Steel with high toughness and ultrahigh strength

Abstract

The invention discloses steel with high toughness and ultrahigh strength, and belongs to the technical field of alloy steels. The steel comprises the following chemical components in percentage by mass: 0.20 to 0.35 percent of C, 0.5 to 2.0 percent of Mn, 1.25 to 2.25 percent of Si, 2.0 to 5.0 percent of Cr, 0.5 to 2.5 percent of Ni, 0.3 to 0.8 percent of Mo, 0.01 to 0.10 percent of Nb, 0.05 to 0.3 percent of V, less than or equal to 0.005 percent of S, less than or equal to 0.01 percent of P, and the balance of Fe. Compared with the conventional steel with ultrahigh strength, the steel has the advantages of ultrahigh strength, high fracture toughness, high hardening property and low cost.

Description

technical field [0001] The invention belongs to the technical field of alloy steel, in particular to a high-toughness ultra-high-strength structural steel with a tensile strength exceeding 1800 MPa and a fracture toughness (K IC ) over 120·MPam 1 / 2 , and low cost. Background of the invention [0002] As we all know, the advantages of low-alloy ultra-high-strength steels such as 4340, 300M, D6AC and 30CrMnSiNi2 lie in high strength and low cost, but such steels have poor toughness, especially fracture toughness, and there are hidden dangers in the use of key engineering structures. Poor permeability also restricts its use in large structural parts; high-alloy ultra-high-strength steels, such as secondary hardening ultra-high-strength steels such as AerMet100, AF1410, G99, 9Ni-4Co and 9Ni-5Co (F175), 18Ni (250 ), 18Ni(300) and other maraging steels, although they have a high combination of strength and toughness, but because they contain more scarce elements Co and Ni, the mat...

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Problems solved by technology

[0002] As we all know, the advantages of low-alloy ultra-high-strength steels such as 4340, 300M, D6AC and 30CrMnSiNi2 lie in high strength and low cost, but such steels have poor toughness, especially fracture toughness, and there are hidden dangers in the use of key engineering structures. Poor permeability also restricts its use in large structural parts; high-alloy ultra-high-strength steels, such as secondary hardening ultra-high-strength steels such as AerMet100, AF1410, G99, 9Ni-4Co and 9Ni-5Co (F175), 18Ni (250 ), 18Ni(300) and other maraging steels, although they have a high combination of strength and toughness, but because they contain more scarce elements Co and Ni, the material cost is expensive, so the research and development of new ultra-high strength steel, in the maintenance Under the premise of the original high toughness, reducing the cost of materials has become a future development trend. For example, the G50 ultra-high-strength steel developed in my country replaces 9Ni-5Co (F175), and the material cost is reduced by 50% without reducing the level of strength and toughness. above

However, with the continuous expansion of ultra-high-strength application fields, the demand is increasing, and the cost of G50 ultra-high-strength steel is relatively high (4.5% Ni)

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