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KR-20260067790-A - Steel for next-generation long-life heavy duty diesel engine and its manufacturing method

KR20260067790AKR 20260067790 AKR20260067790 AKR 20260067790AKR-20260067790-A

Abstract

The next-generation long-life heavy equipment diesel engine steel of the present invention may comprise, in weight percent, C: 0.38~0.42%, Si: 0.2~0.8%, Mn: 1.15~1.35%, P: 0.03% or less (including 0%), S: 0.03% or less (including 0%), Cr: 2.9~4.1%, Ni: 0.4~0.6%, Mo: 0.9~1.1%, Cu: 0.18~0.22%, Al: 0.025~0.035%, V: 0.49~0.51%, Co: 0.01~0.02%, Ti: 0.025~0.035%, Nb: 0.02~0.04%, W: 1.1% or less (including 0%), the remainder being Fe and unavoidable impurities.

Inventors

  • 김병구
  • 김형찬
  • 김병준
  • 김중훈
  • 한종민
  • 이강호

Assignees

  • 한국생산기술연구원

Dates

Publication Date
20260513
Application Date
20241106

Claims (12)

  1. A next-generation long-life heavy-duty diesel engine steel comprising, in weight%, C: 0.38~0.42%, Si: 0.2~0.8%, Mn: 1.15~1.35%, P: 0.03% or less (including 0%), S: 0.03% or less (including 0%), Cr: 2.9~4.1%, Ni: 0.4~0.6%, Mo: 0.9~1.1%, Cu: 0.18~0.22%, Al: 0.025~0.035%, V: 0.49~0.51%, Co: 0.01~0.02%, Ti: 0.025~0.035%, Nb: 0.02~0.04%, W: 1.1% or less (including 0%), and the remainder being Fe and unavoidable impurities.
  2. In paragraph 1, The above steel is a next-generation long-life heavy-duty diesel engine steel having a yield strength (YS) of 1000 MPa or more and a tensile strength (TS) of 1200 MPa or more.
  3. In paragraph 1, The above steel is a next-generation long-life heavy equipment diesel engine steel with a hardness of 40HRc or higher.
  4. In paragraph 1, The above steel is a next-generation long-life heavy-duty diesel engine steel having a high-temperature tensile strength (TS) of 700 MPa or more at 500°C.
  5. In paragraph 1, The above steel is a next-generation long-life heavy-duty diesel engine steel having a mass increase due to oxidation of 1.3 mg/㎠ or less when exposed to the atmosphere at a temperature of 500℃ for 10 hours.
  6. In paragraph 1, Next-generation long-life heavy-duty diesel engine steel in which a Cr oxide film is formed on the surface of the steel when exposed to an atmosphere at a temperature of 500°C.
  7. In paragraph 1, The above steel is a next-generation long-life heavy-duty diesel engine steel comprising, in weight percent, Cr: 2.9~3.1% and W: 0.9~1.1%.
  8. In Paragraph 7, Next-generation long-life heavy-duty diesel engine steel, wherein a Cr oxide film and a Cr-W composite oxide film are formed on the surface of the steel when exposed to an atmosphere at a temperature of 500°C.
  9. Next-generation steel comprising, in wt%, C: 0.38–0.42%, Si: 0.2–0.8%, Mn: 1.15–1.35%, P: 0.03% or less (including 0%), S: 0.03% or less (including 0%), Cr: 2.9–4.1%, Ni: 0.4–0.6%, Mo: 0.9–1.1%, Cu: 0.18–0.22%, Al: 0.025–0.035%, V: 0.49–0.51%, Co: 0.01–0.02%, Ti: 0.025–0.035%, Nb: 0.02–0.04%, W: 1.1% or less (including 0%), and the remainder being Fe and unavoidable impurities, to form a tempered martensite structure by performing solution treatment and tempering. Method for manufacturing steel for long-life heavy equipment diesel engines.
  10. In Paragraph 9, A method for manufacturing a next-generation long-life heavy-duty diesel engine steel, wherein the steel comprises, in weight percent, Cr: 2.9~3.1% and W: 0.9~1.1%.
  11. In Paragraph 9, A method for manufacturing next-generation long-life heavy equipment diesel engine steel, wherein the above solution treatment is carried out at a temperature of 820℃ to 1020℃ for 30 to 90 minutes.
  12. In Paragraph 9, A method for manufacturing next-generation long-life heavy equipment diesel engine steel, wherein the above tempering is carried out at a temperature of 520℃ to 720℃ for 1 to 3 hours.

