CN112410680A - Ultrahigh-strength low-density steel and preparation method thereof - Google Patents
Ultrahigh-strength low-density steel and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
Abstract
The invention provides ultrahigh-strength low-density steel and a preparation method thereof. The ultrahigh-strength low-density steel comprises the following alloy components in percentage by mass: 0.9 to 1.20 percent of C; 22-26% of Mn; 9-11% of Al; cu 0.15-0.35%; p is less than or equal to 0.010 percent; s is less than or equal to 0.005%, and the balance is Fe and inevitable impurity elements. The preparation method comprises the following steps: the smelting process comprises the following steps: according to various alloy compositionsPouring the metal powder material into a vacuum smelting furnace, and heating and melting to obtain a metal liquid; the casting process comprises the following steps: pouring the molten metal obtained by smelting into a casting mould for cooling treatment to obtain a low-density steel casting blank; forging: heating the low-density steel casting blank to 1200-1220 deg.C, initially forging to obtain intermediate blank of 50X 50mm, and final forging to obtain
The round bar of (1); and (3) heat treatment process: the test steel round bars obtained by forging are divided into two groups, one group adopts solid solution water quenching treatment, and the other group adopts aging treatment. The invention provides the austenite-based low-density steel with the density less than or equal to 6.6g/cm3, which has excellent comprehensive mechanical properties, good application prospect and market value.
Description
Technical Field
The invention relates to the technical field of low-density steel, in particular to ultrahigh-strength low-density steel and a preparation method thereof.
Background
With the increasing awareness of environmental protection, more and more environmental protection industrial products are developed and put into use, as is the case with the automotive industry. Automobile steel has been developed for many generations, and low-density high-strength steel is increasingly paid more attention. Particularly, the density of Fe-Mn-Al-C light steel is greatly reduced due to the addition of a large amount of Al. The influence of Al on the layer dislocation energy is particularly serious, which causes the strengthening and toughening mechanism of low-density high-strength steel to become very complicated. The high Al addition makes the high temperature ferrite more stable and retained in the structure, while other more complex second phases such as kappa-carbides, DO3 ordered phases, B2 intermetallic compounds, etc. are generated. The existence of kappa-carbide particularly affects the final performance, and the kappa-carbide distributed in the crystal is generated by Spinodal decomposition during quenching, so that the strength of the material can be improved, and the plastic loss is not brought. When kappa-carbide is precipitated in grain boundary and grows into coarse carbide, the brittleness of the material is obviously increased.
At present, the research on low-density steel is still in the early stage of exploration, and various related theories are still to be perfected. The subject of academic research mainly includes dual-phase low-density steel and single-phase low-density steel, wherein the single-phase low-density steel includes: ferritic single-phase low-density steel and austenitic single-phase low-density steel. The austenite-based low-density steel has higher strength upper limit and property balance, has wide prospect and is also most concerned. Most importantly, when the Al content reaches a certain level (Al > 7%), the stacking fault energy is increased sharply, and the strengthening mechanism in the steel is converted into MBIP (so-called micro-strip induced plasticity) through the common TRIP and TWIP effects, so that the austenite low-density steel is attracted by a plurality of researchers through the unique strengthening and toughening mechanism. However, many researchers focus on test steels obtained by rolling, and no matter whether the test steels are cold rolled or hot rolled, the research on low-density steel forgings is less, and particularly, the forging method for the high-manganese-content low-density steel is not mature, so that the problems of the high-manganese steel in forging, such as forging cracks, need to be solved, and the forging difficulty of the low-density steel after the low-density steel has high Al content is further increased.
One proposal in the prior art provides a hot-rolled low-density steel with Al content of 4.5-7.5% and added with alloy elements such as Cr + Mo + Ni + Cu, etc., and carbides inside the hot-rolled low-density steel present a spherical or short rod-shaped form through regulation and control of heating and heat preservation treatment, thereby improving the toughness and the machinability of the test steel. The disadvantages of this solution are: the hot-rolled low-density steel obtained by the scheme has low strength, the addition amount of Al is relatively low, namely the density reduction level is not ideal (the requirement of light weight cannot be met), and the level of the product of strength and elongation still has room for improvement.
Another scheme in the prior art provides a high-Al and high-C Fe-Mn-Al-C series low-density steel which has excellent product of strength and elongation (higher than 50 GPa.%) and a matrix structure of austenite + ferrite + kappa-carbide. The phase composition of austenite, ferrite and kappa-carbide is obtained by adopting a mode of hot rolling and cold rolling for multiple times, and the mechanical property is relatively excellent. The disadvantages of this solution are: the process of the scheme is relatively complex, the industrial production operability is low, the application prospect is small, and the method is only suitable for small-scale laboratory research.
