CN115011876B - Steel for high-temperature sulfuric acid dew point corrosion resistance and manufacturing method - Google Patents

Steel for high-temperature sulfuric acid dew point corrosion resistance and manufacturing method Download PDF

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CN115011876B
CN115011876B CN202210600764.9A CN202210600764A CN115011876B CN 115011876 B CN115011876 B CN 115011876B CN 202210600764 A CN202210600764 A CN 202210600764A CN 115011876 B CN115011876 B CN 115011876B
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steel
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sulfuric acid
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孙傲
刘志伟
张瑞琦
郭晓宏
王鑫
吴成举
高洪涛
唐明宇
孙杭
严平沅
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Angang Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • C—CHEMISTRY; METALLURGY
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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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    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
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Abstract

The invention relates to a high temperature sulfuric acid dew point corrosion resistant steel and a manufacturing method thereof, wherein the steel comprises the following chemical components: c:0.052% -0.087%, si:0.21 to 0.63 percent, mn:0.34 to 1.04 percent, P: less than or equal to 0.015 percent, S: less than or equal to 0.006 percent, cr:0.43 to 1.23 percent, ni:0.22 to 0.43 percent, cu:0.17 to 0.27 percent, sb:0.06% -0.13%, ti:0.013 to 0.043 percent, sn:0.04% -0.11%, nb:0.012% -0.024%, alt:0.024% -0.054%, N:0.008 to 0.014 percent, ca:0.0034 to 0.0041 percent. The advantages are that: the steel plate structure is uniform and fine ferrite, pearlite distributed in a dispersed manner and a small amount of bainite.

Description

Steel for high-temperature sulfuric acid dew point corrosion resistance and manufacturing method
Technical Field
The invention relates to steel for high-temperature sulfuric acid dew point corrosion resistance and a manufacturing method thereof.
Background
In a flue gas treatment system using heavy oil or coal as a main fuel in the industrial fields of metallurgy, electric power, petrochemical industry and the like, sulfuric acid is generated after a series of reactions such as combustion and the like due to higher sulfur content in the fuel, so that the problem of corrosion and damage to equipment due to 'sulfuric acid dew point corrosion' is generally caused. In recent years, as the use of the steel plate gradually progresses to a high-temperature environment, the yield strength of the steel plate is reduced and the oxidizing property of acid is enhanced due to the increase of the service environment temperature of the steel plate, the high-temperature sulfuric acid corrosion hazard of a metal material is relatively large, and the mechanical property and the sulfuric acid corrosion resistance of the original steel plate are reduced and can not meet the use requirements in the high-temperature environment. Among the solutions to the high-temperature sulfuric acid corrosion problem, the most economical, effective and feasible method is to use a steel plate with stronger high-temperature sulfuric acid dew point corrosion resistance.
Aiming at the problem of sulfuric acid corrosion, most of large steel enterprises mainly use a Cu-Cr system in the design of steel grade components, but the large steel enterprises have the characteristics. Such as: patent publication number CN1052150a discloses a low alloy sulfuric acid dew point corrosion resistant steel, the composition of the components is: c is less than or equal to 0.13 percent, si:0.20 to 0.80 percent of Mn:0.20 to 1.0 percent, P is less than or equal to 0.035 percent, S:0.01 to 0.035 percent, cu:0.20 to 0.40 percent of Cr: 0.40-1.0%, RE not more than 0.20%, and Fe and impurities in balance. Elements such as Sb and Sn with good sulfuric acid dew point corrosion resistance are ignored in component design, so that the corrosion resistance is not ideal in an acidic environment; patent publication number CN 101892439A discloses a sulfuric acid dew point corrosion resistant steel, which comprises the following components: c:0.05 to 0.10 percent of Si:0.10 to 0.35 percent of Mn:0.30 to 0.80 percent, P is less than 0.02 percent, S is less than 0.01 percent, cr:0.50 to 1.0 percent of Cu:0.20 to 0.50 percent of Sb:0.07 to 0.12 percent of Ti:0.01 to 0.06 percent of Ca:0.0004 to 0.001 percent, and the balance of Fe. When the Cu-Ni is not matched and compositely used in component design, severe thermal embrittlement performance is often caused to the steel plate, surface cracks are easy to generate, and even the edge of the steel plate is cracked; patent publication No. CN 106282839A discloses a high-performance sulfuric acid dew point resistant steel plate and a manufacturing method thereof, wherein the component design adopts high Cr, high Cu, high Ni, nb, V and Ti for microalloying, and adopts a controlled rolling and tempering process to improve the sulfuric acid corrosion resistance and strength of the steel, but excessive alloy elements in the example cause the increase of production cost, the welding performance of the steel plate is affected by high-content Cr, and corrosion conditions and comparison steel types are not given.
