CN111020379A - Rare earth composite reinforced hot-rolled steel bar and preparation method thereof - Google Patents
Rare earth composite reinforced hot-rolled steel bar and preparation method thereof Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/08—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement
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- C22C33/04—Making ferrous alloys by melting
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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Abstract
The invention discloses a rare earth composite reinforced hot-rolled steel bar, which is obtained by hot-rolling rare earth composite steel, wherein the rare earth composite steel comprises the following components in percentage by mass: 0.25-0.30% of C, 0.77-0.83% of Si, 1.54-1.66% of Mn, less than or equal to 0.04% of S, less than or equal to 0.045% of P, Y: 0.001-0.01%, Ce: 0.01-0.03%, 0.01-0.02% of La, and the balance of iron and inevitable impurities. The hot-rolled low-carbon rare earth composite steel bar provided by the invention does not need to penetrate water in the production process, is simple in production process, and has higher strength and tensile property.
Description
Technical Field
The invention relates to a rare earth material section bar and a preparation method thereof, in particular to a rare earth composite reinforced hot rolled steel bar formed by a hot rolling process and a preparation method thereof.
Background
From 11 months and 1 day in 2018, the domestic steel enterprises will implement new national standards for producing building steel, and the new national standard codes are as follows: GB/T1499.2-2018, original old national standard GB/T1499.2-2007 formally denudes historical stage. The implementation of the new national standard can further improve the quality of building steel, promote energy conservation and emission reduction, eliminate out-dated capacity and better meet the requirements of the fields of house construction, bridges, railways, highways and the like on hot-rolled ribbed steel bars. Compared with the original national standard GB/T1499.2-2007, the biggest change of the new national standard lies in that the production of the 'water through' deformed steel bar is avoided by increasing the requirements for metallographic structure inspection and the matched macroscopic metallographic phase, section Vickers hardness, microstructure and inspection method thereof, and the imitation of hot rolled steel bars by water through steel bars is avoided. Through the water penetrating process, a 'martensite ring' can be formed on the outer layer of the steel bar, so that the strength of the steel bar can be improved. Although the steel bar treated using the water-passing process can reach the previous national standards in strength and reduce the cost of adding alloy elements, the steel bar is very easily rusted and the strength is easily deteriorated due to water-passing to destroy an oxide film generated on the surface of the steel bar in a high-temperature state. Meanwhile, the water penetration process also easily causes surface cracks of the steel bars, edge quenching cracks and even crystal cracks and the like to seriously affect the cold bending performance and the welding performance of the steel bars. For these reasons, the new national standard specifies that the deformed steel bar can only be produced by converter or arc furnace processes, and the performance is improved by adding alloys, thereby effectively limiting the production and circulation of "through-water" deformed steel bars. The addition proportion of the alloy is also specified in the new national standard. After the new national standard is implemented, the production cost of the deformed steel bar is directly increased. According to estimation, the average cost of the thread or the increase of about 70 yuan/ton to 100 yuan/ton due to the increase of the addition amount of alloy elements such as Mn, V and the like. Wherein, the cost increased by adding Mn element is about 18-30 yuan/ton, accounting for about 25-30%; the added V element increases the cost by about 52-74 yuan/ton, and accounts for about 70-75%.
Patent CN109930056A discloses a method for producing a twisted steel bar with low cost and high quality by adding a small amount of alloy elements such as Ti, Cr, V, Nb, etc., improving smelting technology and rolling process, and utilizing inclusion to induce a fine grain strengthening mechanism, thereby improving the strength of the bar, reducing the addition of precious alloy elements. However, the invention adds more alloy elements in the actual production, the variety and the quantity of the inclusions are various, the difficulty in controlling the size and the quantity of the inclusions is high, and the difficulty is brought to the production.
Patent CN109628829A discloses a twisted steel bar and a preparation method thereof, wherein a composite strengthening alloy consisting of nitrogen, titanium, boron, silicon, manganese, carbon and rare earth is added on the basis of the components of C-Si-Mn, and refining process and rolling process are strictly controlled in the production process, so as to improve the strength of the steel bar. The addition of a plurality of alloy elements increases the alloy cost, and the adoption of lower rolling temperature increases the load of a rolling mill, thereby bringing difficulty to production.
