CN110951946B - Heat treatment process of low-density steel and preparation method thereof - Google Patents
Heat treatment process of low-density steel and preparation method thereof Download PDFInfo
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- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
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- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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Abstract
The invention discloses a heat treatment process of low-density steel and a preparation method thereof, belonging to the field of metallurgical production. The heat treatment process comprises solution treatment, carbide treatment and aging treatment, can effectively improve the strength and toughness of the low-density steel, and meets the use requirements of partial structural parts. The preparation method comprises smelting, casting, hot rolling and heat treatment, wherein the heat treatment adopts the heat treatment process of the low-density steel, so that the mechanical property and the processing property of the low-density steel can be effectively improved, and the low-density steel with higher strength and toughness is prepared.
Description
Technical Field
The invention belongs to the technical field of metallurgical production, and particularly relates to a heat treatment process of low-density steel and a preparation method thereof.
Background
In recent years, with the rapid development of the automobile industry, the demand and the production of automobiles are increasing, people have higher and higher requirements on the performance of the automobiles, and the automobile industry is gradually developed towards light weight and safety. For the automobile industry, reducing the dead weight is a necessary way for reducing the cost and sustainable development, and the use of the low-density material can effectively reduce the weight of the automobile, the consumption of energy and the pollution to the environment, and reduce the use cost. Therefore, how to prepare low-density materials with excellent performance becomes an important issue in automobile manufacturing.
In the production process of automobiles and other industries, some structural steel parts with certain requirements on light weight are often needed, but the strength of the light weight steel parts cannot ensure the rigidity of the structure, so that the density of high-strength steel is needed to be reduced to meet the requirements of the light weight structural parts. The prior art generally meets the requirements of the developing industry and manufacturing industry by changing the types and amounts of components in steel to obtain the desired low density steel. Wherein, the aluminum component is added into the high manganese steel, because the aluminum has low density, good ductility and easy oxide film formation on the surface, the low density Fe-Mn-Al-C steel has low density, good ductility, corrosion resistance and the like. And by adjusting the addition amount of the manganese-aluminum metal, the material with good mechanical properties can be obtained, so that the density can be reduced, and meanwhile, the better structure property and mechanical properties can be maintained. However, there is no fixed range for adjusting various components in the material, and it is difficult to determine the composition range of high performance value, and on the other hand, the performance of the steel depends not only on the composition of the material, but also on the preparation process of the steel, therefore, how to obtain a suitable material composition range and adopt a reasonable preparation process for the material in the composition range is an important issue to be researched.
The Chinese patent application numbers are: CN201910676713.2, published date: patent literature on 2019, 9 and 6 discloses a heat treatment method of ferro-manganese-aluminum-carbon austenite low-density steel, which comprises the following steps: (1) carrying out pre-deformation treatment on the Fe-Mn-Al-C austenite low-density steel in an initial state; the total strain is controlled to be 4-35%; (2) carrying out aging treatment on the iron-manganese-aluminum-carbon austenite low-density steel after the pre-deformation treatment; the aging treatment is single-stage aging treatment or bipolar aging treatment: the single-stage aging temperature is 600-700 ℃, the heat preservation time is 10-60min, and the air cooling is carried out at room temperature; the two-stage aging is as follows: the primary aging temperature is 450-550 ℃, the heat preservation time is 0.5-4h, and the temperature is rapidly increased to the secondary aging temperature after the primary aging is finished; the secondary aging temperature is 600-700 ℃, the heat preservation time is 10-40min, and the air cooling is carried out at room temperature. The invention carries out heat treatment processes such as solid solution, aging and the like on low-density iron-manganese-aluminum carbon steel to improve the performance of the low-density iron-manganese-aluminum carbon steel, but the composition proportion of the steel is not explained, the heat treatment process corresponds to the iron-manganese-aluminum-carbon steel with all the composition proportion, the applicability is wide, but the specification can also show that the elongation is basically below 20 percent, the effect of high-requirement low-density steel is probably not achieved, the steel carbide can also influence the performance of the steel in the heat treatment process, and the process does not carry out corresponding measures aiming at the point.
