Steel material with low cost, light weight, high strength and high plasticity as well as preparation method and application of steel material

Abstract

The invention discloses a low-cost light high-strength high-plasticity steel material and a preparation method and application thereof, and belongs to the technical field of steel material preparation. The invention provides a high-strength and high-plasticity steel material. The high-strength and high-plasticity steel material comprises the following raw materials in percentage by mass: 18-22 parts of manganese; 2-7 parts by mass of aluminum; 0.3 to 0.5 part by mass of carbon; 0.6 to 0.8 part by mass of vanadium; the total mass part of the raw materials of the steel material is 100, and the balance is iron. By combining the combined action of the manganese element, the aluminum element, the carbon element and the vanadium element and controlling the content of all the elements, solid solution strengthening is achieved, and the strength and plasticity of the steel are effectively improved. The method provided by the invention is simple and easy to implement and relatively low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel material preparation, and in particular relates to a low-cost, lightweight, high-strength, high-plasticity steel and a preparation method and application thereof. Background Art

[0002] With the continuous development of the times, human beings have a deeper understanding of the concept of sustainable development. Therefore, it is urgent to lightweight the traditional structural steel used in the fields of construction, automobiles, etc. to meet today's demand for energy saving, green and sustainable development. After heat treatment, high manganese steel can obtain high yield strength and tensile strength while maintaining good toughness. This enables it to perform well when subjected to impact loads and show good corrosion resistance in certain environments. Although it is not a steel specially designed for corrosion resistance, it can still maintain a long service life in some less corrosive environments and is widely used in the market.

[0003] In the prior art, high manganese steel is deficient in tensile strength and plasticity. In some application scenarios with high strength requirements, such as aerospace, automobile manufacturing and other fields, insufficient material strength may cause the structural parts to be unable to withstand the corresponding loads, thereby affecting the overall performance and safety. For example, if the material strength of components such as aircraft wings and automobile engine cylinders is insufficient, deformation, fracture and other problems may occur during flight or driving, causing serious safety accidents. Insufficient plasticity leads to defects such as cracks and fractures during the processing process, which affects the molding and processing quality of the material and increases production costs and production cycles. At the same time, during use, materials with poor plasticity may not be able to absorb energy through plastic deformation, thereby reducing the material's impact resistance and toughness, making the material more easily damaged when impacted or vibrated. Summary of the invention

[0004] In view of the defects existing in the above-mentioned prior art, the purpose of the present invention is to design and provide a low-cost, lightweight, high-strength and high-plasticity steel material and its preparation method and application. The present invention combines the joint action of manganese, aluminum, carbon and vanadium elements, controls the content of each element, realizes solid solution strengthening, and effectively improves the strength and plasticity of the steel. The method provided by the present invention is simple and easy to implement, and has low cost.

[0005] In one aspect, the present invention provides a high-strength and high-plasticity steel material, comprising the following raw materials in terms of mass percentage:

[0006] Manganese 18-22 parts by weight;

[0007] Aluminum 2-7 parts by mass;

[0008] Carbon 0.3-0.5 parts by mass;

[0009] Vanadium 0.6-0.8 parts by mass;

[0010] Taking the total weight of the steel material as 100, the remainder is iron.

[0011] In the present invention, the Mn element is an austenite stabilizing element, which can be dissolved in austenite and has a good solid solution strengthening effect. Compared with the Ni element added in traditional austenitic steel, its cost is lower.

[0012] In the present invention, the aluminum element can inhibit the formation of cementite and improve the plasticity and toughness of the steel.

[0013] In the present invention, the addition of the carbon element can improve the stability of austenite in the steel, and after being dissolved in the matrix, it can improve the ability of the matrix to hinder dislocation, thereby improving the mechanical properties of the steel.

[0014] In the present invention, the addition of the vanadium element can effectively refine the material grains and improve the material strength and plasticity.

[0015] The high-strength and high-plasticity steel material comprises the following raw materials in percentage by mass:

[0016] 19 to 21 parts by mass of manganese; more preferably 20 parts by mass of manganese;

[0017] Aluminum 2-7 parts by mass;

[0018] Carbon 0.4 parts by mass;

[0019] Vanadium 0.7 parts by mass;

[0020] Taking the total weight of the steel material as 100, the remainder is iron.

