CN115029607A - Medium-carbon quasi-bainite steel and method for preparing same by using iron-rich non-ferrous metallurgical slag - Google Patents
Medium-carbon quasi-bainite steel and method for preparing same by using iron-rich non-ferrous metallurgical slag Download PDFInfo
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Abstract
The invention discloses medium-carbon quasi-bainite steel and a method for preparing the medium-carbon quasi-bainite steel by using iron-rich non-ferrous metallurgical slag. The method for preparing the medium-carbon quasi-bainite steel by using the iron-rich non-ferrous metallurgical slag comprises the following steps: reducing and smelting the iron-rich non-ferrous metallurgical slag serving as a raw material to obtain molten iron; adding alloy auxiliary materials into the molten iron according to the components of the molten iron, degassing and slagging to obtain molten steel; and (3) casting blanks by adopting a continuous casting method, and preparing the medium-carbon quasi-bainite steel by a controlled rolling and controlled cooling process. The invention forms a process route from iron-rich non-ferrous metallurgical slag to medium-carbon quasi-bainite steel products by linking the non-ferrous metallurgical slag solid waste utilization with the steel industry, thus effectively improving the utilization rate of the metallurgical slag and promoting the recycling and harmless bulk disposal of the metallurgical slag; the value of alloy elements in the metallurgical slag is fully exerted, the types of steel production raw materials are enriched, the production cost is reduced, and the added value of products is improved; has the advantages of energy saving, environmental protection and green production.
Description
Technical Field
The invention relates to the technical field of metallurgical slag treatment, in particular to medium-carbon quasi-bainite steel and a method for preparing the medium-carbon quasi-bainite steel by using iron-rich non-ferrous metallurgical slag.
Background
The steel production in China mainly takes a long process as a main part, most steel is refined by iron ore, but at present, the iron ore is poor in quality, rich in ore, high in mining requirement and high in technical difficulty, the average mining taste is only 10% -30%, and the economical efficiency is poor, so that the iron ore has high external dependence and is nonrenewable to the iron ore, and the search for alternative resources of the iron ore is bound to be a necessary way for promoting the healthy development of the iron and steel industry.
The non-ferrous metallurgical slag is waste slag generated in the smelting process of non-ferrous metal minerals, the scale of the non-ferrous metallurgical industry is huge at present, the annual generation amount of the metallurgical slag is large, the metallurgical slag is various, and the non-ferrous metallurgical slag mainly comprises copper slag, red mud, nickel slag, electrolytic manganese slag, lead-zinc slag and the like. The discharge amount of the nonferrous metallurgical slag is different according to the ore taste and the production process. For example, about 2.2 tons of copper slag can be discharged per ton of copper produced, about 0.6-2.5 tons of red mud can be generated per ton of aluminum oxide produced, the mass ratio of the nickel-iron slag of the electric furnace to the correspondingly produced nickel-iron alloy can reach about 14:1, the production amount of electrolytic manganese slag is about 7-11 tons of manganese, and about 0.7-0.9 tons of lead-zinc slag can be generated per ton of lead/zinc produced. A large amount of nonferrous metallurgical slag is subjected to a treatment method of open-air stockpiling for a long time, so that on one hand, a large amount of land resources are consumed, and the enterprise cost is increased; on the other hand, under the action of long-term weathering leaching, heavy metal ions and toxic elements in the slag can permeate into underground water, rivers and soil, so that the ecological environment is directly seriously damaged, and the health of surrounding people, animals and plants is harmed. The reduction, the harmlessness and the resource utilization of the metallurgical slag are common problems in the whole nonferrous metal industry and core problems which disturb the green development of the industry. Therefore, the massive utilization of the nonferrous metallurgical slag is imminent.
