Production method of ultra-efficient and uniform austenitizing industrial pure iron

Abstract

The invention relates to a production method of ultra-efficient and uniform austenitizing industrial pure iron. The production method comprises the steps of casting blank heating, cogging rolling, steel head cutting, continuous rolling, hot saw segmentation and cooling bed cooling. The continuous casting billet is heated in a heating furnace, the temperature of a heating section I is 830-930 DEG C, the temperature of a heating section II is 990-1130 DEG C, the temperature of a heating section III is 1230-1290 DEG C, and the temperature of a soaking section is 1210-1270 DEG C; the heating section I lasts for more than 60 minutes, the time of the section III and the soaking section lasts for 100-200 minutes, and the total in-furnace time lasts for 260-380 minutes; blooming rolling is conducted, wherein the blooming temperature ranges from 1140 DEG C to 1210 DEG C; continuous rolling: the final rolling temperature is 980-1100 DEG C; the method has the advantages that the corner part which is cooled quickly is always in an austenite phase region, so that cracks at the corner part and the center of the steel can be avoided, and a uniform austenite structure is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial pure iron production, and in particular relates to a method for producing ultra-efficient and uniform austenitized industrial pure iron. Background Art

[0002] Industrial pure iron is a type of iron with an extremely low carbon content (typically less than 0.02 wt%), meaning it contains virtually no other alloying elements. Due to its high purity, industrial pure iron has very good ductility and low hardness, while also exhibiting good electromagnetic properties. Due to its exceptional electromagnetic properties, industrial pure iron is widely used in the electromagnetic and electronics industries, such as in the manufacture of transformers, motors, and solenoid valves. In some cases, pure iron is also used to make precision alloys that require extremely high purity, such as those used in aerospace, medical devices, and scientific research.

[0003] The heating system and rolling process during the production of industrial pure iron directly affect the quality of the final product and also restrict the production efficiency during mass production. Industrial pure iron production mostly adopts low-temperature ferrite phase rolling. Although it can avoid cracks in the corners of square steel, it has problems such as long heating time and high deformation resistance during rolling. The efficiency is low in mass production, resulting in high coal and electricity consumption, and ultimately high production costs. Therefore, it is necessary to develop a new rolling production method for industrial pure iron to optimize product performance, improve product quality, and increase production efficiency, which has become a key research topic for steel rolling workers. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for producing ultra-efficient and uniform austenitized industrial pure iron. By rationally designing the heating process of each section of the heating furnace, controlling the steel tapping temperature, and adopting a method of eliminating high-pressure water descaling, the start rolling temperature can be guaranteed to the maximum extent. By designing rolling parameters and processes, the rolling production efficiency is improved, the final rolling temperature is guaranteed, and the steel is completely in the austenite phase region during the rolling deformation process. After rolling is completed, a uniform austenite structure is obtained, and the generation of corner cracks and center crack defects in the finished product is avoided. In addition, batch production can be carried out efficiently, and production costs are reduced.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for producing ultra-efficient and uniform austenitized industrial pure iron, comprising heating of ingots, slab rolling, steel cutting, continuous rolling, hot sawing, and cooling on a cooling bed, characterized in that:

[0007] Ingot heating: The continuous casting ingot is heated in a heating furnace. The temperature of heating section I is 830-930℃, the temperature of heating section II is 990-1130℃, the temperature of heating section III is 1230-1290℃, and the temperature of soaking section is 1210-1270℃. The heating time of heating section I is more than 60 minutes, the time of section III + soaking section is 100-200 minutes, and the total time in the furnace is 260-380 minutes.

[0008] Bloom rolling: After the continuous casting slab is heated, high-pressure water descaling is not performed, and the starting rolling temperature is controlled at 1140-1210°C;

[0009] Continuous rolling: The continuous rolling speed is above 0.7m / s, and the final rolling temperature is controlled at 980~1100℃.

[0010] The cross-sectional dimensions of the continuous casting billet are (380-400 mm)×(500-520 mm).

[0011] The slab rolling is carried out by using a reversible slab rolling machine, which rolls 7 to 13 times, with the rolling speed of each time being controlled at 2.0 to 4 m / s.

[0012] The continuous rolling is performed in 4 to 8 passes.

[0013] The industrial pure iron has a uniform structure and a grain size of ≥5 levels.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention rationally designs the heating process for each section of the heating furnace, controls the tapping temperature, and performs high-temperature rapid heating in a relatively short period of time, resulting in complete austenitization of the continuous casting billet. Rapid multi-pass rolling is then performed in the austenite phase. The start and finish rolling temperatures are controlled to ensure that the corners, where the temperature drops rapidly, remain in the austenite phase. This prevents cracks in the steel's corners and center, while also achieving a uniform austenite structure and an actual grain size of ≥5 for the finished product. While ensuring steel quality, the rolling line can achieve an hourly output of over 170 tons. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the metallographic structure diagram of Comparative Example 1.

