CN115652209B - 650MPa grade sulfuric acid dew point corrosion resistant rare earth steel and manufacturing method thereof - Google Patents
650MPa grade sulfuric acid dew point corrosion resistant rare earth steel and manufacturing method thereof Download PDFInfo
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Abstract
The invention provides 650MPa grade sulfuric acid dew point corrosion resistant rare earth steel and a manufacturing method thereof, wherein the steel comprises the following components in percentage by weight: c:0.074% -0.095%, si:0.41 to 0.64 percent of Mn:0.87% -1.18%, P: less than or equal to 0.017 percent, S: less than or equal to 0.0050 percent, cr:0.92 to 1.17 percent of Ni:0.26 to 0.37 percent of Cu:0.16 to 0.26 percent, 0.102 to 0.132 percent of Sb, 0.064 to 0.085 percent of Ti, 0.58 to 0.73 percent of Sn, and Als:0.018% -0.041%, ce:0.048% -0.058%, O: less than or equal to 3.8ppm, and the balance of Fe and unavoidable impurities. The manufacturing method comprises smelting, continuous casting, casting blank heating, rolling, laminar cooling and coiling; the yield strength of the rare earth steel produced by the invention is more than 650MPa, the tensile strength is between 759 and 791MPa, and the elongation is more than 19%.
Description
Technical Field
The invention belongs to the field of metal materials, and particularly relates to 650 MPa-grade sulfuric acid dew point corrosion-resistant rare earth steel and a manufacturing method thereof.
Background
At present, a flue gas system using heavy oil or fire coal as main fuel in various industrial fields such as electric power, metallurgy, petrochemical industry and the likeThe problem of "sulfuric acid dew point corrosion" is common in the past. In particular, in devices such as boiler preheaters and economizer apparatus, air preheater heat exchange elements, dust collectors, and flue gas and stack stacks, the sulfur content in the flue gas is relatively high to catalyze the formation of sulfides (SO 3 ) Then combines with water vapor in the flue gas to form sulfuric acid vapor, and condenses into sulfuric acid on the metal wall below the dew point temperature of sulfuric acid, thereby generating acid corrosion problem on equipment. In order to reduce the maintenance cost and prolong the safe service life of the steel structural member, it is highly required to develop acid-resistant steel with excellent sulfuric acid dew point corrosion resistance.
The invention discloses a rare earth alloy steel resistant to sulfuric acid dew point corrosion (publication number: CN 1386886A), which comprises the following components: c: less than or equal to 0.15 percent, si:0.15 to 1.20 percent of Mn:0.30 to 1.50 percent of Cu:0.20% -0.80%, W:0.10% -0.60%, mo:0.10 to 0.50 percent, 0.05 to 0.30 percent of Sn, 0.05 to 0.30 percent of Sb, less than or equal to 0.50 percent of RE and S: less than or equal to 0.035 percent, P: less than or equal to 0.035 percent, and the balance of Fe and impurities; the noble metal W is added, and the addition of W in steel tends to increase the alloy cost.
The invention discloses a rare earth sulfuric acid dew point corrosion resistant steel and a preparation method thereof (publication number: CN 111206178A), wherein the steel comprises the following components: c:0.07 to 0.11 percent of Si:0.20 to 0.50 percent of Mn:0.40% -0.65%, P: less than or equal to 0.020%, S: less than or equal to 0.035%, 0.010% -0.060% of Al, 0.85% -1.10% of Cr, cu:0.30 to 0.45 percent, 0.04 to 0.10 percent of Sb, and Ni:0.15 to 0.35 percent RE:0.001% -0.010%, and the balance of Fe and impurities. In the aspect of performance inspection, the corrosion resistance of the test steel is not given, the corrosion resistance effect is unknown, and the invention describes a laboratory smelting-rolling method, wherein a die casting process is adopted to produce the steel plate, but the die casting process cannot be used for producing the large-scale steel plate in the field actual production.