The current way of consuming nonferrous metallurgical slag is mainly to extract valuable metals and produce cement concrete building raw materials. For producing building materials by using colored slag, some industries in China have formed series specifications and can realize industrial application, such as 'ferronickel slag powder for cement and concrete' given by JC/T2503-. In contrast, the development of metals extracted from colored slag is not sufficient. Although the chinese patent CN106086428B discloses a method for producing ferroalloy by using non-ferrous slag, which needs to be pelletized and then subjected to reduction melting treatment at 1500-1700 ℃, the process is complex and the energy consumption is high. The Chinese application CN109207718A proposes a method for preparing stainless steel raw material sinter by nickel slag, but the raw materials thereof adopt hematite powder, magnetite concentrate powder, nickel slag (accounting for about 20 percent), limestone, dolomite, return fines, coke powder, corncob granules and the like, and have the problems of complex raw materials and low utilization rate of colored slag.
Disclosure of Invention
Based on the problems, the invention provides an effective treatment method which can apply the iron-rich metal extracted from the nonferrous metallurgical slag to steel production, can greatly consume the nonferrous slag and provide raw materials for steel making, is beneficial to enriching the types of steel making raw materials and making up the defects of self-mining iron ores, and becomes a research direction of the invention. Based on the above, according to an embodiment of the present invention, an object of the present invention is to provide a method for preparing medium-carbon quasi-bainite steel by using iron-rich non-ferrous metallurgical slag, so as to solve the problems of various raw material types, complex process, high energy consumption, low utilization rate of non-ferrous metallurgical slag, and the like existing in the current iron-rich non-ferrous metallurgical slag iron extraction and steel making. The other aim of the steel is to provide the medium-carbon quasi-bainite steel.
The above object can be achieved by the following technical solution:
according to one aspect of the invention, the invention provides a method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag, which comprises the following steps:
reducing and smelting the iron-rich non-ferrous metallurgical slag serving as a raw material to obtain molten iron;
adding alloy auxiliary materials into the molten iron according to the components of the obtained molten iron, degassing and slagging to obtain molten steel with qualified components;
and casting the molten steel by adopting a continuous casting method, and obtaining the medium-carbon quasi-bainite steel by a controlled rolling and controlled cooling process.
Optionally, after the step of degassing and slagging, the method further comprises: and (4) refining outside the furnace, and adjusting the components of the molten steel to obtain the molten steel with qualified components.
Optionally, the molten steel with qualified composition comprises the following alloy compositions in percentage by mass: 0.2 to 0.3 percent of C, 1.0 to 1.5 percent of Si, 1.5 to 2.0 percent of Mn, 0.2 to 0.5 percent of Mo, 0.3 to 0.8 percent of Cr, 0.04 to 0.08 percent of Nb, less than or equal to 0.003 percent of B, less than or equal to 0.003 percent of N, less than or equal to 0.005 percent of O, 0.01 percent of P and less than or equal to 0.01 percent of S.
Optionally, the step of obtaining the medium-carbon quasi-bainite steel by controlled rolling and controlled cooling process includes: soaking for 60-120 min at 1120-1200 deg.c; carrying out multi-pass rolling; after rolling, the steel plate is quickly cooled to 400-430 ℃, the cooling speed is controlled to be 0.5-1 ℃/s, and the steel plate is cooled to the room temperature.
Optionally, performing two-pass rolling, and controlling the air cooling temperature and adjusting the rolling reduction during each pass of rolling; the method comprises the following steps: air cooling to 1050-1080 ℃, and rolling for the first pass, wherein the reduction is 40%; air cooling to 820-860 ℃ for second rolling, wherein the rolling reduction is 30%.
Optionally, the step of reduction smelting comprises: adding a reducing agent and a fusing agent, carrying out reduction smelting at 1300-1550 ℃, keeping the temperature for 60-180 min, and tapping when the iron reduction rate in the slag is more than or equal to 90% through dynamic monitoring.
Optionally, the mass ratio of the iron-rich nonferrous metallurgical slag to the reducing agent to the flux is as follows: 100: 5-15: 10 to 30.
Optionally, in the iron-rich nonferrous metallurgical slag, the TFe is > 30%.
Optionally, the method further comprises: and synchronously preparing active micro powder by using secondary slag. Further, the secondary slag comprises: one or two of reducing slag produced by reduction smelting and steel slag produced by degassing and slagging are adopted.
Optionally, the specific surface area is prepared by adopting a mode of direct grinding or grinding after adding an active excitant>350m 2 Active micro powder/kg.