The Chinese patent application numbers are: CN201410727962.7, published date: 2016, 6, 8 and discloses a 7005 aluminum alloy heat treatment method, which sequentially comprises three steps of solution treatment, water quenching and aging treatment, wherein the temperature of the solution treatment is between 430 and 530 ℃, and the time of the solution treatment is 30 minutes; the aging treatment is two-stage aging treatment, the temperature of the first-stage aging treatment is 80-110 ℃, and the time of the first-stage aging treatment is 8 hours; the temperature of the secondary aging treatment is 120-140 ℃, and the time of the secondary aging treatment is 24 hours. The 7005 aluminum alloy sample treated by the method has better plastic deformation capability, completely meets the requirement of large plastic deformation, and is more suitable for being used in the fields of bicycles and the like. However, the specification shows that the strength treated by the scheme is not high and cannot meet the performance requirements of the steel in the related automobile industry.
Disclosure of Invention
1. Problems to be solved
Aiming at the problem that the performance of the existing low-density steel can not meet the use requirements of partial structural members in the industries such as automobiles and the like, the invention provides the heat treatment process of the low-density steel, which can effectively improve the strength and toughness of the low-density steel and meet the use requirements of the partial structural members.
The invention also provides a preparation method of the low-density steel, and the mechanical property and the processing property of the low-density steel can be effectively improved by adopting the heat treatment process of the low-density steel, so that the low-density steel with higher strength and toughness can be prepared.
2. Technical scheme
In order to solve the above problems, the present invention adopts the following technical solutions.
A heat treatment process of low-density steel comprises the following steps:
first, solution treatment
Preserving the heat of the low-density steel for 25-35 minutes at 380-420 ℃, then heating to 630-670 ℃ at a heating rate of 190-210 ℃/h, preserving the heat for 25-35 minutes, then heating to 1050-1150 ℃ at a heating rate of 190-210 ℃/h, preserving the heat for 2-3 hours, and cooling to room temperature by water;
di, carbide treatment
Heating the low-density steel obtained in the step one to 650-800 ℃, preserving heat for 2-3 hours, and then cooling to room temperature in air;
thirdly, aging treatment
And (4) heating the low-density steel obtained in the step two to 450-550 ℃, preserving heat for 9-12 hours, and cooling to room temperature by water.
As a further improvement of the technical scheme, the low-density steel comprises the following chemical components in percentage by mass: mn: 25-30%; al: 9-10%; c: 0.9-1%; mo: 0.45 to 0.5 percent; si: 0.8-1%; p is less than or equal to 0.003 percent; less than or equal to 0.003 percent of S, and the balance of Fe and inevitable impurities.
As a further improvement of the technical scheme, the heating modes of the first step, the second step and the third step are vacuum-pumping heating.
As a further improvement of the technical scheme, the density of the low-density steel is 6.9-7.2 g/cm3。
The preparation method of the low-density steel comprises smelting, casting, hot rolling and heat treatment, wherein the heat treatment adopts the heat treatment process of the low-density steel.
As a further improvement of the technical scheme, during smelting, an additive is added into molten steel, the mass of the additive is 0.01-0.02% of that of the molten steel, and the additive comprises the following chemical components in parts by mass: rare earth: 9-11 parts; kaolin: 4-6 parts; biomass: and 2 parts.
As a further improvement of the technical scheme, the casting step adopts die casting, the superheat degree of the molten steel is controlled to be 20-30 ℃ during casting, and the die temperature of the die is 9-11% of the temperature of the molten steel.
As a further improvement of the technical scheme, the bottom of the mold is paved with the covering slag, the mass of the covering slag is 0.2-0.3% of the mass of the molten steel, and the covering slag comprises the following chemical components in parts by mass: bauxite: 4.5-5.5 parts; dolomite: 18-22 parts; blast furnace slag: 2.5-3.5 parts; cement clinker: 1 part; wollastonite: 1 part.
According to the further improvement of the technical scheme, during casting, the molten steel in the die is electromagnetically stirred, the electromagnetic stirring frequency is 5-7 Hz, and the current intensity is 200-400A.
