Continuous casting billet of high-aluminum steel and its heating method

Abstract

The present application discloses a high-aluminum steel continuous casting billet and a heating method therefor. The method includes providing a high-aluminum steel continuous casting billet with a thickness of 190 mm to 250 mm; preheating the high-aluminum steel continuous casting billet so that the preheating temperature of the high-aluminum steel continuous casting billet is ≤ 770°C; heating the preheated high-aluminum steel continuous casting billet so that the heating temperature of the high-aluminum steel continuous casting billet is ≤ 1220°C; soaking the heated high-aluminum steel continuous casting billet so that the soaking temperature of the high-aluminum steel continuous casting billet is ≤ 1180°C. According to the heating method of the high-aluminum steel continuous casting billet of the embodiments of the present application, by selecting appropriate temperatures for preheating, heating, and soaking during the heating process, the stability of the shape of the continuous casting billet during the heating process is ensured, which not only avoids softening, deformation, or overburning of the high-aluminum steel continuous casting billet during the heating process, but also achieves the purpose of uniform heating and smooth rolling out of the furnace.

Description

Technical Field

[0001] This application belongs to the technical field of steel material processing, and particularly relates to a high-aluminum steel continuous casting billet and a heating method thereof. Background Art

[0002] When aluminum is added to steel as an alloying element, high-aluminum steel with excellent properties can be prepared by controlling the production process. High-aluminum steel has good corrosion resistance, low magnetic permeability, wear resistance and other characteristics, as well as advantages such as high dimensional accuracy, high strength, low density and good ductility after treatment. Therefore, it is gradually applied to fields such as ships, military industry, aerospace, ocean engineering, automobiles, and chemicals.

[0003] At present, although a large amount of research has been carried out on high-aluminum steel, the focus of these research results is mostly on the smelting continuous casting and deformation mechanism of high-aluminum steel, and little mention is made of how to achieve stable heating of high-aluminum steel. Compared with ordinary steel, high-aluminum steel has a high alloy content, a low heating expansion coefficient, low high-temperature strength, high-temperature phase change temperature, softening range and phase change range, which are completely different from ordinary steel. The original billet heating parameters can no longer meet the production requirements of high-aluminum steel. Using the original heating parameters is likely to cause softening deformation of the high-aluminum steel continuous casting billet and make it difficult to roll out of the furnace. Summary of the Invention

[0004] The embodiment of this application provides a heating method for a high-aluminum steel continuous casting billet, which can avoid softening deformation of the high-aluminum steel continuous casting billet during the heating process, so as to ensure stable rolling out of the furnace.

[0005] In a first aspect, this application provides a heating method for a high-aluminum steel continuous casting billet, and the method includes:

[0006] Providing a high-aluminum steel continuous casting billet with a thickness of 190 mm to 250 mm;

[0007] Preheating the high-aluminum steel continuous casting billet so that the preheating temperature of the high-aluminum steel continuous casting billet ≤ 770°C;

[0008] Heating the preheated high-aluminum steel continuous casting billet so that the heating temperature of the high-aluminum steel continuous casting billet ≤ 1220°C;

[0009] Soaking the heated high-aluminum steel continuous casting billet so that the soaking temperature of the high-aluminum steel continuous casting billet ≤ 1180°C.

[0010] The heating method of the high-aluminum steel continuous casting billet according to the embodiment of the present application controls the preheating temperature of the high-aluminum steel continuous casting billet not to exceed 770 °C to ensure that the heating expansion and phase change expansion of the high-aluminum steel continuous casting billet are stable and slow, without damaging the quality of the continuous casting billet. The maximum heating temperature of the high-aluminum steel continuous casting billet in the heating stage does not exceed 1220 °C because the high-temperature strength of high-aluminum steel is low, and too high a temperature makes it enter the high-temperature ferrite phase region, accelerating the softening of the continuous casting billet and causing the continuous casting billet to deform, making it difficult to discharge from the furnace. In the soaking stage, controlling the temperature of the high-aluminum steel continuous casting billet not to exceed 1180 °C can not only achieve the purpose of homogenization but also ensure the stability of the size and morphology of the continuous casting billet, so as to smoothly discharge from the furnace for rolling. Homogenization means that the precipitated phase is dissolved back into the matrix tissue as much as possible, and at the same time, the composition is as uniform as possible.

[0011] In one embodiment, the high-aluminum steel continuous casting billet, by mass percentage, comprises the following components in the following contents: C: 0-0.1%, Si: 0.1-0.5%, Mn: 0.5-1.5%, P≤0.025%, S≤0.015, Al: 2.5-5.5%, N: 0-0.01%, and the rest is Fe and inevitable impurities.

