffusion deoxidizer is one or more of aluminum wire, silicon carbide, carbon powder, and calcium carbide. The control of Al content in the LF process is mainly to reduce the oxygen potential in the molten steel and improve the cleanliness of the molten steel. The addition of lime is mainly to increase the basicity of the refining slag, which helps to reduce the S content of the molten steel and the floating removal of inclusions. The diffusion deoxidizer is mainly used to reduce the oxidizability of the refining slag, and also serves the purpose of reducing the oxygen content of the molten steel and improving the cleanliness.

[0024] In the RH furnace refining process, the ultimate vacuum time is 10 minutes, the static stirring time is 25 minutes, and the aluminum wire is fed first, and then the calcium wire is fed, and the aluminum wire is ≤50m, and the calcium wire is ≤200m. The ultimate vacuum is mainly to remove H and N elements in the molten steel, the static stirring time is mainly for the floating of inclusions, the addition of Ca wire is mainly to prevent nozzle blockage and ensure the smooth continuous casting process, and the addition of Al wire is mainly to ensure that the Al content meets user requirements.

[0025] The heating furnace used in the heating process is a walking beam heating furnace, which is divided into a preheating section, a heating section, a heating section, a heating section and a soaking section. Among them, the furnace temperature of the preheating section is ≤700℃, the furnace temperature of the heating section is 700-950℃, the furnace temperature of the heating section is 850-1050℃, the furnace temperature of the heating section is 1000-1200℃, the furnace temperature of the soaking section is 1050-1250℃, and the furnace time is ≥120min. Considering that the Cu element is easy to accumulate on the surface of the billet under certain temperature conditions, which will lead to cracking and surface quality problems of the billet, the temperature of the soaking section is set to a high temperature condition of 1050-1250℃ to ensure the surface quality of the hot-rolled narrow strip steel.

[0026] The final rolling temperature of the rolling process is 850-980°C, and the coiling temperature is ≤720°C. The final rolling temperature requirement is mainly to ensure that the material is in the volatile area, which is helpful for the control of plate shape and size.

[0027] Therefore, the technical solution of this application meets the use scenario requirements of weather-resistant gaskets through component design. The design of the content of Cu, Cr, and Ni elements ensures the corrosion resistance of the weather-resistant gaskets. Combined with the content design of C, Si, and Mn elements, the strength and hardness of the weather-resistant gaskets are ensured, and their performance is guaranteed. Through the control of the steel-making system, deoxidation system, and slag-making system, the O and S content in the molten steel is reduced, and the corrosion resistance and cleanliness of the molten steel are further improved. Finally, through the control of the pressure and time of the vacuum process, the content of harmful gas elements is reduced. The steel rolling process realizes the size and surface quality control of narrow strip steel through high-temperature heating and controlled rolling and cooling.

[0028] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A narrow strip steel for weather-resistant gaskets, characterized in that: Its chemical composition and mass percentage are: 0.20%≤C≤0.40%, 0.10%≤Si≤0.40%, 0.70%≤Mn≤1.20%, 0.60%≤Cr≤1.20%, 0.10%≤Ni≤0.60%, 0.10%≤Mo≤0.40%, 0.01%≤Al≤0.08%, P≤0.020%, S≤0.015%, and the balance is Fe and unavoidable impurities.

2. A method for preparing the narrow strip steel for weather-resistant gasket according to claim 1, characterized in that: The process includes the following steps: Converter smelting, LF furnace refining, RH furnace refining, continuous casting, heating, rolling, cooling; Among them, in the converter smelting process, the converter steel-making conditions are: C≥0.08%, P≤0.02%, temperature≥1600°C, Ni element is added in the converter furnace, and Ni≥0.10%.

3. The method for preparing narrow strip steel for weather-resistant gasket according to claim 2, characterized in that: In the converter smelting process, the order of adding materials in the steel-making process is: deoxidizer, alloy, pre-melted slag, lime, the content of the deoxidizer is 1.0-2.5kg / t, the content of the pre-melted slag is 2-4kg / t, the content of the lime is 4-6kg / t, the deoxidizer is aluminum or aluminum-iron alloy, and the alloy includes Si, Mn, Cr, and Mo elements.

4. The method for preparing narrow strip steel for weather-resistant gasket according to claim 2, characterized in that: In the LF furnace refining process, the initial aluminum content is ≥0.02%, the amount of lime added is 1-3kg / t, and the diffusion deoxidizer is ≤2.0kg / t. The diffusion deoxidizer is one or more of aluminum wire, silicon carbide, carbon powder, and calcium carbide.

5. The method for preparing narrow strip steel for weather-resistant gasket according to claim 2, characterized in that: In the RH furnace refining process, the ultimate vacuum time is ≥8 min, the static stirring time is ≥20 min, the aluminum wire is fed first, and then the calcium wire is fed, and the aluminum wire is ≤50 m, and the calcium wire is ≤200 m.

6. The method for preparing narrow strip steel for weather-resistant gasket according to claim 2, characterized in that: The heating furnace used in the heating process is a walking-beam heating furnace, which is divided into a preheating section, a heating section, a heating section, a heating section and a soaking section. The furnace temperature of the preheating section is ≤700°C, the furnace temperature of the heating section is 700-950°C, the furnace temperature of the heating section is 850-1050°C, the furnace temperature of the heating section is 1000-1200°C, the furnace temperature of the soaking section is 1050-1250°C, and the time in the furnace is ≥120min.

7. The method for preparing narrow strip steel for weather-resistant gasket according to claim 2, characterized in that: The final rolling temperature of the rolling process is 850-980°C, and the coiling temperature is ≤720°C.

8. The method for preparing narrow steel strip for weather-resistant gasket according to claim 2, characterized in that: The thickness of the narrow steel strip used to make the weather-resistant gasket is 1.5-12 mm, and the width is 150-450 mm.