In summary, there is an urgent need for a design of forging heat treatment process and components of high-manganese, high-Al, and low-density steel to meet the future requirements of scientific research and industrial production.
Disclosure of Invention
Embodiments of the present invention provide an ultra-high strength low density steel and a method for manufacturing the same to overcome the problems of the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme.
According to one aspect of the invention, an ultrahigh-strength low-density steel is provided, which comprises the following alloy components in percentage by mass: 0.9 to 1.20 percent of C; 22-26% of Mn; 9-11% of Al; cu 0.15-0.35%; p is less than or equal to 0.010 percent; s is less than or equal to 0.005%, and the balance is Fe and inevitable impurity elements.
Preferably, the alloy composition of the ultra-high strength low density steel comprises: 0.9 to 1.0 percent of C; 22-24% of Mn; 9-10% of Al; cu 0.15-0.25%, and Fe in balance.
Preferably, the alloy composition of the ultra-high strength low density steel comprises: : 1.0 to 1.2 percent of C; 22-24% of Mn; 9-10% of Al; cu 0.15-0.25%, and Fe in balance.
Preferably, the alloy composition of the ultra-high strength low density steel comprises: 1.0 to 1.2 percent of C; mn 24-26%; 10-11% of Al; cu 0.15-0.25%, and Fe in balance.
Preferably, the ultra-high strength low density steel further comprises the following alloying elements: 0.5 to 3.5 percent of Ni; v is 0.15 to 0.55; 0.02 to 0.08 percent of Nb.
Preferably, the ultra-high strength, low density steel comprises an austenite-based, low density steel.
According to another aspect of the present invention, there is provided an ultra-high strength low density steel, the method for manufacturing the ultra-high strength low density steel comprising: smelting, casting, forging and heat treatment;
the smelting process comprises the following steps: forming metal powder materials according to the mass percentage of various alloy components of the ultrahigh-strength low-density steel, pouring the metal powder materials into a vacuum smelting furnace, and heating and melting the metal powder materials by the vacuum smelting furnace to obtain metal liquid;
the casting process comprises: pouring the molten metal obtained by smelting into a casting mould, and cooling the molten metal by using the casting mould to obtain a low-density steel casting blank;
the forging process comprises the following steps: heating the low-density steel casting blank to 1200-1220 deg.C, holding the temp for 3 hr or more, and initially forging to 50X 50mmIntermediate blank and finish forging
The round bar of (1);
the heat treatment process comprises the following steps: dividing the forged test steel round bars into two groups, wherein one group adopts solid solution water quenching treatment, heating to 1050 ℃, preserving heat for 40 minutes, and performing water quenching treatment; and the other group is subjected to aging treatment, heating to 1050 ℃, heat preservation for 40 minutes, water quenching treatment, heat preservation for 12 hours at 550 ℃, and water quenching treatment to obtain the ultrahigh-strength low-density steel of the embodiment of the invention.
Preferably, the initial forging temperature in the forging process is 1050-1200 ℃, the final forging temperature is not lower than 900 ℃, the furnace return is not less than 2 times in the forging process, and the forging process is followed by cooling to room temperature in an air cooling or water cooling mode.
Preferably, the tensile strength of the austenite-based low-density steel obtained by adopting the aging treatment is more than or equal to 1100MPa, the yield strength is more than or equal to 1050MPa, the elongation is more than or equal to 27 percent, and the density is less than or equal to 6.6g/cm3；
The tensile strength of the austenite-based low-density steel obtained by adopting solution treatment is more than or equal to 860MPa, the yield strength is more than or equal to 690MPa, and the elongation is more than or equal to 69 percent; the density is less than or equal to 6.6g/cm3。
According to the technical scheme provided by the embodiment of the invention, the austenite-based low-density steel with the density less than or equal to 6.6g/cm3 is obtained through alloy composition design. The embodiment of the invention designs two proper heat treatment processes by utilizing thermodynamic results, so that the test steel achieves the tensile strength of 1100MPa level and the elongation of 70% level respectively, and has excellent comprehensive mechanical properties, good application prospect and market value.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 shows a heat treatment process curve of the ultra-high strength low density steel according to an embodiment of the present invention.
Fig. 2 shows a microstructure of an ultra-high strength, low density steel of an embodiment of the present invention, wherein fig. 2(a) is a solution treatment test sample; FIG. 2(b) is an aging test sample.
Fig. 3 shows a thermodynamic calculation property diagram of the ultra-high strength low density steel of the embodiment of the present invention.
