CN114318126A - Hot-rolled pickled steel plate for acid corrosion resistant enamel heat exchanger and manufacturing method thereof - Google Patents
Hot-rolled pickled steel plate for acid corrosion resistant enamel heat exchanger and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses a hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger and a manufacturing method thereof, and mainly solves the technical problems of poor acid corrosion resistance and high production cost of the existing hot-rolled pickled steel plate for the enamel heat exchanger. The technical scheme is that the hot-rolled pickled steel plate for the acid corrosion resistant enamel heat exchanger comprises the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.005-0.035%, Mn: 0.40-0.80%, P is less than or equal to 0.018%, S is less than or equal to 0.010%, N is less than or equal to 0.0050%, Al: 0.020 to 0.055%, Ti: 0.03-0.06%, Cu: 0.20-0.40%, Sb: 0.04-0.12% of iron and inevitable impurities in balance; the hot-rolled pickled steel sheet having a thickness of 1.5 to 2.0mm has a crown of 20 to 40 μm. Is used for manufacturing the acid corrosion resistant enamel heat exchanger.
Description
Technical Field
The invention relates to a hot-rolled pickled steel plate, in particular to a hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger and a manufacturing method thereof, belonging to the technical field of iron-based alloys.
Background
The heat exchanger usually can be in service with smoke and acid medium environments, and has strong corrosivity. In order to solve the corrosion problem of the heat exchanger, the characteristics of acid resistance, alkali resistance and abrasion resistance of the enamel can be utilized, and the enamel on the surface of the metal is a common protection mode.
The thickness of the heat exchanger influences the heat transfer efficiency, so the thickness specification of the product is usually thinner, and the thickness of a common steel plate is 1.5-2.0 mm. The thinner the thickness specification of the hot rolled product is, the longer the hot rolled steel strip is, the surface area is multiplied, the heat dissipation is fast in the production and manufacturing process, and the temperature drop is large. The traditional hot continuous rolling steel strip rolling mill can meet the requirement of stably producing hot rolled products with the thickness of more than 2.0mm in batches. And for the products with the thickness specification of 1.5-2.0 mm, the production of the products with the specification is limited because the finishing temperature cannot meet the set requirement of the controlled rolling and controlled cooling process.
The heat exchanger may cause local enamel protective layer peeling in the links of transportation, construction and assembly and in the presence of SO4 2-、Cl-、NO3 -In the existing acidic corrosive environment, the heat exchanger can corrode and perforate quickly, and medium pollution is caused. In order to prolong the service cycle of the enamel heat exchanger, the acid corrosion resistance function of the steel plate used by the enamel heat exchanger needs to be added. Therefore, the steel plate used for the enamel heat exchanger not only needs to meet the process requirements of enamel processing, but also needs the steel grade to have the functional characteristic of acid corrosion resistance. The enamel steel plate used by the existing enamel heat exchanger has no acid corrosion resistance. Under the background, a hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger and a manufacturing method thereof are provided.
Disclosure of Invention
The invention aims to provide a hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger and a manufacturing method thereof, and mainly solves the technical problems of poor acid corrosion resistance and high production cost of the existing hot-rolled pickled steel plate for the enamel heat exchanger.
The technical idea of the invention is that by adopting proper component design and hot rolling process control, the obtained steel plate has proper strength and good forming performance, has the function of resisting acid medium corrosion, and eliminates the defect of porcelain explosion of enamel, the manufactured enamel heat exchanger can relieve the problem of corrosion perforation of the heat exchanger caused by peeling off of an enamel layer, the service cycle of the enamel heat exchanger is prolonged, and the technical defect of corrosion perforation of the existing enamel heat exchanger caused by peeling off of the enamel layer is overcome.
The invention adopts the technical scheme that a hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger comprises the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.005-0.035%, Mn: 0.40-0.80%, P is less than or equal to 0.018%, S is less than or equal to 0.010%, N is less than or equal to 0.0050%, Al: 0.020 to 0.055%, Ti: 0.03-0.06%, Cu: 0.20-0.40%, Sb: 0.04-0.12%, and the balance of iron and inevitable impurities.