Patent CN105779866A discloses an HRB400 steel bar and a production method thereof, which adds Cr alloy elements on the basis of C-Si-Mn components to replace V alloy elements, and strictly controls the refining process and rolling process in the production process, thereby improving the strength of the steel bar. The addition of Cr increases the alloy cost, and the adoption of lower rolling temperature increases the load of a rolling mill, thereby bringing difficulty to production.
Patent CN103469064A discloses a HRB400E high-strength anti-seismic steel bar and a preparation method thereof, different V element addition amounts are adopted for steel bars with different diameters, and stepped rolling is adopted, so that the cost is reduced, and the strength is improved. However, the steel bar needs to be added with V with the content of 0.030-0.045%, the V microalloying cost is increased, and the consumption of V resources is caused.
Patent CN102400044A discloses a niobium-titanium composite micro-alloying hot-rolled ribbed steel bar and a production method thereof, wherein the Nb-Ti composite micro-alloying process is adopted to reduce the addition of micro-alloy and achieve HRB400 strength level. Since Nb is a precious alloy resource and requires a large amount of import, the large amount of application in reinforcing steel bars is not favorable for saving precious resources.
Disclosure of Invention
In order to solve the problems, the hot-rolled low-carbon rare earth composite steel bar provided by the rare earth composite reinforced hot-rolled steel bar disclosed by the invention does not need to penetrate water in the production process, is simple in production process, and has higher strength and tensile property.
The invention discloses a rare earth composite reinforced hot-rolled steel bar, which is obtained by hot-rolling rare earth composite steel, wherein the rare earth composite steel comprises the following components in percentage by mass:
0.25-0.30% of C, 0.77-0.83% of Si, 1.54-1.66% of Mn, less than or equal to 0.04% of S, less than or equal to 0.045% of P, Y: 0.001-0.01%, Ce: 0.01-0.03%, 0.01-0.02% of La, and the balance of iron and inevitable impurities.
The invention discloses an improvement of rare earth composite reinforced hot rolled steel bar, the content of rare earth elements in the rare earth composite steel is as follows: y: 0.005-0.01%, Ce: 0.02-0.025% and 0.01-0.015% of La.
The invention discloses an improvement of a rare earth composite reinforced hot rolled steel bar, wherein at least part of Y, Ce and La in the rare earth composite steel is added through an intermediate alloy at least containing one of the three elements.
The invention discloses an improvement of a rare earth composite reinforced hot rolled steel bar, wherein an intermediate alloy is a rare earth silicon-iron alloy containing Y, Ce and La elements. The intermediate alloy used in the method comprises rare earth silicon-iron alloy which is a material with the content of Y, Ce and La elements higher than that of rare earth elements in the steel bar.
The invention discloses a further improvement of rare earth composite reinforced hot rolled steel bar, the rare earth composite steel also comprises Nb, the content of which is calculated by mass fraction: 0.005-0.01 percent.
The invention discloses an improvement of a rare earth composite reinforced hot rolled steel bar, wherein the rare earth composite steel also comprises V, and the content of V is calculated by mass fraction: 0.005-0.01 percent.
The invention discloses an improvement of a rare earth composite reinforced hot rolled steel bar, wherein the total amount of rare earth composite steel Nb and V is calculated by mass fraction: 0.005-0.01 percent.
The invention discloses a method for preparing rare earth composite reinforced hot rolled steel bar, which comprises the following steps,
A. alloy smelting, namely preparing the molten rare earth composite steel in a form that the rare earth alloy covered wire is added into molten steel, wherein the molten rare earth composite steel comprises the following components in percentage by mass:
0.25-0.30% of C, 0.77-0.83% of Si, 1.54-1.66% of Mn, less than or equal to 0.04% of S, less than or equal to 0.045% of P, Y: 0.001-0.01%, Ce: 0.01-0.03%, 0.01-0.02% of La and the balance of iron and inevitable impurities; wherein the rare earth alloy covered wire is obtained from an intermediate alloy containing at least one of Y, Ce and La, and the casting blank is prepared by smelting the alloy;
B. the casting blank is hot rolled to obtain the steel bar.
The invention discloses an improvement of a preparation method of a rare earth composite reinforced hot rolled steel bar, wherein a middle alloy is a rare earth silicon-iron alloy containing Y, Ce and La elements.
The invention discloses an improvement of a preparation method of a rare earth composite reinforced hot rolled steel bar, wherein the contents of three rare earth elements contained in rare earth silicon-iron alloy are as follows: y: 0.005-0.01%, Ce: 0.02-0.025% and 0.01-0.015% of La.
