Corrosion resistant structural steel with ultra high strength

Abstract

This invention relates to an ultrahigh-strength and corrosion-resistant structural steel, whose chemical composition is: C less than or equal to 0.02 wt.%, Si less than or equal to 0.15 wt.%, Mn less than or equal to 0.15 wt.%, S less than or equal to 0.01 wt.%, P less than or equal to 0.01 wt.%, Cr 8.0-10.0 wt.%, Ni 11.5-14.5 wt.%, Mo 0.5-2.5 wt.%, Ti 1.0-2.0 wt.%, Al 0.02-0.5 wt.%, and Fe as balance. The strength of the structural steel is 1800-1900 MPa. The structural steel has such advantages as low cost, high strength, high fracture toughness, and high corrosion resistance.

Description

technical field [0001] The invention belongs to the field of alloy steel, and in particular relates to an ultra-high-strength corrosion-resistant structural steel, the strength of which reaches 1800-1900Mpa, and simultaneously has relatively high toughness and corrosion resistance. Background technique [0002] In the existing technology, with the development of science and technology and the progress of human civilization, the development of corrosion-resistant metal materials with ultra-high strength has become an inevitable trend and a goal pursued by science and technology. Because corrosion not only loses material, damages component surfaces, and degrades material properties. According to a report in 2006, the direct loss caused by material corrosion in the United States is 279 billion US dollars per year, which is equivalent to 3.2% of the national GDP. If the cost of surface treatment such as cadmium plating and damage to the environment are considered, the loss cause...

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Problems solved by technology

[0003] As we all know, the steel with strength exceeding 1600MPa mainly adopts low-alloy ultra-high-strength steel 300M and 18Ni maraging steel and other steel types. Although these steels have ultra-high strength and good toughness, they do not contain Cr elements and are corrosion-resistant. Poor toughness, taking 18Ni(300) maraging steel as an example, the fracture toughness is 70-80MPa.m 1 / 2 between, but dropped to 30MPa.m in 3.5% brine 1 / 2 Below, therefore, the use of these steels as structural materials in corrosion-resistant environments is increasingly limited

Although traditional precipitation hardening stainless steels such as 13-8Mo and 17-4PH have good corrosion resistance, their strength is low. Recently, the Ti-strengthened Custom465 maraging stainless steel developed in the United States has good corrosion resistance, but its strength is not enough. High, maraging steel lower than 18Ni(250), not ideal as a structural material

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