Patent publication No. CN 108286017A discloses a thick-specification Q420-grade high-temperature and high-pressure sulfuric acid dew point corrosion resistant steel plate and a production method thereof, wherein the strength grade of the steel is Q420MPa, and only the sulfuric acid corrosion resistance under high-temperature and high-pressure conditions is given. However, the yield strength of the steel material tends to be lowered under the high-temperature use condition, and the high-temperature tensile properties of the steel plate are not clarified in the patent; patent publication No. CN 201010211471.9 discloses a rare earth low alloy steel resistant to dew point corrosion of high-temperature sulfuric acid, RE (La, ce) is added in the aspect of alloy design, elements such as Sb and Sn which are favorable for corrosion resistance are not added, and a related specific production process is not provided. And the method is implemented in a laboratory, and in actual production, the adding method of rare earth and the smelting difficulty are difficult problems, and the feasibility of industrial production is not known.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide the steel for high-temperature sulfuric acid dew point corrosion resistance and the manufacturing method thereof, and the steel has good high-temperature corrosion resistance and higher high-temperature tensile property in an acidic corrosion environment, can meet the requirements of industries such as coal chemical industry, electric power, flue-cured tobacco furnaces and the like on the high-temperature tensile property, the sulfuric acid dew point corrosion resistance and the comprehensive property, and particularly can be used in the high-temperature and acidic corrosion environment.
In order to achieve the above purpose, the present invention is realized by the following technical scheme:
the steel for high-temperature sulfuric acid dew point corrosion resistance comprises the following chemical components in percentage by weight:
c:0.052% -0.087%, si:0.21 to 0.63 percent, mn:0.34 to 1.04 percent, P: less than or equal to 0.015 percent, S: less than or equal to 0.006 percent, cr:0.43 to 1.23 percent, ni:0.22 to 0.43 percent, cu:0.17 to 0.27 percent, sb:0.06% -0.13%, ti:0.013 to 0.043 percent, sn:0.04% -0.11%, nb:0.012% -0.024%, alt:0.024% -0.054%, N:0.008 to 0.014 percent, ca:0.0034% -0.0041% and the balance of Fe and unavoidable impurities.
C: as one of the main reinforcing elements, a lower C content affects the strength of the steel, but at the same time, an excessively high C content not only reduces the impact toughness and the welding performance of the steel sheet, but also seriously deteriorates the sulfuric acid dew point corrosion resistance of the steel sheet. By combining the factors, the content of the invention is controlled to be 0.052% -0.087%.
Si: belongs to strong deoxidizing elements, improves the yield strength of steel in a solid solution form, forms a Si02 film on the surface when Si is heated in an oxidizing atmosphere, and can improve the oxidation resistance of the steel in a high-temperature environment. Considering that when the Si content is too high, the toughness of the product is reduced, oxide scales which are difficult to remove are easily generated, and the appearance of the steel plate are affected. The Si content of the invention is controlled to be 0.21-0.63%.
Mn: since the solid solution strengthening effect is sufficient to cover the strength loss caused by the lower C content, mn is the main element reaching the predetermined strength level. However, too high Mn content deteriorates the weldability and formability of the steel. Therefore, the Mn content in the present invention is controlled to be 0.34% to 1.04%.