According to the technical scheme disclosed in the invention (publication number: CN 1475580A) of the rare earth addition amount optimization control method of rare earth weathering steel, 0.010-0.030% of rare earth is added into the weathering steel; although the corrosion resistance of the product is improved by adding Cu and Re, the independent addition of Cu is easy to cause the phenomenon of copper embrittlement of the steel plate, and the difficulty of the hot rolling process is increased. Meanwhile, the steelmaking and rolling process, especially the rare earth adding process, is not clear. In addition, the various mechanical property indexes of the steel are not explicitly described.
The invention discloses a rare earth element-containing coating-free weathering steel and a preparation method thereof (publication number: CN 109252092A), wherein the steel comprises the following components: c:0.03 to 0.09 percent of Si:0.10 to 0.30 percent of Mn:1.00% -1.50%, P:0.005% -0.015%, S: less than or equal to 0.005 percent, 0.35 to 0.70 percent of Cr, and Ni:0.25% -0.55%, cu:0.25% -0.55%, mo:0.03 to 0.25 percent of Re: 0.005-0.060 percent of Nb 0.015-0.040 percent of Ti 0.008-0.025 percent of Al 0.015-0.040 percent of Ca:0.003 to 0.018 percent, and the balance being Fe and impurities. The corrosion resistance of the steel is evaluated by the atmospheric corrosion resistance index I, the index is calculated according to a theoretical formula and is not verified by a corrosion test, so that the actual corrosion resistance effect is unknown; in addition, the tempering technology is adopted to improve the mechanical property of the steel, so that the technology is complex, and the production cost is increased.
The invention discloses a rare earth low alloy steel resistant to high temperature sulfuric acid dew point corrosion, which is disclosed in publication No.: the technical scheme disclosed in CN 101892438A is that the sulfuric acid dew point corrosion resistance of the product is improved by adding corrosion resistant elements such as Cr+Cu+Ni+RE, but the method has the defects that the method adopts higher Cu content and has higher production cost. The invention only emphasizes the influence on corrosion resistance, and does not give the comprehensive mechanical condition of the steel. In addition, no related steelmaking and rolling processes, especially rare earth addition processes during smelting, are provided. The adding method and the yield of the rare earth are difficult problems in the actual smelting process.
Disclosure of Invention
The invention aims to overcome the problems and the shortcomings and provide the 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel suitable for being used in an acidic industrial corrosion environment and the manufacturing method thereof, and the steel plate not only has good and stable mechanical properties, but also has higher sulfuric acid dew point corrosion resistance.
The invention aims at realizing the following steps:
a650 MPa grade sulfuric acid dew point corrosion resistant rare earth steel comprises the following components in percentage by weight: c:0.074% -0.095%, si:0.41 to 0.64 percent of Mn:0.87% -1.18%, P: less than or equal to 0.017 percent, S: less than or equal to 0.0050 percent, cr:0.92 to 1.17 percent of Ni:0.26 to 0.37 percent of Cu:0.16 to 0.26 percent, 0.102 to 0.132 percent of Sb, 0.064 to 0.085 percent of Ti, 0.58 to 0.73 percent of Sn, and Als:0.018% -0.041%, ce:0.048% -0.058%, O: less than or equal to 3.8ppm, and the balance of Fe and unavoidable impurities.
Further, the microstructure of the rare earth steel is ferrite and bainite, wherein the volume percentage of ferrite is 44.7-49.8%;
further, the Sn/Ce value in the rare earth steel is 12.0-14.1, and Ce is precipitated along the grain boundary of 20-25 nm in the rare earth steel 5 Sn 3 。
Furthermore, the yield strength of the rare earth steel is more than 650MPa, the tensile strength is between 759 and 791MPa, and the elongation is more than 19 percent
The reason for designing the components of the invention is as follows:
c: as one of the main reinforcing elements, an increase in C content is advantageous for improvement of strength and hardness of the steel sheet, but a large amount of C adversely affects properties such as impact toughness and plasticity of the steel sheet. The content of the C is limited to 0.074% -0.095% in the invention.