The metallographic structure of the hot-rolled pickled steel plate is ferrite and a small amount of pearliteThe grain size of ferrite in the metallographic structure is 9.0 to 11.0, and the yield strength R of a hot-rolled pickled steel plate with a thickness of 1.5 to 2.0mmP0.2330 to 430MPa, tensile strength Rm400 to 520MPa, elongation after break A50 mm22 to 45% and the hot-rolled pickled steel sheet has a crown of 20 to 40 μm.
The reason why the chemical composition of the hot-rolled pickled steel sheet for the acid corrosion resistant enamel heat exchanger of the present invention is limited to the above range is as follows:
carbon: the carbon content range of the present invention needs to be strictly limited because the steel plate enamel is sensitive to the carbon content. Too high carbon content can form more and coarse carbide particles in steel, and the carbide particles are combined with O in the enamel process to produce CO gas, which is unfavorable for the compactness of an enamel layer. Meanwhile, the excessive carbon content increases the welding carbon equivalent, which is not beneficial to welding processing. The carbon content is low, the phase transformation point of steel is improved, and in a finish rolling process, particularly for thin products, the finish rolling temperature cannot meet the process design requirement, so that the problems of poor plate shape, edge mixed crystals and the like caused by two-phase region rolling can be caused. The C element is also an effective element for reducing the phase change point, and a certain content of the C element must be ensured in order to ensure the stable production of the finish rolling process and avoid the generation of edge mixed crystals. The carbon content set by the invention is 0.03-0.10%.
Silicon: the silicon solid solution has certain strengthening effect in the steel plate matrix, and the proper amount of silicon contained in the steel during smelting is beneficial to deoxidation and desulfurization. However, the present invention must control the silicon content, and when the silicon content is high, severe Fe is formed on the surface of the hot rolled plate2O3And is difficult to be removed by acid washing in the subsequent acid washing process. The invention limits the content of Si to be 0.005-0.035%.
Manganese: manganese is a traditional strengthening alloy element, the content of Mn is increased, the strength of the product is also improved, but the cost of steel is correspondingly increased, the carbon equivalent is also increased, and the welding is not facilitated. And the Mn element can obviously reduce the phase change point of the steel, and the content of the Mn element is required to have certain limitation in order to ensure that thin products avoid rolling in a two-phase region and avoid the generation of edge mixed crystals. The invention limits the Mn content to be 0.40-0.80%.
Sulfur and phosphorus: sulfur forms sulfide inclusions in the steel, reducing its ductility and toughness. When steel is rolled, the anisotropy of the steel is increased due to the elongation of MnS inclusions along the rolling direction, and steel plates are delaminated when the anisotropy is severe. Meanwhile, the high sulfur content is unfavorable for the weldability of steel. The high phosphorus increases the cold brittleness of the steel, raising the brittle transition temperature of the steel. However, considering the actual process control capability, the invention limits S to be less than or equal to 0.010 percent and P to be less than or equal to 0.018 percent.
Nitrogen: the nitrogen is an additional product in steel making production, can be fully utilized, and the N in the steel, the Ti and the C produce fine and dispersed two-phase particle Ti (CN) compounds, which is beneficial to the production for preventing the enamel fish scaling explosion defect. However, too high a nitrogen content will seriously reduce the plasticity and toughness of the material. But too low a nitrogen content would increase the corresponding nitrogen control production cost. The invention limits N to be less than or equal to 0.0050%.
Aluminum: the aluminum plays a role in steelmaking deoxidization in the invention, and the deoxidization product is Al2O3Can be removed after being combined with the steel slag, and Al remained in the steel can play a role in refining grains. However, the increase in Al content causes an increase in steel-making cost and also causes difficulty in the production structure of continuous casting. The invention limits the Al content to be 0.020-0.055%.
