Production method of stainless steel medium plate

Abstract

The invention discloses a production method of a stainless steel medium plate. The stainless steel medium plate comprises the following components in percentage by mass: 0.04-0.065% of C, 0.2-1.0% of Si, 1.0-2.0% of Mn, 0.010-0.050% of Al, 5.0-12.0% of Ni, 10.0-20.0% of Cr, 1.0-5.0% of Mo, less than or equal to 0.050% of Ti, less than or equal to 0.015% of P, less than or equal to 0.005% of S, less than or equal to 0.0050% of N, less than or equal to 0.0005% of B and the balance of iron and inevitable impurity elements. According to the method, the slab heating, rough rolling, finish rolling and cooling procedures and the descaling operation process are optimized and improved, the slab heating temperature and the heat preservation time of the slab heating procedure are controlled, and the technological parameters of rough rolling and finish rolling and the descaling technology in the process are controlled, so that the stainless steel medium and thick plate is small in rolling risk, good in surface quality and straight in plate shape.

Description

Technical Field

[0001] The invention relates to the technical field of steel, and in particular to a production method of a stainless steel medium and thick plate. Background Art

[0002] 316 series stainless steel belongs to common austenitic stainless steel, which contains a large amount of alloy elements such as chromium, nickel, molybdenum, etc., which makes it have excellent corrosion resistance, aesthetics and heat resistance. However, due to the high alloy content, compared with ordinary medium and thick plate steel materials, it has high deformation resistance, low hardness, no magnetism, and high surface quality requirements, making its production extremely difficult.

[0003] At present, the main methods used for thick-gauge high-quality austenitic stainless steel plates are forging and rolling. The billet used in the rolling method is a continuous casting billet. For the continuous casting billet, there are defects such as segregation and looseness inside it, which makes the core performance of the rolled steel plate significantly deteriorate with the increase of thickness. At the same time, due to the compression ratio requirement, the maximum thickness of the steel plate that can be produced by the continuous casting billet is limited. In the rolling process, it is easy to have problems such as warping and difficulty in removing the oxide scale, which makes it difficult to control the quality of medium and thick plates. Summary of the invention

[0004] Technical problems to be solved: In view of the technical problems existing in the production process of medium and thick stainless steel plates in the prior art, the present invention provides a production method of medium and thick stainless steel plates to improve the production stability and slab quality of the medium and thick plates.

[0005] Technical solution: A method for producing a stainless steel medium and thick plate according to the present invention, wherein the components of the stainless steel are as follows by mass percentage: C 0.04-0.065%, Si 0.2-1.0%, Mn 1.0-2.0%, Al 0.010-0.050%, Ni 5.0-12.0%, Cr 10.0-20.0%, Mo 1.0-5.0%, Ti≤0.050%, P≤0.015%, S≤0.005%, N≤0.0050%, B≤0.0005%, and the rest are iron and unavoidable impurity elements; The production method includes the steps of slab heating, rough descaling, rough rolling, finishing rolling, hot straightening of steel plates, cooling on a cooling bed, shearing, and warehousing; the thickness of the slab is greater than 300 mm, and the thickness of the medium and thick plate is 10-30 mm; The slab heating step heats the rolled steel slab to a temperature above the required temperature and keeps the temperature for a period of time so that the slab crystal phase is completely converted into an austenite structure; The descaling process removes the iron oxide scale on the surface of the slab by spraying high-pressure water; The rolling process adopts a single-stand rolling mill, and the rolling passes are ≥16 times; The steel plate hot straightening process adopts a three-pass straightening method. The hot-straightened slab is air-cooled to room temperature on a cooling bed and then sheared and stored.

[0006] Preferably, the heating temperature of the slab heating process is controlled at 1150-1300° C., the lower surface temperature of the slab is 10-30° C. higher than the upper surface temperature of the slab, and the slab is in the furnace for more than 1.5 min / mm.

[0007] Preferably, the rolling torque of the rolling process is 0~6140KNm, and the rolling speed is 2~6m / s.

[0008] Preferably, the reduction rate of the rolling process is ≤20%, and the final rolling temperature of the slab is ≥950°C.

[0009] Preferably, the high-pressure water pressure in the rough descaling process is greater than 18 MPa; the rough rolling process performs one descaling operation; and the finishing rolling process performs one descaling operation.

