301L stainless steel chilled plate for high-speed train and preparation method of 301L stainless steel chilled plate

Abstract

The invention belongs to the technical field of train metal material preparation, and particularly relates to a 301L stainless steel chilled plate for a high-speed train and a preparation method thereof.The 301L stainless steel chilled plate comprises C smaller than or equal to 0.03%, Si 0.40%-1.00%, Mn smaller than or equal to 2.0%, P smaller than or equal to 0.045%, S smaller than or equal to 0.03%, Cr 16.00%-18.00%, Ni 6.00%-8.00%, N 0.10%-0.20%, Cu smaller than or equal to 0.5% and the balance Fe and inevitable impurities, and the preparation method comprises the following steps that (1) the rolling process is adjusted, in the first rolling process, the total pass is 5-7; in the finished product rolling process, the total deformation rate of the finished product rolling process is designed according to different strength levels; (2) rolling mill parameters are adjusted, wherein the cone length and taper of a first intermediate roll and the convexity of a second intermediate roll and a working roll are optimized; and (3) a cold line adjusting procedure: carrying out solid solution and acid pickling treatment on the cold-rolled strip steel in the first rolling process, and carrying out acid pickling, stretch bending and straightening treatment on the cold-hard strip steel in the finished rolling process. By adopting the method, the problems of edge wave plate shape defects and large performance fluctuation are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of train metal material preparation, and in particular relates to a 301L stainless steel chilled plate for high-speed trains and a preparation method thereof. Background Art

[0002] 301L stainless steel cold-hardened plate is widely used in various high-speed train structural parts. The market demand is increasing year by year. However, customers have extremely high requirements on the plate shape, surface and performance of this product. The plate shape unevenness must be ≤5mm / m, the surface must not have defects that cannot be polished away, and the mechanical properties must be precise.

[0003] 301L stainless steel chilled plate products are divided into two grades, MT and HT, according to tensile strength. After rolling, 301L stainless steel chilled plate with a thickness of ≥2.5mm is not annealed in the wide cold line process, but only pickled, flattened and straightened. Problems such as edge wave plate shape defects and large performance fluctuations occur during the production process, which cannot meet the increasingly precise requirements of customers. Summary of the invention

[0004] The purpose of the present invention is to provide a 301L stainless steel cold-hardened plate for high-speed trains and a preparation method thereof, so as to solve the problems of edge wave plate shape defects and large performance fluctuations in the production process.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: A 301L stainless steel chilled plate for high-speed trains, the chemical composition of which, measured by weight percentage, comprises: C≤0.03%, Si: 0.40%-1.00%, Mn≤2.0%, P≤0.045%, S≤0.03%, Cr: 16.00%-18.00%, Ni: 6.00%-8.00%, N: 0.10%-0.20%, Cu≤0.5%, and the rest being Fe and unavoidable impurities.

[0006] The preparation method of the 301L stainless steel chilled plate for the high-speed train comprises the following contents: (1) Adjust the rolling process: adopt the double rolling process, the first rolling process: the total number of passes is 5-7, the target curve of the plate shape of each pass is "U" type, and the actual stress deviation value of the edge plate shape is controlled at 40~100N / mm 2 The actual stress deviation value of the middle plate shape is controlled at -30~0N / mm 2 , the total deformation rate of the first rolling process is controlled at 30-45%; the second rolling process (finished product rolling process): the total deformation rate of the finished product rolling process is designed according to different strength levels, the MT strength level series with thickness specifications of <5.0mm adopts one-pass rolling, the plate shape target curve is wavy, and the actual stress deviation value of the edge plate shape is controlled at 20~40N / mm 2The actual stress deviation value of the middle plate shape is controlled at 0~20N / mm 2 , rolling speed ≤ 50m / min; MT strength above ≥5.0mm and all HT strength are all rolled in two passes, the deformation rate of the last pass is controlled at 2~6%, the target curve of the plate shape in the first rolling pass is "U" type, and the actual stress deviation value of the edge plate shape is controlled at 20~40N / mm 2 The actual stress deviation value of the middle plate shape is controlled within -10~0N / mm 2 The target curve of the rolled product shape is wavy, and the actual stress deviation of the edge shape is controlled at 20~40N / mm 2 The actual stress deviation value of the middle plate shape is controlled within the range of 0~20N / mm 2 Within the range, the first rolling speed is controlled to be ≤100m / min, the finished rolling speed is controlled to be ≤50m / min, the total deformation rate of the finished product with strength level MT is 6.0~7.0%, and the total deformation rate of the finished product with strength level HT is 16.0~19.0%; (2) Adjust the rolling mill parameters: optimize the cone length and taper of the first intermediate roll, the crown of the second intermediate roll and the working roll. The cone length is 570 mm, the shape of the 0-420 mm position is a straight cone, the cone length: cone height is 1: 0.001-0.002, the shape of the 420-570 mm position is a straight cone, the cone length: cone height is 1: 0.0002-0.0004; the crown of the second intermediate roll is selected to be 0.25-0.35 mm, and the crown of the working roll is selected to be 0.05-0.15 mm; (3) Adjust the cold line process: The first rolling process cold-rolled strip is subjected to solution treatment and pickling, and the finished rolling process cold-hardened strip is subjected to pickling and bending straightening treatment.

