CN110863136A - High-hole-expansion-performance hot rolled steel plate for enamel liner of water heater and manufacturing method thereof - Google Patents
High-hole-expansion-performance hot rolled steel plate for enamel liner of water heater and manufacturing method thereof Download PDFInfo
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- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
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- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/003—Cementite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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Abstract
The invention discloses a hot rolled steel plate with high hole expansion performance for an enamel liner of a water heater and a manufacturing method thereof, and solves the technical problem that the existing hot rolled steel plate for the enamel liner of the water heater cannot meet the hole expansion flanging preparation requirement of the enamel liner of the water heater. The invention provides a high-hole-expansion-performance hot-rolled steel plate for an enamel inner container of a water heater, which comprises the following chemical components in percentage by weight: c: 0.02-0.10%, Si is less than or equal to 0.03%, Mn: 0.2-0.8%, P is less than or equal to 0.02%, S is less than or equal to 0.006%, Als: 0.01-0.05%, N: 0.004-0.007%, Cu: 0.01-0.08%, Ti: 0.03-0.08%, Ca: 0.004-0.008% and the balance of iron and inevitable impurities. The hole expansion performance lambda of the hot rolled steel plate is 80-140%, and the hot rolled steel plate is suitable for an enamel liner, an enamel structural part and the like of a water heater.
Description
Technical Field
The invention relates to a hot rolled steel plate for an enamel inner container of a water heater, in particular to a high-hole-expansion-performance hot rolled steel plate for the enamel inner container of the water heater and a manufacturing method thereof, belonging to the technical field of iron-based alloy.
Background
The existing enamel inner container of the water heater generally adopts a structure of two end sockets and a barrel body, and the structural mode of the inner container has a straight line welding line and two annular welding lines. The liner structure has the advantages that the requirement of punch forming of the seal head can be met by adopting a DQ-grade steel plate; the defects are that the T-shaped welding seam at the joint of the straight seam and the circular seam is a weak link in the process structure, is easy to become a water leakage point of the liner and seriously influences the service life of the enamel liner.
In order to improve the quality and the service life of the inner container of the water heater, the most direct and effective technical measure is to eliminate the T-shaped welding line through the change of the structural form. Therefore, the technical personnel have proposed two-section water heater enamel inner bag structure, through adopting the mode of head deep-drawing stamping forming, lengthen the mode that the head straightway passes through deep-drawing forming process, directly with the mode of two head butt joints + circumferential weld welding, compare traditional three-section enamel inner bag structure, can reduce a transversal joint and a circumferential weld, thoroughly eliminated the T shape welding point of transversal joint and circumferential weld, just reach the emergence probability that reduces enamel inner bag and leak from inner bag structural design change.
In order to fixedly install the heating pipe of the water heater, a flange is required to be arranged on the end socket of the enamel inner container in a pressing mode, and sealing and fixing of the heating pipe are facilitated. The connection between the end socket and the flange, the inner ring is fixed by adopting a reaming, flanging and riveting mode. The outer ring is fixed in a welding mode. The manufacture process of the enamel inner container of the water heater is changed, and the corresponding performance requirement on the raw material, namely the steel plate, is changed. Besides the requirement that the steel plate has excellent enamel performance, the steel plate has strict requirements on the steel plate performance of a steel blank of an enamel liner of a water heater, particularly the stamping forming performance, and besides the excellent forming performance, the steel plate also has excellent hole expanding and flanging performance, and the hole expanding performance lambda of a hot-rolled steel plate meeting the conditions through research is more than or equal to 70 percent, and the elongation A after fracture is more than or equal to 28 percent.
The hole expansion performance lambda of the existing hot rolled steel plate for manufacturing the enamel liner of the water heater is only 50 percent; the elongation A after fracture is more than or equal to 22 percent, and can not meet the requirement of the two-section type water heater enamel liner material.
Disclosure of Invention
The invention aims to provide a hot rolled steel plate with high hole expansion performance for an enamel inner container of a water heater and a manufacturing method thereof, and mainly solves the technical problem that the existing hot rolled steel plate for the enamel inner container of the water heater cannot meet the preparation requirement of hole expansion flanging of the enamel inner container of the water heater.
The invention adopts the technical scheme that a high-hole-expansion-performance hot-rolled steel plate for an enamel inner container of a water heater comprises the following chemical components in percentage by weight: c: 0.02-0.10%, Si is less than or equal to 0.03%, Mn: 0.2-0.8%, P is less than or equal to 0.02%, S is less than or equal to 0.006%, Als: 0.01-0.05%, N: 0.004-0.007%, Cu: 0.01-0.08%, Ti: 0.03-0.08% of Ca, 0.004-0.008% of Ca, and the balance of iron and inevitable impurities.