Optionally, the using amount ratio of the secondary slag to the active exciting agent is 100: 5-30.
Optionally, the activity activator is one or more of blast furnace slag, fly ash, quicklime, cement, clinker, byproduct gypsum, sodium silicate, sodium hydroxide, sodium sulfate, tailings, triethanolamine, propylene glycol and the like.
Optionally, the active micro powder is used as a cement admixture or a concrete admixture, and the addition amount is more than or equal to 30%.
According to another aspect of the invention, the medium-carbon quasi-bainite steel is prepared by the method for preparing the medium-carbon quasi-bainite steel by using the iron-rich non-ferrous metallurgical slag.
Optionally, the medium-carbon quasi-bainite steel has a metallographic structure formed by a bainite ferrite lath and a residual austenite film which are arranged in an interphase mode.
Optionally, the medium carbon quasi bainitic steel has a yield strength greater than 750 MPa.
Optionally, the medium-carbon quasi-bainite steel has tensile strength of more than 1200MPa, impact energy of more than 40J and elongation of more than 15%.
Has the advantages that: the solid waste utilization of the non-ferrous metallurgical slag is linked with the steel industry, the iron-rich non-ferrous metallurgical slag is used as a raw material, molten steel with qualified components is obtained after reduction smelting, degassing, slagging and alloying, and then the medium-carbon quasi-bainite steel is produced through continuous casting blank casting and controlled rolling and controlled cooling process, so that a process route from the iron-rich non-ferrous metallurgical slag to a medium-carbon quasi-bainite steel product is formed, the utilization rate of the metallurgical slag is practically improved, the problems of various raw materials, complex process, high energy consumption and low utilization rate of the non-ferrous slag existing in the current iron-rich non-ferrous metallurgical slag iron extraction and steelmaking are solved, and the recycling and harmless treatment of the metallurgical slag are promoted; the value of alloy elements in the metallurgical slag is fully exerted, the types of steel production raw materials are enriched, the production cost is reduced, and the added value of products is improved; has the advantages of energy saving, environmental protection and green production.
Drawings
FIG. 1 is a process flow diagram of a method of the present invention for preparing medium-carbon quasi-bainite steel using iron-rich nonferrous metallurgical slag.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Aiming at the problems of various raw material types, complex process, high energy consumption, low utilization rate of non-ferrous slag and the like existing in the prior art of extracting iron from iron-rich non-ferrous metallurgical slag, the invention forms a process route from the iron-rich non-ferrous metallurgical slag to a medium-carbon quasi-bainite steel product by linking the utilization of the non-ferrous metallurgical slag and the steel industry, namely the invention provides the method for preparing the medium-carbon quasi-bainite steel by using the iron-rich non-ferrous metallurgical slag. The method comprises the following steps: the iron-rich nonferrous metallurgical slag is taken as a raw material, and molten steel with qualified components is obtained after reduction smelting, degassing, slagging and alloying; the medium-carbon quasi-bainite steel is produced by continuous casting blanks and controlled rolling and cooling processes. Thereby improving the utilization rate of the metallurgical slag practically and promoting the resource and harmless bulk disposal of the metallurgical slag; meanwhile, the value of alloy elements in the metallurgical slag is fully exerted, the types of steel production raw materials are enriched, the production cost is reduced, and the added value of products is improved.
The metallurgical slag in the invention can be one or more of copper slag, red mud, nickel slag, electrolytic manganese slag, lead-zinc slag and the like. Table 1 specifically describes several kinds of nonferrous metallurgical slag components, and it can be seen from table 1 that the total iron content of most iron-rich nonferrous metallurgical slag is high, for example, high-iron bayer red mud, nickel iron slag, copper slag, etc. in which the iron-rich nonferrous metallurgical slag reaches TFe > 40%, which are far higher than the average mining grade of iron ore in our country. In the invention, the iron-rich nonferrous metallurgical slag TFe is preferably more than 30 percent, such as one or more selected from copper slag, Bayer process red mud, blast furnace nickel slag, lead-zinc slag and the like.