[0021] In a second aspect, the present invention provides a method for preparing the high-strength and high-plasticity steel material, comprising the following steps:

[0022] (1) weighing manganese (such as electrolytic manganese flakes), aluminum (such as pure aluminum), carbon (such as carbon rods), vanadium and iron (such as industrial pure iron) as raw materials, mixing them, pre-treating them, placing them in a non-consumable vacuum arc furnace, and melting them under a protective gas atmosphere. After completion, turning them over and melting them again, and repeating the turning over and melting several times, an alloy ingot is obtained;

[0023] The present invention repeatedly performs non-consumable arc melting treatment, which is beneficial to ensuring that the composition of the ingot is more uniform.

[0024] (2) preheating and heat-insulating the alloy ingot, taking it out, and then rolling and deforming it to obtain a steel plate;

[0025] The present invention is conducive to eliminating defects in the ingot, compacting the alloy structure, refining the grains, improving the microstructure, and generating a large number of dislocations through preheating and heat preservation treatment and rolling deformation treatment, which is conducive to improving the mechanical properties of the alloy. In the rolling deformation process of the present invention, a part of the austenite grains are forcibly broken during rolling, and recrystallization forms an equiaxed structure during the heat preservation process, and a part of the austenite grains are elongated along the rolling direction, and no crystallization occurs during the heat preservation process, which effectively improves the strength and plasticity of the steel.

[0026] (3) After the steel plate obtained above is annealed, it is immediately taken out and immersed in room temperature water for water quenching and cooling, and then polished and washed to remove the oxide scale on the surface of the plate to obtain a high-strength and high-plasticity steel material.

[0027] After hot rolling, the hot rolled product is subjected to annealing and water quenching in sequence, which can retain the microstructure state of the alloy after rolling deformation as much as possible, increase the grain boundary density, and improve the strength and plasticity. When the rolling temperature is near the austenite phase temperature, the grain refinement effect is more obvious, and during the rolling deformation, the stress can be reduced, thereby ensuring that a certain strength is increased while having a certain plasticity.

[0028] The preparation method and the pretreatment method are as follows: immersing the mixed raw materials in anhydrous ethanol, ultrasonically cleaning, and air-drying.

[0029] The preparation method, the smelting conditions are: vacuum degree vacuum degree 3×10 -3 Pa~9×10 -3 Pa, preferably 3×10 -3 Pa~7×10 -3 Pa, more preferably 5×10 -3 Pa; pressure 0.06MPa, working current 300-400A, preferably 320-380A, more preferably 380A, melting temperature 1700-2000°C, preferably 1850-1950°C; melting time 10-20min, preferably 12-18min;

[0030] The number of repeated turning and melting is 4 to 7 times, preferably 5 to 7 times;

[0031] The protective gas is argon.

[0032] The preparation method, the conditions for the preheating and heat preservation treatment are: heating to 1000-1200°C, preferably 1050°C, 1080°C or 1100°C, at a heating rate of 5-15°C / min, preferably 10°C / min, and keeping warm for 30-50 minutes, preferably 30-40 minutes.

[0033] The preparation method, the rolling deformation conditions are: the rolling temperature is 1050°C;

[0034] The rolling deformation is a multi-pass rolling deformation, the number of times is 5 to 6 times, the pressing thickness of each rolling deformation is 1.5 to 2.5 mm, preferably 2 mm; the interval of each deformation is 4 to 6 minutes at 1000 to 1200°C, preferably 1050°C, preferably 4.5 to 5.5 minutes, more preferably 5 minutes. The rolling deformation is carried out in a 200-type double-roll synchronous rolling mill.

[0035] In the preparation method, the rolling deformation is performed to a deformation amount of 70% to 75%.

[0036] In the preparation method, the annealing treatment condition is: keeping the temperature at 500-900°C, preferably 600-800°C for 50-70 minutes, preferably 60 minutes. In the present invention, the annealing treatment is carried out in a muffle furnace.

[0037] In a third aspect, the present invention provides the use of the steel material, or the steel material obtained by any one of the preparation methods as a structural steel with high strength and high plasticity.