[0012] In one embodiment, a continuous heating furnace is used to preheat, heat, and soak the high-aluminum steel continuous casting billet. After the high-aluminum steel continuous casting billet enters the furnace, the calorific value of the gas ≥11500 KJ / m 3 ³, and the gas pressure ≥110 Mbar. The continuous heating furnace uses gas as fuel for heating. Of course, in other embodiments, electric furnace heating can also be applied, and the controlled heating temperature is the same as that of using a continuous heating furnace.

[0013] In one embodiment, the heating furnace uses an air-fuel ratio of 2.3-2.8 and an air excess coefficient of 1.1-1.3 to preheat the high-aluminum steel continuous casting billet, and the preheating time is 50 minutes to 90 minutes.

[0014] In one embodiment, the heating furnace uses an air-fuel ratio of 2.1-2.6 and an air excess coefficient of 1.0-1.3 to heat the high-aluminum steel continuous casting billet, and the heating time is 150 minutes to 200 minutes.

[0015] In one embodiment, the heating furnace uses an air-fuel ratio of 1.8-2.5 and an air excess coefficient of 0.8-1.1 to soak the high-aluminum steel continuous casting billet, and the soaking time is 20 minutes to 50 minutes.

[0016] In one embodiment, the heating time of the heating method of the high-aluminum steel continuous casting billet ≥240 minutes, and the solution time ≥40 minutes. Solution means that the precipitated phase is evenly distributed in the later stage of heating and the soaking process. If the solution time is short, the solution is insufficient, the element distribution uniformity is poor, and the segregation is serious, which may lead to delamination during the rolling process.

[0017] The heating method of the high-aluminum steel continuous casting billet in the embodiments of the present application is applicable to high-aluminum steel with an Al content of 2.5 wt% to 5.5 wt%.

[0018] In a second aspect, the present application provides a high-aluminum steel continuous casting billet, which is prepared according to the heating method of the high-aluminum steel continuous casting billet described above.

[0019] The heating method of the high-aluminum steel continuous casting billet in the embodiments of the present application ensures the stability of the billet shape during the heating process by selecting appropriate preheating, heating, and soaking temperatures during the heating process. It not only avoids softening, deformation, or overburning of the high-aluminum steel continuous casting billet during the heating process but also achieves uniform heating and the purpose of smooth rolling after discharging from the furnace.

[0020] In addition, by adopting the heating process of the present application, not only the smooth heating of the high-aluminum steel continuous casting billet is ensured, but also high production efficiency and low fuel consumption are guaranteed. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required to be used in the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 is a flowchart of the heating method of the high-aluminum steel continuous casting billet of the present application;

[0023] Figure 2 is a high-aluminum steel continuous casting billet with a complete internal morphology in the heating furnace and about to be rolled after discharging from the furnace in Embodiment 1 of the present application;

[0024] Figure 3 is a high-aluminum steel casting billet with a complete morphology after heating in Embodiment 2 of the present application;

[0025] Figure 4 is a softened and deformed high-aluminum steel casting billet in the heating furnace after heating in Comparative Example 1;

[0026] Figure 5 is a softened and deformed high-aluminum steel casting billet in the heating furnace after heating in Comparative Example 2;

[0027] Description of the Reference Numerals:

[0028] 1. High-aluminum steel continuous casting billet. Detailed Embodiments

[0029] The features and exemplary embodiments of various aspects of the present application will be described in detail below. To make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application and not to limit the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present application by showing examples of the present application.

[0030] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0031] To solve the problems of the prior art, an embodiment of the present application provides a heating method for a high-aluminum steel continuous casting billet. The heating method for the high-aluminum steel continuous casting billet provided by the embodiment of the present application will be introduced first below.

[0032] Figure 1 The flowchart of the heating method for the high-aluminum steel continuous casting billet provided by an embodiment of the present application is shown. As Figure 1 shown, the heating method for the high-aluminum steel continuous casting billet includes:

[0033] S1. Provide a high-aluminum steel continuous casting billet with a thickness of 190 mm to 250 mm. The high-aluminum steel continuous casting billet, by mass percentage, includes the following components: C: 0 to 0.1%, Si: 0.1 to 0.5%, Mn: 0.5 to 1.5%, P ≤ 0.025%, S ≤ 0.015, Al: 3.0 to 4.5%, N: 0 to 0.01%, and the balance is Fe and unavoidable impurities;