The invention discloses a further improvement of the preparation method of the rare earth composite reinforced hot rolled steel bar, wherein the rare earth composite steel also comprises Nb, and the content of Nb is calculated by mass fraction: 0.005-0.01 percent.
The invention discloses an improvement of a preparation method of a rare earth composite reinforced hot rolled steel bar, wherein the rare earth composite steel also comprises V, and the content of V is calculated by mass fraction: 0.005-0.01 percent.
The invention discloses an improvement of a preparation method of rare earth composite reinforced hot rolled steel bars, wherein the total amount of rare earth composite steel Nb and V is calculated by mass fraction: 0.005-0.01 percent.
In the scheme of the invention, the element composition and the content thereof have specific requirements:
c is an essential component for securing the strength of the reinforcing bar, and if the C content is too high, the content of carbides precipitated along grain boundaries increases to deteriorate the toughness. Too high a C content also tends to form martensitic rings. Therefore, the C content is controlled to be 0.25 to 0.3%.
Si mainly has the solid solution strengthening effect, the strengthening to the matrix is not obvious if the content is too low, and the strength is reduced and the toughness is reduced if the content is too high. Therefore, the Si content is 0.77-0.83%.
Mn is an element for improving the strength of the steel bar. In addition, Mn is easy to form MnS inclusions with S in steel, so that the content of Mn is not easy to be too high and is easy to form long-strip harmful inclusions, the combination probability of S and RE in steel is reduced, and the formation of the single-position micron-sized REOxSy composite inclusions is difficult to promote, so that the impact toughness cannot be smoothly improved. Therefore, the Mn content is designed to be 1.54 to 1.66%.
Nb: nb is combined with carbon, nitrogen and sulfur in steel to generate stable carbide and carbonitride, and the stable carbide and carbonitride plays a role in fine grain strengthening and dispersion strengthening. The strengthening effect of Nb is more obvious under the condition of rare earth existence.
V: inhibiting the recrystallization of austenite and preventing the growth of crystal grains, thereby refining ferrite crystal grains and improving the strength and the toughness of the steel.
It is emphasized that O, S content must be less than 80ppm, Y, La and Ce are added compositely to form single-site micron-sized rare earth inclusions, and if the content is too high, the size of the inclusions is increased, the inclusions cannot be dispersed and distributed, and the comprehensive performance is deteriorated. If it is too low, the REOxSy composite inclusion cannot be formed, and thus the effect of "oxide metallurgy" cannot be obtained.
Through the compound addition of yttrium, lanthanum and cerium, the main effects are reflected in the following aspects:
the light rare earth Ce, La and O, S have strong binding capacity, so that fine dispersed inclusions are more easily formed, and the method is very favorable for reducing the size of the original non-metallic inclusions and improving the morphology of the inclusions;
the addition of a small amount of heavy rare earth Y has a higher solid solubility in Fe than La and Ce rare earth due to a smaller atomic radius, and the maximum solid solubility is that harmful elements with low melting points interact at a crystal boundary, so that the segregation of the elements at the crystal boundary is inhibited, and the crystal boundary is purified and strengthened. More importantly, the grain boundary segregation of Y can inhibit the segregation of the main strengthening element Mn in the grain boundary, thereby being beneficial to forming fine and dispersed carbide precipitation and improving the strength and the toughness.
The application of low-cost rare earth elements represented by La and Ce in steel is wider and more mature, while the citation of heavy rare earth elements represented by Y in steel is still in a preliminary exploration stage, the patent integrates the action of light rare earth in steel and the application characteristics of heavy rare earth in partial light metal and special steel, and adopts the composite addition of Y, La and Ce to optimize the performance of hot-rolled steel bars, which is mainly attributed to the following points:
y, La and Ce each have an atomic radius of
And
the heavy rare earth Y has lighter atomic radius and small atomic radius of the rare earth elements La and Ce, so the heavy rare earth element Y is added into the steel and is likely to be easily dissolved into a matrix and occupy the position of a grain boundary, thereby playing the role of microalloying. Improve the high-temperature plasticity and the high-temperature oxidation resistance of the steel.
According to the Stocks formula, the floating speed of the YOxSy composite inclusion formed by the heavy rare earth Y and O, S in molten steel is doubled compared with that of the La (Ce) OxSy composite inclusion, so that the effect of deeply purifying the molten steel is very obvious.