[0038] The steel provided by the present invention is used as a structural material, has high strength and high plasticity, and can meet the requirements of structural materials.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The steel provided by the present invention has an equiaxed structure. The existence of the equiaxed structure reduces the grain size of the steel. The grain boundaries will hinder the movement of dislocations. The smaller the grains, the more grain boundaries there are, the more positions there are to hinder dislocations, and the entanglement of dislocations is difficult to move, which is manifested as high strength of the alloy; equiaxed crystals are conducive to the coordinated movement between grains, uniform deformation, and reduce the dislocation accumulation in a certain part of the alloy, which will not produce stress concentration, and the macroscopic performance is good plasticity of the steel. Therefore, the steel provided by the present invention has both high strength and good plasticity.

[0041] On the other hand, during the rolling deformation process of the present invention, a portion of the austenite grains are forcibly broken during rolling, and recrystallized during the insulation process to form an equiaxed structure. Part of the austenite grains are elongated along the rolling direction and no crystallization occurs during the insulation process, thereby effectively improving the strength and plasticity of the steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a metallographic optical micrograph of the steel obtained in Example 1;

[0043] Figure 2 This is a metallographic optical micrograph of the steel obtained in Example 2;

[0044] Figure 3 This is a metallographic optical micrograph of the steel obtained in Example 3;

[0045] Figure 4 is the XRD diagram of the steel of the present invention;

[0046] Figure 5 This is the structure diagram of the uniaxial tensile specimen. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0048] Embodiment 1:

[0049] According to the alloy mass percentage composition Fe-20Mn-2Al-0.4C-0.7V (Fe: 76.9wt%, Mn: 20wt%, Al: 2.0wt%, C: 0.4wt%, V: 0.7wt%), 76.9g of industrial pure iron, 20g of electrolytic manganese sheet, 2g of pure aluminum, 0.4g of carbon rod and 0.7g of pure vanadium were immersed in anhydrous ethanol, ultrasonically cleaned and air-dried.

[0050] The pretreated raw materials were placed in a clean water-cooled copper crucible in a non-consumable vacuum arc furnace and heated to 5 × 10 -3 Pa, non-consumable arc melting was carried out in an argon atmosphere with a pressure of 0.06 MPa, the melting temperature was 1800°C, the working current during the melting process was 380 A, after each melting was completed, the ingot was turned over, and then the melting was carried out again, each melting time was 10 minutes, the ingot was turned over 6 times, and an alloy ingot was obtained.

[0051] The steel ingot was placed in a muffle furnace and heated to 1050°C at a heating rate of 10°C / min. After being kept warm for 0.5h, it was quickly taken out and rolled on a double-roll mill. The rolling temperature was 1050°C and multiple deformation passes were used. The reduction amount of each rolling deformation pass was 2mm. The final deformation of the alloy reached 75%. The ingot was kept warm at 1050°C for 5min between each deformation pass. After the rolling deformation was completed, the thickness of the steel plate was 5mm.

[0052] The obtained steel plate was placed in a muffle furnace and kept at 700°C for 60 minutes, then quickly taken out and immersed in room temperature water for water quenching. Finally, the surface oxide layer of the steel plate was polished clean to obtain low-cost, lightweight, high-strength, high-plastic steel. The metallographic microstructure of the low-cost, lightweight, high-strength, high-plastic steel prepared in Example 1 was tested, and the results were as follows: Figure 1 Shown is the metallographic microstructure of the low-cost, lightweight, high-strength and high-plasticity steel prepared in Example 1.

[0053] Embodiment 2:

[0054] According to the alloy mass percentage composition Fe-20Mn-5Al-0.4C-0.7V (Fe: 73.9wt%, Mn: 20wt%, Al: 5.0wt%, C: 0.4wt%, V: 0.7wt%), 73.9g of industrial pure iron, 20g of electrolytic manganese sheet, 5g of pure aluminum, 0.4g of carbon rod and 0.7g of pure vanadium were immersed in anhydrous ethanol, ultrasonically cleaned and air-dried.

[0055] The pretreated raw materials were placed in a clean water-cooled copper crucible in a non-consumable vacuum arc furnace and heated to 5 × 10 -3 Pa, non-consumable arc melting is carried out in an argon atmosphere with a pressure of 0.06 MPa, the melting temperature is 1800°C, the working current during the melting process is 360 A, after each melting is completed, the ingot is turned over, and then the melting is carried out again, each melting time is 20 minutes, the ingot is turned over 6 times, and a steel ingot is obtained.

