CN112575269A - Low-temperature acid dew point corrosion resistant cold-rolled steel and manufacturing method thereof - Google Patents
Low-temperature acid dew point corrosion resistant cold-rolled steel and manufacturing 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
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- C21D1/26—Methods of annealing
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- 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
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- 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
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- 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
- C21D8/0236—Cold rolling
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- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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Abstract
The invention discloses low-temperature acid dew point corrosion resistant cold rolled steel, which comprises the following chemical elements in percentage by mass: c: 0.04-0.12%, Si: 0.20 to 0.40%, Mn: 0.35-0.65%, S: 0.005-0.020%, Cu: 0.20-0.50%, Cr: 0.7-1.2%, Mo: 0.03-0.10%, Sb: 0.06-0.12%, Ti: 0.002-0.035%, and the balance of Fe and inevitable impurity elements. In addition, the invention also discloses a manufacturing method of the cold rolled steel resisting the low-temperature acid dew point corrosion, which comprises the following steps: (1) smelting and casting; (2) hot rolling: wherein the heating temperature during hot rolling is 1200-1250 ℃, and the finishing temperature is 850-950 ℃; (3) coiling: the coiling temperature is 600-680 ℃; (4) cold rolling; (5) continuous annealing; (6) and (7) flattening.
Description
Technical Field
The invention relates to cold-rolled steel and a manufacturing method thereof, in particular to corrosion-resistant cold-rolled steel and a manufacturing method thereof.
Background
In the industrial fields of thermal power generation, metallurgy, petrochemical industry and the like, flue gas generated by fuel oil or coal generally contains a large amount of corrosive gases such as sulfide, nitride, chloride and the like, and is easy to be condensed into high-concentration acidic liquid drops at low-temperature parts of a boiler, such as an air preheater, an economizer, a flue, a chimney, a desulphurization device and other equipment of the boiler, so that the corrosion to the equipment is caused.
In order to solve the problem of sulfuric acid dew point corrosion, acid-resistant steel suitable for resisting sulfuric acid dew point corrosion is developed continuously at home and abroad in the years, and the dew point corrosion of the steel in sulfur-containing flue gas is improved mainly by adding Cu or Cu and Sb elements from the aspect of components, and the designed steel types can meet the requirement of resisting sulfuric acid dew point corrosion in system equipment with the flue gas emission higher than 100 ℃.
In recent years, however, with the requirement of environmental protection and energy conservation, the flue gas in a fuel oil and coal burning system is required to be discharged at the temperature lower than 100 ℃. The low-temperature discharge not only aggravates the sulfuric acid dew point corrosion, but also causes the hydrochloric acid dew point corrosion, namely, the sulfuric acid and hydrochloric acid mixed dew point corrosion occurs, so that the dew point corrosion of the boiler low-temperature section smoke exhaust system is more complicated and more serious. The acid-resistant steel used or disclosed at present is mainly suitable for dew point corrosion of sulfuric acid liquor generated at high temperature of flue gas, but not suitable for the service environment after low temperature of flue gas.
However, no domestic patent on acid-resistant steel resistant to dew point corrosion of a mixed acid of sulfuric acid and hydrochloric acid has been reported. The characteristics of high-sulfur coal quality and smoke components of the coal are combined, and the comprehensive cost of the material needs to be reduced as much as possible when the steel plate is designed. It is desirable to obtain a low temperature resistant sulfuric acid and hydrochloric acid mixed acid steel which can perform well in corrosion resistance.
Disclosure of Invention
The invention aims to provide low-temperature acid dew point corrosion resistant cold-rolled steel which is suitable for being used in a sulfuric acid and hydrochloric acid mixed dew point corrosion resistant environment and can meet the requirements on corrosion resistance of low-temperature smoke exhaust parts in thermal power, petrochemical, metallurgy, waste incineration flue gas treatment and waste heat recovery systems.