The metallographic structure of the hot rolled steel plate with high hole expansibility for the enamel liner of the water heater is ferrite and free cementite, the grain size grade of the ferrite is 8-10 grade, and the yield strength R of the hot rolled steel plate with the thickness of 1.5-4.0 mmP0.2280-340MPa, tensile strength Rm400 to 480MPa, elongation after break A50mm30-40% and 80-140% of reaming property lambda.
The reason why the chemical composition of the hot rolled steel plate with high hole expansibility for the enamel liner of the water heater is limited within the above range is as follows:
carbon: c is the most obvious element of the strengthening effect of the steel and is also a key element influencing the stamping forming performance of the steel plate. From the viewpoint of lowering the strength of the steel grade and improving the press formability of the steel sheet, it is desirable that the lower the C content, the better. However, when the C content is too low, the transformation point of the steel is increased, and the finish rolling temperature for hot rolling reaches 900 ℃ or higher, which is difficult to realize in the hot rolling process. The content of the C element is properly increased, and the limitation condition that the finishing temperature is below 900 ℃ can be met. The content of C is set to be 0.02-0.10%.
Silicon: si element improves various elements with beneficial hole expanding performance of steel, but the increase of Si content in the steel can influence the quality of subsequent enamel and can cause the problem that the oxide scales on the surface of the steel plate are difficult to remove. The Si content is set to be less than or equal to 0.03 percent. Unlike high-hole-expansion steel used for manufacturing automobile chassis.
Manganese: mn is also one of common strengthening elements of steel grades, and the low Mn content is easy to cause the increase of the risk of continuous casting bleed-out and is not beneficial to the continuous casting production of a steelmaking process; increasing the Mn content inevitably leads to an increase in the cost of the steel-making process. Therefore, according to the requirement of users on the strength performance of the steel plate, the Mn content is set to be 0.2-0.8%, and the most economic range is set.
Phosphorus: p is also an element which is inevitably present in the steel smelting process, but has certain influence on the deep drawability of the steel plate, and the P element is an element which is easy to segregate, preferably the lower the P element is, but the lower the P element is, the cost of the steel-making process is increased, and the control of the lower P content is difficult, so that the P content is set to be less than or equal to 0.02 percent.
Sulfur: s is also an element beneficial to the fish scaling resistance of the enamel. The conventional hot-rolled enamel steel needs to retain a certain amount of S element. However, since the S element is extremely harmful to the improvement of the hole expansibility of steel, the content of the S element must be limited. In consideration of improving the reaming and flanging performance of the steel grade, the invention sets the S content as follows: s is less than or equal to 0.006 percent.
Aluminum: al is mainly used for converter steelmaking deoxidization, and the deoxidization product is Al2O3Can be removed after being combined with the steel slag, and Als is remained in the steel. The proper content of Als in the steel can ensure the cleanliness of the steel; meanwhile, Als can also play a role in refining grains. However, the increased content of Als causes an increase in steel-making cost and also causes difficulty in the production structure of continuous casting. The invention sets the Al content as follows: 0.01 to 0.05 percent.
Nitrogen: n is an additional product in the converter steelmaking production, can be fully utilized, and the N in the steel, Ti and C produce fine dispersed two-phase particle Ti (CN) compounds, thereby being beneficial to the production for preventing the enamel fish scaling explosion defect. The invention sets the N content as follows: 0.004-0.007%.
Titanium: on one hand, the Ti element can fix C, N interstitial atoms of the steel grade and improve the formability of the steel. The technical scheme of the invention fully utilizes the interaction of Ti element and N, C element in steel. The hot rolled steel plate needs to be controlled to have lower performance strength, and the deep drawing forming performance of the steel plate is favorably improved. After the inner container is manufactured by deep drawing forming and enameling, the enamel process treatment is fully carried out by using 800-. In order to achieve the above purpose, the present invention sets the content of Ti as follows: 0.03-0.08%, which is the most economical and the most convenient control range in production.
Cu: a proper amount of Cu element can be enriched on the surface of the steel in the production process of the steel, and the sintering bonding strength between the steel plate and the enamel glaze powder can be improved. The Cu element content is too high, which causes the increase of the manufacturing cost and also causes the problem that the iron scale on the surface of the pickling process is difficult to pickle. Too low to have an effect of increasing the adherence of the enamel. The invention sets the Cu content as follows: 0.01 to 0.08 percent.
Ca is a process treatment mode mainly aiming at removing and spheroidizing the inclusions in the steel grade, and is a very key process technical measure for improving the reaming and flanging performance of the steel. To ensure the process effect of Ca treatment. The invention sets the Ca content as follows: 0.004-0.008%.