As a further improvement of the technical proposal, the method also comprises a forging step; the forging step is carried out after casting and before hot rolling, and comprises the following specific steps: heating the casting blank obtained by casting to 1100-1200 ℃, preserving heat for 1.5-2.5 hours, and forging into a square blank by a forging and pressing machine.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the heat treatment process of the low-density steel, the chemical components of the low-density steel are reasonably adjusted, so that the low-density steel with more excellent performance compared with the conventional low-density steel can be obtained, particularly, the process adopts a unique heat treatment process aiming at the low-density steel with the chemical components, can effectively eliminate grain boundaries in steel body tissues and residual carbides in the grains, and simultaneously, the strength and the toughness of finished steel are greatly improved by matching with a unique solution treatment and aging treatment mode;
(2) according to the heat treatment process of the low-density steel, the vacuumizing heating mode is adopted in the heat treatment process, so that the quality reduction of finished steel due to reoxidation of a workpiece in the heating process can be prevented;
(3) according to the preparation method of the low-density steel, the billet is subjected to heat treatment by adopting the heat treatment process, so that the strength and toughness of a final product can be effectively improved, meanwhile, a finished product of the low-density steel with the strength-elongation product of more than 50% is prepared by matching with a mode of adding a protective agent in smelting and a mode of adding protective slag in casting, the preparation success rate is stable, and the market demand can be well met;
(4) according to the preparation method of the low-density steel, the molten steel in the die is electromagnetically stirred during casting, so that growing columnar crystals and tail-end dendritic crystals can be broken, the broken and free dendritic crystals can serve as new nucleation cores, the nucleation cores of casting blank crystals are increased, and isometric crystal areas in the centers of the casting blanks are enlarged, so that the compactness of a solidification structure is remarkably improved, the mechanical property of finished steel is enhanced, and the product of strength and elongation of the finished steel is improved;
(5) the invention relates to a preparation method of low-density steel, which comprises the steps of forging a casting blank between casting and hot rolling of the casting blank, applying pressure to the casting blank by using a forging and pressing machine to enable the casting blank to generate plastic deformation, eliminating the defects of casting state looseness and the like generated in the smelting process of the casting blank, optimizing a microstructure, enabling the mechanical property of a forged workpiece to be superior to that of a casting made of the same material, and further improving the product of strength and elongation of a final product.
Drawings
FIG. 1 is an equilibrium phase diagram of a low density steel.
Detailed Description
The invention is further described with reference to specific embodiments and the accompanying drawings.
The inventors of the present application have participated in the development of patent applications with the following numbers: CN201710903836.6, name: the scheme is that the low-density high-manganese steel with the high strength-elongation product of more than 50 percent can be prepared by reasonably designing the chemical components of the steel and adopting a corresponding preparation process. However, in actual production, the elongation after fracture of the low-density steel prepared by the scheme is generally lower than 50%, and the product steel has a low product of strength and elongation of a part of steel, especially the elongation after fracture often has a low elongation after fracture, so that the toughness of the steel does not reach the standard, and the processing requirements of products in some markets are not met. Therefore, the inventors of the present application have made extensive experimental observations and summaries, and have proposed the following solutions to this problem.
Low-density steel (density of 6.9-7.2 g/cm)3) The heat treatment process is used for carrying out heat treatment on the low-density steel to improve the mechanical property and the processing property of the low-density steel, and comprises the following steps of:
first, solution treatment
Putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 25-35 minutes at 380-420 ℃, then heating the heating furnace to 630-670 ℃ at a heating rate of 190-210 ℃/h, keeping the temperature for 25-35 minutes, then heating to 1050-1150 ℃ at a heating rate of 190-210 ℃/h, keeping the temperature for 2-3 hours, then taking out the steel plate, and cooling to room temperature at a cooling rate of 18-22 ℃/s. A large number of experiments show that the steel plate is sequentially in a plurality of temperature stages for heat preservation and heating, so that austenite grains in the steel plate can grow, a banded ferrite structure is divided into small islands, the content of banded ferrite in a hot rolling structure is reduced, and the transverse mechanical property of the steel plate is improved. In addition, the stepwise heat preservation solution treatment mode effectively promotes the disappearance of carbides, so that the comprehensive mechanical property of the hot rolled steel plate after solution treatment is improved, and the plasticity and the impact toughness of the steel plate are enhanced.
Di, carbide treatment
And (3) putting the low-density steel obtained in the step one into a vacuum heating furnace in a vacuum state, heating to 650-800 ℃, preserving heat for 2-3 hours, taking out, and air-cooling to room temperature. As shown in fig. 1, the equilibrium phase diagram of the internal structure of the low-density steel obtained by the inventor through experiments in the heat treatment at different temperatures shows that the steel is basically composed of austenite and carbide is basically precipitated when the temperature is 650 to 800 ℃, so that the low-density steel is kept at 650 to 800 ℃ for 2 to 3 hours, the grain boundary and the carbide in the steel structure can be effectively eliminated, and the strength and the toughness of the steel are improved.
Thirdly, aging treatment
And (4) heating the low-density steel obtained in the step (II) to 450-550 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9-12 hours, and cooling the steel to room temperature at a cooling speed of 18-22 ℃/s. The step is carried out for a long time of heat preservation in a lower temperature environment, so that the dispersion precipitation of carbide on austenite can be further promoted, and the steel is subjected to dispersion hardening under the condition of not reducing the toughness of the steel, so that the strength of the steel is improved.