In order to achieve the aim, the invention provides low-temperature acid dew point corrosion resistant cold-rolled steel which comprises the following chemical elements in percentage by mass:
c: 0.04-0.12%, Si: 0.20 to 0.40%, Mn: 0.35-0.65%, S: 0.005-0.020%, Cu: 0.20-0.50%, Cr: 0.7-1.2%, Mo: 0.03-0.10%, Sb: 0.06-0.12% of Ti, 0.002-0.035% of Ti, and the balance of Fe and inevitable impurity elements.
In the low-temperature acid dew point corrosion resistant cold-rolled steel, the design principle of each chemical element is as follows:
c: in the low-temperature acid dew point corrosion resistant cold-rolled steel, C is a main strengthening element, and when the mass percentage of C is too low, the strength of the steel plate is insufficient, and the smelting cost is increased; however, if the mass percentage of C is too high, the plasticity of the steel sheet is affected and the acid resistance is also deteriorated. Based on the above, the mass percent of C in the low-temperature acid dew point corrosion resistant cold rolled steel is controlled to be 0.04-0.12%.
Si: in the low-temperature acid dew point corrosion resistant cold-rolled steel, Si is a deoxidizing element and improves the strength of the steel plate in a solid solution strengthening mode, and the coexistence of Si and Cu is beneficial to improving the corrosion resistance of the steel, but when the mass percentage of Si is excessively high, the hot workability and the welding performance of the steel plate are deteriorated. Therefore, the mass percent of Si is controlled within a reasonable range, the acid corrosion resistance of the material is improved while the processability is ensured, and based on the control, the mass percent of Si is controlled to be 0.20-0.40%.
Mn: in the low-temperature acid dew point corrosion resistant cold-rolled steel, Mn mainly exists in a solid solution state in the steel plate and plays a composite role with C, so that the strength of the steel plate is improved; mn and S form MnS, so that the hot brittleness tendency of steel is reduced; however, too high mass% of Mn causes center segregation of the cast slab, affects hot workability of the steel sheet, and is disadvantageous in welding performance. Based on the above, the mass percent of Mn in the cold-rolled steel resisting low-temperature acid dew point corrosion is controlled to be 0.35-0.65%.
S: in the low-temperature acid dew point corrosion resistant cold-rolled steel, the Cu/S ratio is controlled to promote the Cu to be formed on the surface of the steel plate2S is a passive film, so that the anode reaction and the cathode electrochemical reaction are inhibited, and the acid resistance of the steel plate is improved; however, too high S content tends to cause center segregation of the cast slab, leading to hot shortness, and adversely affecting the formability of the steel sheet. Therefore, the mass percent of S in the low-temperature acid dew point corrosion resistant cold rolled steel is controlled to be 0.005-0.020%.
Cu: in the low-temperature acid dew point corrosion resistant cold-rolled steel, Cu is an important element for improving atmospheric corrosion resistance and acid corrosion resistance, plays a role of an active cathode in the steel corrosion process, and can promote the steel to generate anode passivation under a certain condition, so that the corrosion rate of the steel is reduced. In addition, Cu reacts with S to form Cu2The S protective film retards the cathode and anode reactions, so that the corrosion potential of the steel surface is increased, and meanwhile, the steel surface has lower Viton current and the acid resistance of the material is improved. However, the mass percentage of Cu is too high, and the hot workability of the material is deteriorated. Based on the above, the mass percent of Cu in the low-temperature acid dew point corrosion resistant cold rolled steel is controlled to be 0.20-0.50%.
Cr: in the low-temperature acid dew point corrosion resistant cold rolled steel, Cr is dissolved in ferrite to inhibit an anode reaction, Cr carbide is generated in cementite to inhibit a cathode reaction, and the corrosion resistance of the material is improved; in addition, Cr forms a dense oxide film on the surface of the steel sheet, thereby improving oxidation resistance. However, if the amount of Cr added is too large, the hot workability of the steel sheet is deteriorated. Based on the above, the mass percent of Cr in the low-temperature acid dew point corrosion resistant cold rolled steel is controlled to be 0.7-1.2%.