[0017] Figure 2 This is the metallographic structure diagram of Comparative Example 2.

[0018] Figure 3 This is the metallographic structure diagram of Example 1.

[0019] Figure 4 This is the metallographic structure diagram of Example 2.

[0020] Figure 5This is the metallographic structure diagram of Example 3. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0022] A method for producing ultra-efficient and uniform austenitized industrial pure iron comprises heating of cast slabs, rolling of cast slabs, cutting of steel ends, continuous rolling, hot sawing of steel sections, and cooling on a cooling bed. The cross-sectional dimensions of the continuous casting slabs are (380-400 mm) x (500-520 mm). The heating system for the continuous casting slabs is shown in Table 1.

[0023]

[0024]

[0025] Bloom rolling: After the continuous casting slab is heated, high-pressure water descaling is not performed, and the starting rolling temperature is controlled at 1140-1210°C to ensure that the continuous casting slab is fully austenitized.

[0026] Continuous rolling: Rolling is performed on a reversible bloom mill, with a total of 7 to 13 passes, each at a speed of 2.0 to 4 m / s. After blooming, the material is reduced to 220 mm x 220 mm. After passing through a hydraulic shear head, it enters the continuous rolling mill for four passes, with a line speed exceeding 0.7 m / s. The final product is a 150 mm x 150 mm square bar. High-speed rolling is employed, with a controlled final rolling temperature of 980 to 1100°C. This ensures that the entire rolling process is completed within the austenite phase.

[0027] After multiple rolling passes, the finished product is obtained with uniform structure and fine grains, and the actual grain size is ≥ level 5.

[0028] After rolling, the square steel is segmented by hot saw and cooled on cooling bed before finishing and collection.

[0029] Comparative Example 1:

[0030] The raw material is continuous casting billet with specifications of 390mm×510mm×5810mm.

[0031] Heating in the heating furnace: the temperature of heating section I of the heating furnace is 750-770℃, the heating time is 100min, the temperature of heating section II is 950-970℃, the temperature of heating section III is 1170-1190℃, the temperature of the soaking section is 1160-1180℃, the time of section III + soaking is 200min, and the total heating time is 420min. After heating, high-pressure water descaling is not performed, and rolling is performed directly, with the starting temperature being 1080±10℃. The blanking machine rolls a total of 11 passes, and the rolling speed of each pass ranges from 2.0 to 2.5m / s. The continuous rolling is performed for four passes, and the rolling line speed of the finished product is 0.715m / s. The final rolling temperature is 920±10℃. There are small cracks at the corners of the 150mm×150mm finished material, and there is no central crack in the low-magnification inspection. The hourly output of the rolling production line is about 109 tons. The actual grain size of the finished product is uneven, and there is mixed crystal. Figure 1 .

[0032] Comparative Example 2:

[0033] The raw material is continuous casting billet with specifications of 390mm×510mm×5810mm.

[0034] Heating in the heating furnace: the temperature of heating section I of the heating furnace is 800-820℃, the heating time is 85min, the temperature of heating section II is 1000-1020℃, the temperature of heating section III is 1210-1230℃, the temperature of the soaking section is 1200-1220℃, the time of section III + soaking is 170min, and the total heating time is 360min. After heating, high-pressure water descaling is not performed, and rolling is carried out directly, with the starting temperature of 1150±10℃. The blanking machine rolls a total of 11 passes, and the rolling speed of each pass ranges from 2.0 to 3.0m / s. The continuous rolling is performed for four passes, and the rolling line speed of the finished product is 0.715m / s. The final rolling temperature is 980±10℃. There are no cracks at the corners of the 150mm×150mm finished material, and there are no center cracks in the low-magnification inspection. The hourly output of the rolling production line is about 127 tons. The actual grain size of the finished product is uniform but the grain size is relatively large, and the grade is 4.5. Figure 2 .

[0035] Example 1:

[0036] The raw material is continuous casting billet with specifications of 390mm×510mm×5810mm.

[0037] Heating in the heating furnace: the temperature of heating section I of the heating furnace is 910-930℃, the heating time is 65min, the temperature of heating section II is 1110-1130℃, the temperature of heating section III is 1270-1290℃, the temperature of the soaking section is 1250-1270℃, the time of section III + soaking is 130min, and the total heating time is 270min. After heating, high-pressure water descaling is not performed, and rolling is performed directly, with the starting temperature being 1200±10℃. The blanking machine rolls a total of 11 passes, and the rolling speed of each pass ranges from 2.0 to 3.5m / s. The continuous rolling is performed for four passes, and the rolling line speed of the finished product is 0.715m / s. The final rolling temperature is 1060±10℃. There are no cracks at the corners of the 150mm×150mm finished material, and there are no center cracks in the low-magnification inspection. The hourly output of the rolling production line is about 170 tons. The actual grain size of the finished product is uniform, and the grade is 5.0. Figure 3 .