TABLE 1 chemical composition of nonferrous metallurgical slag
Fig. 1 schematically shows a process flow of a method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to an embodiment of the present invention. As shown in figure 1, the method for preparing the medium-carbon quasi-bainite steel by using the iron-rich nonferrous metallurgical slag comprises the following steps:
(1) adding a reducing agent and a fusing agent in a certain proportion into the iron-rich nonferrous metallurgical slag, uniformly mixing, then sending into a high-temperature smelting device for reduction smelting to obtain molten iron and reducing slag, wherein the reducing slag melt is on the upper layer of the molten iron, and tapping and deslagging are carried out irregularly.
The high-temperature smelting device can be an electric arc furnace, a side-blown smelting furnace, an ore-smelting furnace and the like, preferably adopts equipment or a system capable of providing molten pool stirring, the stirring mode can be one or more of gas stirring, electromagnetic stirring and mechanical stirring, and the reaction process can be accelerated by adopting the high-temperature smelting device with the stirring structure. The iron-rich nonferrous metallurgical slag TFe is more than 30 percent, has better economy and can be selected from various metallurgical slags such as copper slag, Bayer process red mud, blast furnace nickel slag, lead-zinc slag and the like. The reducing agent is a carbonaceous material, and can be bituminous coal, anthracite, lignite and the like. The flux is used for adjusting alkalinity and can be one or more of limestone, dolomite, fluorite, lime and industrial alkali.
Preferably, during reduction smelting, the iron-rich nonferrous metallurgical slag: reducing agent: flux is 100: 5-15: 10 to 30. After the materials in the furnace form a molten pool at 1300-1550 ℃, the temperature is kept for 60-180 min, and the materials can be fully melted and reduced by controlling the temperature and the heat-preservation time.
Further, during reduction smelting, the method also comprises the step of dynamically monitoring the content of iron elements in the slag, tapping and deslagging can be carried out when the reduction rate of iron in the slag is more than or equal to 90%, most of iron in the slag is reduced, and tapping is carried out to obtain molten iron required by the subsequent steel making process. Furthermore, the slag-blocking operation is required during tapping.
(2) According to the components of the molten iron, alloy auxiliary materials with a certain proportion are added into the molten iron, and the molten steel with qualified components and a steel slag byproduct are obtained after degassing, slagging and alloying.
The steel-making process can be carried out in a traditional oxidizing atmosphere converter, and alloy auxiliary materials can also be directly added into a reduction smelting furnace after slag tapping to carry out four-step separation (C, P, S, O), slagging and alloying processes.
Optionally, if the components of the molten steel subjected to degassing and slagging are difficult to meet the requirements, external refining can be selected to further adjust the components of the molten steel so as to further ensure that molten steel with qualified components is obtained, and then the medium-carbon quasi-bainite steel meeting the requirements is prepared. Wherein, the external refining can be selected from one or more of LF, VD, VOD, RH and SKF furnaces.
The alloy auxiliary materials are mainly used for providing alloy elements which cannot be fully met in the nonferrous metallurgical slag and adjusting alloy components such as ferrosilicon, ferrochrome, ferrocolumbium, molybdenum and the like. The molten steel with qualified components, which is required by the invention, comprises the following alloy components (mass fraction): 0.2-0.3% of C, 1.0-1.5% of Si, 1.5-2.0% of Mn, 0.2-0.5% of Mo, 0.3-0.8% of Cr, 0.04-0.08% of Nb, less than or equal to 0.003% of B, less than or equal to 0.003% of N, less than or equal to 0.005% of O, less than or equal to 0.01% of P and less than or equal to 0.01% of S; the qualified molten steel of the components can ensure that a quasi-bainite structure can be obtained.
Alloy auxiliary materials are added to control the alloy components, the existing valuable metal elements in the nonferrous metallurgical slag are reasonably utilized, the consumption of the alloy auxiliary materials is reduced, and the production cost is reduced. The alloy comprises the following components: c, improving the hardness and strength of the material; si as a non-carbide-forming element, suppressing carbides (especially Fe) 3 C) To enrich the unconverted residual austenite with carbon; mn and Mo play roles in solid solution strengthening and tissue bainite promotion; cr can improve the strength and enhance the stability of austenite; nb mainly plays a role in fine grain strengthening and precipitation strengthening; B. when the content of N is too high, a BN brittle phase is easily formed in the steel, which is not beneficial to improving the performance, and the content of the N should be controlled.