Si: the strong deoxidizing element in the steelmaking process can be used as a solid solution strengthening element to improve the yield strength of the steel plate, but the excessively high content not only can reduce the welding performance of the steel plate, but also can form a red iron oxide scale which is difficult to remove after the steel plate is rolled. The Si content is limited to 0.41-0.64% in the invention.
Mn: the steel mainly plays a solid solution strengthening role in steel, and can improve the tensile strength of the steel plate. However, too high Mn content causes segregation, deteriorating the weldability and formability of the steel. Therefore, the Mn content in the present invention is controlled to be 0.87% -1.18%.
P: although one of the alloying elements that functions as solid solution strengthening and remarkably improves corrosion resistance, segregation occurs at grain boundaries when the content is high, and the weldability, plasticity, and toughness of the steel sheet are lowered. The steel of the invention is controlled below 0.017%.
S: is a harmful impurity element, is liable to form defects such as segregation and inclusion, and deteriorates the impact toughness and hot workability of the steel sheet. Therefore, the S content in the present invention should be controlled to be 0.005% or less.
Cr: a compact oxide film Cr2O3 is easy to form on the surface of the steel plate, and the adhesive force of the rust layer and the matrix can be improved, so that the passivation capability of the steel is improved. In addition, the improvement of Cr element is favorable for refining alpha-FeOOH, so that the strength and toughness of the steel plate can be improved. However, if the content is too high, the weldability of the steel sheet is deteriorated. Therefore, the Cr content in the invention is controlled to be 0.92-1.17%.
Cu: is an essential element for improving the corrosion resistance of the steel plate, and can play a solid solution strengthening role at the same time, so that the strength of the steel plate is improved, but when the content is higher, the hot shortness of the steel plate is easily caused. Meanwhile, the content range of the invention is limited to 0.16-0.26% by considering the cost factor.
Ni: the corrosion-resistant alloy is one of elements for improving the strength and the impact toughness of the steel plate, and can not only improve the problem of copper brittleness of the steel plate, but also obviously improve the corrosion resistance of the steel plate when being reasonably matched with Cu. However, ni is a noble metal element, and the addition amount of Ni in the present invention is 0.26 to 0.37% from the viewpoint of cost control.
Ti is one of the alloying elements which play a role in strengthening. The Ti compound in the steel can effectively prevent the growth of austenite grains in the heating process, plays a role in fine grain strengthening, and TiC precipitated in the cooling process also plays a role in precipitation strengthening. And meanwhile, the welding performance of the steel plate can be improved. The range of the invention is limited to 0.064% -0.085%.
Sb is an effective element for improving corrosion resistance, plays a role in catalyzing enrichment of corrosion-resistant elements, promotes enrichment of Cu, cr and other corrosion-resistant elements on the surface of a rust layer, forms a layer of compact oxide film containing Sb, cr, cu and other corrosion-resistant elements and having obvious corrosion-resistant effect on the surface of a steel plate, can effectively improve the acid corrosion resistance of the steel plate, but has insignificant catalysis effect when the content is low, so that the invention is limited to be 0.102-0.132%.
Sn is generally a residual impurity element in steel, and is easily segregated at grain boundaries. However, sn is an effective element for improving acid corrosion resistance and enhancing precipitation in the present invention. When the corrosion-resistant protective film is added in combination with Cr, cu and Sb elements, the enrichment of each corrosion-resistant element on the surface of a rust layer is promoted, and the generated stable-state SnO2 corrosion product protective film can effectively improve the acid corrosion resistance of the steel plate. When the Ce is added in a matching way, ce-Sn compound Ce5Sn3 with high melting point and 20-25 nm can be generated by the interaction of the Ce-Sn compound Ce5Sn3 and the steel plate, and the steel plate is often separated out along a grain boundary in the cooling process, thereby playing a good role in precipitation strengthening. In the invention, the Sn/Ce value is 12.0-14.1, and the Sn content is set to be 0.58-0.73%.