Mo: in the low-temperature acid dew point corrosion resistant cold-rolled steel, Mo can improve the acid dew point corrosion resistance of the steel plate. The addition of Mo can promote the passivation of Fe-Cr alloy, and the addition of a proper amount of Mo can move the corrosion potential to the direction which is not easy to corrode, so that the hydrochloric acid resistance dew point corrosion performance of the steel plate is improved under the condition of not damaging the sulfuric acid resistance performance. However, if the amount of the acid is excessively added, the corrosion resistance of the steel sheet to sulfuric acid and hydrochloric acid mixed acid is lowered. Based on the above, the mass percent of Mo in the low-temperature acid dew point corrosion resistant cold rolled steel is controlled to be 0.03-0.10%.
Sb: in the low-temperature acid dew point corrosion resistant cold-rolled steel, Sb is an element for effectively improving the sulfuric acid resistance and hydrochloric acid resistance of the steel plate, and Sb can be generated on the surface of the steel by adding Sb2O5The oxide inhibits anodic reactions, thereby reducing the corrosion rate. In addition, the Sb with higher mass percentage can promote the formation of the Cu-containing compound with high corrosion resistance and inhibit the occurrence of cathode reaction. However, Sb and Cu are low-melting elements, and when added in excess, the hot workability of the steel sheet deteriorates. Based on the above, the mass percent of Sb in the low-temperature acid dew point corrosion resistant cold rolled steel is controlled to be 0.06-0.12%.
Ti: in the low-temperature acid dew point corrosion resistant cold rolled steel, Ti is a carbon nitrogen compound forming element, and formed carbon or nitride has high melting point and can prevent austenite grains from growing. In the rolling process, the austenite grain boundary can be effectively formed, and the growth of austenite grains is inhibited. Therefore, a proper amount of Ti element is added into the steel, which is beneficial to refining crystal grains, reducing potential difference between matrixes and avoiding intergranular corrosion. However, when the mass percentage of Ti element is too high, the carbon or nitrogen compound precipitated in the matrix is aggregated and coarsened, which causes too large inter-crystalline potential difference and promotes inter-crystalline corrosion. Based on the above, the mass percent of Ti in the cold-rolled steel resisting low-temperature acid dew point corrosion is controlled to be 0.002-0.035%,
furthermore, in the cold-rolled steel resisting low-temperature acid dew point corrosion, the content of Ti element is 0.002-0.03%.
Furthermore, in the cold-rolled steel resisting low-temperature acid dew point corrosion, P is less than or equal to 0.035% of other inevitable impurities.
In the scheme, P is an inevitable inclusion element in the steel plate, and if the mass percentage of P is too high, the center segregation of a casting blank can be caused, the hot workability of the steel plate is influenced, and the acid resistance of the steel plate is reduced. Based on the above, the mass percent P of the P in the cold-rolled steel resisting the low-temperature acid dew point corrosion is controlled to be less than or equal to 0.035%.
Furthermore, in the low-temperature acid dew point corrosion resistant cold-rolled steel, the microstructure matrix is ferrite and pearlite, wherein the phase proportion of the pearlite is 8-12%, and Ti (C, N) precipitates are contained on the matrix.
Furthermore, in the cold-rolled steel resisting low-temperature acid dew point corrosion, the size of more than 95% of Ti (C, N) precipitates is 15-30 nm.
Furthermore, in the cold-rolled steel resisting low-temperature acid dew point corrosion, the average grain size is 5-10 μm.