And smelting of the rare earth composite steel is a conventional adding process of adding rare earth elements, and the rare earth composite steel is mainly added into a refining furnace. Different from other technologies, the method for adding the rare earth alloy comprises the following steps: the rare earth Y, La and Ce alloy is made into a linear product, and then the linear product is added into a continuous casting crystallizer through a wire feeding device. One of the smelting schemes is as follows:
step 1: smelting and refining
Smelting molten iron and/or scrap steel to obtain molten steel; when the condition is satisfied: the steel is tapped at the temperature of 1620-1680 ℃, the mass fraction of carbon is 0.1-0.2%, the mass fraction of oxygen is 0.02-0.05%, the mass fraction of phosphorus is 0.01-0.04%, the mass fraction of sulfur is 0.01-0.03%;
when the steel tapping amount is 1/2-3/4, adding silicon and manganese, and after steel tapping, adjusting the contents of C, Si and Mn elements in molten steel according to chemical components of hot rolled steel bars;
the ladle enters an LF refining furnace for refining, in order to ensure the stability of the final rare earth content, a calcium wire is fed firstly, the oxygen content in the molten steel is less than 50ppm, the sulfur content is less than 30ppm, and the optimal scheme is that the O + S content is less than 60 ppm. The calcium wire is fed to reduce the oxygen and sulfur content, protect the subsequent rare earth alloy wire and stabilize the absorption rate of the rare earth. The cheaper calcium is selected for pre-deoxidation and sulphur treatment, which is also beneficial to reducing the production cost. The soft argon blowing time is 5-10min, and the degassing time is less than 15 min.
Step 2: continuous casting
The continuous casting is a conventional process, molten steel is conveyed to an arc-shaped continuous casting workshop for continuous casting, and the specification of cast ingots is square billets.
During continuous casting, the molten steel liquid level in the crystallizer is ensured to be stable, and the fluctuation is preferably less than 15-20 mm. The crystallizer is fed with the composite rare earth alloy cored wire, the wire diameter is 6-9mm, the wire weight is 250-380 g/m, the adding amount is 2-4.5 m/ton of molten steel, and the adding speed is 2-4.5 m/min. The synchronization of the core-spun yarn adding speed and the continuous casting billet drawing speed is realized through signal sharing. The temperature is controlled between 1530 and 1550. After adding rare earth yttrium, lanthanum and cerium, the melting point and the alkalinity of the molten steel covering slag are changed, so that the components of the covering slag are adjusted, and 4-7% of one or more of boron trioxide, alumina powder, yttrium oxide, lanthanum and cerium are added on the basis of the conventional covering slag to adjust the melting point and the alkalinity of a slag system.
Feeding rare earth alloy wires into a crystallizer, wherein the rare earth content is as follows: y: 0.001-0.01%, Ce: 0.01-0.03%, 0.01-0.02% of La, and the optimal scheme is as follows: y: 0.005-0.01%, Ce: 0.02-0.025% and 0.01-0.015% of La.
And step 3: heating of continuous cast slab
And heating by using a walking beam heating furnace, wherein the heating temperature is 1150-1260 ℃, and the heating time is 30-120 min.
And 4, step 4: rolled steel bar
The initial rolling temperature is 1000-1040 ℃, the final rolling temperature is 900-980 ℃, and the rare earth composite inclusion is beneficial to refining grains.
And 5: cooling down
And naturally cooling the hot-rolled steel bar in the air to obtain a finished product.
The invention relates to a rare earth composite reinforced steel bar and a preparation method thereof, and the design concept is as follows:
the original production process of the steel bar has low requirement on the purity of the molten steel, and the steel bar is subjected to phase change through a water penetrating process so as to improve the performance of the steel bar and cover the adverse effect of the purity of the molten steel on the performance of the steel bar. Since the new national standard strictly prohibits the steel bar water-through process, it becomes impossible to strengthen the steel bar by the phase change. Therefore, under the condition of not changing production equipment, alloy strengthening is achieved by increasing the addition amount of alloy elements, and the method becomes the choice of various manufacturers, but the production cost is greatly increased, and meanwhile, the resource consumption is caused. The impurity content in the steel bar is reduced by improving the purity of the molten steel, and the adverse effect of the impurity on the performance of the steel bar can be reduced by changing the appearance of the residual impurity. Through principle and technical innovation, the production cost is reduced.