Als: the main deoxidizing element is favorable for refining grains and improving the mechanical property of the steel plate, and the range of the deoxidizing element is limited to be 0.018% -0.041%.
Ce: ce in the present invention has the following effects: (1) The morphology and the variety of impurities such as Sn, al2O3, mnS and the like are changed, the plasticity and the toughness of the steel are obviously improved, and the anisotropy of impact performance can be particularly reduced. (2) Due to the change of the morphology of the inclusions, the potential difference between the inclusions and the matrix is reduced, the trend of electrochemical corrosion in steel is reduced, and the corrosion resistance of the steel plate is effectively improved; (3) Has stronger affinity with Sn with low melting point, can obviously inhibit the segregation of Sn at the grain boundary, and forms a Ce-Sn compound with high melting point and nanometer grade with Sn at the grain boundary to improve the strength of the steel plate. (4) The CeO particles distributed in a dispersed manner gather at the grain boundary to obviously block the movement of dislocation, so that the strength of the steel plate is improved. However, the lower Ce content in the steel does not play a role in corrosion resistance, so that the Ce content in the steel is controlled to be 0.048-0.058% in order to make the added Ce fully play a role.
O: as a harmful and strong oxidizing element in the steel, the rare earth element is easy to react with the added rare earth element to form corresponding rare earth oxide. The excessive O content can cause that a large amount of rare earth inclusions are formed in the molten steel to influence the fluidity of the molten steel, and when serious, the inclusions can block a water gap to cause flocculation. Therefore, the free O content in the steel of the present invention should be controlled to 3.8ppm or less.
The second technical proposal of the invention is to provide a manufacturing method of 650MPa grade sulfuric acid dew point corrosion resistant rare earth steel, which comprises smelting, continuous casting, casting blank heating, rolling, laminar cooling and coiling;
smelting:
(1) Pre-desulphurisation of molten iron
In order to improve the smelting efficiency of the converter, desulfurization powder is sprayed into a torpedo ladle car filled with molten iron to carry out desulfurization pretreatment, so that S is less than or equal to 0.003%, and slag removal is thorough for solid slag such as CaS, mgS and the like.
(2) Converter steelmaking:
adopting a top-bottom combined converting process, wherein the tapping temperature of the converter is 1678-1698 ℃, and the final slag alkalinity R is more than or equal to 4.0. Argon is blown in the whole tapping process, 1.57-1.73 kg/ton of molten steel modifier is added after tapping to carry out modification treatment on top slag, and the argon blowing time after adding is more than or equal to 7min.
(3) LF+RH external refining
Heating treatment is carried out in an advanced LF furnace for 33-43min, the temperature is raised to above 1614 ℃, stirring is carried out for 11-15min after heating, and calcium treatment is carried out, so that the content of calcium fed into molten steel is controlled to be more than or equal to 0.006%.
And then the ladle is moved out and poured into an RH furnace, at the moment, the free O content in the steel is controlled below 5ppm, the furnace temperature is controlled above 1599 ℃, the mass fraction of Ce in the Fe-Ce rare earth alloy added into the RH furnace is 19.4-20.6%, the adding amount of the Ce is 3.72-4.74 kg/ton of molten steel, then argon weak blowing is carried out, the inclusion in the molten steel is promoted to float upwards, the weak blowing time is 5.2-6.2 min, and the molten steel is carried out of a crane.