Titanium: titanium is one of the main elements for generating ti (cn) two-phase particles, and the addition amount thereof is usually more than 0.03%. However, Ti is a strong deoxidizing element and is easy to oxidize in molten steel to generate an oxide with a high melting point, which causes great difficulty to the continuous casting production structure; the high Ti content in the steel easily causes the large fluctuation of the strength performance of the product. The technical scheme of the invention selects the Ti with the mass percentage content as follows: 0.03-0.06%, which is the control range most easily realized in production.
Copper: copper and iron are mutually soluble elements in a solid phase, and the alpha iron phase transformation line can be reduced from 850 ℃ to 780 ℃ after a proper amount of Cu is added according to an Fe-Cu phase diagram. The Cu element is added to reduce the temperature of the phase transition point, so that the rolling process window of the thin product can be expanded, and the problem of two-phase region rolling of the thin product is solved. Meanwhile, the copper element can play a role of an activating cathode, promote steel to generate anodic passivation, prevent H from being separated out in the acid corrosion process and achieve the aim of acid corrosion resistance. In order to achieve the effect of enriching Cu in the rust layer, Cu is required to be more than 0.20%. However, too high content of Cu easily causes the problem of surface copper enrichment caused by selective oxidation during steel-making, thereby affecting the surface quality of the steel plate. Therefore, the technical scheme of the invention selects the Cu with the mass percentage content as follows: 0.20 to 0.40 percent.
Antimony: antimony (Sb) element can inhibit anode reaction and simultaneously form Cu with Cu element in steel2Sb can inhibit cathode reaction and has obvious effect of preventing the acid solution from corroding the steel plate substrate. For forming Cu on the surface of steel2The Sb film is required to have an Sb element content of more than 0.04%. However, the increase of the Sb content in the steel easily causes the reduction of the stamping property and the welding property of the steel grade. The technical scheme of the invention selects the Sb element content to be 0.04-0.12%.
The method for manufacturing the hot-rolled pickled steel plate for the acid corrosion resistant enamel heat exchanger comprises the following steps:
continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following components in percentage by mass: c: 0.03-0.10%, Si: 0.005-0.035%, Mn: 0.40-0.80%, P is less than or equal to 0.018%, S is less than or equal to 0.010%, N is less than or equal to 0.0050%, Al: 0.020 to 0.055%, Ti: 0.03-0.06%, Cu: 0.20-0.40%, Sb: 0.04-0.12%, and the balance of iron and inevitable impurities.
Heating the continuous casting plate blank to 1200-1230 ℃, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the rolling is carried out at a temperature above the austenite recrystallization temperature, and the finish temperature of the rough rolling is 980-1030 ℃; after rough rolling, controlling the thickness of the intermediate blank to be 36-40 mm; the finish rolling is 7-pass continuous rolling, rolling is carried out in an austenite single-phase region, and the finish rolling finishing temperature is 810-860 ℃; the pressure of the descaling water at the inlet of the finishing mill is 18-20 MPa, and the pressure of the descaling water between frames of the finishing mill is 10-12 MPa; after finish rolling, controlling the thickness of the steel plate to be 1.5-2.0 mm and the convexity of the steel plate to be 20-40 mu m; laminar cooling adopts a three-section cooling mode, the first-section cooling adopts water cooling, the cooling speed is 20-50 ℃/s, and the final cooling temperature of the first section is 650-700 ℃; air cooling is adopted in the second stage of cooling, and the air cooling time is 4-15 s; the third section of cooling adopts water cooling, and the cooling speed is 30-60 ℃/s; and obtaining the hot rolled steel coil when the coiling temperature is 600-640 ℃.
And re-uncoiling the hot-rolled steel coil on an uncoiler, and coiling to obtain a finished hot-rolled pickled steel plate through straightening, pickling, wherein the straightening elongation is 1.2-1.5%.