[0034] Use a continuous reheating furnace to heat the high-aluminum steel continuous casting billet, with a total heating time ≥ 240 minutes and a solution time ≥ 40 minutes; wherein, after the high-aluminum steel continuous casting billet enters the furnace, the calorific value of the gas ≥ 11500 KJ / m 3 and the gas pressure ≥ 110 Mbar;

[0035] Specifically, the continuous casting billet of high-aluminum steel in a continuous reheating furnace includes the following steps:

[0036] S2. Preheat the continuous casting billet of high-aluminum steel in a continuous reheating furnace with an air-fuel ratio of 2.3 - 2.8 and an air excess coefficient of 1.1 - 1.3 for 50 to 90 minutes, so that the preheating temperature of the continuous casting billet of high-aluminum steel ≤ 770 °C;

[0037] S3. Heat the preheated continuous casting billet of high-aluminum steel in a continuous reheating furnace with an air-fuel ratio of 2.1 - 2.6 and an air excess coefficient of 1.0 - 1.3 for 150 to 200 minutes, so that the heating temperature of the continuous casting billet of high-aluminum steel ≤ 1220 °C;

[0038] S4. Soak the heated continuous casting billet of high-aluminum steel in a continuous reheating furnace with an air-fuel ratio of 1.8 - 2.5 and an air excess coefficient of 0.8 - 1.1 for 20 to 50 minutes, so that the soaking temperature of the continuous casting billet of high-aluminum steel ≤ 1180 °C.

[0039] The heating method of the continuous casting billet of high-aluminum steel in the embodiment of the present application ensures the stability of the billet shape during the heating process by selecting appropriate preheating, heating, and soaking temperatures. It not only avoids softening, deformation, or overburning of the continuous casting billet of high-aluminum steel during the heating process but also achieves uniform heating and the purpose of smooth rolling out of the furnace. By controlling the ratio of fast air and fuel and the air excess coefficient, the oxidation of high-aluminum steel can be reduced while the continuous casting billet of high-aluminum steel is being heated.

[0040] The technical solutions and advantages of the heating method of the continuous casting billet of high-aluminum steel in the present application will be described in more detail through specific embodiments below.

[0041] Example 1:

[0042] The chemical composition of the continuous casting billet of high-aluminum steel is as follows: by mass percentage, C: 0.05%, Si: 0.12%, Mn: 1.1%, P: 0.020%, S: 0.011%, Al: 4.2%, N: 0.006%, and the rest is Fe and inevitable impurities. The thickness of the continuous casting billet of high-aluminum steel is 230 mm. After the slab enters the furnace, the calorific value of the gas: 11800 KJ / m 3 , gas pressure: 120 Mbar.

[0043] During the preheating stage, the air-fuel ratio of the heating furnace is 2.7, the air excess coefficient is 1.2, the highest preheating temperature of the continuous casting billet of high-aluminum steel in the preheating stage is 760 °C, and the preheating stage time is 78 min.

[0044] During the heating stage, the air-fuel ratio of the heating furnace is 2.5, the excess air coefficient is 1.2, the maximum heating temperature of the high-aluminum steel continuous casting billet is 1205 °C, and the heating stage time is 166 min.

[0045] During the soaking stage, the air-fuel ratio of the heating furnace is 2.0, the excess air coefficient of the heating furnace is 0.9, the soaking temperature of the high-aluminum steel continuous casting billet is 1160 °C, and the soaking stage time range is 25 min.

[0046] The total heating time is 269 min, among which the solution time is 45 min.

[0047] After heating, the morphology of the high-aluminum steel casting billet before discharging from the furnace is as Figure 2 shown. The surface of the high-aluminum steel continuous casting billet 1 is flat, the side lines of the continuous casting billet are straight, the morphology of the continuous casting billet is complete and not softened or deformed, which is beneficial to the smooth discharging and rolling of the continuous casting billet.

[0048] Example 2:

[0049] The chemical composition of the high-aluminum steel continuous casting billet is as follows: by mass percentage, C: 0.06%, Si: 0.20%, Mn: 1.2%, P: 0.019%, S: 0.010%, Al: 4.1%, N: 0.006%, and the rest is Fe and inevitable impurities. The thickness of the high-aluminum steel continuous casting billet is 230 mm. After the slab enters the furnace, the calorific value of the gas: 12500 KJ / m 3 and the gas pressure: 130 Mbar.

[0050] During the preheating stage, the air-fuel ratio of the heating furnace is 2.5, the excess air coefficient is 1.3, the maximum preheating temperature of the high-aluminum steel continuous casting billet is 755 °C, and the preheating stage time is 56 min.