Further, in the cold-rolled steel with resistance to low-temperature acid dew point corrosion, the performance of the cold-rolled steel meets at least one of the following conditions:
the yield strength is more than or equal to 260 MPa;
the tensile strength is more than or equal to 400 MPa;
the elongation is more than or equal to 30 percent;
11.4 wt.% H at 60 deg.C2SO4+1.2wt.％HCl+1.0wt.％FeCl3Soaking in mixed acid solution for 24h, wherein the mixed acid corrosion resistance rate is less than 4mg/cm2·h。
Correspondingly, the invention also aims to provide the manufacturing method of the low-temperature acid dew point corrosion resistant cold rolled steel, and the low-temperature acid dew point corrosion resistant cold rolled steel obtained by the manufacturing method is suitable for being used in a sulfuric acid and hydrochloric acid mixed dew point corrosion resistant environment and can meet the corrosion resistance requirements of low-temperature smoke exhaust parts in thermal power, petrochemical, metallurgy, waste incineration flue gas treatment and waste heat recovery systems.
In order to achieve the above object, the present invention provides a method for manufacturing the cold rolled steel with resistance to low temperature acid dew point corrosion, comprising the steps of:
(1) smelting and casting;
(2) hot rolling: wherein the heating temperature during hot rolling is 1200-1250 ℃, and the finishing temperature is 850-950 ℃;
(3) coiling: the coiling temperature is 600-680 ℃;
(4) cold rolling;
(5) continuous annealing;
(6) and (7) flattening.
In the manufacturing method of the invention, the hot rolling heating temperature is controlled to be 1200-1250 ℃ because: the continuous casting slab heating process generates the dissolution of second phase particles such as Ti (C, N) and the like, the particles can be separated out again in the hot rolling coiling process, but the particles are smaller in size and more dispersed in distribution compared with the continuous casting slab, and the mechanical and acid resistance of the steel plate can be improved. When the heating temperature is too low during hot rolling, the dissolution degree of second phase particles is reduced, precipitation in the post-processing process is influenced, and the mechanical property and the acid resistance are not facilitated; when the heating temperature is too high, the crystal grains are coarsened, the generated oxide skin is thick, and the subsequent procedures are difficult to remove; and the mechanical property of the steel plate is low. Therefore, in the manufacturing method of the present invention, the hot rolling heating temperature is controlled to be 1200 to 1250 ℃.
In addition, the finishing temperature is controlled to be 850-950 ℃, because: when the finishing temperature is too low, the hot rolling in the all-austenite region can not be realized, so that mixed crystals appear in steel, and the stability of the structure and the performance is influenced; when the finishing rolling temperature is too high, crystal grains are easy to coarsen, and the mechanical property of the steel plate is reduced. Therefore, in the manufacturing method of the invention, the finishing temperature is controlled to be 850-950 ℃.
In addition, when coiling is carried out in a proper temperature range, fine and dispersed cementite precipitation can be realized, the cementite is easy to dissolve in the subsequent continuous annealing process, the ferrite and pearlite structure is favorably formed, and the influence of carbide particles on the corrosion performance of the material is reduced. Therefore, in the manufacturing method according to the present invention, the winding temperature is controlled: 600-680 ℃.
Further, in the manufacturing method of the present invention, in the step (4), the cold rolling reduction is controlled to be 50 to 80%.
In the scheme, the r value of the cold-rolled steel sheet generally increases along with the increase of the cold rolling reduction, the cold rolling reduction is increased, the deformation energy in the steel is increased, and the recrystallization driving force is improved, so that the recrystallization temperature is reduced, and the {111} texture is favorably formed after annealing; however, when the reduction rate exceeds 85%, the load of the rolling mill is significantly increased, the production efficiency of the cold rolling mill train is reduced, and the manufacturing cost is increased. Therefore, in some preferred embodiments, the cold rolling reduction is controlled to be 50 to 85%.
Further, in the manufacturing method, in the step (5), the continuous annealing temperature is 720-840 ℃, and the heat preservation time is 80-120 s; and/or in the step (6), controlling the leveling rate to be 0.8-1.6%.