The technical key of the invention is realized mainly by the reasonable regulation and control technology of component design, hot rolling process and acid pickling straightening and withdrawal. For a hot continuous rolling unit, the thinner the hot rolled steel plate is, the longer the hot rolled steel plate is, the surface area is also multiplied, so that the heat dissipation is fast, the temperature drop is large, and the final rolling temperature cannot meet the design requirement of the controlled rolling and cooling process. In order to prevent the rolled piece in the finish rolling process from entering a two-phase region for rolling. When the components of the steel grade are designed, the temperature of a phase transition point is reduced by properly increasing the proportion of C, Mn and Cu elements; the steel component proportion designed by the invention has the advantages that the minimum temperature of the dynamic phase transition point is 803 ℃ under the cooling condition of 5 ℃/s, and the rolled piece in the finish rolling procedure can be rolled in an austenite single-phase region.
The production process adopted by the invention has the following reasons:
1. setting of heating temperature of continuous casting slab
In order to ensure that the finish rolling temperature of the finish rolling procedure meets the requirements of the controlled rolling and controlled cooling process, the steel burning temperature is set to be within the range of 1200-1230 ℃. The method has the advantages that the steel burning temperature is improved, the physical sensible heat brought by rolled pieces in the finish rolling procedure can be obviously increased, the requirement of the controlled rolling and controlled cooling process on the finish rolling temperature is met, and meanwhile, the improvement of the rolling stability of the finish rolling procedure is facilitated.
2. Setting of roughing finishing temperature
The rough rolling finishing temperature affects the scale on the surface of the steel plate, if the rough rolling finishing temperature is too high, excessive secondary scale on the surface of the intermediate billet is formed on the roller way from the rough rolling unit to the finishing rolling unit, the finish rolling process is not easy to remove, the scale spot defect of the scale on the surface of the steel plate can be formed after acid pickling, or the use of a final product is affected due to the scale explosion defect of enamel after the enamel is formed. The rough rolling finishing temperature is set to be 980-1030 ℃.
3. Setting of thickness of intermediate blank
The thickness of the intermediate billet affects the finish rolling temperature of the steel plate, particularly the finish rolling temperature of the edge of the steel plate, the thickness of the intermediate billet is thin, the surface area of a rolled piece is large, the heat dissipation is fast, the temperature drop of the process is large, the subsequent finish rolling temperature is too low, particularly the temperature drop of the edge of the steel plate is large, the edge of the steel plate is rolled in a ferrite and austenite two-phase region, and the forming performance is rapidly deteriorated. Rolling a product with the thickness specification of 1.5-2.0 mm, and setting the thickness of the intermediate blank to be 36-40 mm.
4. Setting of descaling water pressure in finishing mill
When the heating temperature of the continuous casting slab is too high, excessive iron scale is generated on the surface of the slab and cannot be completely removed in the subsequent hot rolling and rough rolling processes, and the iron scale is pressed into the surface of a steel plate by a roller in the finish rolling process to form iron scale press-in holes or press-in pits. Therefore, the scale removing water between the frames must be added between the finish rolling frames F0-F1 to remove the scales brought in by the rough rolling, so that the problem that the scales pressed into holes or pits by the subsequent frames cannot be removed in the subsequent pickling process is avoided, and surface defects are formed on the surface of the steel plate.
In order to meet the requirement of high surface quality, the pressure of descaling water at the inlet of a finishing mill is 18-20 MPa; the pressure of the descaling water between the frames of the finishing mill is 10-12 MPa. The double descaling water process is a necessary means for ensuring that the surface quality of the subsequent acid-washing product meets the requirements of the enameling process.
5. Setting of finish Rolling finishing temperature
The finish rolling process of the invention is rolling in an austenite single-phase region, if the finish rolling temperature is too low, and the finish rolling process is rolling in a ferrite and austenite two-phase region, a hot rolling texture which is not beneficial to stamping deformation can be formed, so that the forming performance index plastic strain ratio of the steel plate is sharply reduced, and particularly the anisotropy of the steel plate is serious, thereby causing the steel plate to crack or form earing defects during stamping deformation. And when the finish rolling finishing temperature is too high, the iron scale on the surface of the steel plate is serious and is not easy to remove during acid washing. The finish rolling finishing temperature is set to be 810-860 ℃.