Continuous casting: the continuous casting process is put into a dynamic soft reduction technology, the soft reduction is controlled between 3.2 and 7.2mm, so that center porosity and segregation are strictly controlled, the internal quality of a casting blank is ensured, and the thickness specification of the continuous casting blank is 230 to 250mm. In addition, the whole process uses the protective slag to protect the molten steel so as to prevent oxygen from entering the molten steel for secondary oxidation, and the thickness of a slag layer is controlled to be more than 18 mm. In order to reduce the steel flocculation property of the water gap and ensure the smooth casting of the rare earth steel, the temperature of the tundish is controlled at 1550-1570 ℃ and the blank pulling speed is 1.31-1.41 m/min.
Heating a casting blank: in order to ensure that each element can be fully dissolved in solid and avoid unnecessary billet oxidation loss caused by overhigh heating temperature, the temperature of a casting blank soaking section is controlled between 1234 ℃ and 1256 ℃ and the total furnace time is 204-224 min, wherein the soaking section has the heat preservation time of 46-58 min.
Rolling: the two-stage controlled rolling process is adopted, the rough rolling outlet temperature is 1094-1114 ℃, and the thickness of the obtained intermediate blank is more than 3 times of the thickness of the finished product. The initial rolling temperature of the finish rolling is 1085-1105 ℃, and the final rolling temperature of the finish rolling is 889-911 DEG C
Laminar cooling and coiling: and (3) carrying out laminar cooling on the rolled steel plate, wherein the laminar cooling adopts rear-section concentrated cooling. Cooling at 26-36 deg.c/s to 626-645 deg.c, coiling, and air cooling to room temperature. And (5) coiling, and air cooling to room temperature after coiling.
The invention has the beneficial effects that:
the invention adds Fe-Ce rare earth alloy into steel by adopting a new adding process during smelting, thereby not only ensuring that the rare earth can be uniformly and stably reserved in the steel, but also obtaining higher rare earth yield which is more than 55 percent, and providing the rare earth steel for resisting sulfuric acid dew point corrosion with the yield strength of more than 650 MPa. The yield strength of the steel of the embodiment of the invention is more than 650MPa, the tensile strength is between 759 and 791MPa, the elongation is more than 19%, the average value of impact energy at minus 40 ℃ is not less than 63J, the anisotropy of impact performance can be reduced, the average value of horizontal impact energy and longitudinal impact energy is not more than 2J, the steel plate has excellent comprehensive mechanical properties, and the corrosion rate of the steel plate is 4.9 to 6.2mg/cm 2 H, the corrosion rate of the alloy is 14.24 to 16.14% relative to Q345B. The acid-resistant rare earth steel plate has simple manufacturing process and excellent comprehensive performance, particularly acid corrosion resistance, and can be widely applied to equipment manufacturing in a flue gas treatment system taking heavy oil or coal as a main raw material.
Detailed Description
The invention is further illustrated by the following examples.
According to the technical scheme, the embodiment of the invention carries out smelting, continuous casting, casting blank heating, rolling, laminar cooling and coiling.
Heating a casting blank: the temperature of the casting blank soaking section is 1234-1256 ℃, the total furnace time is 204-224 min, and the heat preservation time of the soaking section is 46-58 min;
rolling: adopting a two-stage controlled rolling process, wherein the rough rolling outlet temperature is 1094-1114 ℃, and the thickness of the intermediate billet is more than 3 times of the thickness of the finished product; the initial rolling temperature of the finish rolling is 1085-1105 ℃, and the final rolling temperature of the finish rolling is 889-911 ℃;
laminar cooling and coiling: the rolled steel plate is subjected to laminar cooling, and the back section concentrated cooling is adopted for the laminar cooling; cooling at 26-36 deg.c/s to 626-645 deg.c, coiling, and air cooling to room temperature.
Further; molten iron pre-desulfurization in the smelting process: in order to improve the smelting efficiency of the converter, desulfurizing powder is sprayed into a torpedo ladle car filled with molten iron for desulfurization pretreatment, so that S is less than or equal to 0.003%, and slag removal is thorough for solid slag such as CaS, mgS and the like;
converter steelmaking in the smelting process: adopting a top-bottom combined converting process, wherein the tapping temperature of the converter is 1678-1698 ℃, and the final slag alkalinity R is more than or equal to 4.0; argon is blown in the whole tapping process, 1.57-1.73 kg/ton of molten steel modifier is added after tapping to carry out modification treatment on top slag, and the argon blowing time after adding is more than or equal to 7min.