[0056] The obtained steel ingot is placed in a muffle furnace, heated to 1050°C at a heating rate of 10°C / min, kept warm for 0.5h, and then quickly taken out and rolled on a double-roll mill. The rolling temperature is 1050°C, and multiple deformation passes are used. The reduction amount of each rolling deformation is 2mm, and the final deformation of the alloy reaches 75%. The ingot is kept warm at 900°C for 5min between each deformation pass. After the rolling deformation is completed, the thickness of the obtained steel plate is 5mm. The obtained steel plate is placed in a muffle furnace, kept warm at 700°C for 60min, and then quickly taken out and immersed in room temperature water for water quenching. The surface oxide layer of the steel plate is polished clean to obtain low-cost, lightweight, high-strength and high-plasticity steel. The metallographic microstructure diagram of the low-cost, lightweight, high-strength and high-plasticity steel prepared in Example 2 is shown in the figure. Figure 2 shown.

[0057] Embodiment 3:

[0058] According to the alloy mass percentage composition Fe-20Mn-7Al-0.4C-0.7V (Fe: 71.9wt%, Mn: 20wt%, Al: 7.0wt%, C: 0.4wt%, V: 0.7wt%), 71.9g of industrial pure iron, 20g of electrolytic manganese sheet, 7g of pure aluminum, 0.4g of carbon rod and 0.7g of pure vanadium were immersed in anhydrous ethanol, ultrasonically cleaned and air-dried.

[0059] The pretreated raw materials were placed in a clean water-cooled copper crucible in a non-consumable vacuum arc furnace and heated to 5 × 10 -3Pa, non-consumable arc melting was carried out in an argon atmosphere with a pressure of 0.06 MPa, the melting temperature was 1800°C, the working current during the melting process was 380 A, after each melting was completed, the ingot was turned over, and then the melting was carried out again, each melting time was 15 minutes, the ingot was turned over 6 times, and an alloy ingot was obtained.

[0060] The obtained alloy ingot is placed in a muffle furnace, heated to 1050°C at a heating rate of 10°C / min, kept warm for 0.5h, then quickly taken out and rolled on a double-roll mill. The rolling temperature is 1050°C, and multiple deformation passes are used. The reduction amount of each rolling deformation is 2mm, and the final deformation of the alloy reaches 75%. The ingot is kept warm at 1050°C for 5min between each deformation pass. After the rolling deformation is completed, the thickness of the obtained steel plate is 5mm. The obtained steel plate is placed in a muffle furnace, kept warm at 700°C for 60min, then quickly taken out and immersed in room temperature water for water quenching. The surface oxide layer of the steel plate is polished clean to obtain low-cost, lightweight, high-strength and high-plasticity steel. The metallographic microstructure of the low-cost, lightweight, high-strength and high-plasticity steel prepared in Example 3 is shown in the figure. Figure 3 shown.

[0061] It can be seen that the organization of the steel obtained in different embodiments of the present invention is an equiaxed austenite organization and a combination of an equiaxed austenite organization and an equiaxed ferrite organization, wherein the original austenite grain boundary and the ferrite boundary are clearly visible and the original austenite grains and the ferrite grains are further refined. The grains are all equiaxed and relatively uniform, with strong plasticity; the grains are relatively small, and the average grain size does not exceed 50 microns, with high strength; there are almost no defects such as pores and inclusions in the material, the effective bearing area of ​​the material is increased, the stress concentration phenomenon is reduced, the strength will be improved, and during the plastic deformation process, it is not easy to produce defects such as cracks and cause premature fracture.

[0062] The steel materials obtained in Examples 1-3 were tested. Figure 4 It can be seen that when the Al content is low, the material's structure is only austenite, but when the Al content increases to 7% (wt%), ferrite phase appears in the material, the tensile strength of the material does not show obvious changes, and the elongation decreases, but is still higher than that of Comparative Example 1.

[0063] Comparative Example 1:

[0064] According to the alloy mass percentage composition Fe-0.17Mn-0.35Si-0.035S-0.035P (Fe: 99.41wt%, Mn: 0.17wt%, Si: 0.35wt%, S: 0.035wt%, P: 0.035wt%), 99.41g of industrial pure iron, 0.17g of electrolytic manganese sheet and 0.35g of pure silicon were immersed in anhydrous ethanol, ultrasonically cleaned and air-dried; then, non-consumable arc melting, preheating and insulation treatment, rolling deformation, solution treatment, water quenching and annealing were carried out in sequence according to the method of Example 1 to obtain structural steel.