In the above scheme, considering that the continuous annealing process is a process of recovery and recrystallization of deformed grains, a certain time is required for kinetics. If the temperature is too low and the heat preservation time is too short, the recrystallization of the rolled hard plate is insufficient, the plasticity of the material is low, and the processability is poor; if the annealing temperature is too high and the heat preservation time is too long, the grain size of the steel plate is too large, and the strength of the finished steel plate is low. Therefore, in some preferred embodiments, the annealing temperature is controlled to be 720-780 ℃ and the holding time is controlled to be 80-120 s.
In addition, in consideration of the fact that the leveling can realize optimization of the surface roughness, the shape and the mechanical property of the product, the leveling rate can be controlled to be 0.8-1.6% in some preferred embodiments.
Compared with the prior art, the low-temperature acid dew point corrosion resistant cold-rolled steel and the manufacturing method thereof have the advantages and beneficial effects as follows:
the low-temperature dew point corrosion resistant cold-rolled steel can give consideration to both low-temperature sulfuric acid resistance and hydrochloric acid resistance, and has excellent mechanical properties which can reach that of: the yield strength is more than or equal to 260MPa, the tensile strength is more than or equal to 400MPa, and the elongation is more than or equal to 30%, so that the performance requirements of parts such as heat exchange elements of rotary air preheaters, heat exchanger fins or fins, dust remover anode plates and the like in thermal power, petrochemical, metallurgical and waste incineration flue gas treatment and waste heat recovery systems are well met.
In addition, the manufacturing method of the present invention also has the advantages and beneficial effects described above.
Drawings
FIG. 1 is a graph showing the relationship between the sulfuric acid and hydrochloric acid mixed acid corrosion resistance and Ti content of a steel sheet produced by the method for producing a cold-rolled steel having resistance to low-temperature-calculated dew point corrosion according to the present invention.
FIG. 2 is a graph showing the relationship between the sulfuric acid and hydrochloric acid mixed acid corrosion resistance and the soaking time of a steel sheet produced by the method for producing a cold-rolled steel having resistance to low-temperature-calculated dew point corrosion according to the present invention.
Detailed Description
The cold-rolled steel with resistance to low-temperature acid dew point corrosion and the manufacturing method thereof according to the present invention will be further explained and illustrated with reference to specific examples, which, however, should not be construed to unduly limit the technical scope of the present invention.
Examples 1 to 6
The low temperature acid dew point corrosion resistant cold rolled steels of examples 1-6 were prepared using the following steps:
(1) smelting and casting were carried out according to the chemical compositions shown in Table 1.
(2) Hot rolling: wherein the heating temperature during hot rolling is 1200-1250 ℃, and the finishing temperature is 850-950 ℃.
(3) Coiling: the coiling temperature is 600-680 ℃.
(4) Cold rolling: controlling the cold rolling reduction rate to be 50-80%;
(5) and (3) continuous annealing: the continuous annealing temperature is 720-840 ℃, and the heat preservation time is 80-120 s.
(6) Leveling: the leveling rate is controlled to be 0.8-1.6%.
Table 1 shows the mass percentages of the chemical elements of the cold-rolled steel sheets resistant to low-temperature acid dew point corrosion of examples 1 to 6 and the conventional steel sheet of comparative example 1.
TABLE 1 (wt%, balance Fe and unavoidable impurities other than P)
Table 2 lists specific process parameters for the cold rolled steel sheets resistant to low temperature acid dew point corrosion of examples 1-6 and the conventional steel sheet of comparative example 1.
Table 2.
In order to verify the working effect of the present case and to prove the excellent effect of the present case compared to the prior art, the low temperature acid dew point corrosion resistant cold rolled steels of examples 1 to 6 and the conventional steel sheet of comparative example 1 were tested and the test results are shown in table 3.
