2000MPa grade superhigh intensity high tenacity steel plate and manufacturing method thereof

Abstract

The invention provides a 2000MPa super high-strength and high-toughness steel sheet and a manufacturing method thereof. The 2000MPa super high-strength and high-toughness steel sheet comprises the following chemical components: 0.20 percent to 0.60 percent of C, 1.0 percent to 3.0 percent of Si, 1.0 percent to 5.0 percent of Mn, 0.10 percent to 0.60 percent of Mo, and the rest are Fe and inevitable impurities. In the invention, Mn-Si-Mo series components are adopted, and the steel sheet with bainite / martensite duplex phase as the tissue characteristic is obtained through a controlled rolling and cooling technology. The yield strength of the steel sheet is more than or equal to 1000Mpa, the tensile strength is more than or equal to 2000Mpa, the yield ratio is more than or equal to 0.75, the charpy impact power Akv (-40DEG C) is more than 50J, and the 50 percent ductile-brittle transition temperature FATT is lower than -40 DEG C.

Description

technical field [0001] The invention relates to high-strength steel, in particular to a 2000MPa-level ultra-high-strength and high-toughness steel plate and a manufacturing method thereof. Background technique [0002] Ultra-high-strength steel is a high-strength, high-toughness alloy steel developed on the basis of alloy structural steel. The thermal processing process is simple and the cost is relatively low. It has been widely used by aviation and aerospace departments. key material. Ultra-high-strength steels are more sensitive to hydrogen than normal-strength steels, and hydrogen-induced fractures may occur during use. Different microstructures have different sensitivities to hydrogen embrittlement, which generally increase in the following order: ferrite, pearlite, bainite, low carbon martensite, a mixture of martensite and bainite. [0003] However, due to the low toughness of most ultra-high-strength steels, this will shorten their service life, making it a restric...

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Problems solved by technology

[0005] At present, the alloy composition of hot-rolled multiphase steel is generally Mn-Cr-Mo-V-Nb-B series or Mn-Si-Cr-Al-B series: for example, the chemical composition of dual-phase steel involved in US20040118489 is: C: 0.02~0.15%, Mn: 0.30~2.50%, Cr: 0.10~2.00%, Al: 0.01~0.20%, Mo≤0.50%, Ni≤0.50%, Cu≤0.50%, Nb≤0.20%, Ti≤0.20% , V ≤ 0.20%, P ≤ 0.10%, S ≤ 0.03%, Ca: 0.001-0.01%, the yield strength of the steel is 800MPa, and many kinds of alloying elements are added to the composition, such as Cr, Ni, Ti, etc. , increasing the cost of raw materials; another example is EP1553202 involving a hydrogen embrittlement-resistant ultra-high-strength steel, whose chemical composition is: C: 0.06-0.6%, Si+Al: 0.5-3%, Mn: 0.5-3%, P≤ 0.15%, S≤0.02%, the microstructure is composed of polygonal ferrite (≤50%), bainite and retained austenite, and the tensile strength reaches 1180MPa; another example is DE19936151, which discloses a chemical composition of high-strength steel Composition: C: 0.05-0.20%, Si: 0-1.00%, Mn: 0.80-2.00%, P: 0-0.100%, S: 0-0.015%, Al: 0.02-0.40%, N: 0-0.005% , Cr: 0.25~1.00%, B: 0.002-0.010%, the trace element B is added to this steel, the purpose is to improve the hardenability of the steel, but the smelting yield of B is extremely unstable, and it is difficult to control in production. And B is easy to cause B (boron) brittleness, which brings great damage to the toughness of steel

[0006] In addition, in order to obtain more bainite in the steel structure, the above-mentioned steel types have reduced the amount of C added, but once the C content is too small, its strengthening effect will be reduced, resulting in a decrease in the strength of the steel. From the perspective of microstructure, the tensile strength of traditional hot-rolled low-yield ratio steel produced under industrial conditions is difficult to reach 2000MPa

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