P: is one of the most effective alloying elements for improving the corrosion performance of steel, but is an element which is easy to segregate at grain boundaries and is harmful to the welding performance and impact toughness, and the content of P is controlled below 0.015 percent in consideration of the steelmaking condition and the cost.
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 this patent should be controlled below 0.006%.
Cr: can improve the passivation capability of the steel plate, and especially can easily form a compact passivation film Cr on the surface of the steel plate under the environment of high temperature and high sulfuric acid concentration 2 O 3 Can improve the high temperature resistance and sulfuric acid dew point corrosion resistance of steel, and when being matched with Cu for useThe corrosion resistance is more obvious. When the content is too high, the weldability of the steel sheet is deteriorated. Therefore, the Cr content in the present invention is controlled to be 0.43% to 1.23%.
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. While taking into consideration the cost factor, the present invention is therefore limited to a content range of 0.17% to 0.27%.
Ni: is one of elements for improving the strength and obtaining excellent impact toughness of the steel plate, and can also improve the problem of copper brittleness of the steel plate. Ni is not an effective high-temperature oxidation resistance element, but when the Ni is added in a matched manner with Cr, the high-temperature oxidation resistance of steel can be improved, the stability of a passivation film on the surface of the steel can be promoted under the high-temperature and acid environment, and the corrosion resistance of the steel is obviously enhanced, and the addition amount of the Ni is 0.22-0.43%.
Ti: the Ti-containing compound in the steel can effectively prevent austenite grains from growing in the heating process, plays a role in refining the grains, and particularly can improve the welding performance of the steel plate. The content of the composition is controlled to be 0.013% -0.043%.
Sb: the method has the advantages that the effective elements for improving the corrosion resistance are improved, the enrichment of catalytic corrosion-resistant elements is realized, the enrichment of corrosion-resistant elements such as Cu, cr and the like on the surface of the rust layer is promoted, and a layer of compact oxide film containing corrosion-resistant elements such as Sb, cr, cu and the like and having obvious corrosion-resistant effect is formed on the surface of the steel plate. Meanwhile, the higher Sb content is favorable for refining the stable phase alpha-FeOOH in the rust layer, and can effectively improve the acid corrosion resistance of the steel plate, but the corrosion resistance effect is not obvious when the content is lower, so the invention is limited to be in the range of 0.06-0.13%
Sn: generally, as a residual impurity element in steel, segregation is likely to occur at grain boundaries. However, sn is an effective element for improving acid corrosion resistance and enhancing precipitation in the present invention. When being added in combination with Cr, cu and Sb elements, the corrosion resistant element not only promotes the enrichment of each corrosion resistant element on the surface of the rust layer, but also can effectively resist SO 4 2- The ion is immersed into the protective film of the generated steady-state SnO corrosion productsCan effectively improve the acid corrosion resistance of the steel plate. Proper addition of Sn can reduce migration rate of grain boundary to reduce grain size in steel, and when added in combination with Nb, the interaction of Nb and Nb can generate Nb with high melting point 2 Sn is precipitated in the form of punctiform and dispersed distribution in the crystal during the cooling process of the steel plate, and plays a good role in precipitation strengthening. Accordingly, the Sn content in the present invention is set to 0.04% to 0.11%.
Nb: one of the main strengthening elements in the present invention. The element can form intermetallic compound Fe with iron 2 Nb 2 The solubility of the compound in alpha iron decreases with increasing temperature, and the yield point of steel can be improved. Nb also forms corresponding compounds with carbon and nitrogen in the steel, and the compounds play roles in fine crystal strengthening and dispersion strengthening. Accordingly, the Nb content in the present invention is set to 0.012% to 0.024%.
Alt: the main deoxidizing and nitrogen fixing elements form AlN capable of refining austenite grains, so that the content range of AlN is 0.024-0.054%.