[0010] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention optimizes and improves the slab heating, rough rolling, finish rolling, cooling procedures and the descaling process, and controls the slab heating temperature and insulation time in the slab heating procedure, thereby reducing the generation of iron oxide scale that is difficult to handle; and controls the process parameters of rough rolling and finish rolling as well as the descaling process in the process, thereby making the rolling risk of stainless steel medium and thick plates small, the surface quality good, the plate shape straight, and the production process smooth. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a production flow chart of stainless steel medium and thick plates according to an embodiment of the present invention; Figure 2 This is a diagram showing the descaling effect of the slab after it comes out of the furnace according to an embodiment of the present invention; Figure 3 This is a diagram showing the plate shape effect after slab rolling according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the attached Figures 1 to 3 The technical solutions of the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the described embodiments of the present invention belong to the scope of protection of the present invention.

[0013] A specific implementation mode of the present invention is described by taking a 3500mm production line as an example.

[0014] Example 1: Figure 1As shown, in the method for producing a stainless steel medium and thick plate according to the embodiment of the present invention, the initial thickness of the slab is 320 mm, and the final rolling thickness of the ship plate steel medium and thick plate is 22 mm. The composition of the stainless steel is as follows by mass percentage: C 0.04%, Si 0.54%, Mn 1.33%, Ni 10.03%, Cr 16.74%, Mo 2.03%, P 0.01%, N 0.0050%, Ti, S, B, Al, Nb, V elements are not detected, and the rest are iron and unavoidable impurity elements.

[0015] The production method includes slab heating, rough descaling, rough rolling, finishing rolling, steel plate hot straightening, cooling on a cooling bed, shearing, and storage. The specific process of each process is as follows: (1) Slab heating process: The lower surface temperature of the rolled steel slab is heated to 1278°C and the upper surface temperature of the slab is 1261°C. The slab is kept in the furnace for more than 1.5 min / mm, so that the slab crystal phase is completely transformed into an austenite structure.

[0016] (2) Descaling process: The iron oxide scale on the surface of the steel billet or steel plate is removed by spraying high-pressure water to prevent the iron oxide scale from being pressed into the surface of the slab during rolling to produce pitting. The high-pressure water pressure of the rough descaling process is 22 MPa; one descaling pass is performed in the rough rolling process and one descaling pass is performed in the finishing rolling process. The descaling process during the slab rolling process is precisely controlled to improve the removal effect of the iron oxide scale on the slab surface.

[0017] (3) Rolling process: A single-stand rolling mill is used for rolling. The rolling torque of the rolling process is 4500 KNm, the rolling speed is 5 m / s, the total number of rolling passes is 18, the rolling reduction rate is 19.86%, and the final rolling temperature of the slab is 985°C.

[0018] (4) The hot straightening process adopts a three-pass straightening method.

[0019] (5) The hot-corrected slab is air-cooled to room temperature on a cooling bed. After cooling, the slab is sheared and put into storage.

[0020] Example 2: Figure 1 As shown, in the method for producing a stainless steel medium and thick plate according to the embodiment of the present invention, the initial thickness of the slab is 320 mm, and the final rolling thickness of the ship plate steel medium and thick plate is 20 mm. The composition of the stainless steel is as follows by mass percentage: C 0.04, Si 0.58%, Mn 1.370%, Ni 10.03%, Cr 16.56%, Mo 2.04%, P 0.01%, N 0.02%, Ti, S, B, Al, Nb, V elements are not detected, and the rest are iron and unavoidable impurity elements.

[0021] The production method includes slab heating, rough descaling, rough rolling, finishing rolling, steel plate hot straightening, cooling on a cooling bed, shearing, and storage. The specific process of each process is as follows: (1) Slab heating process: The lower surface temperature of the rolled steel slab is heated to 1279°C, and the upper surface temperature of the slab is 1253°C. The slab is kept in the furnace for more than 1.5 min / mm, so that the slab crystal phase is completely transformed into an austenite structure.

[0022] (2) Descaling process: The iron oxide scale on the surface of the steel billet or steel plate is removed by spraying high-pressure water to prevent the iron oxide scale from being pressed into the surface of the slab during rolling to produce pitting. The high-pressure water pressure of the rough descaling process is 18 MPa; one descaling pass is performed in the rough rolling process and one descaling pass is performed in the finishing rolling process. The descaling process during the slab rolling process is precisely controlled to improve the removal effect of the iron oxide scale on the slab surface.

[0023] (3) Rolling process: A single-stand rolling mill is used for rolling. The rolling torque of the rolling process is 4900 KNm, the rolling speed is 4 m / s, the total number of rolling passes is 20, the rolling reduction ratio is 18.97%, and the final rolling temperature of the slab is 972°C.

[0024] (4) The hot straightening process adopts a three-pass straightening method.