Table 3 shows the test results of the cold rolled steel having resistance to low temperature acid dew point corrosion of examples 1 to 6 and the conventional steel sheet of comparative example 1.
Table 3.
Note: the test conditions for the mixed acid corrosion resistance rate in Table 3 were 11.4 wt.% H at 60 deg.C2SO4+1.2wt.％HCl+1.0wt.％FeCl3Soaking for 24 h.
As can be seen from Table 3, the microstructure matrix of the cold rolled steel resistant to low temperature acid dew point corrosion of the examples of the present invention is ferrite + pearlite, wherein the phase ratio of pearlite is 8 to 12%, Ti (C, N) precipitates are present on the matrix, and wherein the size of 95% or more of the Ti (C, N) precipitates is 15 to 30nm, and the average grain size is 5 to 10 μm. In addition, the mechanical property and the corrosion resistance of the cold-rolled steel resisting the low-temperature acid dew point corrosion of each embodiment are excellent, the cold-rolled steel resisting the low-temperature acid dew point corrosion of each embodiment is obviously superior to the conventional steel plate of the comparative example 1, the yield strength of the cold-rolled steel resisting the low-temperature acid dew point corrosion of each embodiment is not less than 260MPa, and the tensile strength of the cold-rolled steel resisting the lowThe degree is more than or equal to 400MPa, the elongation is more than or equal to 30 percent, and the percentage of H is 11.4 wt.% at 60 DEG C2SO4+1.2wt.％HCl+1.0wt.％FeCl3Soaking in mixed acid solution for 24h, wherein the mixed acid corrosion resistance rate is less than 4mg/cm2·h。
FIG. 1 is a graph showing the relationship between the sulfuric acid and hydrochloric acid mixed acid corrosion resistance and Ti content of a steel sheet produced by using the cold-rolled steel having resistance to low-temperature-calculated dew point corrosion according to the present invention.
As shown in fig. 1, as Ti element is added, the weight loss rate of the steel sheet decreases, thereby indicating an increase in acid resistance; however, when the Ti content exceeds 0.03%, the weight loss rate of the steel sheet increases, indicating a decrease in acid resistance. Therefore, in order to ensure that the steel plate has certain mixed acid resistance, the mass percentage of Ti is controlled to be 0.002-0.035%, and preferably 0.002-0.03%.
It should be noted that the test of fig. 1 uses the standard JBT 7901-: 60 ℃, 11.4 wt.% H2SO4+1.2wt.％HCl+1.0wt.％FeCl3。
The acid resistance was evaluated by measuring the rate of corrosion weight loss of the steel sheet, as follows:
wherein, Wt-W0Represents the corrosion weight loss after soaking for t time, unit: mg; a represents the sample surface area, unit: cm2(ii) a T represents the sample immersion time in units: h.
FIG. 2 is a graph showing the relationship between the sulfuric acid and hydrochloric acid mixed acid corrosion resistance and the soaking time of a steel sheet produced by the method for producing a cold-rolled steel having resistance to low-temperature-calculated dew point corrosion according to the present invention.
As shown in fig. 2, the weight loss rate of the steel plate tends to decrease with the increase of the soaking time, and particularly for the steel plate containing 0.03 wt.% Ti, the weight loss rate decreases by about 68% in 72h compared with 24 h.
It should be noted that the test of fig. 2 uses the standard JBT 7901-: 60 ℃, 11.4 wt.% H2SO4+1.2wt.％HCl+1.0wt.％FeCl3。
The acid resistance was evaluated by measuring the rate of corrosion weight loss of the steel sheet, as follows:
wherein, Wt-W0Represents the corrosion weight loss after soaking for t time, unit: mg; a represents the sample surface area, unit: cm2(ii) a T represents the sample immersion time in units: h.
in conclusion, the low-temperature dew point corrosion resistant cold-rolled steel can give consideration to both low-temperature sulfuric acid resistance and hydrochloric acid resistance, and has excellent mechanical properties which can reach the following levels: the yield strength is more than or equal to 260MPa, the tensile strength is more than or equal to 400MPa, and the elongation is more than or equal to 30%, so that the performance requirements of parts such as heat exchange elements of rotary air preheaters, heat exchanger fins or fins, dust remover anode plates and the like in thermal power, petrochemical, metallurgical and waste incineration flue gas treatment and waste heat recovery systems are well met.