It is noted that the chemical components and mass percentages of the low-density steel corresponding to the heat treatment process are as follows: mn: 25-30%; al: 9-10%; c: 0.9-1%; mo: 0.45 to 0.5 percent; s: 0.8-1%; p is less than or equal to 0.003 percent; less than or equal to 0.003 percent of S, and the balance of Fe and inevitable impurities. Aiming at the low-density steel with the components, the heat treatment process can greatly improve the toughness and the strength of the finished steel, and particularly on the point of toughness, the post-fracture elongation of the finished steel after the heat treatment process is obviously improved.
The overall manufacturing method of the above low density steel will be described below.
First, smelting
According to the weight percentage: adding 25-30% of Mn, 9-10% of Al, 0.9-1% of C, 0.45-0.5% of Mo, 0.8-1% of Si, less than or equal to 0.003% of P, less than or equal to 0.003% of S and the balance of Fe into a vacuum induction smelting furnace for smelting, introducing argon into the furnace in the smelting process, and simultaneously adding an additive into molten steel in the smelting process, wherein the temperature of the molten steel is 1500-1700 ℃. The additive is added in an amount of 0.01-0.02% of the molten steel, and comprises the following chemical components in parts by weight: rare earth: 9-11 parts; kaolin: 4-6 parts; biomass: and 2 parts. The addition of the additive into the molten steel reduces the anisotropy of the toughness of the low-density steel, prevents the steel from being torn in a layered mode, and improves the elongation percentage of the steel after fracture. Elements such as Ca, Mg and the like in the additive promote the denaturation of inclusions, and reducing gas generated by the decomposition of biomass in the additive in the smelting process has a good stirring effect on molten steel, promotes the combination of Ca, Mg and the inclusions, improves the effect of Ca and Mg denaturation treatment, and improves the comprehensive performance of low-density steel. In addition, the gas generated by the decomposition of the biomass and the argon gas act together to promote the floating of impurities and impurities, so that the comprehensive performance of the low-density steel is further improved.
Second, casting
Preparing a corresponding mould, laying 2 layers of horse dung paper on the bottom surface of the mould, uniformly paving covering slag on the horse dung paper, pouring molten steel into the mould for casting, wherein the mould temperature of the mould is 9-11% (140-180 ℃) of the molten steel temperature, the superheat degree of the molten steel is controlled to be 20-30 ℃, and the low superheat degree can ensure that the temperature gradient of a two-phase region is small and the time of directional heat transfer is shortened, so that the formation of fine grains is facilitated, the growth of columnar grains is inhibited, the central segregation is reduced, and the performance of a casting blank is improved. The total addition amount of the covering slag is 0.2-0.3% of the mass of the molten steel, and the covering slag comprises the following chemical components in parts by mass: bauxite: 4.5-5.5 parts; dolomite: 18-22 parts; blast furnace slag: 2.5-3.5 parts; cement clinker: 1 part; wollastonite: 1 part. By laying the protecting slag, the content of S + P + O + H + N in molten steel can be controlled to be less than or equal to 100ppm, and the adverse effect of impurity elements on Mn segregation and Al brittleness generation can be reduced. In addition, the covering slag is a slag charge which is covered on the surface of molten steel in the steel ingot mould in the casting process and can maintain normal casting. In addition, the powder slag is adopted as the protective slag, so that the powder slag has good spreading property, can prevent molten steel in the die from being secondarily oxidized, has good slag forming property, forms a very thin slag film between a casting blank and the die, has good heat preservation property, can slow down the thermal stress of the casting blank, and prevents the surface cracks of the casting blank.
In addition, the step is carried out with electromagnetic stirring while casting, wherein the electromagnetic stirring frequency is 5-7 Hz, and the current intensity is 200-400A. The method can break the growing columnar crystal and tail end dendritic crystal, so that the broken and dissociated dendritic crystal can be used as a new nucleation core, the nucleation core of casting blank crystallization is increased, and an equiaxial crystal area at the center of the casting blank is enlarged, thereby obviously improving the compactness of a solidification structure, enhancing the mechanical property of finished steel and improving the product of strength and elongation of the finished steel.