[0007] During the solution treatment in the first rolling process in the cold line process (3), the plate temperature is controlled at 1080-1110°C and the holding time is 0.8-1.0 min / mm; when the cold line process produces the finished cold-hardened strip steel, the furnace temperature is ≤400°C, the tension of the stretch straightening treatment is 50-90 tons, and the elongation is 0.5%-2.0%.

[0008] The straightening treatment in (3) is performed by a straightening machine, which includes three sets of straightening rollers. The pressing amounts of the three sets of straightening rollers from right to left are 40-50 mm, 20-40 mm and 20-40 mm respectively.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) By optimizing the chemical composition, the raw material composition in the cold rolling process is precisely adjusted to form a martensitic structure during the cold rolling process and achieve the final performance indicators; (2) By adjusting the rolling process, rolling mill parameters and roll shape design during the rolling process, the rolling process and the target shape curve are matched to ensure that the performance and shape of the finished product are precisely controlled at the same time, ensuring that the strip shape is straight and the thickness is accurate after rolling, avoiding edge wave shape defects and large performance fluctuations; (3) By standardizing the solid solution and tensile straightening processes in the first rolling process of the cold line process, the actual plate shape is improved to the greatest extent, ensuring that the plate shape unevenness reaches ≤5mm / m. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is the target curve of plate shape during the first rolling process in the rolling process; Figure 2 It is the target curve of plate shape during the rolling process of the finished product. DETAILED DESCRIPTION

[0011] The embodiments of the present invention are described in detail below in conjunction with the embodiments and drawings.

[0012] A roll of 301LHT stainless steel chilled plate with a specification of 4.0*1265mm is produced. The chemical composition, by weight percentage, includes: C: 0.020%, Si: 0.517%, Mn: 1.051%, P: 0.027%, S: 0.001%, Cr: 17.102%, Ni: 7.079%, N: 0.103%, Cu: 0.028%, and the rest is Fe and unavoidable impurities. The product production adopts a double rolling process, the first rolling process is 7.806mm rolling 4.82mm, and the finished rolling process is 4.82mm rolling 3.95mm; the SUNDWING SFC 20H-406×1625 model 20-high rolling mill is used, and a composite cone intermediate roll is used, the cone length is 570mm, the shape of the 0-420mm position is a straight cone, the cone length: cone height is 1:0.0015, and the shape of the 420-570mm position is a straight cone, the cone length: cone height is 1:0.0003; the crown of the second intermediate roll is selected as 0.30mm, and the crown of the working roll is selected as 0.10mm. When rolling in the first rolling process, the total number of passes is 5, and the target curve of the plate shape of each pass is as follows Figure 1 As shown in Figure 2, the actual stress deviation values ​​of the edge plate shape in the 1st to 5th passes are 80, 65, 50, 45 and 40 N / mm respectively. 2 The actual stress deviation values ​​of the plate shape in the middle of the 1st to 5th passes are controlled at -30, -25, -10, -5 and 0 N / mm 2The first rolling process is to roll the steel coil to a thickness of 4.82mm, and then the steel coil is subjected to solution treatment and pickling treatment in the cold line. The plate temperature is controlled at 1100℃ and the holding time is 0.95min / mm. After the cold line production is completed, the steel coil is rolled on the SUNDWING SFC 20H-406×1625 model twenty-high rolling mill for the second rolling process. Two passes are adopted, the first pass is 13.55%, and the deformation rate of the finished product pass is controlled at 5.2%. The target curve of the plate shape of the first rolling pass is as follows: Figure 1 As shown, the actual stress deviation value of the edge plate shape is controlled at 30N / mm 2 The actual stress deviation value of the middle plate shape is controlled at -5N / mm 2 ; The target curve of finished product pass shape is as follows Figure 2 As shown, the actual stress deviation value of the edge plate shape is controlled at 30N / mm 2 The actual stress deviation value of the middle plate shape is controlled at 10N / mm 2 The first rolling speed is 80m / min, and the finished product rolling speed is 50m / min. After the cold hardened plate is rolled, it is put on the cold line again for pickling, bending and straightening treatment. The furnace temperature is 356℃. The straightening tension of the stretching straightening treatment is 60 tons, and the elongation is 0.8%. The straightening unit has three sets of straightening rollers, and the reduction amounts are 45mm, 40mm and 40mm respectively.