In addition, the manufacturing method of the present invention also has the advantages and beneficial effects described above.
It should be noted that the prior art in the protection scope of the present invention is not limited to the examples given in the present application, and all the prior art which is not inconsistent with the technical scheme of the present invention, including but not limited to the prior patent documents, the prior publications and the like, can be included in the protection scope of the present invention.
In addition, the combination of the features in the present application is not limited to the combination described in the claims of the present application or the combination described in the embodiments, and all the features described in the present application may be freely combined or combined in any manner unless contradictory to each other.
It should also be noted that the above-mentioned embodiments are only specific embodiments of the present invention. It is apparent that the present invention is not limited to the above embodiments and similar changes or modifications can be easily made by those skilled in the art from the disclosure of the present invention and shall fall within the scope of the present invention.
Claims (10)
1. The low-temperature acid dew point corrosion resistant cold-rolled steel is characterized by comprising the following chemical elements in percentage by mass: c: 0.04-0.12%, Si: 0.20 to 0.40%, Mn: 0.35-0.65%, S: 0.005-0.020%, Cu: 0.20-0.50%, Cr: 0.7-1.2%, Mo: 0.03-0.10%, Sb: 0.06-0.12% of Ti, 0.002-0.035% of Ti, and the balance of Fe and inevitable impurity elements.
2. The cold-rolled steel with low temperature acid dew point corrosion resistance of claim 1, wherein the content of Ti element is 0.002-0.03%.
3. The cold rolled steel resistant to low temperature acid dew point corrosion according to claim 1, wherein P is 0.035% or less among other unavoidable impurities.
4. The cold-rolled steel with low-temperature acid dew point corrosion resistance according to claim 1, wherein a microstructure matrix is ferrite + pearlite, wherein the phase ratio of the pearlite is 8-12%, and Ti (C, N) precipitates are contained in the matrix.
5. The cold rolled steel with low temperature acid dew point corrosion resistance according to claim 4, wherein the size of 95% or more Ti (C, N) precipitates is 15 to 30 nm.
6. The cold rolled steel with low temperature acid dew point corrosion resistance according to claim 1, wherein the average grain size is 5 to 10 μm.
7. The cold rolled steel having resistance to low temperature acid dew point corrosion according to any one of claims 1 to 6, wherein the properties satisfy at least one of:
the yield strength is more than or equal to 260 MPa;
the tensile strength is more than or equal to 400 MPa;
the elongation is more than or equal to 30 percent;
11.4 wt.% H at 60 deg.C2SO4+1.2wt.％HCl+1.0wt.％FeCl3Soaking in mixed acid solution for 24h, wherein the mixed acid corrosion resistance rate is less than 4mg/cm2·h。
8. The method for manufacturing cold rolled steel resistant to low temperature acid dew point corrosion according to any one of claims 1 to 7, comprising the steps of:
(1) smelting and casting;
(2) hot rolling: wherein the heating temperature during hot rolling is 1200-1250 ℃, and the finishing temperature is 850-950 ℃;
(3) coiling: the coiling temperature is 600-680 ℃;
(4) cold rolling;
(5) continuous annealing;
(6) and (7) flattening.
9. The method according to claim 8, wherein in the step (4), the cold rolling reduction is controlled to be 50 to 80%.
10. The method according to claim 8, wherein in the step (5), the continuous annealing temperature is 720 to 840 ℃ and the holding time is 80 to 120 s; and/or in the step (6), the leveling rate is controlled to be 0.8-1.6%.
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