N: the element is easily dissolved in ferrite to form an interstitial solid solution, so that the strength of the steel can be improved. The invention utilizes the reaction of N in steel and Nb to generate high-melting-point NbN interstitial mesophase, and the relative dislocation has the functions of pinning and inhibiting the growth of grains, thereby being beneficial to the improvement of the strength of the steel plate. However, since an increase in the N content in steel also reduces the plasticity and toughness of steel, the Sn content in the present invention is set to 0.008% to 0.014%.
Ca: the components, the shapes and the number of nonmetallic inclusion in steel are changed, the potential difference between the inclusion and a matrix is reduced, the trend of electrochemical corrosion in steel is reduced, and the corrosion resistance of the steel plate is improved. In the invention, calcium is dissolved in MnS in a solid way, and is subjected to denaturation treatment to generate (Mn.Ca) S inclusion, so that adverse effects of MnS on mechanical properties are eliminated. When the composite oxide is added in combination with Si, composite oxides of Si and Ca are formed on the surface of the rust layer, which is more beneficial to the formation of stable phase alpha-FeOOH in the rust layer. In addition, in sulfuric acid corrosive environment, the method uses SO in the corrosive medium 4 2- Reaction to produce CaSO 4 Can effectively improve the corrosion resistance of the passivation film on the surface of the steel plate. Therefore, the Ca content in the present invention is set to 0.0034% to 0.0041%.
A manufacturing method of steel for high temperature sulfuric acid dew point corrosion resistance comprises the following process flows: molten iron pretreatment, converter smelting, external refining, calcium treatment, slab continuous casting, hot delivery or stacking slow cooling, casting blank heating, rolling, laminar cooling and coiling, and is characterized in that:
adopting a two-stage rolling process, wherein the rough rolling start temperature is 1044-1056 ℃, the thickness of an intermediate billet is more than 2.5 times of the thickness of a finished product, the single-pass rolling reduction is not less than 11%, and the accumulated rolling reduction is not less than 42%; the initial rolling temperature of the finish rolling is 1052-1072 ℃, and the final rolling temperature of the finish rolling is 841-863 ℃; the rolled steel plate is subjected to laminar cooling, wherein front-stage concentrated cooling is adopted for the laminar cooling, and the cooling rate is 22-31 ℃/s; cooling to 591-614 deg.c, coiling, and air cooling to room temperature.
Smelting:
1) Pre-desulphurisation of molten iron
In order to improve the conversion rate smelting efficiency, the desulfurization powder is sprayed into a torpedo ladle car filled with molten iron for desulfurization pretreatment, the dosage of the desulfurization powder is 1008-1017 kg, S is less than or equal to 0.004%, and the slag skimming of the solid slag is thorough;
2) Converter steelmaking:
adopting a furnace top and bottom combined converting process, wherein the tapping temperature of the converter is 1614-1624 ℃; adding ferromanganese, ferrosilicon alloy and 932-942 kg lime in the tapping process to deoxidize, and blowing argon in the whole tapping process;
3) External refining
Performing LF treatment for 32-38 min, stirring for 4-7 min at a large flow rate, then performing Si-Ca wire treatment, wherein the length of each steel wire is 520-620 m, and the outlet temperature of an LF furnace is 1562-1573 ℃;
4) Continuous casting: the continuous casting process is put into a dynamic soft reduction technology, the soft reduction is controlled to be 2-5 mm, so that center porosity and segregation are strictly controlled, the internal quality of a casting blank is ensured, and the thickness of the continuous casting blank is 230-250 mm; in the process, the temperature of the tundish is controlled to be 1492-1512 ℃ and the blank pulling speed is controlled to be 0.8-1.0 m/min.
And heating the casting blank: the heating temperature is controlled to be 1183-1203 ℃, the temperature is controlled to be lower than 1081 ℃, and the heating speed is 8.2-9.2 ℃/min; high-temperature quick-firing at the temperature of more than 1081 ℃ with the heating rate of 14.2-15.2 ℃/min and the total furnace time of 202-212 min, wherein the heat preservation time of the soaking section is 47-57 min.