6. Setting of crown of hot rolled steel sheet
The thickness of the hot rolled steel plate is slightly thicker in the middle and slightly thinner on two sides in the width direction of the steel plate, which mainly aims to ensure that the steel plate does not move on two sides during hot rolling. However, if the convexity is too large, the thickness variation is large at different portions of the steel sheet, particularly in the sheet width direction, and this is disadvantageous in subsequent press forming. Therefore, the convexity of the steel plate set by the invention is 20-40 μm.
7. Method of laminar cooling after finish rolling and setting of cooling rate
After finish rolling, laminar cooling adopts a three-section cooling mode, the first section of cooling adopts water cooling, the first section of cooling after finish rolling aims to supercool austenite in the material to a certain temperature, if the cooling speed is too low, ferrite grains obtained by material phase change are coarse, and the plasticity and the hole expansion performance of a steel plate are not facilitated; if the cooling speed is too high, the temperature of the phase change point can be reduced, which is not beneficial to obtaining the ferrite phase proportion with proper proportion in the second stage of cooling process; if the final cooling temperature is too high, ferrite grains after phase transformation are easy to grow, if the final cooling temperature is too low, the ferrite amount with a sufficient proportion cannot be obtained, and the plasticity and the hole expanding performance of the final material are too low. Comprehensively considering, the method is set that water cooling is adopted in the first section, the cooling speed is 20-50 ℃/s, and the final cooling temperature of the first section is 650-700 ℃.
The second stage of cooling adopts air cooling, the second stage of cooling is a stage for converting austenite into partial ferrite in the material, if the air cooling time is too short, the ferrite content with enough proportion can not be obtained, and if the air cooling time is too long, the excessive ferrite can be obtained. Comprehensively considering, the air cooling time of the second stage is set to be 4-15 s.
The third stage of cooling adopts water cooling, the third stage of cooling converts the residual austenite in the material of the invention into Ti (CN) for precipitation, if the cooling speed is too low and the coiling temperature is too high, partial pearlite structure can be obtained, and the reaming performance of the material is seriously reduced; if the cooling speed is too high, the coiling temperature is too low, and the plasticity and the hole expanding performance of the material are not favorable. Comprehensively considering, the third stage of cooling is water cooling, and the cooling speed is 30-60 ℃/s.
8. Setting of coiling temperature in Hot Rolling
When the hot rolling coiling temperature is too high, the thickness of the iron scale on the surface of the steel plate is obviously increased in the period from the finish rolling to coiling, and the subsequent pickling is influenced. If the hot rolling coiling temperature is too low, the strength of the steel sheet increases, the elongation decreases, and the formability is also deteriorated. A suitably low coiling temperature is advantageous for eliminating the discontinuous yield phenomenon because it is advantageous for distortion dislocations generated when the steel sheet is hot rolled to fix C, N atoms in a free state. The coiling temperature range set by the invention is 600-640 ℃.
9. Setting of withdrawal and straightening elongation
The aim of meeting the requirement of enamel processing in the subsequent procedure by replacing a cold-rolled sheet with a hot-rolled sheet is fulfilled. The hot rolling delivery state is extended to the hot rolling pickling surface for delivery. The pickling straightening and withdrawal process of the invention has very important influence on the shape and performance of the plate. On one hand, the pulling and straightening can be performed with mechanical scale breaking before the steel plate enters the pickling tank, which is beneficial to improving the efficiency of subsequent pickling. On the other hand, the residual stress of the hot rolling process of the steel plate can be eliminated through withdrawal and straightening, and the shape of a thin-specification product is obviously improved. The effect of improving the plate shape cannot be achieved due to the fact that the withdrawal and straightening rate is too low, but the withdrawal and straightening rate is too high, the work hardening of the steel plate is serious, and the elongation and the forming performance are reduced. The withdrawal and straightening elongation of the present invention is set to 1.2 to 1.5%.