Fig. 4 shows the engineering stress-strain curve and strain-hardening curve of the ultra-high strength low density steel of an embodiment of the present invention.
Fig. 5 shows a fracture morphology in a tensile test of the ultra-high strength low density steel of the embodiment of the present invention, wherein (a) is an ST sample and (b) is an AT sample.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the convenience of understanding the embodiments of the present invention, the following description will be further explained by taking several specific embodiments as examples in conjunction with the drawings, and the embodiments are not to be construed as limiting the embodiments of the present invention.
In view of the current situation that the strength of the existing austenite-based low-density steel is generally reduced, the embodiment of the invention designs a novel ultrahigh-strength low-density steel, which comprises the following alloy components in percentage by mass: 0.9 to 1.20 percent of C; 22-26% of Mn; 9-11% of Al; cu 0.15-0.35%; p is less than or equal to 0.010 percent; s is less than or equal to 0.005%, and the balance is Fe and inevitable impurity elements.
In one embodiment, the alloy composition of the ultra-high strength and low density steel may be: 0.9 to 1.0 percent of C; 22-24% of Mn; 9-10% of Al; cu 0.15-0.25%, and Fe in balance. The following alloying elements may also be added: 0.5 to 3.5 percent of Ni; v is 0.15 to 0.55; 0.02 to 0.08 percent of Nb.
In one embodiment, the alloy composition of the ultra-high strength and low density steel may be: 1.0 to 1.2 percent of C; 22-24% of Mn; 9-10% of Al; cu 0.15-0.25%, and Fe in balance. The following alloying elements may also be added: 0.5 to 3.5 percent of Ni; v is 0.15 to 0.55; 0.02 to 0.08 percent of Nb.
In one embodiment, the alloy composition of the ultra-high strength and low density steel may be: 1.0 to 1.2 percent of C; mn 24-26%; 10-11% of Al; cu 0.15-0.25%, and Fe in balance. The following alloying elements may also be added: 0.5 to 3.5 percent of Ni; v is 0.15 to 0.55; 0.02 to 0.08 percent of Nb.
The ultra-high strength low density steel includes austenite-based low density steel.
The preparation method of the ultrahigh-strength low-density steel comprises the following steps: smelting, casting, forging and heat treatment. Wherein the content of the first and second substances,
the smelting process comprises the following steps: according to the ultrahigh-strength low-density steel disclosed by the embodiment of the invention, the metal powder materials are composed of various alloy components in percentage by mass, the metal powder materials are poured into a vacuum smelting furnace, and the vacuum smelting furnace heats and melts the metal powder materials to obtain the molten metal.
The casting process comprises the following steps: and pouring the molten metal obtained by smelting into a casting mould, and cooling the molten metal by using the casting mould to obtain the low-density steel casting blank.
The forging process comprises the following steps: heating the low-density steel casting blank to 1200-1220 ℃, and preserving the heat for more than or equal to 3 hours. Homogenizing at high temperature for 4 hr, forging to obtain intermediate blank of 50 × 50mm, and final forging to obtain final product
The round bar of (1). The initial forging temperature is 1050-1200 ℃, and the final forging temperature is not lower than 900 ℃. And the time of the remelting in the forging process is not less than 2 times. And cooling to room temperature by adopting an air cooling or water cooling mode after forging.
The heat treatment process comprises the following steps: dividing the forged test steel round bars into two groups, wherein one group adopts solid solution water quenching treatment, heating to 1050 ℃, preserving heat for 40 minutes, and immediately performing water quenching; the other group adopts aging treatment, and the solid solution water quenching process is carried out in the same way, namely heating to 1050 ℃, preserving the heat for 40 minutes, carrying out water quenching treatment, preserving the heat for 12 hours at 550 ℃, and then carrying out water quenching treatment. The ultrahigh-strength low-density steel of the embodiment of the invention is obtained, and is an austenite-based low-density steel.
