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CN-121992177-A - Manufacturing method for improving mechanical property uniformity of high-chromium steel and product thereof

CN121992177ACN 121992177 ACN121992177 ACN 121992177ACN-121992177-A

Abstract

The invention discloses a manufacturing method for improving the uniformity of mechanical properties of high-chromium steel and a product thereof, and relates to the technical field of manufacturing weather-resistant steel for railway vehicles, photovoltaics and the like. The method comprises the steps of carrying out heat supplement on an intermediate billet after a rough rolling process is finished, wherein the heat supplement process comprises the steps of heating two side edges of the intermediate billet in the width direction by adopting medium-frequency induction heating to prevent the two side edges from being excessively fast in temperature reduction, wherein the heat supplement range is a range of 28-32 mm of the two side edges, the heat supplement temperature is 50 ℃ multiplied by K, K is a hardenability coefficient, dimensionless is achieved, and K= [14 multiplied by omega (Cr) +5.5 multiplied by omega (Ni) +16 multiplied by omega (Mn) ]/100. The high-chromium steel product provided by the invention has the advantages that good structure homogeneity and excellent mechanical property homogeneity are obtained from the design of key components, the design of rolling and cooling processes and other aspects.

Inventors

  • WANG FEI
  • LI ZHONGYI
  • HU XUEWEN
  • HE BO
  • WANG HAIBO
  • DAI SIYUAN
  • GUO RUI
  • WANG LIBING
  • CHENG ZHIYUAN
  • SHI DONGYA

Assignees

  • 马鞍山钢铁有限公司

Dates

Publication Date
20260508
Application Date
20260129

Claims (10)

  1. 1. A manufacturing method for improving the uniformity of the mechanical properties of high-chromium steel is characterized by comprising the following steps of slab heating, rough rolling, finish rolling, coiling and slow cooling, wherein the rough rolling is finished, the heat supplementing process comprises the steps of heating two side edges of the middle slab in the width direction by adopting medium-frequency induction heating to prevent the two side edges from being excessively fast reduced, the heat supplementing temperature is 50 ℃ multiplied by K within the range of 28-32 mm, K is the hardenability coefficient, and K= [14 xω (Cr) +5.5 xω (Ni) +16 xω (Mn) ]/100, ω (Cr), ω (Ni) and ω (Mn) respectively refer to the mass percentage of Cr, ni and Mn elements in the high-chromium steel product; the high-chromium steel comprises, by mass, 1.0-5.0% of Cr, 0.15-0.50% of Ni and 0.2-0.5% of Mn.
  2. 2. The manufacturing method according to claim 1, wherein the high chromium steel further comprises the following chemical components in mass percent ：C：0.03~0.06%;Si：0.1~0.4%;P≤0.020%;S≤0.005%;Cu：0.20~0.40%;Nb：0.020~0.050%;Ti：0.010~0.030%;Als：0.02~0.05%.
  3. 3. The method according to claim 1, wherein in the slab heating step, the tapping temperature of the cast slab is 1220 to 1250 ℃ and the holding time is 150 to 180 minutes.
  4. 4. The method according to claim 1, wherein the thickness of the intermediate billet obtained after the completion of the rough rolling step is 35 to 40mm, and the thickness of the hot rolled steel strip obtained after the completion of the finish rolling step is 3 to 8mm.
  5. 5. The method according to claim 1, wherein the entire length of the intermediate billet is kept warm by using a heat-retaining cover until entering the finish rolling head frame after the completion of the heat-supplementing process.
  6. 6. The method according to claim 1, wherein in the finish rolling step, a U-type finish rolling and U-type coiling process is used, and wherein the U-type finish rolling and U-type coiling process comprises controlling the finish rolling temperature and coiling temperature as follows: During the rolling period from the beginning of finish rolling to the length of the steel strip being 18-22 m, the finish rolling temperature is 890-920 ℃, and the coiling temperature is 690-720 ℃; During the intermediate rolling, the finish rolling temperature is controlled to be 850-880 ℃, and the coiling temperature is controlled to be 640-670 ℃; and during the rolling period from the start of finish rolling to the end of finish rolling at a distance of 28-32 m, the finish rolling temperature is 890-920 ℃ and the coiling temperature is 680-710 ℃.
  7. 7. The method according to claim 1, wherein the finish rolling step is performed by cooling the finish rolled strip to a coiling temperature by laminar flow cooling, wherein the laminar flow cooling step is performed by edge shielding and two-sided cooling water header shielding, and wherein the width of the one-sided header shielding is 0.05Kb, wherein K is a hardenability coefficient, and b is the strip width, and wherein mm.
  8. 8. The method according to claim 1, wherein in the coiling process, a coiler pinch roll and a wrapper roll are set by water-avoiding, wherein the water-avoiding setting comprises that the cooling water of the pinch roll is closed when the last stand of the finish rolling bites steel, boiled water is used when the mandrel is opened, the last stand of the finish rolling is closed after the steel is thrown, and the cooling water of the wrapper roll is boiled water after the coil is discharged.
  9. 9. The manufacturing method according to any one of claims 1 to 8, wherein the slow cooling process adopts an incubator for slow cooling, and when the temperature of the hot curled portion is more than or equal to 400 ℃, the incubator is covered and slowly cooled in time, and the slow cooling time period is more than or equal to 48 hours.
  10. 10. The high-chromium steel product is characterized by being prepared by the manufacturing method according to any one of claims 1-9, and comprises the following chemical components ：Cr：1.0~5.0%;Ni：0.15~0.50%;Mn：0.2~0.5%;C：0.03~0.06%;Si：0.1~0.4%;P≤0.020%;S≤0.005%;Cu：0.20~0.40%;Nb：0.020~0.050%;Ti：0.010~0.030%;Als：0.02~0.05%, in percentage by mass and the balance of Fe and unavoidable impurity elements.