[0025] (5) The hot-corrected slab is air-cooled to room temperature on a cooling bed. After cooling, the slab is sheared and put into storage.

[0026] Example 3: Figure 1 As shown, in the method for producing a stainless steel medium and thick plate according to the embodiment of the present invention, the initial thickness of the slab is 320 mm, and the final rolling thickness of the ship plate steel medium and thick plate is 18 mm. The composition of the stainless steel is as follows by mass percentage: C 0.055%, Si 0.62%, Mn 1.41%, Ni 10.05%, Cr 17.1%, Mo 2.01%, P 0.02%, N 0.005%, Ti, S, B, Al, Nb, V elements are not detected, and the rest are iron and unavoidable impurity elements.

[0027] The production method includes slab heating, rough descaling, rough rolling, finishing rolling, steel plate hot straightening, cooling on a cooling bed, shearing, and storage. The specific process of each process is as follows: (1) Slab heating process: The lower surface temperature of the rolled steel slab is heated to 1265°C, and the upper surface temperature of the slab is 1242°C. The slab is kept in the furnace for more than 1.5 min / mm, so that the slab crystal phase is completely transformed into an austenite structure.

[0028] (2) Descaling process: The iron oxide scale on the surface of the steel billet or steel plate is removed by spraying high-pressure water to prevent the iron oxide scale from being pressed into the surface of the slab during rolling to produce pitting. The high-pressure water pressure of the rough descaling process is 18 MPa; one descaling pass is performed in the rough rolling process and one descaling pass is performed in the finishing rolling process. The descaling process during the slab rolling process is precisely controlled to improve the removal effect of the iron oxide scale on the slab surface.

[0029] (3) Rolling process: A single-stand rolling mill is used for rolling. The rolling torque of the rolling process is 6140 KNm, the rolling speed is 2 m / s, the total number of rolling passes is 22, the rolling reduction rate is 17.77%, and the final rolling temperature of the slab is 968 °C.

[0030] (4) The hot straightening process adopts a three-pass straightening method.

[0031] (5) The hot-corrected slab is air-cooled to room temperature on a cooling bed. After cooling, the slab is sheared and put into storage.

[0032] The stainless steel plates produced in Examples 1 to 3 of the present invention have good descaling effect after being fired, and there is no iron oxide scale on the surface (such as Figure 1 The stainless steel slab rolling process is smooth and the plate shape is straight after rolling (as shown in Figure 2 shown).

[0033] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for producing medium and thick stainless steel plates, characterized in that: The composition of the stainless steel is as follows by mass percentage: C 0.04-0.065%, Si 0.2-1.0%, Mn 1.0-2.0%, Al 0.010-0.050%, Ni 5.0-12.0%, Cr 10.0-20.0%, Mo 1.0-5.0%, Ti≤0.050%, P≤0.015%, S≤0.005%, N≤0.0050%, B≤0.0005%, and the rest are iron and unavoidable impurity elements; The production method includes the steps of slab heating, rough descaling, rough rolling, finishing rolling, hot straightening of steel plates, cooling on a cooling bed, shearing, and warehousing; the thickness of the slab is greater than 300 mm, and the thickness of the medium and thick plate is 10-30 mm; The slab heating step heats the rolled steel slab to a temperature above the required temperature and keeps the temperature for a period of time so that the slab crystal phase is completely converted into an austenite structure; The descaling process removes the iron oxide scale on the surface of the slab by spraying high-pressure water; The rolling process adopts a single-stand rolling mill, and the rolling passes are ≥16 times; The steel plate hot straightening process adopts a three-pass straightening method. The hot-straightened slab is air-cooled to room temperature on a cooling bed and then sheared and stored.

2. The method for producing a medium and thick stainless steel plate according to claim 1, characterized in that: The heating temperature of the slab heating process is controlled at 1150-1300° C., the lower surface temperature of the slab is 10-30° C. higher than the upper surface temperature of the slab, and the slab is kept in the furnace for more than 1.5 min / mm.

3. The method for producing a medium and thick stainless steel plate according to claim 1, characterized in that: The rolling torque of the rolling process is 0~6140KNm, and the rolling speed is 2~6m / s.

4. The method for producing a medium and thick stainless steel plate according to claim 3, characterized in that: The reduction rate of the rolling process is ≤20%, and the final rolling temperature of the slab is ≥950°C.

5. The method for producing a medium and thick stainless steel plate according to claim 1, characterized in that: The high-pressure water pressure in the rough descaling process is greater than 18 MPa; the rough rolling process performs one descaling operation; and the finishing rolling process performs one descaling operation.

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