Method for producing ultrathin ultrahigh-strength steel plate

Abstract

The invention provides a technical scheme of a method for producing an ultrathin ultrahigh-strength steel plate. The steel of the scheme comprises the following chemical ingredients by weight percent: 0.12-0.15% of C, 0.0-0.10% of Si, 0.9-1.3% of Mn, no more than 0.0015% of P, no more than 0.008% of S, 0.35-0.60% of Ni, 0.15-0.30% of Cr, 0.25-0.40% of Mo, 0.008-0.035% of Ti, 0.030-0.050% of Al, and the balance of iron and inevitable impurities. A production technology adopts clean steel smelting, hot continuous rolling forming, rolled plate unfolding and hot rolling base plate quenching tempering, heating temperature of casting blanks is controlled, the action of heavy pressing during rolling is exerted, the maximum potential of thermal treatment is excavated, and the structure is enabled to be ultra-thinned through a technological method, so that a finished product is the ultrathin ultrahigh-strength steel plate with the ultrathin specification of 3-10mm and tensile strength of 1000-1500Mpa. The steel plate has excellent low-temperature toughness index, and the carbon equivalent is controlled to be smaller than or equal to 0.4% according to the European committee for standardization (CEN); and the steel plate has good welding performance and is suitable for mass production.

Description

technical field [0001] The invention relates to a production method of a steel plate, in particular to a production method of an economical ultra-thin ultra-high-strength steel plate with excellent low-temperature toughness. Background technique [0002] In recent years, large-scale, heavy-duty, lightweight, etc. have become the main tone of the development of key steel consumption industries such as automobiles, ships, buildings, bridges, and construction machinery. To achieve the above goals, nothing less than reflected in three aspects: new materials, new structures and structural optimization. High-strength steel is reflecting the broad prospects of new materials in downstream applications. In the construction machinery industry, crane jib materials with a thin specification of less than 20mm and a tensile strength of 950 and 980 MPa (corresponding to Q890 and Q960) have been adopted in batches, thereby greatly reducing the self-weight of the jib and providing materials...

AI Technical Summary

Problems solved by technology

However, the current supply is mainly the WELDOX series of ultra-high-strength steel products from SSAB in Sweden. The specifications are concentrated in 4-16mm, and the strength levels are mainly WELDOX700, 900, and 960; however, limited by the capacity of hot rolling mills and coiling equipment, domestically available products Steel plates below 20mm are mainly low-strength coiled flat products below 800MPa. Some companies can supply Q960 hot-rolled products, but generally they have not received technical approval from pump truck manufacturers, mainly because direct application of flat sheets still exists. The large residual stress makes the product prone to buckling problems during subsequent cutting and bending; the thinnest specification of the original flat plate rolled by the medium and heavy plate is 5-6mm, and the strength level is basically 1000Mpa

For products with thinner specifications and higher strength, it is difficult to meet the requirements of users with existing production technologies and processes. Therefore, when producing steel with thinner specifications and higher strength for construction machinery, how to eliminate residual stress, ensure subsequent use safety, and satisfy users Demand has become an urgent problem for iron and steel enterprises to solve

[0003] An application number of Baoshan Iron and Steel Co., Ltd. published by the State Intellectual Property Office is 200510024756.0, which is entitled "ultra-high strength steel plate with a yield strength of 1100 MPa or more and its manufacturing method". The patent application discloses the use of controlled rolling The disadvantage of the post-direct quenching and tempering process is that it requires online direct quenching, its cooling rate is high (up to 50°C / s), and the actual on-line cooling production of such high-strength steel plates is prone to shape problems. The equipment capacity requirements are extremely high; the thickness of the steel plate can only be guaranteed to be 16 or 25mm, and it is difficult to produce thinner steel plates by this method, and its low-temperature impact toughness at -40°C is only 30-40J

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