The metallographic structure of the hot-rolled pickled steel plate produced by the method is ferrite and a small amount of pearlite, the grain size grade of the ferrite in the metallographic structure is 9.0-11.0 grades, and the yield strength R of the hot-rolled pickled steel plateP0.2330 to 430MPa, tensile strength Rm400 to 520MPa, elongation after break A50 mm22-45%; the hot-rolled pickled steel sheet has a crown of 20 to 40 μm.
Compared with the prior art, the invention has the following positive effects: 1. according to the invention, through proper component design and hot rolling process design, the limitation link of producing thin products by the existing controlled rolling and controlled cooling process is overcome, and the limitation of the thickness specification of the enamel steel of 2.0-5.0 mm is expanded to 1.5-5.0 mm. 2. Yield strength R of hot-rolled pickled steel plate produced by the inventionP0.2The steel plate for the structure is 330-430MPa, the tensile strength Rm is more than or equal to 440MPa, the elongation percentage A after fracture is more than or equal to 22 percent, and the steel plate for the structure has excellent comprehensive performance of enamel scale explosion resistance and acid corrosion resistance. 3. The hot-rolled pickled steel plate produced by the invention has good acid corrosion resistance at 30 DEG C
10％H2SO4In a 24-hour test of solution corrosion soaking, the corrosion resistance of the steel is more than 20 times that of the common structural steel Q345. 4. The hot-rolled pickled steel plate produced by the invention meets the manufacturing process requirements of the enamel heat exchanger manufactured by cold-rolled plates with the same thickness specification, and achieves the purpose of replacing the cold-rolled plates with the hot-rolled pickled plates. 5. The hot-rolled pickled steel plate does not need to be added with alloy elements such as Cr, Ni, Nb and the like, saves the cost of the alloy elements by about 150-250 yuan/ton, and has remarkable economical efficiency.
Drawings
FIG. 1 is a photograph of a metallographic structure of a hot-rolled pickled steel sheet according to example 1 of the present invention.
Detailed Description
The present invention will be further described with reference to examples 1 to 5, which are shown in tables 1 to 5. Table 1 shows the chemical composition (in weight percent) of the steel of the examples of the present invention, with the balance being Fe and unavoidable impurities.
Table 1 chemical composition of the steels of the examples of the invention, in units: and (4) weight percentage.
According to the design requirements of the components of the material, molten iron is adopted for pre-desulfurization, the top and the bottom of a converter are subjected to combined blowing, an LF furnace is used for refining and removing S, the temperature is raised to the temperature meeting the requirements of the continuous casting process, then low-carbon steel casting powder is adopted, Ar protection is blown in the whole process to cast the continuous casting slab, the thickness of the continuous casting slab is 210 or 230mm, the width is 800-1630 mm, and the length is 8500-11000 mm.
And (3) sending the fixed-length plate blank produced in the steel-making process to a heating furnace for reheating, taking out the plate blank from the furnace for descaling, and sending the plate blank to a hot continuous rolling mill for rolling. Controlled rolling and controlled cooling are carried out by a rough rolling and finish rolling continuous rolling unit, and then coiling is carried out. The thickness of the hot rolled steel plate is 1.5-2.0 mm. The main process control parameters of hot rolling are shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
The hot rolled steel plate obtained by the invention is subjected to a GB/T228.1-2010 metal material tensile test part 1: room temperature test method "was used for tensile test, and the mechanical properties are shown in Table 3.
TABLE 3 mechanical Properties of Hot rolled Steel sheets according to examples of the present invention
And re-uncoiling the hot-rolled steel coil on an uncoiler, and coiling to obtain a finished hot-rolled pickled steel plate through straightening and pickling, wherein the straightening elongation is 1.2-1.5%. The withdrawal and straightening elongation rates adopted in the examples of the present invention are shown in table 4.