[0038] Example 2:

[0039] The raw material is continuous casting billet with specifications of 390mm×510mm×5810mm.

[0040] Heating in the heating furnace: the temperature of heating section I of the heating furnace is 830-850℃, the heating time is 65min, the temperature of heating section II is 990-1010℃, the temperature of heating section III is 1230-1250℃, the temperature of the soaking section is 1210-1230℃, the time of section III + soaking is 130min, and the total heating time is 270min. After heating, high-pressure water descaling is not performed, and rolling is performed directly, with the starting temperature being 1150±10℃. The blanking machine rolls a total of 11 passes, and the rolling speed of each pass ranges from 2.0 to 3.5m / s. The continuous rolling is performed for four passes, and the rolling line speed of the finished product is 0.715m / s. The final rolling temperature is 990±10℃. There are no cracks at the corners of the 150mm×150mm finished material, and there are no center cracks in the low-magnification inspection. The hourly output of the rolling production line is more than 170 tons. The actual grain size of the finished product is uniform, and the grade is 5.5. See Figure 4 .

[0041] Example 3:

[0042] The raw material is continuous casting billet with specifications of 390mm×510mm×5810mm.

[0043] Heating in the heating furnace: the temperature of heating section I of the heating furnace is 870-890℃, the heating time is 63min, the temperature of heating section II is 1060-1080℃, the temperature of heating section III is 1255-1275℃, the temperature of the soaking section is 1245-1265℃, the time of section III + soaking is 125min, and the total heating time is 260min. After heating, high-pressure water descaling is not performed, and rolling is performed directly, with the starting temperature being 1190±10℃. The blanking machine rolls a total of 11 passes, and the rolling speed of each pass ranges from 2.0 to 3.5m / s. The continuous rolling is performed for four passes, and the rolling line speed of the finished product is 0.715m / s. The final rolling temperature is 1030±10℃. There are no cracks at the corners of the 150mm×150mm finished material, and there are no center cracks in the low-magnification inspection. The hourly output of the rolling production line is about 175 tons. The actual grain size of the finished product is uniform, and the grade is 6.0. Figure 5 .

[0044] The present invention rationally designs the heating process for each section of the heating furnace, controls the tapping temperature, and performs high-temperature rapid heating in a relatively short period of time, resulting in complete austenitization of the continuous casting billet. Rapid multi-pass rolling is then performed in the austenite phase. The start and finish rolling temperatures are controlled to ensure that the corners, where the temperature drops rapidly, remain in the austenite phase. This prevents cracks in the steel's corners and center, while also achieving a uniform austenite structure and an actual grain size of ≥5 for the finished product. While ensuring steel quality, the rolling line can achieve an hourly output of over 170 tons.

Claims

1. A method for producing ultra-efficient uniform austenitized industrial pure iron, characterized in that: The production method includes heating of the casting, rolling of the casting, cutting of the steel head, continuous rolling, hot sawing and cooling on a cooling bed, and is characterized in that: Ingot heating: The continuous casting ingot is heated in a heating furnace. The temperature of heating section I is 830-930℃, the temperature of heating section II is 990-1130℃, the temperature of heating section III is 1230-1290℃, and the temperature of soaking section is 1210-1270℃. The heating time of heating section I is more than 60 minutes, the time of section III + soaking section is 100-200 minutes, and the total time in the furnace is 260-380 minutes. Bloom rolling: After the continuous casting slab is heated, high-pressure water descaling is not performed, and the starting rolling temperature is controlled at 1140-1210°C; Continuous rolling: The continuous rolling speed is above 0.7m / s, and the final rolling temperature is controlled at 980~1100℃.

2. The method for producing ultra-high efficiency uniform austenitized industrial pure iron according to claim 1, characterized in that: The cross-sectional dimensions of the continuous casting billet are (380-400 mm)×(500-520 mm).

3. The method for producing ultra-high efficiency uniform austenitized industrial pure iron according to claim 1, characterized in that: The slab rolling is carried out by using a reversible slab rolling machine, which rolls 7 to 13 times, with the rolling speed of each time being controlled at 2.0 to 4 m / s.

4. The method for producing ultra-high efficiency uniform austenitized industrial pure iron according to claim 1, characterized in that: The continuous rolling is performed for 4 to 8 passes.

5. The method for producing ultra-high efficiency uniform austenitized industrial pure iron according to claim 1, characterized in that: The industrial pure iron has a uniform structure and a grain size of ≥5 levels.

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