The invention is optimized in terms of components and production process: refining molten steel by LF, adding a calcium wire to control O, S content, thereby controlling the number of oxygen-sulfur inclusions and preparing molten steel pretreatment for later addition of rare earth to form fine rare earth oxysulfide; 2. the rare earth alloy wire is fed into the crystallizer, so that the problems of nozzle nodulation and nozzle blockage after the rare earth is added into the tundish are solved; 3. the rare earth is added into the crystallizer, so that the yield of the rare earth is improved, and the stability of the action of the rare earth is improved; 4, the rare earth Y has high solubility in steel, plays a role in strengthening the alloy, and can also inhibit the grain boundary segregation of Mn element, thereby being beneficial to forming fine and dispersed carbide precipitation and improving the elongation and the toughness; y can also improve the high-temperature plasticity and the high-temperature oxidation resistance of steel, and can reduce the rolling temperature in the process of rolling the steel bars, thereby reducing the production cost and reducing the loss of moulds. 4. After the rare earth is added, the rare earth can fix carbon and inhibit the segregation of the carbon, thereby improving the toughness and the elongation of the steel bar. Therefore, the aim of improving the strength of the steel bar can be achieved by increasing the content of cheaper carbon element without reducing the elongation and the toughness of the steel bar. The highest carbon content of the invention will exceed the national standard.
The invention has the beneficial effects that:
1. according to the invention, on the premise of controlling impurity elements such as S, O and the like within a certain range, the components of the hot-rolled steel bar are optimized, the rare earth Y, La and Ce are added in a compounding manner, the excellent effects of heavy rare earth and light rare earth elements are fully and comprehensively utilized, the comprehensive performance of the hot-rolled steel bar is greatly improved, and the production cost is obviously reduced.
2. The invention has simple production process, easy control and no need of large adjustment of the process.
3. The invention is beneficial to energy conservation and consumption reduction, alloy resource saving and effective utilization of high-abundance rare earth resources, and sustainable development is realized.
Drawings
Figure 1 SEM photograph/lamellar pearlite for the comparative example 1 sample;
figure 2 SEM photograph/lamellar pearlite for the example 7 sample;
figure 3 SEM photograph/tensile section of the sample of comparative example 1;
figure 4 SEM photograph/tensile section of example 7 sample;
FIG. 5, SEM photograph/tensile section of a sample of example 7, FIG. 4 is a partial enlargement;
figure 6 EDS energy spectrum of example 7 sample.
Detailed Description
The present invention is further illustrated by the following specific embodiments, which are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
Example 1
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.25%, Si: 0.8 percent of Mn, 1.55 percent of Mn, 0.024 percent of P, 0.0016 percent of S, 0.005 percent of Y, 0.021 percent of Ce, 0.015 percent of La and the balance of Fe and other inevitable impurities.
According to the components, the production process of the product comprises the following steps: oxygen top and bottom combined blowing converter → argon blowing → continuous casting → hot conveying → heating → rolling → cooling bed → finished product inspection → collection, packaging → weighing and hanging card → warehousing.
Specifically, a conventional oxygen top-bottom combined blown converter is adopted, argon is blown, and then continuous casting is carried out. A finished product of the deformed steel bar is obtained by adopting a rolling mode, a casting blank is heated to 1150 ℃ along with a furnace and is kept warm for 1.5 hours, so that all alloy elements in the steel are ensured to be dissolved and fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1040 ℃, the final rolling temperature is 950 ℃, and air cooling is adopted after rolling. Including but not limited to the implementation of the present solution, and the content that is not explicitly defined or required can be implemented by the conventional techniques in the art, as follows.
Example 2
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.83 percent, 1.6 percent of Mn, 0.017 percent of P, 0.0021 percent of S, 0.0082 percent of Y, 0.024 percent of Ce, 0.015 percent of La and the balance of Fe and other inevitable impurities.
According to the components, a conventional oxygen top-bottom combined blowing converter is adopted, argon is blown, continuous casting is carried out, a casting blank is heated to 1250 ℃ along with the furnace, heat preservation is carried out for 1.5 hours, all alloy elements in steel are ensured to be dissolved in solid, the alloy elements are fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1030 ℃, the final rolling temperature is 980 ℃, and air cooling is adopted after rolling.
