Super high-strength, high-toughness and wear-resistant steel and preparation method thereof

Abstract

The invention discloses super high-strength, high-toughness and wear-resistant steel and a preparation method thereof. The steel comprises the chemical composition by the weight percentage: 0.25 to 0.55 wt% of C, 1.50 to 2.50 wt% of Si, 1.50 to 2.20 wt% of Mn, 0.3 to 1.0 wt% of Cr, 0.2 to 0.8 wt% of Mo, 0.01 to 0.1 wt% of Re, less than 0.01 wt% of S, less than 0.01 wt% of P, and the balance Fe. Steel scrap or molten iron is smelted with an alloying material through an electric arc furnace or medium frequency induction furnace and then refined by VOD or LF, and molding is carried out by continuous casting or mold casting. The continuous casting billet or casting ingot is molded through rolling or forging and is subjected to special heat treatment, then the tensile strength of a part is 1800to 2000 MPa, the elongation percentage is 16 to 18%, the impact toughness aku is 60 to 80 J/cm<2>, and the hardness HRC is 55 to 62. The super strong wear-resistant steel not only has welding performance, but also has prominent plasticity, and is 2000 MPa-graded super high-strength steel having the elongation percentage at break reaching 18%.

Description

technical field [0001] The invention relates to a 1800-2000MPa grade SiMnCrMoRe series medium-carbon low-alloy ultra-high-strength high-toughness wear-resistant steel, in particular to an ultra-high-strength high-toughness wear-resistant steel and a manufacturing method thereof. Background technique [0002] There is a huge demand for wear-resistant materials in the field of metallurgy, coal mines. Compared with wear-resistant cast iron, wear-resistant steel is the most widely used wear-resistant material because of its comprehensive properties of hardness, strength and toughness. In the development history of wear-resistant steel, it has been clearly concluded that bainite steel, austenite / bainite dual-phase steel, martensite / bainite dual-phase steel, etc. have shown the most excellent comprehensive performance. In recent years, with silicon as the main alloying element, silicon can strongly inhibit the precipitation of carbides in the process of bainite transformation, a...

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Problems solved by technology

In recent years, with silicon as the main alloying element, silicon can strongly inhibit the precipitation of carbides in the process of bainite transformation, and it is possible to obtain carbide-free bainitic ferrite and residual austenite stabilized by carbon and silicon. Austenitic Austenitic dual-phase structure, because no carbide eliminates the crack or peeling incentives, so it has excellent comprehensive mechanical properties of strength and toughness, and is currently the most popular new generation of high-strength, high-toughness wear-resistant steel in the world. However, The isothermal transformation of supercooled austenite to low-temperature bainite for a long time (1 to 3 weeks) at a temperature slightly higher than the martensitic transformation temperature of the steel, although lath bainitic ferrite with a thickness of 30 to 100 nanometers is obtained Nanostructured carbide-free bainite composed of body and retained austenite, and has ultra-high strength, high fracture toughness, and good compression plasticity, but its isothermal transformation speed is extremely slow

Due to the long cycle and low efficiency of industrial production, and its carbon content exceeds 0.6%, it is a high-carbon alloy steel with poor welding performance, so it is difficult to be applied

Although in the follow-up research, adding Co and Al accelerated the bainite transformation speed, reducing Mn can accelerate bainite transformation more effectively than increasing Co, and brought significant cost reduction, but in large-scale production, especially The austempering process of large workpieces is difficult to achieve in industrial production

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