Search

CN-117015628-B - Hot rolled steel sheet for vacuum train pipeline and method for manufacturing same

CN117015628BCN 117015628 BCN117015628 BCN 117015628BCN-117015628-B

Abstract

According to an aspect of the present invention, it is possible to provide a hot rolled steel sheet having excellent yield strength, vibration damping ratio and low temperature toughness, and thus having physical properties suitable for vacuum train pipes, and a method of manufacturing the same.

Inventors

  • LIANG HONGSHUO
  • PU JUNXUE
  • XU SHIZONG

Assignees

  • 浦项股份有限公司

Dates

Publication Date
20260505
Application Date
20211203
Priority Date
20201210

Claims (7)

  1. 1. A hot rolled steel sheet for a vacuum train pipe, comprising, in weight%, 0.15 to 0.25% of carbon (C), 0.3 to 1.3% of silicon (Si), 1.0 to 2.0% of manganese (Mn), and the balance of Fe and other unavoidable impurities, the microstructure having a ferrite and pearlite composite structure, and the hot rolled steel sheet satisfying the following relational expressions 1 to 3, the average grain size D of the ferrite being more than 10 μm and 30 μm or less, [ Relation 1] 350≤11+394 xD (-0 . 5) +448 [ C ] +94 [ Si ] +69 [ Mn ] [ Relation 2] 100≤186-210. D (-0 . 5) -121. C ] -13.2. Si ] +13.7. Mn ] [ Relation 3]303.78-85.22 x ln (D) >27 In the relational expressions 1 to 3, D represents an average grain size of ferrite of the hot rolled steel sheet, wherein units of the sizes are μm, [ C ], [ Si ], and [ Mn ] represent contents of carbon (C), silicon (Si), and manganese (Mn), respectively, of the hot rolled steel sheet, wherein units of the contents are% by weight.
  2. 2. The hot rolled steel sheet for vacuum train tubes as claimed in claim 1, wherein the microstructure of the hot rolled steel sheet is composed of 60-90 area% ferrite, 10-40 area% pearlite and other unavoidable structures.
  3. 3. The hot rolled steel sheet for vacuum train tubes as claimed in claim 1, wherein the total amount of titanium (Ti), niobium (Nb) and vanadium (V) inevitably contained in the hot rolled steel sheet is less than 0.01% and includes 0%.
  4. 4. The hot-rolled steel sheet for vacuum train pipes according to claim 1, wherein the hot-rolled steel sheet has a yield strength of 350MPa or more, a charpy impact energy of 27J or more at-20 ℃, and a vibration damping ratio measured at a frequency of 1650Hz in a flexural vibration mode after the hot-rolled steel sheet is processed into a test piece having a length of 80 x 20 x 2mm and a thickness of 80 x 20 x 2mm is 100 x 10 -6 or more.
  5. 5. The hot-rolled steel sheet for vacuum train pipes according to claim 1, wherein the thickness of the hot-rolled steel sheet is 10mm or more.
  6. 6. A method of manufacturing the hot rolled steel sheet for vacuum train pipes as claimed in claim 1, comprising the steps of: Heating a slab at a heating temperature T 1 of 1100-1300 ℃, the slab comprising, in wt%, 0.15-0.25% carbon (C), 0.3-1.3% silicon (Si), 1.0-2.0% manganese (Mn), the balance Fe and other unavoidable impurities; Hot-rolling the heated slab at a finish rolling temperature T 2 of 900-1000 ℃ to provide a hot-rolled steel sheet, and The hot rolled steel plate is coiled at the coiling temperature T 3 of 600-700 ℃, Wherein the heating temperature T 1 , the finish rolling temperature T 2 and the winding temperature T 3 satisfy the following relation 4, [ Relation 4]1≤ 0.0284 [ T 1 ]+0.071*[T 2 ]+0.045*[T 3 ] -131≤3 ] In the above-mentioned relation 4, [ T 1 ]、[T 2 ] and [ T 3 ] represent a slab heating temperature T 1 , a finish rolling temperature T 2 and a winding temperature T 3 , respectively, wherein the units of the temperatures are set to be a temperature.
  7. 7. The method of manufacturing a hot rolled steel sheet for a vacuum train pipe as claimed in claim 6 wherein the total amount of titanium (Ti), niobium (Nb) and vanadium (V) inevitably contained in the slab is less than 0.01% and includes 0%.