TABLE 4 elongation by withdrawal straightening for examples of the invention
| Hot rolling parameters | Thickness/mm of hot-rolled pickled steel sheet | Withdrawal elongation/%) |
| The invention | 1.5-2.0 | 1.2-1.5 |
| Example 1 | 1.5 | 1.5 |
| Example 2 | 1.7 | 1.2 |
| Example 3 | 1.8 | 1.2 |
| Example 4 | 2.0 | 1.2 |
| Example 5 | 1.61 | 1.5 |
Referring to fig. 1, the hot-rolled pickled steel sheet obtained by the above method has a metallographic structure of ferrite and a small amount of pearlite, the grain size of the ferrite in the metallographic structure is 9.0 to 11.0, and the yield strength R of the hot-rolled pickled steel sheetP0.2330 to 430MPa, tensile strength Rm400 to 520MPa, elongation after break A50mm22-45%; the hot-rolled pickled steel sheet has a crown of 20 to 40 μm.
TABLE 5 mechanical Properties of Hot-rolled pickled Steel sheets according to examples of the present invention
The hot-rolled pickled steel plate and the common structural steel Q345 are subjected to a sulfuric acid soaking corrosion comparison test, and the test method comprises the following steps: soaking a steel plate sample in 10% sulfuric acid at 30 ℃ for 24h, and calculating the corrosion rate and corrosion resistanceThe erosion rate is calculated as follows: v ═ Δ w/(sxt), where: Δ w: weight loss (mg); s: surface area (cm)2) (ii) a T: soaking time (h). The control parameters of the sulfuric acid soaking corrosion test of the embodiment of the invention are shown in the table 6.
TABLE 6 control parameters for sulfuric acid immersion corrosion test of inventive examples
As shown in Table 6, 10% H at 30 deg.C2SO4In a solution corrosion soaking test for 24 hours, the corrosion resistance rate of the hot-rolled pickled steel plate is more than 20 times of that of the common structural steel Q345.
The hot-rolled pickled steel plate with the thickness of 1.5-2.0 mm has a proper strength range and good forming performance index, well meets the process control requirements of forming, welding and the like of a water heater heat exchanger element manufactured in a post-process, and can realize the effect of replacing a cold-rolled product.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (5)
1. A hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger comprises the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.005-0.035%, Mn: 0.40-0.80%, P is less than or equal to 0.018%, S is less than or equal to 0.010%, N is less than or equal to 0.0050%, Al: 0.020 to 0.055%, Ti: 0.03-0.06%, Cu: 0.20-0.40%, Sb: 0.04-0.12% of iron and inevitable impurities in balance; the metallographic structure of the hot-rolled pickled steel plate is ferrite and a small amount of pearlite, and the grain size grade of the ferrite in the metallographic structure is 9.0-11.0.
2. The hot-rolled pickled steel sheet for acid corrosion resistant enamel heat exchanger as claimed in claim 1, wherein the yield strength R of the hot-rolled pickled steel sheet having a thickness of 1.5 to 2.0mm isP0.2330 to 430MPa, tensile strength RmIs 400 to 520MPa, and is elongated after breakingRate A50mm22 to 45% and the hot-rolled pickled steel sheet has a crown of 20 to 40 μm.
3. A method for manufacturing a hot-rolled pickled steel plate for an acid corrosion resistant enamel heat exchanger is characterized by comprising the following steps:
continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following components in percentage by mass: c: 0.03-0.10%, Si: 0.005-0.035%, Mn: 0.40-0.80%, P is less than or equal to 0.018%, S is less than or equal to 0.010%, N is less than or equal to 0.0050%, Al: 0.020 to 0.055%, Ti: 0.03-0.06%, Cu: 0.20-0.40%, Sb: 0.04-0.12%, and the balance of iron and inevitable impurities.