Compared with the prior art, the invention has the beneficial effects that:
the yield strength of the steel plate for high-temperature sulfuric acid dew point corrosion resistance with the thickness of 4-16 mm is more than 480MPa, the tensile strength is more than 560MPa, and the elongation is more than 28%; the average value of Charpy longitudinal impact energy at 20 ℃ is more than 125J, the yield strength at 300 ℃ is more than 380MPa, the tensile strength is more than 500MPa, the elongation is more than 24%, and the average corrosion rate is (6.34-7.83) mg/cm under the conditions of medium temperature 70 ℃, sulfuric acid concentration 50% and full immersion for 24 hours 2 The corrosion rate of h relative to Q235B is 17.74-21.91%, and the average corrosion rate is (13.76-16.81) mg/cm under the conditions of 130 ℃ and 80% sulfuric acid concentration and 24 hours of full immersion at high temperature 2 H, the relative corrosion rate of Q235B is 19.62-23.97%. The final steel plate structure is uniform and fine ferrite, pearlite distributed in a dispersing way and a small amount of bainite, the ferrite grain size is 10.5 grade on average, and the steel plate has excellent strong plasticity and impact toughness. The steel has good high-temperature corrosion resistance and higher high-temperature tensile property in high-temperature and acidic corrosion environments, can meet the requirements of industries such as coal chemical industry, electric power, flue-cured tobacco furnaces and the like on the high-temperature tensile property, sulfuric acid dew point corrosion resistance and comprehensive performance, and particularly can be used in the high-temperature and acidic corrosion environments.
Drawings
FIG. 1 is a drawing showing the metallographic structure of example 2 in the vicinity of a fracture after high-temperature stretching.
FIG. 2 is a second metallographic structure in the vicinity of a fracture after high-temperature stretching in example 2.
FIG. 3 is a third metallographic diagram showing the vicinity of a fracture after high-temperature stretching in example 2.
Detailed Description
The present invention will be described in detail below with reference to the drawings of the specification, but it should be noted that the practice of the present invention is not limited to the following embodiments.
The chemical compositions of examples 1-7 are shown in Table 1, the heating, rolling and cooling process parameters are shown in Table 2, the mechanical property detection results are shown in Table 3, the high-temperature tensile properties are shown in Table 4, the full immersion corrosion test results are shown in Table 5, and the gold phase diagrams of the finished steel plate of example 2 near the fracture after high-temperature stretching are shown in FIGS. 1-3.
TABLE 1 examples chemical composition wt%
Examples C Si Mn P S Cr Ni Cu Sb Ti Sn Alt Nb N Ca
1 0.052 0.21 1.04 0.014 0.005 0.43 0.33 0.27 0.12 0.013 0.04 0.024 0.012 0.008 0.0034
2 0.058 0.28 0.93 0.013 0.004 0.56 0.43 0.25 0.07 0.019 0.06 0.034 0.014 0.010 0.0035
3 0.064 0.35 0.81 0.015 0.004 0.69 0.29 0.23 0.06 0.024 0.07 0.029 0.016 0.012 0.0036
4 0.070 0.42 0.69 0.014 0.003 0.83 0.26 0.22 0.08 0.029 0.09 0.049 0.018 0.011 0.0037
5 0.076 0.49 0.58 0.013 0.006 0.97 0.22 0.20 0.10 0.035 0.08 0.039 0.020 0.009 0.0038
6 0.082 0.56 0.46 0.014 0.004 1.23 0.37 0.18 0.11 0.039 0.10 0.045 0.024 0.013 0.0040
7 0.087 0.63 0.34 0.015 0.003 1.11 0.40 0.17 0.13 0.043 0.11 0.054 0.022 0.014 0.0041
Table 2 examples heating, rolling, cooling process parameters
Figure BDA0003669864020000061
In the rolling process, the rough rolling can adopt a 3+3 rolling mode or other rolling modes.
