Ultrahigh-strength all-austenite low-density steel and preparation method

Abstract

The invention discloses ultrahigh-strength all-austenite low-density steel and a preparation method, and belongs to the technical field of metal materials and preparation thereof. The ultrahigh-strength all-austenite low-density steel comprises, by weight, 1.0%-1.6% of C, 25.0%-30.0% of Mn, 9.0%-13.0% of Al, 0.6%-1.0% of Mo, 1.0%-1.2% of V, 0.01%-0.04% of Ti, 0.02%-0.04% of Nb, less than or equal to 0.03% of P, less than or equal to 0.002% of S and less than or equal to 0.006% (60ppm) of N. And the balance of Fe and inevitable impurities are used for preparing raw materials. A uniform and stable all-austenite steady-state structure is obtained through casting, controlled rolling and controlled cooling technologies, and VC and MoC precipitated phases of 1-10 nanometers and a k phase of 10-50 nanometers are obtained on the basis of the stable all-austenite steady-state structure through the aging precipitation technology. The ultrahigh-strength all-austenite low-density steel and the preparation method are suitable for various fields of automobiles, buildings, engineering machinery and the like.

Description

technical field [0001] The invention belongs to the technical field of metal materials and their preparation, and in particular relates to an ultra-high-strength low-density steel and a preparation method. Background technique [0002] Reducing energy consumption, reducing environmental pollution and saving limited resources is a very important and urgent problem that people are facing today. Reducing the weight of automobiles is one of the important measures to improve the fuel economy and save energy consumption of automobiles. At present, the development and research of automobile lightweight projects at home and abroad, and the development of high-strength or ultra-high-strength steel plates, reduce the weight of cars by reducing the thickness of the steel plates used. The application of high-strength steel and advanced high-strength steel to replace traditional low-strength grade steel can increase the specific strength (ratio of strength to density) of automotive steel...

AI Technical Summary

Problems solved by technology

CN104928569A and CN106011652B disclose a kind of 800MPa grade high ductility light steel and its preparation method. The material is low-density steel with medium carbon and medium manganese, its strength is only 800MPa, and the production process of this method is relatively complicated

CN108642403A discloses a low-density steel of 780MPa grade. Because the C content is too high and there are certain problems in the proportion design of the alloy components, the strength is low and the full austenite structure cannot be obtained.

CN104674109A and CN103667883B disclose a low-density steel with ultra-high Al, the density can be reduced to 6.65-6.80g / cm 3 , although the strong plastic product can reach about 40GPa·%, but the strength can only reach 900MPa level, and it is still α+γ duplex structure

CN102690938B discloses an Al-containing steel with ultra-low C and ultra-high Mn. Through the manufacturing method of intermediate frequency induction furnace and electroslag remelting, a fully austenitic low-density steel is obtained, although the strong plastic product can reach 52.8GPa·% , but since the Al content is only 1.85%, the predicted density of the steel reaches 7.5g / cm 3 , and the strength is only 700MPa, so it is basically impossible to reduce the weight of existing vehicles, construction and engineering machinery related load-bearing structures

The national invention patent (patent number: CN106399858A) strengthens the alloy by adding 5-20wt% Ti to precipitate Ti3Al intermetallic compound, and obtains high strength under the premise of ensuring low density. However, the price of Ti element is high, and the addition of a large amount of Ti element increases Alloy cost

CN106399858A discloses a high-strength Fe-Mn-Al-C low-density cast steel and its preparation method. Although the tensile strength reaches 1400MPa level, its plasticity is poor and the cost is too high, which is not suitable for industrial production and popularization and application

The 1200MPa grade low-density steel invented by CN108486492B adds about 4% Ni, adopts the method of NiAl strengthening phase to make the tensile strength 1200-1300MPa, the elongation reaches more than 30%, and the density is 6.4-7.0g / cm 3 , but the actual process is more complicated, including smelting, homogenization treatment, forging, hot rolling, solid solution, cold rolling, annealing, etc., and the addition of more expensive Ni makes the overall cost higher

CN109628850B authorizes a multi-purpose fully austenitic low-density steel with a tensile strength of 1300MPa and a high-strength low-density steel with a yield of 1100MPa and an elongation of 25%, and its density ranges from 7.0 to 7.4g / cm 3 , the strength and toughness of this material are significantly improved compared with the previous invention, but the light weight is limited by the amount of Al added

[0007] It can be seen that the main composition system currently used is Fe-Mn-Al-C system, the strength is still limited, and the lightweight still needs to be further improved

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