(3) And (3) obtaining a continuous casting billet from the molten steel with qualified components through a crystallizer by adopting a continuous casting method, carrying out controlled rolling and controlled cooling processes after soaking treatment, and further obtaining the medium-carbon quasi-bainite steel with qualified tissue.
The invention adopts a continuous casting process. Compared with die casting, the invention adopts the continuous casting method, thereby not only simplifying the production process flow, but also improving the metal yield, reducing the energy consumption, improving the quality of finished products and the like. The controlled rolling and controlled cooling is Thermo-mechanical Control Process (TMCP), and TMCP is adopted to produce steel products, so that the steel performance is improved. Moreover, the production process of controlling cooling by continuous casting and rolling is adopted to prepare the quasi-bainite steel, and compared with the traditional method for preparing the quasi-bainite structure by long-time isothermal quenching, the production process is more beneficial to energy conservation, environmental protection and green production, and improves the economic and environmental benefits.
In order to further improve the performance of the steel product, the controlled rolling and controlled cooling process parameters are continuously optimized and improved on the basis of the set chemical components, and the performance of the steel product is greatly improved by selecting the optimized controlled rolling and controlled cooling process parameters. Optimized parameter control in this embodiment: and (3) feeding the continuous casting billets into a tunnel soaking furnace, and keeping the temperature of the soaking furnace at 1120-1200 ℃ for 60-120 min. And then the steel is sent into a hot rolling mill group, air cooling is carried out to 1050-1080 ℃ for the first pass of rolling, the reduction is 40%, air cooling is carried out to 820-860 ℃ for the second pass of rolling, the reduction is 30%, then the steel is quickly cooled to 400-430 ℃ and is controlled to be cooled to the room temperature at the cooling rate of 0.5-1 ℃/s, and the steel with the medium carbon steel mainly comprising the quasi-bainite structure and the carbon content of 0.2-0.3% is obtained.
The quasi-bainite steel obtained by the invention has a metallographic structure formed by a bainite ferrite lath and a residual austenite film, has good toughness and plasticity matching, has the yield strength of more than 750MPa, the tensile strength of more than 1200MPa, the impact energy (V opening) of more than 40J and the elongation of more than 15 percent, and can be used for producing high-strength steel bars and the like. The main reasons are that: through reasonable alloying design and rolling-cooling process control, the effects of interstitial solid solution strengthening of carbon atoms and fine crystal strengthening of a batten substructure are exerted, so that the steel has excellent strength characteristics; the presence of the thin film of retained austenite in turn imparts to the bainitic structure the ability to absorb deformation energy, resist crack initiation and propagation.
In an alternative embodiment, as shown in fig. 1, the method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag further includes: the generated secondary slag is recycled, so that the full components of the metallurgical slag are fully utilized.
Specifically, the building raw materials such as cement admixture or concrete admixture are prepared by adopting reducing slag obtained in the reducing smelting process and steel slag obtained in the steelmaking process. The two secondary slags obtained by the invention mainly comprise CaO, MgO and SiO 2 And Al 2 O 3 The composition is similar to the components of cement, is used for producing building raw materials, avoids the generation of a large amount of secondary slag, and realizes the full utilization of the nonferrous metallurgical slag.
Optionally, the secondary slag with higher activity can be directly prepared into active micro powder after being ground, and the active micro powder can be used as an auxiliary cementing material for building material external sale enterprises. For lower activityThe secondary slag is mixed with an active excitant and then ground together to prepare the active micro powder. Wherein, the activity excitant can be one or more of blast furnace slag, fly ash, quicklime, cement, clinker, byproduct gypsum, sodium silicate, sodium hydroxide, sodium sulfate, tailings, triethanolamine, propylene glycol and the like. Preferably, the secondary slag: activity activator 100:5 to 30. Further, the specific surface area of the ground active micro powder>350m 2 The admixture/kg can be used as a cement admixture or a concrete admixture. And when the active micro powder is used as a cement admixture or a concrete admixture, the addition amount is more than or equal to 30 percent, and the higher addition amount also shows the high resource utilization efficiency of the metallurgical slag.