Further; LF+RH external refining in smelting process
And (3) heating in an LF furnace for 33-43min, and heating to above 1614 ℃. Stirring for 11-15min after heating, and performing calcium treatment to control the content of calcium fed into molten steel to be more than or equal to 0.006%;
then the ladle is moved out and poured into an RH furnace, at the moment, the free O content in the steel is controlled to be lower than 5ppm and the furnace temperature is controlled to be higher than 1599 ℃, fe-Ce rare earth alloy is added into the RH furnace, then argon weak blowing is carried out, the inclusion in the molten steel is promoted to float upwards, the weak blowing time is 5.2-6.2 min, and the molten steel is carried out of the furnace; preferably, the mass fraction of Ce in the Fe-Ce rare earth alloy is 19.4-20.6%, and the addition amount is 3.72-4.74 kg/ton of steel.
Further; continuous casting: the continuous casting process is put into a dynamic soft reduction technology, the whole process uses the covering slag to protect molten steel, and the thickness of a slag layer is controlled to be more than 18 mm; the temperature of the tundish is controlled at 1550-1570 ℃, the blank pulling speed is 1.31-1.41 m/min, and the thickness of the continuous casting blank is 230-250 mm; preferably, the light reduction is controlled to 3.2-7.2 mm.
The smelting process parameters of the steel of the embodiment of the invention are shown in Table 1, the continuous casting process parameters of the steel of the embodiment of the invention are shown in Table 2, the components of the steel of the embodiment of the invention are shown in Table 3, the main heating and rolling process parameters of the steel of the embodiment of the invention are shown in Table 4, the addition amount and yield of Ce in the steel of the embodiment of the invention are shown in Table 5, the performance of the steel of the embodiment of the invention is shown in Table 6, the microstructure of the steel of the embodiment of the invention is shown in Table 7, and the total immersion corrosion test result of the steel of the embodiment of the invention is shown in Table 8.
TABLE 1 Main technological parameters for smelting Steel according to an embodiment of the invention
TABLE 2 main process parameters for continuous casting of steel in accordance with the embodiment of the invention
| Examples | Reduction per mm | Thickness/mm of casting blank | Slag thickness/mm | Tundish temperature/°c | Pulling speed m/min |
| 1 | 3.2 | 230 | 18.6 | 1550 | 1.36 |
| 2 | 3.6 | 230 | 19.1 | 1554 | 1.31 |
| 3 | 4.3 | 230 | 19.4 | 1563 | 1.34 |
| 4 | 4.7 | 230 | 20.2 | 1558 | 1.37 |
| 5 | 5.7 | 230 | 20.6 | 1561 | 1.38 |
| 6 | 6.3 | 250 | 21.4 | 1567 | 1.39 |
| 7 | 6.4 | 250 | 21.8 | 1564 | 1.40 |
| 8 | 7.2 | 250 | 22.3 | 1570 | 1.41 |
TABLE 3 composition (wt%) of the inventive example steel
Note that: s is S n /C e No unit
TABLE 4 heating and Rolling Main Process parameters of the inventive example Steel
TABLE 5 addition amount and yield of Ce in the inventive example steel
TABLE 6 mechanical Properties of the inventive example steels
TABLE 7 microstructure of inventive example steels
TABLE 8 Corrosion resistance of the inventive example steels
As can be seen from Table 5, the Ce yield in the examples is higher, ranging from 55.42 to 61.27%; as can be seen from Table 6, the yield strength of the steel of the embodiment of the invention is more than 650MPa, the tensile strength is between 759 and 791MPa, the elongation is more than 19%, the cold bending performance is qualified, the transverse and longitudinal performances are stable, the difference of the transverse and longitudinal strengths is not more than 8MPa, and the average difference of the transverse and longitudinal impact energy is not more than 2J; the results in Table 7 show that the structure of the steel of the invention is composed of ferrite and bainite, and the structure is uniform and fine, and the grades of various inclusions are lower.
