Low-cost, high-performance ultra-high-strength steel for construction machinery and manufacturing method thereof

Abstract

Low-cost, high-performance ultra-high-strength steel for construction machinery and its manufacturing method, its composition weight percentage is: C: 0.18% to 0.22%, Si: ≤0.10%, Mn: 1.30% to 1.60%, P: ≤0.013%, S: ≤0.0030%, Cr: 0.30%~0.60%, Mo: 0.10%~0.30%, B: 0.0010%~0.0020%, Ti: 0.008%~0.018%, Nb: 0.010%~0.030%, Al: 0.030% ~0.070%, N: ≤0.0050%, O≤0.0030%, Mg: 0.001%~0.004%, the rest is iron and unavoidable inclusions. The invention adopts the combination of controlled rolling + online DQST, on the basis of adding a small amount of precious Mo alloy, while obtaining ultra-high strength, the low-temperature toughness, weldability and fatigue impact load resistance of the steel plate are also excellent, and successfully solves the problem of ultra-high strength. The contradiction between the strength, low temperature plasticity and toughness, delayed crack resistance and weldability of high-strength steel plate and the problem of overquenching of the surface (sub) surface of the steel plate.

Description

technical field [0001] The present invention relates to ultra-high-strength steel and its manufacturing method, in particular to a low-cost, high-performance ultra-high-strength steel for engineering machinery and its manufacturing method. 40°C Charpy transverse impact energy (single value) ≥ 27J, elongation at break δ 5 ≥10% and -20°C Charpy impact energy in welding heat affected zone ≥27J (average value) / 21J (single value) has excellent fatigue impact resistance. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler containers, building structures, automobile industry, railway transportation and engineering machinery manufacturing Among them; the performance of low carbon (high strength) low alloy steel depends on its chemical composition and manufacturing process, among which st...

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Problems solved by technology

[0006] Chinese Patent No. ZL201110445792.X discloses an ultra-high-strength construction machinery steel with excellent performance and its manufacturing method. Although the performance indicators and weldability of the steel plate are excellent, due to the addition of about 0.50% Mo element and the need for offline recycling Pyrothermal treatment, the manufacturing cost is relatively high, the manufacturing cycle is relatively long, and it cannot meet the requirements of the increasingly competitive thick plate market; more importantly, the yield strength and tensile strength of the steel plate produced by this invention technology cannot reach 1300MPa and 1500MPa, It cannot meet the requirements for the production of ultra-high-strength steel plates with a tensile strength of 1500MPa

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