[0013] The mechanical properties of 301LHT stainless steel cold-hardened plate with a specification of 4.0*1265mm meet the requirements, and the plate unevenness reaches 3mm / m.

[0014] After adopting the method of the present invention, 301L stainless steel thick-gauge cold-hardened plates for high-speed trains were successfully prepared, and customer needs were met. The performance compliance rate reached 100%, and the plate unevenness was ≤5mm / m.

Claims

1. A 301L stainless steel chilled plate for high-speed trains, characterized in that: The chemical composition, by weight percentage, includes: C≤0.03%, Si: 0.40%~1.00%, Mn ≤2.0%, P≤0.045%, S≤0.03%, Cr: 16.00%~18.00%, Ni: 6.00%~8.00%, N: 0.10%~0.20%, Cu≤0.5%, and the rest are Fe and unavoidable impurities.

2. The method for preparing a 301L stainless steel chilled plate for high-speed trains according to claim 1, characterized in that: Includes the following: (1) Adjust the rolling process: adopt the double rolling process, the first rolling process: the total number of passes is 5-7, the target curve of the plate shape of each pass is "U" type, and the actual stress deviation value of the edge plate shape is controlled at 40~100N / mm 2 The actual stress deviation value of the middle plate shape is controlled at -30~0N / mm 2 , the total deformation rate of the first rolling process is controlled at 30-45%; the second rolling process (finished product rolling process): the total deformation rate of the finished product rolling process is designed according to different strength levels, the MT strength level series with thickness specifications of <5.0mm adopts one-pass rolling, the plate shape target curve is wavy, and the actual stress deviation value of the edge plate shape is controlled at 20~40N / mm 2 The actual stress deviation value of the middle plate shape is controlled at 0~20N / mm 2 , rolling speed ≤ 50m / min; MT strength above ≥5.0mm and all HT strength are all rolled in two passes, the deformation rate of the last pass is controlled at 2~6%, the target curve of the plate shape in the first rolling pass is "U" type, and the actual stress deviation value of the edge plate shape is controlled at 20~40N / mm 2 The actual stress deviation value of the middle plate shape is controlled within -10~0N / mm 2 The target curve of the rolled product shape is wavy, and the actual stress deviation of the edge shape is controlled at 20~40N / mm 2 The actual stress deviation value of the middle plate shape is controlled within the range of 0~20N / mm 2 Within the range, the first rolling speed is controlled to be ≤100m / min, the finished rolling speed is controlled to be ≤50m / min, the total deformation rate of the finished product with strength level MT is 6.0~7.0%, and the total deformation rate of the finished product with strength level HT is 16.0~19.0%; (2) Adjust the rolling mill parameters: optimize the cone length and taper of the first intermediate roll, the crown of the second intermediate roll and the working roll. The cone length is 570 mm, the shape of the 0-420 mm position is a straight cone, the cone length: cone height is 1: 0.001-0.002, the shape of the 420-570 mm position is a straight cone, the cone length: cone height is 1: 0.0002-0.0004; the crown of the second intermediate roll is selected to be 0.25-0.35 mm, and the crown of the working roll is selected to be 0.05-0.15 mm; (3) Adjust the cold line process: The first rolling process cold-rolled strip is subjected to solution treatment and pickling, and the finished rolling process cold-hardened strip is subjected to pickling and bending straightening treatment.

3. The method for preparing a 301L stainless steel chilled plate for high-speed train according to claim 2, characterized in that: During the solution treatment in the first rolling process in the cold line process (3), the plate temperature is controlled at 1080-1110°C and the holding time is 0.8-1.0 min / mm; when the cold line process produces the finished cold-hardened strip steel, the furnace temperature is ≤400°C, the tension of the stretch straightening treatment is 50-90 tons, and the elongation is 0.5%-2.0%.

4. The method for preparing a 301L stainless steel chilled plate for high-speed train according to claim 3, characterized in that: The straightening treatment in (3) is performed by a straightening machine, which includes three sets of straightening rollers. The pressing amounts of the three sets of straightening rollers from right to left are 40-50 mm, 20-40 mm and 20-40 mm respectively.

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