The total immersion corrosion test was carried out according to the test method prescribed by JB/T7901-1999 under the conditions of 20 ℃ temperature, 20% sulfuric acid concentration and 24 hours total immersion. Table 8 shows the results of comparison of sulfuric acid corrosion resistance of the inventive example steel and the comparative steel. As can be seen from Table 8, the corrosion rate of the steel sheet of the present invention is 4.9 to 6.2mg/cm 2 And h, the sulfuric acid dew point corrosion resistance of the steel of the embodiment of the invention is obviously superior to that of the comparative steel Q345B, and the durability of the steel plate in an acid corrosion environment can be effectively improved.
The present invention has been properly and fully described in the foregoing embodiments by way of example only, and not by way of limitation, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, any modification, equivalent substitution, improvement, etc. should be included in the scope of the invention, and the scope of the invention is defined by the claims.
Claims (8)
1. A650 MPa grade sulfuric acid dew point corrosion resistant rare earth steel is characterized by comprising the following components in percentage by weight: c:0.074% -0.095%, si:0.41 to 0.64 percent of Mn:0.87% -1.18%, P: less than or equal to 0.017 percent, S: less than or equal to 0.0050 percent, cr:0.92 to 1.17 percent of Ni:0.26 to 0.37 percent of Cu:0.16 to 0.26 percent, 0.102 to 0.132 percent of Sb, 0.064 to 0.085 percent of Ti, 0.58 to 0.73 percent of Sn, and Als:0.018% -0.041%, ce:0.048% -0.058%, O: less than or equal to 3.8ppm, and the balance of Fe and unavoidable impurities; the Sn/Ce value in the rare earth steel is 12.0-14.1, and 20-25 nm Ce is precipitated along the grain boundary 5 Sn 3 ；
The manufacturing method of the 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel comprises smelting, continuous casting, casting blank heating, rolling, laminar cooling and coiling;
heating a casting blank: the temperature of the casting blank soaking section is 1234-1256 ℃, the total furnace time is 204-224 min, and the heat preservation time of the soaking section is 46-58 min;
rolling: adopting a two-stage controlled rolling process, wherein the rough rolling outlet temperature is 1094-1114 ℃, and the thickness of the intermediate billet is more than 3 times of the thickness of the finished product; the initial rolling temperature of the finish rolling is 1085-1105 ℃, and the final rolling temperature of the finish rolling is 889-911 ℃;
laminar cooling and coiling: the rolled steel plate is subjected to laminar cooling, and the back section concentrated cooling is adopted for the laminar cooling; cooling at 26-36 deg.c/s to 626-645 deg.c, coiling, and air cooling to room temperature.
2. The 650 MPa-level sulfuric acid dew point corrosion resistant rare earth steel according to claim 1, wherein the microstructure is ferrite+bainite, and wherein the ferrite is 44.7% -49.8% by volume.
3. The 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel according to claim 1, wherein the yield strength of the rare earth steel is above 650MPa, the tensile strength is between 759 and 791MPa, and the elongation is greater than 19%.
4. The 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel according to claim 1, wherein:
molten iron pre-desulfurization in the smelting process: spraying desulfurization powder into a torpedo ladle car filled with molten iron to carry out desulfurization pretreatment, so that S is less than or equal to 0.003%, and slagging off is thoroughly carried out on solid slag such as CaS, mgS and the like;
converter steelmaking in the smelting process: adopting a top-bottom combined converting process, wherein the tapping temperature of a converter is 1678-1698 ℃, and the final slag alkalinity R is more than or equal to 4.0; argon is blown in the whole tapping process, 1.57-1.73 kg/ton of molten steel modifier is added after tapping to carry out modification treatment on top slag, and the argon blowing time after adding is more than or equal to 7min.