Example 3
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.27%, Si: 0.80 percent of Mn, 1.66 percent of Mn, 0.02 percent of P, 0.0025 percent of S, 0.008 percent of Nb, 0.01 percent of Y, 0.025 percent of Ce, 0.015 percent of La and the balance of Fe and other inevitable impurities.
According to the components, a conventional oxygen top-bottom combined blowing converter is adopted, argon is blown, continuous casting is carried out, a casting blank is heated to 1250 ℃ along with the furnace, heat preservation is carried out for 1.5 hours, all alloy elements in steel are ensured to be dissolved in solid, the alloy elements are fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1030 ℃, the final rolling temperature is 950 ℃, and air cooling is adopted after rolling.
Example 4
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.27%, Si: 0.80 percent of Mn, 1.66 percent of Mn, 0.02 percent of P, 0.0025 percent of S, 0.005 percent of Nb, 0.008 percent of Y, 0.024 percent of Ce, 0.014 percent of La and the balance of Fe and other unavoidable impurities.
According to the components, a conventional oxygen top-bottom combined blowing converter and argon blowing are adopted, continuous casting is carried out, a casting blank is heated to 1260 ℃ along with the furnace, heat preservation is carried out for 1.5 hours, all alloy elements in the steel are ensured to be dissolved in solid, the alloy elements are fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1020 ℃, the final rolling temperature is 950 ℃, and air cooling is adopted after rolling.
Example 5
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.79 percent of Mn, 1.65 percent of Mn, 0.019 percent of P, 0.0022 percent of S, 0.008 percent of V, 0.009 percent of Y, 0.023 percent of Ce, 0.013 percent of La and the balance of Fe and other inevitable impurities.
According to the components, a conventional oxygen top-bottom combined blowing converter is adopted, argon is blown, continuous casting is carried out, a casting blank is heated to 1250 ℃ along with the furnace, heat preservation is carried out for 1.5 hours, all alloy elements in steel are ensured to be dissolved in solid, the alloy elements are fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1030 ℃, the final rolling temperature is 960 ℃, and air cooling is adopted after rolling.
Example 6
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.30%, Si: 0.79 percent of Mn, 1.65 percent of Mn, 0.019 percent of P, 0.0022 percent of S, 0.005 percent of V, 0.005 percent of Y, 0.020 percent of Ce, 0.011 percent of La and the balance of Fe and other inevitable impurities.
According to the components, a conventional oxygen top-bottom combined blowing converter is adopted, argon is blown, continuous casting is carried out, a casting blank is heated to 1250 ℃ along with the furnace, heat preservation is carried out for 1.5 hours, all alloy elements in steel are ensured to be dissolved in solid, the alloy elements are fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1030 ℃, the final rolling temperature is 960 ℃, and air cooling is adopted after rolling.
Example 7
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.25%, Si:0.77 percent, Mn 1.55 percent, P0.026 percent, S0.003 percent, Y0.0082 percent, Ce 0.024 percent, La 0.015 percent and the balance of Fe and other inevitable impurities.
Adopting a conventional oxygen top-bottom combined blown converter, blowing argon, and then continuously casting. The finished product of the deformed steel bar is obtained by adopting a rolling mode, the casting blank is heated to 1200 ℃ along with a furnace and is kept warm for 1.5 hours, so that all alloy elements in the steel are ensured to be dissolved and fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1000 ℃, the final rolling temperature is 900 ℃, and air cooling is adopted after rolling.
Example 8
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.82 percent, Mn 1.54 percent, P0.026 percent, S0.003 percent, Y0.01 percent, Ce 0.022 percent, La 0.01 percent and the balance of Fe and other inevitable impurities.
Adopting a conventional oxygen top-bottom combined blown converter, blowing argon, and then continuously casting. A deformed steel bar finished product is obtained by adopting a rolling mode, a casting blank is heated to 1180 ℃ along with a furnace and is kept warm for 1.5 hours, so that all alloy elements in the steel are ensured to be dissolved and fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1010 ℃, the final rolling temperature is 910 ℃, and air cooling is adopted after rolling.
Example 9
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.82 percent, Mn 1.54 percent, P0.026 percent, S0.003 percent, Y0.01 percent, Ce 0.022 percent, La 0.01 percent, V0.004 percent, Nb 0.003 percent, and the balance of Fe and other inevitable impurities.
