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RU-2026112021-A - HIGH-STRENGTH AND HIGH-IMPACT TENSILE STEEL FOR MINING CHAIN AND ITS MANUFACTURING METHOD

RU2026112021ARU 2026112021 ARU2026112021 ARU 2026112021ARU-2026112021-A

Inventors

  • ВАН, Чэнцюань
  • ЧЖАО, Сысинь
  • ЮЙ, Дацзян
  • Чжан, Цзюнь
  • ВАН, Вэй
  • ГАО, Цзяцян
  • Ван, Цянь

Assignees

  • БАОШАНЬ АЙРОН & СТИЛ КО., ЛТД.

Dates

Publication Date
20260505
Application Date
20240927
Priority Date
20230928

Claims (20)

  1. 1. A chain steel containing the following chemical components in mass percentages: C: 0.19-0.30%, preferably 0.20-0.30%; Si: 0.05-0.6%, preferably 0.21-0.47%; Mn: 1.0-1.8%; Cr: 0.4-0.8%; Ni: 0.5-0.9%; Mo: 0.3-0.55%; Ti: 0.015-0.035%; Al: 0.011-0.05%, preferably 0.02-0.05%; B: 0.0015-0.005%; N: 0.002-0.006%; the balance is Fe and unavoidable impurities.
  2. 2. A chain steel which, in addition to 90% or more of iron and inevitable impurities, further contains the following chemical components in mass percentages: C: 0.19-0.30%, preferably 0.20-0.30%; Si: 0.05-0.6%, preferably 0.21-0.47%; Mn: 1.0-1.8%; Cr: 0.4-0.8%; Ni: 0.5-0.9%; Mo: 0.3-0.55%; Ti: 0.015-0.035%; Al: 0.011-0.05%, preferably 0.02-0.05%; B: 0.0015-0.005%; N: 0.002-0.006%.
  3. 3. The chain steel according to claim 1 or 2, wherein the unavoidable impurities include P, S, O and H, wherein P ≤ 0.012%, S ≤ 0.01%, O ≤ 0.0015% and H ≤ 0.00015%.
  4. 4. Chain steel according to paragraph 3, wherein the chemical composition of the chain steel satisfies the following formula: Ti/(O + 2N) = 2-4; where Ti, O and N respectively represent the content of the corresponding elements in mass percent.
  5. 5. Chain steel according to claim 1 or 2, wherein part of the element B in the chain steel is present in the form of a solid solution, and the proportion of element B present in the form of a solid solution relative to the total content of element B (B solid solution /B total ) = 65-85%.
  6. 6. Chain steel according to claim 1 or 2, wherein the chain steel has a microstructure of tempered martensite and carbides distributed interlamellarly.
  7. 7. Chain steel according to claim 1 or 2, wherein the chain steel has the following properties: yield strength Rp 0.2 ≥ 1150 MPa, tensile strength R m ≥ 1250 MPa, preferably ≥ 1293 MPa, relative elongation A ≥ 13%, reduction in cross-sectional area Z ≥ 50% and impact toughness A kv at room temperature ≥ 60 J.
  8. 8. A method for producing steel for chains according to any one of paragraphs 1-7, comprising the following stages, performed sequentially:
  9. (1) melting and continuously casting molten steel to obtain a casting blank; wherein the melting process sequentially includes melting in an electric furnace, refining in a ladle furnace (LF) device, and vacuum refining; wherein in the vacuum refining process, the holding time of the molten steel before tapping is more than 10 minutes;
  10. (2) rolling the casting blank, quenching and tempering it to obtain chain steel; wherein the heating temperature during quenching is 850-980°C, and the holding time is 1-4 hours; the tempering temperature during tempering is 390-550°C, preferably 400-550°C, more preferably 400-450°C, the tempering time is 1-3 hours, and after tempering, cooling with water to room temperature.
  11. 9. The manufacturing method according to paragraph 8, wherein liquid iron and steel scrap are used as raw materials in the smelting process in an electric furnace, slag foaming is carried out throughout the entire smelting stage in the electric furnace, and the carbon content in the molten steel at the end point is controlled at a level of 0.06-0.10%, at a tapping temperature of molten steel of 1640-1680°C.
  12. 10. The manufacturing method according to paragraph 9, wherein during the smelting process in an electric furnace the percentage content of liquid iron in the raw material is controlled at a level of 30-60%.
  13. 11. The manufacturing method according to claim 8, wherein the refining process in the ladle furnace device includes the following stages, performed sequentially:
  14. 1) adding lime and fluorite to form slag at the initial stage of refining in a ladle furnace;
  15. 2) using aluminum or silicon carbide granules to enhance deoxidation and desulfurization, and feeding aluminum wire according to the target Al content in molten steel;
  16. 3) adjusting the alloy composition and temperature of molten steel to achieve target requirements before tapping.
  17. 12. The manufacturing method according to claim 8, wherein in the vacuum refining process, the molten steel after refining in the ladle furnace (LF) is subjected to slag removal treatment, followed by vacuum degassing and refining in a vacuum degassing furnace (VD) or a circulating vacuum furnace (RH), after which Al is added in accordance with the requirement of the chemical composition of the molten steel, wherein after ensuring the free oxygen content in the molten steel is below 5 ppm, Ca and ferrotitanium are added, and after 5 to 10 minutes, ferroboron is added, so that the composition of the molten steel is adjusted to the target composition.
  18. 13. The manufacturing method according to claim 12, wherein during the vacuum degassing and refining process in a vacuum degassing furnace or a circulation vacuum furnace, intensive mixing is performed for more than 10 minutes at a vacuum level of less than 67 Pa.
  19. 14. The manufacturing method according to paragraph 12, in which titanium wire is selected as ferrotitanium, and boron wire is selected as ferroboron.
  20. 15. The manufacturing method according to paragraph 8, in which the continuous casting process uses casting with full protection, the superheating of the molten steel in the pouring ladle is controlled at a level of 15-30°C, electromagnetic stirring is used in the crystallizer and at the end of solidification, and at the end of solidification a soft compression process of 10-25 mm is carried out to obtain a casting blank.