Third, forging
And (3) heating the casting blank of the low-density steel obtained in the casting step, wherein the casting blank is in a circular truncated cone shape with the diameters of two ends of 160mm and 90mm respectively and the height of 100mm to 1100-1200 ℃, preserving heat for two hours, and then forging the casting blank into a square blank with a certain size (30 multiplied by 200 mm). The forging and pressing machine is used for applying pressure to the casting blank to enable the casting blank to generate plastic deformation, the defects of casting state looseness and the like generated in the smelting process of the casting blank are eliminated, the microstructure is optimized, the mechanical property of the forged workpiece is superior to that of a casting made of the same material, and therefore the product of strength and elongation of a final product is improved.
Fourthly, hot rolling
Heating the steel billet obtained in the forging step at 1150 ℃ and at the heating rate of 0.5 ℃/s, preserving heat for 2h, then carrying out first-pass rolling at 1050 ℃ and the rolling parameters are as follows: the deformation rate is 0.006/s, and the reduction is 33%; after the interval of 10s, carrying out second pass rolling, wherein the rolling parameters are as follows: the deformation rate is 0.6/s, and the reduction is 30 percent; after the interval of 10s, carrying out a third rolling, wherein the rolling parameters are as follows: the deformation rate is 4/s, and the reduction is 28 percent; after the interval of 10s, carrying out fourth pass rolling, wherein the rolling parameters are as follows: the deformation rate is 5/s, and the reduction is 25 percent; after the interval of 10s, carrying out fifth-pass rolling, wherein the rolling parameters are as follows: the deformation rate is 6/s, and the reduction is 20 percent; after the interval of 10s, carrying out sixth pass rolling, wherein the rolling parameters are as follows: the deformation rate is 6/s, and the reduction is 16.7%; the finishing temperature is controlled to be 900 ℃. The multi-pass hot rolling can reduce rolling cracks, promote crystallization of a casting blank, inhibit occurrence and segregation of an ordered structure B2 phase and an Fe-Al intermetallic compound, and improve the mechanical property of the casting blank.
Fifth, heat treatment
The heat treatment process of the low-density steel is adopted, and the finished steel is finally obtained.
In conclusion, the preparation method of the low-density steel reasonably and uniquely designs the chemical components of the low-density steel on the basis of the prior art, and simultaneously, the low-density steel is matched with a unique heat treatment process, under the auxiliary action of forging and electromagnetic stirring, the finished low-density steel with the product of strength and elongation larger than 50% is prepared, the preparation success rate is stable, the condition that the product of strength and elongation does not reach the standard rarely occurs, the prepared finished low-density steel is particularly excellent in toughness performance on the basis of ensuring certain strength, and the market requirements of products with strict requirements can be well met.
The present application is illustrated more clearly below by means of some specific examples and comparative examples, and the results are reported in table 1.
Example 1
First, smelting
Mixing Mn: 30%, Al: 9%, C: 0.9%, Si 1%, Mo: 0.45%, P: 0.003%, S: 0.003 percent of Fe and the balance of Fe are added into a vacuum induction melting furnace for melting, argon is introduced into the furnace in the melting process, and an additive is added into molten steel in the melting process, wherein the temperature of the molten steel is 1623 ℃. The addition amount of the additive is 0.01 percent of the molten steel, and the chemical components and the parts by weight thereof are as follows: rare earth: 10 parts of (A); kaolin: 5 parts of a mixture; biomass: and 2 parts.
Second, casting
Preparing a corresponding mould, laying 2 layers of horse dung paper on the bottom surface of the mould, uniformly laying covering slag on the horse dung paper, pouring molten steel into the mould for casting, wherein the mould temperature of the mould is 150 ℃ and the superheat degree of the molten steel is controlled to be 25 ℃ during casting. The total addition amount of the covering slag is 0.2 percent of the mass of the molten steel, and the covering slag comprises the following chemical components in parts by mass: bauxite: 5 parts of a mixture; dolomite: 20 parts of (1); blast furnace slag: 3 parts of a mixture; cement clinker: 1 part; wollastonite: 1 part. Electromagnetic stirring is carried out while casting, the frequency of the electromagnetic stirring is 6Hz, and the current intensity is 300A.