Description

Steel for next-generation long-life heavy-duty diesel engine and its manufacturing method The present invention relates to a high-efficiency, high-durability steel material used in heavy-duty diesel engines (HDDE), and in particular to a next-generation long-life steel material for heavy-duty diesel engines that operates in ultra-high temperature and high pressure environments capable of meeting EURO 6 exhaust gas regulations, and a method for manufacturing the same. Aluminum alloys have traditionally been used for diesel engine pistons to reduce vehicle weight. However, as development progresses toward increasing engine operating temperature and pressure while reducing engine volume to meet EURO exhaust gas regulations and improve fuel efficiency, the need for new steel materials capable of overcoming the limitations of existing materials has emerged. Development of forged steel parts for passenger cars is currently proceeding mainly in the European market, where diesel vehicles have become popular, and the demand for HD and LVD steel parts as piston materials for passenger car diesel engines is growing rapidly. Since HD and LVD forged parts, which are components of vehicle engines, are subjected to high temperature and high pressure conditions, their physical properties and durability must be significantly excellent under these conditions. Although high-strength hot-forged steel parts are used in certain parts of vehicles, product quality and technological trends demand lighter weight and more precise tolerances, requiring materials to enhance the completeness of product quality. AISI 4140, a commercially available steel material currently in use, has reached its limits in high-temperature strength and wear resistance. Therefore, research is needed on new materials capable of maintaining high durability and physical properties under high temperature and high pressure conditions to solve the aforementioned problems. Figure 1 is the result of microstructural analysis using FE-SEM of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention . FIG. 2 is a graph showing the yield strength (YS) and tensile strength (TS) at room temperature (RT) and high temperature (500℃) of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention. FIG. 3 is a graph showing the elongation (EL) of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention at room temperature (RT) and high temperature (500℃). FIG. 4 is a graph showing the hardness of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention. FIG. 5 is a graph showing the increase in mass at a high temperature (500°C) of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention. FIG. 6 is a diagram showing the EDS analysis of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention. FIG. 7 is a graph showing the oxide layer thickness at a high temperature (500°C) of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention. FIG. 8 is a graph showing the weight reduction ratio according to a wear test in high temperature (500℃) air of a commercial material (P0) and steel materials (P1, P2, P3) according to one embodiment of the present invention. Specific embodiments of the present invention will be described in detail below with reference to the drawings. However, the concept of the present invention is not limited to the presented embodiments. Those skilled in the art who understand the concept of the present invention may easily propose other inventions that are inferior or other embodiments included within the scope of the concept of the present invention by adding, changing, or deleting other components within the same scope of the concept, and such are also to be considered to be included within the scope of the concept of the present invention. Additionally, components with the same function within the scope of the same concept appearing in the drawings of each embodiment are described using the same reference numeral. The next-generation long-life heavy equipment diesel engine steel according to the present invention may comprise, in weight%, C: 0.38~0.42%, Si: 0.2~0.8%, Mn: 1.15~1.35%, P: 0.03% or less (including 0%), S: 0.03% or less (including 0%), Cr: 2.9~4.1%, Ni: 0.4~0.6%, Mo: 0.9~1.1%, Cu: 0.18~0.22%, Al: 0.025~0.035%, V: 0.49~0.51%, Co: 0.01~0.02%, Ti: 0.025~0.035%, Nb: 0.02~0.04%, W: 1.1% or less (including 0%), the remainder being Fe and unavoidable impurities. C may be included in an amount of 0.38 to 0.42%. C imparts strength, and some forms carbides, which can increase wear resistance. Additionally, when added together with substitutional atoms with high affinity, s