TABLE 3 mechanical Properties of examples
Figure BDA0003669864020000062
Figure BDA0003669864020000071
Table 4 example high temperature tensile properties
Figure BDA0003669864020000072
TABLE 5 results of the full immersion corrosion test of the examples
Figure BDA0003669864020000073

Claims (2)

1. The steel for high-temperature sulfuric acid dew point corrosion resistance is characterized by comprising the following chemical components in percentage by weight:
c:0.052% -0.087%, si:0.56 to 0.63 percent, mn:0.34 to 1.04 percent, P: less than or equal to 0.015 percent, S: less than or equal to 0.006 percent, cr:0.43 to 1.23 percent, ni:0.22 to 0.43 percent, cu:0.17 to 0.18 percent, sb:0.11 to 0.13 percent, ti:0.039% -0.043%, sn:0.04% -0.11%, nb:0.012% -0.024%, alt:0.045% -0.054%, N:0.013% -0.014%, ca:0.0034% -0.0041%, and the balance of Fe and unavoidable impurities;
the manufacturing method of the steel for high temperature sulfuric acid dew point corrosion resistance comprises the following process flows: molten iron pretreatment, converter smelting, external refining, calcium treatment, slab continuous casting, hot delivery or stacking slow cooling, casting blank heating, rolling, laminar cooling and coiling, wherein the rolling comprises the following steps of:
adopting a two-stage rolling process, wherein the rough rolling start temperature is 1044-1056 ℃, the thickness of an intermediate billet is more than 2.5 times of the thickness of a finished product, the single-pass rolling reduction is not less than 11%, and the accumulated rolling reduction is not less than 42%; the initial rolling temperature of the finish rolling is 1052-1072 ℃, and the final rolling temperature of the finish rolling is 841-863 ℃; the rolled steel plate is subjected to laminar cooling, wherein front-stage concentrated cooling is adopted for the laminar cooling, and the cooling rate is 22-31 ℃/s; cooling to 591-614 deg.c for coiling, and air cooling to room temperature;
and heating the casting blank: the heating temperature is controlled to be 1183-1203 ℃, the temperature is lower than 1081 ℃ and the heating speed is 8.2-9.2 ℃/min; high-temperature quick-firing at the temperature of more than 1081 ℃ with the heating rate of 14.2-15.2 ℃/min and the total furnace time of 202-212 min, wherein the heat preservation time of the soaking section is 47-57 min.
2. The steel for high temperature sulfuric acid dew point corrosion according to claim 1, wherein the smelting process comprises:
1) Pre-desulphurisation of molten iron
In order to improve the conversion rate smelting efficiency, the desulfurization powder is sprayed into a torpedo ladle car filled with molten iron for desulfurization pretreatment, the dosage of the desulfurization powder is 1008-1017 kg, S is less than or equal to 0.004%, and the slag skimming of the solid slag is thorough;
2) Converter steelmaking:
adopting a top-bottom combined converting process, wherein the tapping temperature of the converter is 1614-1624 ℃; adding ferromanganese, ferrosilicon alloy and 932-942 kg lime in the tapping process to deoxidize, and blowing argon in the whole tapping process;
3) External refining
Performing LF treatment for 32-38 min, stirring for 4-7 min at a large flow rate, then performing Si-Ca wire treatment, wherein the length of each steel wire is 520-620 m, and the outlet temperature of an LF furnace is 1562-1573 ℃;
4) Continuous casting: the continuous casting process is put into a dynamic soft reduction technology, the soft reduction is controlled to be 2-5 mm, so that center porosity and segregation are strictly controlled, the internal quality of a casting blank is ensured, and the thickness of the continuous casting blank is 230-250 mm; in the process, the temperature of the tundish is controlled to be 1492-1512 ℃ and the blank pulling speed is controlled to be 0.8-1.0 m/min.
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