Third, forging
The cast slab of low density steel obtained in the casting step was heated to 1150 ℃ and kept warm for two hours, followed by forging into a square slab of 30X 200 mm. (volume before forging is about 1259255 cubic millimeters, after forging is about 1200000 cubic millimeters)
Fourthly, hot rolling
Heating the steel billet obtained in the forging step at 1150 ℃ and at the heating rate of 0.5 ℃/s, preserving heat for 2h, then carrying out first-pass rolling at 1050 ℃ and the rolling parameters are as follows: the deformation rate is 0.006/s, and the reduction is 33%; after the interval of 10s, carrying out second pass rolling, wherein the rolling parameters are as follows: the deformation rate is 0.6/s, and the reduction is 30 percent; after the interval of 10s, carrying out a third rolling, wherein the rolling parameters are as follows: the deformation rate is 4/s, and the reduction is 28 percent; after the interval of 10s, carrying out fourth pass rolling, wherein the rolling parameters are as follows: the deformation rate is 5/s, and the reduction is 25 percent; after the interval of 10s, carrying out fifth-pass rolling, wherein the rolling parameters are as follows: the deformation rate is 6/s, and the reduction is 20 percent; after the interval of 10s, carrying out sixth pass rolling, wherein the rolling parameters are as follows: the deformation rate is 6/s, and the reduction is 16.7%; the finishing temperature is controlled to be 900 ℃.
Fifth, heat treatment
(1) Solution treatment
And (2) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 30 minutes at the furnace temperature of 400 ℃, then heating the heating furnace to 650 ℃ at the heating rate of 200 ℃/h and keeping the temperature for 30 minutes, then heating to 1100 ℃ at the heating rate of 200 ℃/h, keeping the temperature for 2 hours, then taking out the steel plate, cooling the steel plate to room temperature by water, and cooling at the cooling speed of 20 ℃/s.
(2) Carbide treatment
And (3) putting the low-density steel obtained in the step one into a vacuum heating furnace in a vacuum state, heating to 750 ℃, keeping the temperature for 2 hours, taking out, and cooling to room temperature in air.
(3) Aging treatment
And (4) heating the low-density steel obtained in the step (II) to 450 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and then cooling the steel to room temperature at a cooling speed of 20 ℃/s.
Example 2
The basic steps of this example are substantially the same as those of example 1, except that the following materials are added in the smelting step of this example in percentage by weight: mn: 27%, Al: 10%, C: 1%, Si: 1%, Mo: 0.5%, P: 0.003%, S: 0.003% and the balance Fe.
Example 3
The basic steps of this example are substantially the same as example 1, except that the heat treatment process of this example is as follows:
(1) solution treatment
And (2) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 35 minutes at the furnace temperature of 420 ℃, then heating the heating furnace to 670 ℃ at the heating rate of 210 ℃/h and keeping the temperature for 35 minutes, then heating to 1150 ℃ at the heating rate of 210 ℃/h, keeping the temperature for 2 hours, then taking out the steel plate, cooling the steel plate to room temperature by water, and cooling at the cooling speed of 20 ℃/s.
(2) Carbide treatment
And (3) putting the low-density steel obtained in the step one into a vacuum heating furnace in a vacuum state, heating to 800 ℃, keeping the temperature for 2 hours, taking out, and cooling to room temperature in air.
(3) Aging treatment
And (4) heating the low-density steel obtained in the step (II) to 550 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and then cooling the steel to room temperature at a cooling speed of 20 ℃/s.
Example 4
The basic steps of this example are substantially the same as example 1, except that the heat treatment process of this example is as follows:
(1) solution treatment
And (2) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 25 minutes at the furnace temperature of 380 ℃, then heating the heating furnace to 630 ℃ at the heating rate of 210 ℃/h and keeping the temperature for 25 minutes, then heating to 1050 ℃ at the heating rate of 210 ℃/h, keeping the temperature for 2 hours, then taking out the steel plate, cooling the steel plate to room temperature by water, and cooling at the cooling speed of 20 ℃/s.
(2) Carbide treatment
And (3) putting the low-density steel obtained in the step one into a vacuum heating furnace in a vacuum state, heating to 650 ℃, keeping the temperature for 2 hours, taking out, and cooling to room temperature in air.
(3) Aging treatment
And (4) heating the low-density steel obtained in the step (II) to 500 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and then cooling the steel to room temperature at the cooling speed of 20 ℃/s.
Comparative example 1
The basic procedure of this comparative example is substantially the same as example 1, except that the comparative example is not subjected to electromagnetic stirring at the time of casting.
Comparative example 2
The basic procedure of this comparative example is substantially the same as example 1, except that the comparative example was directly hot rolled without forging at the time of casting.
Comparative example 3
The basic procedure of this comparative example is essentially the same as example 1, except that the heat treatment process of this comparative example is as follows:
(1) solution treatment
And (3) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 2 hours at 1100 ℃, taking out the steel plate, and cooling to room temperature at a cooling speed of 20 ℃/s.
(2) Carbide treatment
And (3) putting the low-density steel obtained in the step one into a vacuum heating furnace in a vacuum state, heating to 750 ℃, keeping the temperature for 2 hours, taking out, and cooling to room temperature in air.