Description

Manufacturing method for improving mechanical property uniformity of high-chromium steel and product thereof Technical Field The invention relates to the technical field of weather-resistant steel manufacturing, in particular to a manufacturing method for improving the uniformity of mechanical properties of high-chromium steel and a product thereof. Background The weather-resistant steel is mainly improved in corrosion resistance to the atmosphere or other media by adding weather-resistant alloying elements such as Cr, ni, cu and the like, and the total addition amount of the corrosion-resistant alloying elements is generally only 0.5-1.0%, but the weather resistance of the alloy is improved only to a limited extent by the corrosion-resistant alloying elements with the addition amount. The high Cr weathering steel is high corrosion-resistant weathering steel with the Cr content, the Ni content and the Cu content increased, and particularly the Cr content up to 1-5%, so that the addition of the high Cr, ni and other alloys can greatly improve the corrosion resistance, but the hardenability is also obviously improved on the basis of improving the corrosion resistance. The hot rolling treatment is carried out in the production process of the high Cr weathering steel, the hot continuous rolled steel coil after the hot rolling treatment is an integral steel coil which is stretched and is hundreds of meters in length and about 900-210mm in width, various media such as cooling water, air, a mandrel and the like can cause the difference of cooling temperature and cooling rate at different positions of the steel coil in a heat conduction or heat convection mode, and the hot continuous rolled steel coil of the high hardenability material is more obviously influenced by the hot continuous rolled steel coil. Therefore, simply increasing the Cr addition can improve the corrosion resistance of the alloy, but can also seriously affect the stability of mechanical properties. Based on the requirement of high corrosion-resistant weather-resistant steel, how to improve the performance stability of high Cr steel hot continuous rolled steel coils in the length and width directions becomes an important research subject in the field, and the stability and safety of the product in the forming processing and finished product service processes are directly affected. At present, a plurality of research results are disclosed on high Cr steel and a manufacturing method thereof, for example, chinese patent application No. CN201710169452.6 discloses a high-toughness high-corrosion-resistance weather-resistant steel plate and a manufacturing method thereof. The chemical components C：≤0.03％、Si：≤0.10％、Mn：0.10％～0.50％、P：≤0.015％、S：≤0.005％、Cr：4.0％～6.0％、Ni：0.40％～0.6％、Cu：0.40~0.60%、Nb：0.030~0.050%、Ti：0.020~0.050%、Al：0.020%~0.060%. are subjected to RH and LF double refining, casting blanks are heated for 3-4 hours, the tapping temperature is 1150-1200 ℃, the finishing temperature is 800-860 ℃ and the coiling temperature is 580-640 ℃. The yield strength is 480-550 MPa, the tensile strength is 600-700 MPa, the elongation is 24-30%. The Charpy V-shaped impact energy at the temperature of 80 ℃ below zero is more than 100J. Although this scheme is also high Cr weathering steel, the patent is mainly directed to the problem of insufficient toughness and corrosion resistance, and does not relate to the relevant description of uniformity of mechanical properties. The Chinese patent application No. CN202410646323.1 discloses a production method for improving the performance stability of 800MPa grade complex phase steel in the width direction and a produced 800MPa grade complex phase steel .C：0.05％～0.10％、Si：0.10％～0.30％、Mn：1.50～2.0％、Als：0.020％～0.060％、P≤0.020％、S≤0.003％、Nb：0.02％～0.10％、Ti：0.05％～0.20％,Cr+Mo+Ni≤1.5％. fixed-width machine side pressure of 100-140 mm, laminar cooling adopts edge shielding, and the finishing temperature is 860-900 ℃ and the coiling temperature is 540-580 ℃. Although the technical measures for improving the performance stability in the width direction are provided, the complex phase steel does not belong to high Cr weathering steel, the strength level is far higher than that of common high Cr steel, the smelting and rolling process difference between different steel types is huge, and related processes cannot be directly used. Therefore, there is a need to provide a manufacturing method for controlling the uniformity of mechanical properties in the long and wide directions of high Cr steel. Disclosure of Invention In order to overcome the defects of the technology, the invention aims to provide a manufacturing method for improving the uniformity of the mechanical properties of high-chromium steel and a product thereof, and solves the problems of uneven and unstable mechanical properties of a high-Cr steel hot-rolled product in the length and width directions. In order to achieve the above purpose, the technical scheme adopted by the in