Description

Hot rolled steel sheet for vacuum train pipeline and method for manufacturing same Technical Field The present invention relates to a hot rolled steel sheet and a method of manufacturing the same, and more particularly, to a hot rolled steel sheet having excellent yield strength, vibration damping ratio and low temperature toughness, thus having physical properties suitable for vacuum train pipes, and a method of manufacturing the same. Background A vacuum train, also known as a super tube train (maglev), is a system in which a magnetic levitation train moves in a vacuum tube. The vacuum train is free from friction with air or rails, which is a cause of a major energy loss, when the train is running, and thus can be operated at an ultra-high speed. Since the energy loss is small and 93% of energy can be saved compared with an airplane, the energy is attracting attention as an environment-friendly next-generation vehicle, and the energy is being actively studied worldwide. The structure and materials utilized for the vacuum pipes of the ultra-high speed vacuum train can affect the performance or cost of the system. Currently, three main studies are made on the pipeline materials of vacuum trains. One is concrete. Concrete pipes are advantageous in terms of cost, but it is difficult to join individual pipes of around 10m to each other. In addition, because of the pores inside the concrete, when vacuum is achieved, external gas intrudes into the inside of the pipe, and thus there is a disadvantage in that the vacuum degree is easily broken. One of the other materials being largely studied is a composite material such as carbon fiber or the like. Composite materials such as carbon fibers are lightweight and have high performance, but the biggest disadvantage is high cost. Currently, the most promising material for vacuum train pipes is steel. Steel is a material that can be mass produced at low cost. Steel has high rigidity and high strength, and is a material that is easy to process. Furthermore, steel is a material that is easy to assemble or weld fittings between or on pipes, and also a material that has an appropriate degassing rate while maintaining vacuum. However, since the running speed of the ultra-high-speed vacuum train is significantly higher than that of the current high-speed train, the safety of passengers and surrounding facilities is primarily considered. Currently, the safety standard of the ultra-high speed vacuum train is not established, and development of materials for pipes for securing the safety of the ultra-high speed vacuum train is insufficient. Therefore, there is an urgent need to develop a material for vacuum train pipes, which has workability and degassing rate suitable for vacuum train pipes and can ensure safety. (Prior art literature) (Patent literature) Korean patent laid-open publication No. 10-2106353 (bulletin of 05 month 04 in 2020) Disclosure of Invention Technical problem to be solved According to an aspect of the present invention, it is possible to provide a hot rolled steel sheet having excellent yield strength, vibration damping ratio and low temperature toughness, and thus having physical properties suitable for vacuum train pipes, and a method of manufacturing the same. The technical problem of the present invention is not limited to the above. Additional technical problems of the present invention will be readily apparent to one skilled in the art based on the entire contents of the present specification. Technical proposal According to an aspect of the present invention, a hot rolled steel sheet for a vacuum train pipe may include, in weight%, 0.15 to 0.25% of carbon (C), 0.3 to 1.3% of silicon (Si), 1.0 to 2.0% of manganese (Mn), and the balance of Fe and other unavoidable impurities, and the microstructure may have a ferrite and pearlite composite structure, and the hot rolled steel sheet may satisfy the following relationship 1 to 3. [ Relation 1] 350≤11+394*D(-0.5)+448*[C]+94*[Si]+69*[Mn] [ Relation 2] 100≤186-210*D(-0.5)-121*[C]-13.2*[Si]+13.7*[Mn] [ Relation 3] 303.78-85.22*ln(D)>27 In the relational expressions 1 to 3, D represents an average grain size (μm) of ferrite of the hot-rolled steel sheet, [ C ], [ Si ] and [ Mn ] represent contents (wt%) of carbon (C), silicon (Si) and manganese (Mn) of the hot-rolled steel sheet, respectively. The microstructure of the hot rolled steel sheet may be composed of 60 to 90 area% ferrite, 10 to 40 area% pearlite and other unavoidable structures. The total amount of titanium (Ti), niobium (Nb), and vanadium (V) inevitably contained in the hot rolled steel sheet may be less than 0.01% (including 0%). The average grain size (D) of the ferrite may be 10 to 30 μm. The hot rolled steel sheet may have a yield strength of 350MPa or more, a charpy impact energy of-20 ℃ or more, and a vibration damping ratio of 100×10: 10 -6 or more measured at a frequency of 1650Hz in a flexural vibration mode (flexural vibration mode) afte