5. The 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel according to claim 1, wherein: LF+RH external refining in smelting process
Heating in an LF furnace for 33-43min, heating to above 1614 ℃, stirring for 11-15min after heating, and performing calcium treatment to control the content of calcium fed into molten steel to above 0.006%;
and then the ladle is moved out and poured into an RH furnace, at the moment, the free O content in the steel is controlled below 5ppm, the furnace temperature is controlled above 1599 ℃, fe-Ce rare earth alloy is added into the RH furnace, then argon weak blowing is carried out, the inclusion in the molten steel is promoted to float upwards, the weak blowing time is 5.2-6.2 min, and the molten steel is carried out.
6. The 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel according to claim 5, wherein: the mass fraction of Ce in the Fe-Ce rare earth alloy is 19.4% -20.6%, and the addition amount of the Ce is 3.72-4.74 kg/ton of steel.
7. The 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel according to claim 1, wherein:
continuous casting: the continuous casting process is put into a dynamic soft reduction technology, the whole process uses the covering slag to protect molten steel, and the thickness of a slag layer is controlled to be more than 18 mm; the temperature of the tundish is 1550-1570 ℃, the blank pulling speed is 1.31-1.41 m/min, and the thickness of the continuous casting blank is 230-250 mm.
8. The 650 MPa-grade sulfuric acid dew point corrosion resistant rare earth steel according to claim 7, wherein: the light rolling reduction is controlled to be 3.2-7.2 mm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211387242.1A CN115652209B (en) | 2022-11-07 | 2022-11-07 | 650MPa grade sulfuric acid dew point corrosion resistant rare earth steel and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1386886A (en) * | 2001-05-23 | 2002-12-25 | 束润涛 | Rare-earth alloy steel resisting dew point corrosion of sulfuric acid |
| CN103397280A (en) * | 2013-08-15 | 2013-11-20 | 卓然(靖江)设备制造有限公司 | Corrosion resistance steel and production method thereof |
| CN104357754B (en) * | 2014-10-17 | 2016-06-22 | 江阴兴澄特种钢铁有限公司 | A kind of corrosionproof steel against sulfuric acid at dew point plate and manufacture method thereof |
| CN105937010B (en) * | 2016-06-30 | 2018-06-19 | 江阴兴澄特种钢铁有限公司 | A kind of modified 09GrCuSb steel for resisting sulfuric acid dew point corrosion and its manufacturing method |
| CN106756602A (en) * | 2016-12-02 | 2017-05-31 | 钢铁研究总院 | A kind of resistance to damp and hot marine atmosphere high-strength weathering steel high |
| CN109628844B (en) * | 2019-02-12 | 2020-05-29 | 鞍钢股份有限公司 | Corrosion-resistant steel with yield strength of 700MPa for coal transportation open wagon and manufacturing method thereof |
| CN111809106A (en) * | 2020-06-15 | 2020-10-23 | 包头钢铁（集团）有限责任公司 | Rare earth microalloyed 650CL wheel steel and production method thereof |
| CN112322976A (en) * | 2020-10-30 | 2021-02-05 | 包头钢铁（集团）有限责任公司 | Rare earth wear-resistant steel NM400 coiled plate with excellent low-temperature-resistant toughness and production method thereof |
| CN113005365B (en) * | 2021-02-18 | 2022-11-01 | 包头钢铁（集团）有限责任公司 | Sulfuric acid corrosion resistant hot rolled steel plate containing rare earth cerium and preparation method thereof |
| CN115011876B (en) * | 2022-05-30 | 2023-07-14 | 鞍钢股份有限公司 | Steel for high-temperature sulfuric acid dew point corrosion resistance and manufacturing method |
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