[0051] During the heating stage, the air-fuel ratio of the heating furnace is 2.3, the excess air coefficient is 1.1, the maximum heating temperature of the high-aluminum steel continuous casting billet is 1190 °C, and the time is 168 min.

[0052] During the soaking stage, the air-fuel ratio of the heating furnace is 2.0, the excess air coefficient is 1.0, the soaking temperature of the high-aluminum steel continuous casting billet is 1150 °C, and the time is 32 min.

[0053] The total heating time is 256 min, among which the solution time is 41 min.

[0054] After heating, the morphology of the high-aluminum steel casting billet before discharging from the furnace is as Figure 3 shown. The plane side lines of the high-aluminum steel continuous casting billet 1 on the conveying chain are straight, with distinct edges and corners, the morphology is complete and not softened or deformed, which is beneficial to the smooth discharging and rolling of the continuous casting billet.

[0055] Comparative Example 1:

[0056] The chemical composition of the high-aluminum steel continuous casting billet is as follows: by mass percentage, C: 0.05%, Si: 0.15%, Mn: 0.95%, P: 0.022%, S: 0.012%, Al: 3.9%, N: 0.005%, and the rest is Fe and unavoidable impurities.

[0057] The thickness of the high-aluminum steel continuous casting billet is 230 mm. After the slab is put into the furnace, the calorific value of the gas is 11800 KJ / m 3 and the gas pressure is 120 Mbar.

[0058] In the preheating stage, the air-fuel ratio of the heating furnace is 2.7, the excess air coefficient is 1.2, the highest preheating temperature of the high-aluminum steel continuous casting billet is 800 °C, and the preheating stage time is 88 min.

[0059] In the heating stage, the air-fuel ratio of the heating furnace is 2.5, the excess air coefficient is 1.2, the highest heating temperature of the high-aluminum steel continuous casting billet is 1255 °C, and the heating stage time is 148 min.

[0060] In the soaking stage, the air-fuel ratio of the heating furnace is 2.0, the excess air coefficient of the heating furnace in the soaking stage is 0.9, the soaking temperature of the high-aluminum steel continuous casting billet in the soaking stage is 1220 °C, and the soaking stage time range is 38 min.

[0061] The total heating time is 274 min, of which the solution time is 45 min.

[0062] After heating, the morphology of the high-aluminum steel casting billet before leaving the furnace is as Figure 4 shown. The edges of the plate surface of the high-aluminum steel continuous casting billet have become uneven and curved, while the plate surface of the undeformed high-aluminum steel continuous casting billet should be a straight plane, indicating that the high-aluminum steel continuous casting billet in the heating furnace of this comparative example has softened and deformed, and it is difficult for the casting billet to leave the furnace and cannot be rolled.

[0063] Comparative Example 2:

[0064] The chemical composition of the high-aluminum steel continuous casting billet is as follows: by mass percentage, C: 0.05%, Si: 0.18%, Mn: 0.88%, P: 0.019%, S: 0.009%, Al: 3.5%, N: 0.005%, and the rest is Fe and unavoidable impurities.

[0065] The thickness of the high-aluminum steel continuous casting billet is 230 mm. After the slab is put into the furnace, the calorific value of the gas is 11800 KJ / m 3 and the gas pressure is 120 Mbar.

[0066] In the preheating stage, the air-fuel ratio of the heating furnace is 2.7, the excess air coefficient is 1.2, the highest preheating temperature of the high-aluminum steel continuous casting billet is 810 °C, and the preheating stage time is 77 min.

[0067] During the heating stage, the air-fuel ratio of the heating furnace is 2.5, the excess air coefficient is 1.2, the maximum heating temperature of the high-aluminum steel continuous casting billet is 1244 °C, and the heating stage time is 131 min.

[0068] During the soaking stage, the air-fuel ratio of the heating furnace is 2.0, the excess air coefficient of the heating furnace is 0.9, the soaking temperature for preheating the high-aluminum steel continuous casting billet is 1200 °C, and the soaking stage time range is 47 min.

[0069] The total heating time is 256 min, of which the solution time is 39 min.

[0070] After heating, the appearance of the high-aluminum steel casting billet out of the furnace is as Figure 5 shown. The edge curve of the plate surface of the high-aluminum steel continuous casting billet is bent and not a straight line in the undeformed state, indicating that the high-aluminum steel continuous casting billet in this comparative example has softened and deformed, and it is difficult for the high-aluminum steel continuous casting billet to run on the roller table after leaving the furnace and cannot be rolled.