(3) Aging treatment
And (4) heating the low-density steel obtained in the step (II) to 450 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and then cooling the steel to room temperature at a cooling speed of 20 ℃/s.
Comparative example 4
(1) Solution treatment
And (3) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 2 hours at 1100 ℃, taking out the steel plate, and cooling to room temperature at a cooling speed of 20 ℃/s.
(2) Aging treatment
And (4) heating the low-density steel obtained in the step (II) to 450 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and then cooling the steel to room temperature at a cooling speed of 20 ℃/s.
Comparative example 5
The basic procedure of this comparative example is substantially the same as example 1, except that the heat treatment process of this comparative example is solution treatment only, and the specific process is as follows:
(1) solution treatment
And (3) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 2 hours at 1100 ℃, taking out the steel plate, and cooling to room temperature at a cooling speed of 20 ℃/s.
Comparative example 6
The basic procedure of this comparative example is substantially the same as example 1, except that the heat treatment process of this comparative example is only aging treatment, and the specific process is as follows:
(1) aging treatment
And (4) heating the low-density steel obtained in the step (II) to 530 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and cooling the steel to room temperature at a cooling speed of 20 ℃/s.
Comparative example 7
The basic procedure of this comparative example is essentially the same as example 1, except that the heat treatment process of this comparative example is as follows:
(1) solution treatment
And (2) putting the low-density steel plate subjected to hot rolling into a vacuum heating furnace in a vacuum state, keeping the temperature for 30 minutes at the furnace temperature of 400 ℃, then heating the heating furnace to 650 ℃ at the heating rate of 200 ℃/h and keeping the temperature for 30 minutes, then heating to 1100 ℃ at the heating rate of 200 ℃/h, keeping the temperature for 2 hours, then taking out the steel plate, cooling the steel plate to room temperature by water, and cooling at the cooling speed of 20 ℃/s.
(2) Aging treatment
And (4) heating the low-density steel obtained in the step (II) to 450 ℃ in a vacuum heating furnace in a vacuum state, preserving the heat for 9 hours, and then cooling the steel to room temperature at a cooling speed of 20 ℃/s.
TABLE 1
| Yield strength/MPa | Tensile strength/MPa | Elongation after rupture/%) | Product of strength and elongation/GPa% | |
| Example 1 | 1035.79 | 1061.62 | 53 | 56.23 |
| Example 2 | 986.08 | 1049.18 | 52.6 | 55.19 |
| Example 3 | 910.79 | 989.26 | 55.06 | 54.49 |
| Example 4 | 967.58 | 1011.39 | 53.89 | 54.50 |
| Comparative example 1 | 889.46 | 950.13 | 54.16 | 51.46 |
| Comparative example 2 | 893.51 | 961.31 | 53.26 | 51.20 |
| Comparative example 3 | 956.53 | 1023.26 | 48.9 | 50.05 |
| Comparative example 4 | 856.34 | 912.35 | 46.79 | 42.69 |
| Comparative example 5 | 846.32 | 908.13 | 47.57 | 43.20 |
| Comparative example 6 | 785.63 | 897.85 | 45.68 | 41.01 |
| Comparative example 7 | 895.34 | 968.26 | 51.67 | 50.03 |
Analyzing the data in table 1, comparing examples 1-4 with comparative examples 1-7, it can be seen that the preparation method of the present application can effectively improve the strength and toughness of the low density steel, so that the product of strength and elongation of the low density steel with chemical components in a certain range reaches about 55%, and the heat treatment process can well improve the toughness and strength of the steel, especially the toughness is improved significantly, the elongation after fracture of the finally prepared finished steel is basically maintained at more than 50%, and the requirements of some processed products with higher toughness requirements can be better satisfied. Particularly, by the heat treatment process, carbide which affects the performance of the finished steel can be greatly precipitated, the performance stability of the finished steel is improved, and the condition that the performance of the finished steel does not reach the standard is reduced.
The examples described herein are merely illustrative of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention, and various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall within the protection scope of the present invention.