Heating the continuous casting plate blank to 1200-1230 ℃, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the rolling is carried out at a temperature above the austenite recrystallization temperature, and the finish temperature of the rough rolling is 980-1030 ℃; after rough rolling, controlling the thickness of the intermediate blank to be 36-40 mm; the finish rolling is 7-pass continuous rolling, rolling is carried out in an austenite single-phase region, and the finish rolling finishing temperature is 810-860 ℃; the pressure of the descaling water at the inlet of the finishing mill is 18-20 MPa, and the pressure of the descaling water between frames of the finishing mill is 10-12 MPa; after finish rolling, the convexity of the steel plate is 20-40 μm; laminar cooling adopts a three-section cooling mode, the first-section cooling adopts water cooling, the cooling speed is 20-50 ℃/s, and the final cooling temperature of the first section is 650-700 ℃; air cooling is adopted in the second stage of cooling, and the air cooling time is 4-15 s; the third section of cooling adopts water cooling, and the cooling speed is 30-60 ℃/s; and obtaining the hot rolled steel coil when the coiling temperature is 600-640 ℃.
And re-uncoiling the hot-rolled steel coil on an uncoiler, and coiling to obtain a finished hot-rolled pickled steel plate through straightening, pickling, wherein the straightening elongation is 1.2-1.5%.
4. The method for producing a hot-rolled pickled steel sheet for an acid-corrosion-resistant enamel heat exchanger as claimed in claim 3, wherein the thickness of the steel sheet is controlled to be 1.5 to 2.0mm after the finish hot rolling.
5. The hot rolled pickled steel plate for acid corrosion resistant enamel heat exchanger as set forth in claim 3The method for producing (1) is characterized in that the hot-rolled pickled steel sheet has a metallographic structure of ferrite and a small amount of pearlite, the ferrite grain size of the metallographic structure is 9.0 to 11.0 grades, and the yield strength R of a hot-rolled pickled steel sheet having a thickness of 1.5 to 2.0mmP0.2330 to 430MPa, tensile strength Rm400 to 520MPa, elongation after break A50mm22 to 45% and the hot-rolled pickled steel sheet has a crown of 20 to 40 μm.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006144106A (en) * | 2004-11-24 | 2006-06-08 | Kobe Steel Ltd | High-strength steel sheet excellent in adhesiveness of coating film |
| CN101370952A (en) * | 2006-01-18 | 2009-02-18 | 新日本制铁株式会社 | Enamelware and glaze |
| CN105088101A (en) * | 2015-07-17 | 2015-11-25 | 武汉钢铁(集团)公司 | Steel for enamel heat transfer element having corrosion resistance and manufacturing method thereof |
| CN105316579A (en) * | 2014-07-29 | 2016-02-10 | 上海梅山钢铁股份有限公司 | Thin hot rolled pickled steel plate and fabrication method thereof for water heater enamel liner |
| CN109487153A (en) * | 2017-09-11 | 2019-03-19 | 上海梅山钢铁股份有限公司 | A kind of tensile strength 440MPa grades high reaming hot rolling acid-cleaning steel plate |
| CN110863136A (en) * | 2018-08-27 | 2020-03-06 | 上海梅山钢铁股份有限公司 | High-hole-expansion-performance hot rolled steel plate for enamel liner of water heater and manufacturing method thereof |
-
2020
- 2020-09-30 CN CN202011060396.0A patent/CN114318126A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006144106A (en) * | 2004-11-24 | 2006-06-08 | Kobe Steel Ltd | High-strength steel sheet excellent in adhesiveness of coating film |
| CN101370952A (en) * | 2006-01-18 | 2009-02-18 | 新日本制铁株式会社 | Enamelware and glaze |
| CN105316579A (en) * | 2014-07-29 | 2016-02-10 | 上海梅山钢铁股份有限公司 | Thin hot rolled pickled steel plate and fabrication method thereof for water heater enamel liner |
| CN105088101A (en) * | 2015-07-17 | 2015-11-25 | 武汉钢铁(集团)公司 | Steel for enamel heat transfer element having corrosion resistance and manufacturing method thereof |
| CN109487153A (en) * | 2017-09-11 | 2019-03-19 | 上海梅山钢铁股份有限公司 | A kind of tensile strength 440MPa grades high reaming hot rolling acid-cleaning steel plate |
| CN110863136A (en) * | 2018-08-27 | 2020-03-06 | 上海梅山钢铁股份有限公司 | High-hole-expansion-performance hot rolled steel plate for enamel liner of water heater and manufacturing method thereof |
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