The tensile strength of the austenite-based low-density steel obtained by adopting the aging treatment is more than or equal to 1100MPa, the yield strength is more than or equal to 1050MPa, and the elongation is more than or equal to 27 percent; the austenite-based low-density steel obtained by solution treatmentThe tensile strength is more than or equal to 860MPa, the yield strength is more than or equal to 690MPa, and the elongation is more than or equal to 69 percent; the density of the two test steels is less than or equal to 6.6g/cm3。
The test steel with excellent mechanical properties is obtained by adopting two typical heat treatment processes, wherein the strength of the sample subjected to aging treatment reaches 1100MPa, and the elongation of the sample subjected to solution treatment reaches 69%. Particularly, after alloy elements such as copper and the like are added, the yield property of the steel is obviously improved, and the condition that the yield property of the all-austenite low-density steel is low is obviously improved. The properties of the austenitic-based low density steels of the examples of the present invention were compared with those of the similar composition test steels, and the comparison results are shown in table 1 below:
table 1: typical low density steel properties
The two experimental steels obtained by the experiment have simple heat treatment system, but are very effective, and are easier to operate in the industrial production process. The structure is fully austenitic, and has great advantages in corrosion resistance and low-temperature performance. Aiming at the current environmental protection concept, the experiment also has a particularly good weight reduction effect, and the weight reduction reaches 18 percent on the basis that the performance reaches the third generation of automobile steel.
Fig. 1 shows a heat treatment process curve of the ultra-high strength low density steel according to an embodiment of the present invention. As shown in figure 1, the test steel is heated to 1050 ℃ from room temperature and then is kept for 40min, the temperature keeping time can be 30-60min in actual production (related experiments prove that the performance is not changed greatly), and a cooling mode of water quenching is adopted after the temperature is kept (oil quenching can be adopted for small-size parts, the effect is equivalent), so that a solid solution Sample (ST) is obtained. And (3) heating the sample to 550 ℃ on the basis of the solid solution sample, and keeping the temperature for 12h (the time can be about 12h during industrial production, no special precision is needed, and then water quenching is carried out to obtain an aging sample (AT)).
Fig. 2 shows a microstructure of an ultra-high strength, low density steel of an embodiment of the present invention, wherein fig. 2(a) is a solution treatment test sample; FIG. 2(b) is an aging test sample. In fig. 2(a), it can be found that austenite in the ST sample exhibits polygonal morphology, wherein a plurality of twin crystals exist, and part of the twin crystals penetrate through the whole austenite grains, so that a certain thinning effect is achieved on the structure. The AT sample has a certain increase in grain size relative to the ST sample, and the proportion and width of twin crystals are slightly increased.
Fig. 3 shows a thermodynamic calculation property diagram of the ultra-high strength low density steel of the embodiment of the present invention. FIG. 3 is a diagram showing equilibrium properties of the composition of a steel sample calculated by Thermo-calc, and it can be found that the austenite content is highest at 1050 ℃, the content of kappa-carbide is not changed basically before 760 ℃, the kappa-carbide starts to be dissolved gradually after 760 ℃, and no kappa-carbide exists at 1050 ℃, but nano-scale kappa-carbide is precipitated during water quenching. At low temperatures, two types of ferrite are present in the structure: high temperature ferrite delta, room temperature ferrite alpha. The high-temperature ferrite δ exists because a large amount of Al element (Al element is a ferrite-forming element) is added to the test steels, but since the Al element is in a non-equilibrium state in actual production, the two groups of test steels can be basically regarded as a single-phase austenite structure.
Fig. 4 shows the engineering stress-strain curve and strain-hardening curve of the ultra-high strength low density steel of an embodiment of the present invention. In the figure, the true stress-strain curves and strain-hardening curves of the two sets of experimental steels exhibit two different mechanical properties. It was found that the ST samples exhibited very excellent strain hardening capacity during the drawing process, in particular in the second stage of strain hardening, corresponding to the progressive development of the dislocation structure in the ST samples, which is also a way of strengthening high-energy-dislocation-energy austenite-based low-density steels. The AT sample has a very high strain hardening rate in the early stage of deformation, and then the strain hardening rate is lower than that of the ST sample along with the rise of strain, and the total strain is not as good as that of the ST sample.
Fig. 5 shows a fracture morphology diagram in a tensile test of the ultra-high strength low density steel of the embodiment of the invention, fig. 5(a) is an ST sample, and fig. 5(b) is an AT sample. The fracture structure of the two test steels in fig. 5 is typical of ductile fracture characteristics, the dimple in the ST sample is very developed, the dimple in the AT sample is large in size, and kappa-carbides generated in the partial aging process exist inside.
In conclusion, the embodiment of the invention obtains the austenite-based low-density steel with the density of less than or equal to 6.6g/cm3 through alloy composition design. The embodiment of the invention designs two proper heat treatment processes by utilizing thermodynamic results, so that the test steel achieves the tensile strength of 1100MPa level and the elongation of 70% level respectively, and has excellent comprehensive mechanical properties, good application prospect and market value.
The method has the advantages of simple process flow, strong operability, simple temperature control in both forging and heat treatment stages and easy realization.