Claims (9)
1. A heat treatment process of low-density steel comprises the following steps:
first, solution treatment
Preserving the heat of the low-density steel for 25-35 minutes at 380-420 ℃, then heating to 630-670 ℃ at a heating rate of 190-210 ℃/h, preserving the heat for 25-35 minutes, then heating to 1050-1150 ℃ at a heating rate of 190-210 ℃/h, preserving the heat for 2-3 hours, and cooling to room temperature by water;
di, carbide treatment
Heating the low-density steel obtained in the step one to 650-800 ℃, preserving heat for 2-3 hours, and then cooling to room temperature in air;
thirdly, aging treatment
Heating the low-density steel obtained in the step two to 450-550 ℃, preserving heat for 9-12 hours, and cooling to room temperature by water;
the low-density steel comprises the following chemical components in percentage by mass: mn: 25-30%; al: 9-10%; c: 0.9-1%; mo: 0.45 to 0.5 percent; si: 0.8-1%; p is less than or equal to 0.003 percent; less than or equal to 0.003 percent of S, and the balance of Fe and inevitable impurities.
2. The heat treatment process of a low density steel according to claim 1, characterized in that: and the heating modes of the first step, the second step and the third step are vacuum-pumping heating.
3. A process for the heat treatment of a low density steel according to claim 1 or 2, characterized in that: the density of the low-density steel is 6.95-7.2g/cm3。
4. A method for producing a low-density steel, comprising smelting, casting, hot rolling and heat treatment, wherein the heat treatment employs a heat treatment process of a low-density steel according to any one of claims 1 to 3.
5. The method of producing a low density steel as claimed in claim 4 wherein: during smelting, an additive is added into molten steel, the mass of the additive is 0.01-0.02% of the mass of the molten steel, and the additive comprises the following chemical components in parts by mass: rare earth: 9-11 parts; kaolin: 4-6 parts; biomass: and 2 parts.
6. The method of producing a low density steel as claimed in claim 4 wherein: the casting step adopts die casting, the superheat degree of the molten steel is controlled to be 20-30 ℃ during casting, and the die temperature of the die is 9-11% of the temperature of the molten steel.
7. The method of producing a low density steel as claimed in claim 6 wherein: the mold comprises a mold body, wherein the bottom of the mold body is paved with mold powder, the mass of the mold powder is 0.2-0.3% of that of molten steel, and the mold powder comprises the following chemical components in parts by mass: bauxite: 4.5-5.5 parts; dolomite: 18-22 parts; blast furnace slag: 2.5-3.5 parts; cement clinker: 1 part; wollastonite: 1 part.
8. The method of producing a low density steel as claimed in claim 6 wherein: during casting, molten steel in the die is electromagnetically stirred, the electromagnetic stirring frequency is 5-7 Hz, and the current intensity is 200-400A.
9. A method of producing a low density steel according to any one of claims 4-8, characterized in that: also comprises a forging step; the forging step is carried out after casting and before hot rolling, and comprises the following specific steps: heating the casting blank obtained by casting to 1100-1200 ℃, preserving heat for 1.5-2.5 hours, and forging into a square blank by a forging and pressing machine.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6063317A (en) * | 1983-09-14 | 1985-04-11 | Kawasaki Steel Corp | Production of high-mn non-magnetic steel for extra-low temperature service |
| CN107641763A (en) * | 2017-09-29 | 2018-01-30 | 安徽工业大学工商学院 | A kind of low-density potassium steel of high strength and ductility |
| CN107674955A (en) * | 2017-09-29 | 2018-02-09 | 安徽工业大学工商学院 | A kind of preparation method of low density steel of the strength and ductility product more than 50GPa% |
| CN108018494A (en) * | 2017-11-30 | 2018-05-11 | 安徽工业大学工商学院 | A kind of production method for the annealing process and low density steel for improving the strong plasticity of low density steel |
| CN108642403A (en) * | 2018-05-28 | 2018-10-12 | 河北工业大学 | A kind of 780MPa grade super strengths Fe-Mn-Al-C systems lightweight cast steel and preparation method thereof |
-
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6063317A (en) * | 1983-09-14 | 1985-04-11 | Kawasaki Steel Corp | Production of high-mn non-magnetic steel for extra-low temperature service |
| CN107641763A (en) * | 2017-09-29 | 2018-01-30 | 安徽工业大学工商学院 | A kind of low-density potassium steel of high strength and ductility |
| CN107674955A (en) * | 2017-09-29 | 2018-02-09 | 安徽工业大学工商学院 | A kind of preparation method of low density steel of the strength and ductility product more than 50GPa% |
| CN108018494A (en) * | 2017-11-30 | 2018-05-11 | 安徽工业大学工商学院 | A kind of production method for the annealing process and low density steel for improving the strong plasticity of low density steel |
| CN108642403A (en) * | 2018-05-28 | 2018-10-12 | 河北工业大学 | A kind of 780MPa grade super strengths Fe-Mn-Al-C systems lightweight cast steel and preparation method thereof |
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