[0065] The mechanical properties of the low-cost, lightweight, high-strength, high-plasticity steels prepared in Examples 1 to 3 and the structural steel prepared in Comparative Example 1 were tested. The testing method is as follows: a uniaxial tensile specimen in the shape of a bone rod is cut from a zirconium alloy plate by wire cutting, and the mechanical properties of the uniaxial tensile specimen are tested in accordance with the national standard GBT228-2002. The structure of the uniaxial tensile specimen is shown in FIG. Figure 5 During the test, at least three tensile specimens were cut from the sample of each embodiment to ensure the repeatability of the data. The room temperature uniaxial tensile test was used for measurement. The test instrument model was Instron 5982 universal material testing machine (manufacturer: Instron, USA). The tensile displacement of the sample was monitored by an extensometer throughout the process. The tensile rate was set to 5×10 -3 s -1 , a tensile test was carried out to obtain the mechanical properties data of the zirconium alloy. The test results are shown in Table 1.

[0066] Table 1 Mechanical properties of steels prepared in Examples 1 to 3 and Comparative Example 1

[0067]

[0068] It can be seen from Table 1 that the steel obtained by the present invention has good strength and plasticity, wherein the tensile strength is 748.04-817.74 MPa and the elongation is 26.32%-56.58%, which indicates that the steel provided by the present invention has both high strength and high plasticity.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-strength and high-plasticity steel material, characterized in that: Contains the following raw materials by mass percentage: Manganese 18-22 parts by weight; Aluminum 2-7 parts by mass; Carbon 0.3-0.5 parts by mass; Vanadium 0.6-0.8 parts by mass; Taking the total weight of the steel material as 100, the remainder is iron.

2. A high-strength and high-plasticity steel material as claimed in claim 1, characterized in that: The raw materials contain the following components in percentage by weight: 19 to 21 parts by weight of manganese; Aluminum 2-7 parts by mass; Carbon 0.4 parts by mass; Vanadium 0.7 parts by mass; Taking the total weight of the steel material as 100, the remainder is iron.

3. The method for preparing a high-strength and high-plasticity steel material according to claim 1 or 2, characterized in that: The following steps are involved: (1) weighing manganese, aluminum, carbon, vanadium and iron raw materials, mixing them, pre-treating them, placing them in a non-consumable vacuum arc furnace, melting them under a protective gas atmosphere, turning them over and melting them again after completion, and repeating the turning and melting several times to obtain an alloy ingot; (2) preheating and heat-insulating the alloy ingot, taking it out, and then rolling and deforming it to obtain a steel plate; (3) After the steel plate obtained above is annealed, it is immediately taken out and immersed in room temperature water for water quenching and cooling, and then polished to obtain a high-strength and high-plasticity steel material.

4. The preparation method according to claim 3, characterized in that: The pretreatment method is: immersing the mixed raw materials in anhydrous ethanol, ultrasonically cleaning, and air-drying.

5. The preparation method according to claim 3, characterized in that: The smelting conditions are: vacuum degree 3×10 -3 Pa~9×10 -3 Pa, pressure 0.06MPa, working current 300~400A, melting temperature 1700~2000℃, melting time 10~20min; The number of repeated turning and melting is 4 to 7 times; The protective gas is argon.

6. The preparation method according to claim 3, characterized in that: The conditions for the preheating and heat preservation treatment are: heating to 1000-1200° C. at a heating rate of 5-15° C. / min, and keeping the temperature for 30-50 minutes.

7. The preparation method according to claim 3, characterized in that: The rolling deformation conditions are as follows: the rolling temperature is 1050°C; the rolling deformation is a multi-pass rolling deformation, the pressing thickness of each rolling deformation is 1.5-2.5mm, and the interval between each deformation is keeping warm at 1000-1200°C for 4-6min.

8. The preparation method according to claim 3, characterized in that: The rolling deformation is performed to a deformation amount of 70% to 75%.

9. The preparation method according to claim 3, characterized in that: The annealing treatment conditions are: keeping the temperature at 500-900° C. for 50-70 minutes.

10. Use of the steel material according to claim 1 or 2, or the steel material prepared by the preparation method according to any one of claims 3 to 7 as a structural steel with high strength and high plasticity.

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