[0071] Comparative Example 3:

[0072] This comparative example provides a high-aluminum steel continuous casting billet, and its chemical composition is: by mass percentage, C: 0.05%, Si: 0.12%, Mn: 1.1%, P: 0.020%, S: 0.011%, Al: 4.2%, N: 0.006%, and the rest are Fe and inevitable impurities.

[0073] The thickness of the high-aluminum steel continuous casting billet is 230 mm. After feeding the slab of the high-aluminum steel continuous casting billet into the continuous heating furnace, the calorific value of the gas: 11800 KJ / m 3 , gas pressure: 120 Mbar.

[0074] During the preheating stage, the air-fuel ratio of the heating furnace is 2.6, the excess air coefficient is 1.3, the maximum preheating temperature of the high-aluminum steel continuous casting billet is 755 °C, and the preheating stage time is 66 min.

[0075] During the heating stage, the air-fuel ratio of the heating furnace is 2.4, the excess air coefficient is 1.2, the maximum heating temperature of the high-aluminum steel continuous casting billet is 1255 °C, and the heating stage time is 165 min.

[0076] During the soaking stage, the air-fuel ratio of the heating furnace is 1.9, the excess air coefficient of the heating furnace is 1.0, the soaking temperature for preheating the high-aluminum steel continuous casting billet is 1215 °C, and the soaking stage time range is 38 min.

[0077] The total heating time is 269 min, of which the solution time is 54 min.

[0078] After heating, the high-aluminum steel continuous casting billet is over-softened, resulting in bending of the casting billet and difficulty in discharging from the furnace.

[0079] From a comparison of Comparative Example 3 with Examples 1 and 2, and Comparative Examples 1 and 2, it can be concluded that when one of the heating temperature parameters in the preheating, heating, and soaking stages exceeds the range set in the present application, the final heating result of the high-aluminum steel continuous casting billet will be softening deformation, making it impossible to carry out subsequent rolling.

[0080] As described above, the above are only specific embodiments of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules, and units described above can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here. It should be understood that the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present application.

Claims

1. A heating method for continuous casting billets of high-aluminum steel, characterized in that, Including: Providing a high-aluminum steel continuous casting billet with a thickness of 190 mm to 250 mm, the high-aluminum steel continuous casting billet, by mass percentage, includes components with the following contents: C: 0 to 0.1%, Si: 0.1 to 0.5%, Mn: 0.5 to 1.5%, P ≤ 0.025%, S ≤ 0.015, Al: 2.5 to 5.5%, N: 0 to 0.01%, and the rest being Fe and inevitable impurities; Preheating the high-aluminum steel continuous casting billet so that the preheating temperature of the high-aluminum steel continuous casting billet ≤ 770°C; Heating the preheated high-aluminum steel continuous casting billet so that the heating temperature of the high-aluminum steel continuous casting billet ≤ 1220°C; Soaking the heated high-aluminum steel continuous casting billet so that the soaking temperature of the high-aluminum steel continuous casting billet ≤ 1180°C.

2. The heating method according to claim 1, wherein The heating method uses a continuous reheating furnace to preheat, heat, and soak the high-aluminum steel continuous casting billet. After the high-aluminum steel continuous casting billet enters the furnace, the calorific value of the gas ≥ 11500 KJ / m 3 , and the gas pressure ≥ 110 Mbar.

3. The heating method according to claim 2, wherein The heating furnace preheats the high-aluminum steel continuous casting billet with an air-fuel ratio of 2.3 to 2.8 and an air excess coefficient of 1.1 to 1.3, and the preheating time is 50 minutes to 90 minutes.

4. The heating method according to claim 2, characterized in that The heating furnace heats the high-aluminum steel continuous casting billet with an air-fuel ratio of 2.1 to 2.6 and an air excess coefficient of 1.0 to 1.3, and the heating time is 150 minutes to 200 minutes.

5. The heating method according to claim 2, characterized in that, The heating furnace soaks the high-aluminum steel continuous casting billet with an air-fuel ratio of 1.8 to 2.5 and an air excess coefficient of 0.8 to 1.1, and the soaking time is 20 minutes to 50 minutes.

6. The heating method according to claim 1, wherein The heating time of the heating method for the high-aluminum steel continuous casting billet ≥ 240 minutes.

7. The heating method according to claim 1, wherein The solution time of the heating method ≥ 40 minutes.

8. A continuous casting billet of high-aluminum steel, characterized in that, Prepared according to the heating method of the high-aluminum steel continuous casting billet according to any one of claims 1 - 7.

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