The embodiment of the invention also has the following advantages:
1) the method takes iron-rich non-ferrous metallurgical slag as a main raw material, designs a process route of 'reduction iron extraction + oxidation blowing + continuous casting and continuous rolling controlled cooling', prepares medium-carbon quasi-bainite steel, fully utilizes metal elements in the non-ferrous slag through alloying design, enriches the raw material types of steel production, reduces the production cost and improves the added value of products.
2) The development of the medium-carbon quasi-bainite steel plate in the 700MPa level is realized by regulating and controlling rolling and cooling parameters, and compared with the traditional process for obtaining a quasi-bainite structure by long-time isothermal quenching, the method is more favorable for energy conservation, environmental protection and green production; and the obtained medium-carbon quasi-bainite steel has good toughness and plasticity matching, excellent strength characteristic, and better capabilities of absorbing deformation energy and resisting crack initiation and propagation.
3) The secondary slag generated in the production process can be directly used for producing cement admixture or concrete admixture and the like or processed to realize the full component utilization of the colored slag. Specifically, the embodiment synchronously prepares the active micro powder by combining medium-carbon quasi-bainite steel prepared by iron-rich non-ferrous metallurgical slag with secondary slag, namely, the non-ferrous, steel and building industries are linked, so that the raw material types of steel production and building materials are enriched, and the resource and harmless bulk disposal of the iron-rich non-ferrous slag is promoted; the whole production process flow is simple, the rhythm is fast, the efficiency is high, the added value of the product is high, the utilization rate of the colored slag can be effectively improved while the green production is realized.
The invention will be further illustrated with reference to a specific embodiment:
example 1
Preparing medium-carbon quasi-bainite steel by using iron-nickel-rich slag with TFe (percent of iron) of 40% as iron-rich nonferrous metallurgical slag:
1) reducing and extracting iron: the high-temperature smelting device is an electric arc furnace. The method comprises the following steps: according to the nickel slag: anthracite coal: limestone 100: 5: mixing at a ratio of 20 and adding into an electric arc furnace for reduction smelting; after the materials in the furnace form a molten pool at 1450 ℃, the temperature is kept for 90min for discharging iron and slag. The iron content of the slag during slag discharging is 2.48%, the obtained molten iron components comprise 0.85% of C, 2.13% of Si, 0.86% of Mn, 0.059% of P, 0.056% of S, 0.15% of Cr and 0.01% of Nb, and the rest required components can be supplemented by auxiliary materials in the next link.
2) Alloying: preparing auxiliary materials, blowing in a converter and refining outside an LF furnace to obtain molten steel, wherein the components of the molten steel are as follows: 0.26% of C, 1.4% of Si, 1.8% of Mn, 0.3% of Mo, 0.5% of Cr, 0.06% of Nb, 0.0025% of B, 0.0028% of N, 0.005% of O, 0.008% of P and 0.007% of S.
3) Continuous casting, controlled rolling and controlled cooling: the molten steel is made into a continuous casting billet through a crystallizer, the continuous casting billet is sent into a tunnel soaking furnace for heat preservation for 120min, and the temperature of the soaking furnace is 1150 ℃. And then sending the steel into a hot rolling unit, air-cooling the steel to 1050 ℃ for first-pass rolling with the reduction of 40%, air-cooling the steel to 850 ℃ for second-pass rolling with the reduction of 30%, and then quickly cooling the steel to 400 ℃ at a cooling rate of 1 ℃/s to room temperature to obtain the medium carbon steel mainly comprising the quasi-bainite structure.
And (3) performance testing: the yield strength is 764MPa, the tensile strength is 1258MPa, the impact energy (V port) is 42J, and the elongation is 16%.
4) Resource utilization of secondary slag: grinding the secondary slag powder to a specific surface area of 436m 2 And/kg, adding 5 percent of high-calcium fly ash as an exciting agent to prepare the active micro powder. The activity indexes of 7d and 28d are measured according to GB-T18046-2017: 7d was 83% and 28d was 106%.