Adopting a conventional oxygen top-bottom combined blown converter, blowing argon, and then continuously casting. A finished product of the deformed steel bar is obtained by adopting a rolling mode, the casting blank is heated to 1240 ℃ along with a furnace and is kept warm for 2 hours, so that all alloy elements in the steel are ensured to be dissolved and fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1000 ℃, the final rolling temperature is 900 ℃, and air cooling is adopted after rolling.
Example 10
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.82 percent, Mn 1.54 percent, P0.026 percent, S0.003 percent, Y0.01 percent, Ce 0.022 percent, La 0.01 percent, V0.002 percent, Nb 0.008 percent, and the balance of Fe and other inevitable impurities.
Adopting a conventional oxygen top-bottom combined blown converter, blowing argon, and then continuously casting. A finished product of the deformed steel bar is obtained by adopting a rolling mode, a casting blank is heated to 1150 ℃ along with a furnace and is kept warm for 2 hours, so that all alloy elements in the steel are ensured to be dissolved and fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1025 ℃, the final rolling temperature is 920 ℃, and air cooling is adopted after rolling.
Example 11
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.82 percent, Mn 1.54 percent, P0.026 percent, S0.003 percent, Y0.01 percent, Ce 0.022 percent, La 0.01 percent, V0.01 percent, and the balance of Fe and other inevitable impurities.
Adopting a conventional oxygen top-bottom combined blown converter, blowing argon, and then continuously casting. A finished product of the deformed steel bar is obtained by adopting a rolling mode, a casting blank is heated to 1150 ℃ along with a furnace and is kept warm for 0.5 hour, so that all alloy elements in the steel are ensured to be dissolved and fully diffused, the structure is homogenized, and partial segregation is eliminated. The initial rolling temperature is 1015 ℃, the final rolling temperature is 905 ℃, and air cooling is adopted after rolling.
Example 12
The embodiment provides a rare earth composite reinforced steel bar, which comprises the following components in percentage by weight: c: 0.26%, Si: 0.82 percent, Mn 1.54 percent, P0.026 percent, S0.003 percent, Y0.01 percent, Ce 0.022 percent, La 0.01 percent, Nb 0.01 percent, and the balance of Fe and other inevitable impurities.
Adopting a conventional oxygen top-bottom combined blown converter, blowing argon, and then continuously casting. And (3) obtaining a deformed steel bar finished product by adopting a rolling mode, heating the casting blank to 1170 ℃ along with a furnace, and preserving heat for 1.5 hours to ensure that all alloy elements in the steel are dissolved and fully diffused, so that the structure is homogenized and partial segregation is eliminated. The initial rolling temperature is 1040 ℃, the final rolling temperature is 950 ℃, and air cooling is adopted after rolling.
Comparative example 1
The difference from the embodiment 7 is that no rare earth element is added in the design components of the deformed steel bar, and the specific components in percentage by weight are as follows: c: 0.24%, Si: 0.77%, Mn 1.55%, P0.026%, S0.003%, and Fe and other inevitable impurities as the rest.
Comparative example 2
The difference from the embodiment is that the content of rare earth elements in the design components of the deformed steel bar is reduced, and the deformed steel bar comprises the following specific components in percentage by weight: c: 0.25%, Si: 0.8%, Mn 1.57%, P0.017%, S0.0025%, Y: 0.004%, Ce 0.008%, La 0.004%, and the balance of Fe and other unavoidable impurities.
Comparative example 3
The difference from the embodiment is that the content of rare earth elements in the design components of the deformed steel bar is increased, and the deformed steel bar comprises the following specific components in percentage by weight: c: 0.27%, Si: 0.77%, Mn 1.6%, P0.013%, S0.001%, Y0.014%, Ce 0.05%, La 0.027%, and the balance Fe and other unavoidable impurities.
The results of tensile property tests on the deformed steels of examples and comparative examples are shown in table 1 below:
TABLE 1 summary of tensile Properties of different deformed steels
From table 1, it is seen that the deformed steel bar with the rare earth added according to the present invention has high strength and high toughness, and the main reasons can be summarized as follows: firstly, as shown in fig. 1 and 2, the lamella spacing of pearlite is obviously reduced after the compound rare earth is added, and the volume fraction of pearlite of the deformed steel bar is increased, so that the strength and the toughness are ensured; on the other hand, as shown in fig. 3, 4, 5 and 6, submicron-sized rare earth composite inclusions are obviously observed in the tensile fracture tough socket core part after rare earth is added (fig. 5), which shows that rare earth not only plays a role in removing impurities, but also plays a role in a second phase and delays the propagation of cracks. The advantages of the product of the invention are reflected in FIGS. 1-6, which are comparative examples of example 7 and comparative example 1.