The low-density steel obtained by the method has excellent performance, wherein the elongation of a solid-solution water-quenched sample is as high as 74%, the tensile strength Rm is 865MPa, and the yield strength Rp0.2 is 695 MPa; the tensile strength Rm of the sample subjected to aging treatment is 1129MPa, the yield strength Rp0.2 is 1082MPa, and the elongation after fracture is 28%. Compared with other researchers, the steel has obvious advantages in testing performance, and has very wide market application prospect.
Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, they are described in relative terms, as long as they are described in partial descriptions of method embodiments. The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. The ultrahigh-strength low-density steel is characterized by comprising the following alloy components in percentage by mass: 0.9 to 1.20 percent of C; 22-26% of Mn; 9-11% of Al; cu 0.15-0.35%; p is less than or equal to 0.010 percent; s is less than or equal to 0.005%, and the balance is Fe and inevitable impurity elements.
2. The ultra-high strength, low density steel of claim 1, wherein said ultra-high strength, low density steel has alloy compositions comprising: 0.9 to 1.0 percent of C; 22-24% of Mn; 9-10% of Al; cu 0.15-0.25%, and Fe in balance.
3. The ultra-high strength, low density steel of claim 1, wherein said ultra-high strength, low density steel has alloy compositions comprising: 1.0 to 1.2 percent of C; 22-24% of Mn; 9-10% of Al; cu 0.15-0.25%, and Fe in balance.
4. The ultra-high strength, low density steel of claim 1, wherein said ultra-high strength, low density steel has alloy compositions comprising: 1.0 to 1.2 percent of C; mn 24-26%; 10-11% of Al; cu 0.15-0.25%, and Fe in balance.
5. An ultra-high strength, low density steel according to claim 2, 3 or 4, further comprising the following alloying elements: 0.5 to 3.5 percent of Ni; v is 0.15 to 0.55; 0.02 to 0.08 percent of Nb.
6. The ultra-high strength, low density steel of claim 1, wherein said ultra-high strength, low density steel comprises an austenite-based, low density steel.
7. An ultra-high strength, low density steel as claimed in any one of claims 1 to 6, wherein said ultra-high strength, low density steel is produced by a method comprising: smelting, casting, forging and heat treatment;
the smelting process comprises the following steps: forming metal powder materials according to the mass percentage of various alloy components of the ultrahigh-strength low-density steel, pouring the metal powder materials into a vacuum smelting furnace, and heating and melting the metal powder materials by the vacuum smelting furnace to obtain metal liquid;
the casting process comprises: pouring the molten metal obtained by smelting into a casting mould, and cooling the molten metal by using the casting mould to obtain a low-density steel casting blank;
the forging process comprises the following steps: heating the low-density steel casting blank to 1200-1220 deg.C, holding the temp. for 3 hr or more, initially forging to obtain intermediate blank of 50X 50mm, and final forging to obtain the finished product
The round bar of (1);
the heat treatment process comprises the following steps: dividing the forged test steel round bars into two groups, wherein one group adopts solid solution water quenching treatment, heating to 1050 ℃, preserving heat for 40 minutes, and performing water quenching treatment; and the other group is subjected to aging treatment, heating to 1050 ℃, heat preservation for 40 minutes, water quenching treatment, heat preservation at 550 ℃ for 12 hours, and water quenching treatment to obtain the ultrahigh-strength low-density steel of the embodiment of the invention.
8. The ultra-high strength low density steel as claimed in claim 7, wherein the initial forging temperature during forging is 1050-1200 ℃, the final forging temperature is not lower than 900 ℃, and the re-melting is not performed for less than 2 times during forging, and the steel is cooled to room temperature by air cooling or water cooling after forging.
9. The ultra-high strength low density steel of claim 7, wherein the austenite-based low density steel obtained by aging has a tensile strength of not less than 1100MPa, a yield strength of not less than 1050MPa, an elongation of not less than 27%, and a density of not more than 6.6g/cm3；
The tensile strength of the austenite-based low-density steel obtained by adopting solution treatment is more than or equal to 860MPa, the yield strength is more than or equal to 690MPa, and the elongation is more than or equal to 69 percent; the density is less than or equal to 6.6g/cm3。
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| CN114480988A (en) * | 2021-12-27 | 2022-05-13 | 北京科技大学 | Multiphase composite high-strength high-toughness low-density steel and preparation method thereof |
| CN114480984A (en) * | 2021-12-15 | 2022-05-13 | 钢铁研究总院 | Ti alloyed low-density high-strength steel and preparation method thereof |
| CN115354231A (en) * | 2022-08-31 | 2022-11-18 | 武汉钢铁有限公司 | Low-density corrosion-resistant spring flat steel and production method thereof |
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