The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (12)
1. A method for preparing medium-carbon quasi-bainite steel by using iron-rich non-ferrous metallurgical slag is characterized by comprising the following steps:
reducing and smelting the iron-rich non-ferrous metallurgical slag serving as a raw material to obtain molten iron;
adding alloy auxiliary materials into the molten iron according to the components of the molten iron, degassing and slagging to obtain molten steel with qualified components;
and (3) casting blanks by adopting a continuous casting method, and preparing the medium-carbon quasi-bainite steel by a controlled rolling and controlled cooling process.
2. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 1, further comprising: preparing active micro powder by using secondary slag; wherein the secondary slag comprises: one or two of reducing slag produced by reduction smelting and steel slag produced by degassing and slagging are adopted.
3. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 1, further comprising, after the step of degassing and slagging: and (4) refining outside the furnace, and adjusting the components of the molten steel to obtain the molten steel with qualified components.
4. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 3, wherein the molten steel with qualified composition comprises the following alloy compositions in percentage by mass: 0.2 to 0.3 percent of C, 1.0 to 1.5 percent of Si, 1.5 to 2.0 percent of Mn, 0.2 to 0.5 percent of Mo, 0.3 to 0.8 percent of Cr, 0.04 to 0.08 percent of Nb, less than or equal to 0.003 percent of B, less than or equal to 0.003 percent of N, less than or equal to 0.005 percent of O, less than or equal to 0.01 percent of P and less than or equal to 0.01 percent of S.
5. The method for preparing the medium-carbon quasi-bainite steel by using the iron-rich nonferrous metallurgical slag according to claim 1, wherein the step of obtaining the medium-carbon quasi-bainite steel by the controlled rolling and controlled cooling process comprises: soaking for 60-120 min at 1120-1200 deg.c; carrying out multi-pass rolling; after rolling, the steel plate is quickly cooled to 400-430 ℃, the cooling speed is controlled to be 0.5-1 ℃/s, and the steel plate is cooled to the room temperature.
6. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 5, wherein two passes of rolling are performed, and the air cooling temperature is controlled and the rolling reduction is adjusted during each pass of rolling; the method comprises the following steps: air cooling to 1050-1080 ℃, and rolling for the first pass, wherein the reduction is 40%; air cooling to 820-860 ℃, and rolling for the second pass, wherein the rolling reduction is 30%.
7. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 1, wherein the step of reduction smelting comprises: adding a reducing agent and a fusing agent, carrying out reduction smelting at 1300-1550 ℃, keeping the temperature for 60-180 min, and tapping when the iron reduction rate in the slag is more than or equal to 90% through dynamic monitoring.
8. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 7, wherein TFe is more than 30% in the iron-rich nonferrous metallurgical slag; the mass ratio of the iron-rich nonferrous metallurgical slag to the reducing agent to the flux is 100: 5-15: 10-30.
9. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 2, wherein the step of preparing the active micropowder by using the secondary slag comprises the step of obtaining the specific surface area by direct grinding or grinding after adding an active activator>350m 2 Active micro powder of/kg; wherein the dosage ratio of the secondary slag to the active excitant is 100: 5-30; the active excitant is one or more of blast furnace slag, fly ash, quicklime, cement, clinker, byproduct gypsum, sodium silicate, sodium hydroxide, sodium sulfate, tailings, triethanolamine, propylene glycol and the like.
10. The method for preparing medium-carbon quasi-bainite steel by using iron-rich nonferrous metallurgical slag according to claim 9, wherein the active micro powder is used as a cement admixture or a concrete admixture and is added in an amount of not less than 30%.
11. The medium-carbon quasi-bainite steel is prepared by the method for preparing the medium-carbon quasi-bainite steel by using the iron-rich nonferrous metallurgical slag according to claim 1.
12. The medium-carbon quasi-bainite steel according to claim 11, wherein the medium-carbon quasi-bainite steel has a metallographic structure in which bainitic ferrite laths and a residual austenite thin film are arranged alternately, and has a yield strength of more than 750 MPa.
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