Low-cost and high-performance ultrahigh-strength steel for engineering machinery and manufacturing method thereof

Abstract

The invention relates to low-cost and high-performance ultrahigh-strength steel for engineering machinery and a manufacturing method thereof. The low-cost and high-performance ultrahigh-strength steel comprises the following components in percentage by weight: 0.18-0.22 percent of C, less than or equal to 0.10 percent of Si, 1.30-0.60 percent of Mn, less than or equal to 0.013 percent of P, less than or equal to 0.0030 percent of S, 0.30-0.60 percent of Cr, 0.10-0.30 percent of Mo, 0.0010-0.0020 percent of B, 0.008-0.018 percent of Ti, 0.010-0.030 percent of Nb, 0.030-0.070 percent of Al, less than or equal to 0.0050 percent of N, less than or equal to 0.0030 percent of O, 0.001-0.004 percent of Mg and the balance of Fe and inevitable impurities. According to the low-cost and high-performance ultrahigh-strength steel, ultrahigh strength of a steel plate is obtained by adopting combination of controlled rolling and online DQST and on the basis of little addition of precious Mo alloy; meanwhile, the low-temperature toughness, the weldability and the fatigue impact load resistance of the steel plate are also excellent; the problems of mutual contradiction among the strength, the low-temperature toughness and the delayed crack resistance of an ultrahigh-strength steel plate as well as surface (subsurface) layer quenching are successfully solved.

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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