The technical range of the embodiment of the invention is not exhaustive, and a new technical scheme formed by equivalent replacement of single or multiple technical features of the cloud system/server by the remote control system in the technical scheme of the embodiment is also within the technical range of the invention; in all the embodiments of the present invention, which are listed or not listed, each parameter in the same embodiment only represents an example (i.e., a feasible embodiment) of the technical solution, and there is no strict matching and limiting relationship between the parameters, wherein the parameters may be replaced with each other without departing from the axiom and the requirements of the present invention, unless otherwise specified.
The technical means disclosed by the scheme of the invention are not limited to the technical means disclosed by the technical means, and the technical scheme also comprises the technical scheme formed by any combination of the technical characteristics. While the foregoing is directed to embodiments of the present invention, it will be appreciated by those skilled in the art that various changes may be made in the embodiments without departing from the principles of the invention, and that such changes and modifications are intended to be included within the scope of the invention.
Claims (10)
1. The rare earth composite reinforced hot-rolled steel bar is obtained by hot-rolling rare earth composite steel, and the rare earth composite steel comprises the following components in percentage by mass:
0.25-0.30% of C, 0.77-0.83% of Si, 1.54-1.66% of Mn, less than or equal to 0.04% of S, less than or equal to 0.045% of P, Y: 0.001-0.01%, Ce: 0.01-0.03%, 0.01-0.02% of La, and the balance of iron and inevitable impurities.
2. The rare earth composite reinforced hot-rolled steel bar as claimed in claim 1, wherein the rare earth content in the rare earth composite steel is as follows: y: 0.005-0.01%, Ce: 0.02-0.025% and 0.01-0.015% of La.
3. The rare earth composite reinforced hot-rolled steel bar as claimed in claim 1 or 2, wherein at least a part of Y, Ce, La in the rare earth composite steel is added through an intermediate alloy containing at least one of the three elements.
4. The rare earth composite reinforced hot-rolled reinforcing steel bar as claimed in claim 3, wherein the intermediate alloy is a rare earth ferrosilicon alloy containing three elements of Y, Ce and La.
5. The rare earth composite reinforced hot-rolled steel bar as claimed in any one of claims 1 to 4, wherein the rare earth composite steel further comprises Nb in an amount of, by mass fraction: 0.005-0.01 percent.
6. The rare earth composite reinforced hot-rolled reinforcing steel bar as claimed in claim 5, wherein the rare earth composite steel further comprises V in an amount of, in mass fraction: 0.005-0.01 percent.
7. The rare earth composite reinforced hot-rolled steel bar as claimed in claim 6, wherein the total amount of the rare earth composite steels Nb and V is, in terms of mass fraction: 0.005-0.01 percent.
8. The preparation method of the rare earth composite reinforced hot rolled steel bar comprises the following steps,
A. smelting molten steel, namely adding the rare earth alloy covered wire into the molten steel to realize the preparation of the molten steel of the rare earth composite steel, wherein the molten steel of the rare earth composite steel comprises the following components in percentage by mass:
0.25-0.30% of C, 0.77-0.83% of Si, 1.54-1.66% of Mn, less than or equal to 0.04% of S, less than or equal to 0.045% of P, Y: 0.001-0.01%, Ce: 0.01-0.03%, 0.01-0.02% of La and the balance of iron and inevitable impurities; wherein the rare earth alloy covered wire is obtained from an intermediate alloy containing at least one of Y, Ce and La, and the casting blank is prepared by smelting the alloy;
B. the casting blank is hot rolled to obtain the steel bar.
9. The method for preparing the rare earth composite reinforced hot-rolled steel bar according to claim 8, wherein the molten steel contains three rare earth elements in the following content: y: 0.005-0.01%, Ce: 0.02-0.025% and 0.01-0.015% of La.
10. The method for preparing the rare earth composite reinforced hot-rolled reinforcing steel bar according to claim 9, wherein the intermediate alloy is rare earth silicon-iron alloy containing three elements of Y, Ce and La.
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