A manufacturing method of a hot rolled steel plate with high hole expansion performance for an enamel inner container of a water heater comprises the following steps:
continuously casting molten steel to obtain a continuous casting plate blank, wherein the molten steel comprises the following components in percentage by weight: c: 0.02-0.10%, Si is less than or equal to 0.03%, Mn: 0.2-0.8%, P is less than or equal to 0.02%, S is less than or equal to 0.006%, Als: 0.01-0.05%, N: 0.004-0.007%, Cu: 0.01-0.08%, Ti: 0.03-0.08 percent of Ca, 0.004-0.008 percent of Ca, and the balance of iron and inevitable impurities;
heating the continuous casting plate blank to 1180-1220 ℃, and then carrying out hot rolling, wherein the hot rolling is a two-section type rolling process, the rough rolling is 6-pass continuous rolling, the rolling is carried out at the temperature above the austenite recrystallization temperature, and the finish temperature of the rough rolling is 1020-1060 ℃; the finish rolling is 7-pass continuous rolling, the rolling is carried out in an austenite non-recrystallization temperature region, the finish rolling temperature is 850-900 ℃, the finish rolling reduction rate is more than or equal to 75%, after the finish rolling, the thickness of the steel plate is 1.5-4.0 mm, the laminar cooling adopts a three-stage cooling mode, the first stage adopts water cooling, the cooling speed is 20-50 ℃/s, the final cooling temperature of the first stage is 650-700 ℃/s, the second stage adopts air cooling, the air cooling time is 4-15s, the third stage adopts water cooling, the cooling speed is 30-60 ℃/s, and the hot rolled steel coil is coiled when the coiling temperature is 600-680 ℃.
The reason of the manufacturing process system adopted by the invention is as follows:
1. setting of heating temperature of continuous casting slab
The heating temperature and time of the continuous casting slab are set to ensure that alloy elements such as C, Mn and the like in the continuous casting slab are fully diffused and dissolved, and coarse carbide particles are dissolved and uniformly distributed in steel. Both too low a temperature and too short a heating time do not achieve the above objectives. The medium slab heating temperature is adopted, the target temperature is 1190 ℃, if the temperature is too high, the heating time is too long, the performance of the steel plate is easy to be high due to the fact that the content of Ti in steel is high and the melting of Ti elements is increased, and the oxide skin on the surface of the slab is thickened, so that the final performance and the surface quality of the steel plate are not facilitated, and energy is consumed. Therefore, the heating temperature of the continuous casting plate blank is set to be 1180-1220 ℃, and the heating time is set to be 200-280 min.
2. Roughing finish temperature setting
The rough rolling process is controlled to be rolled above the austenite recrystallization temperature, and through thermodynamic calculation, the material A of the invention3The point transformation temperature (ferrite transformation in equilibrium state) was 806.4 ℃. In order to ensure that austenite is repeatedly deformed and recrystallized, uniform and fine austenite grains are obtained. Therefore, the rough rolling finishing temperature is set to be 1020-1060 ℃.
3. Setting of reduction ratio of finish rolling
The temperature of the billet in the previous pass of finish rolling is high, the deformation resistance rate is low, and a large deformation is adopted as far as possible, so that the risk of the reduction of rolling stability caused by the increase of the load of a rolling mill due to the reduction of the temperature and the increase of the deformation resistance of the billet in the subsequent pass is reduced. Therefore, the finish rolling reduction rate is set to be more than or equal to 75 percent.
4. Finish rolling finish temperature setting
The finish rolling temperature of the invention is set to have two functions, on one hand, flat austenite grains with deformation zones inside are obtained by rolling the material in an austenite non-recrystallization area and are converted into fine ferrite grains in the subsequent laminar cooling process, thus playing the roles of refining the grains and reducing the zonal segregation; on the other hand, if the finishing temperature is too low, the rolling load is too large, and the rolling stability is impaired. Therefore, the finish rolling finishing temperature is set to be 850-900 ℃.
5. Setting of laminar cooling mode after finish rolling
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 invention sets that the first section adopts water cooling, the cooling speed is 20-50 ℃/s, and the final cooling temperature of the first section is 650-.
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. And 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 invention sets that the third section of cooling is water cooling, and the cooling speed is 30-60 ℃/s.
6. Setting of coiling temperature in Hot Rolling
The hot rolling coiling temperature mainly influences the structure and the performance of the material and the subsequent Ti (CN) precipitation effect. By adopting a lower coiling temperature, the generation of proeutectoid ferrite can be reduced, the thick interlayer spacing of pearlite plates is prevented, the structure distribution is uniform, and the strip segregation is reduced. However, the hot rolling coiling temperature is too low, a large amount of bainite structures can be generated, the strength is too high, and the processing by users is not facilitated. Therefore, the hot rolling coiling temperature is set to be 600-680 ℃.
The Ti content is combined with the particularity of the enameling process of the existing hot rolled steel plate during enameling, the fine grain strengthening effect of the steel plate is ineffective due to the cooling system after enameling of the hot rolled steel plate, and the strength performance of the steel plate is reduced due to the growth of grains; aiming at solving the problem of the strength reduction of the steel plate after the enameling; the effect of precipitation strengthening of two-phase particles formed by Ti element and N, C and other elements cannot be fully exerted in the temperature window of 600-680 ℃ of the coiling temperature of the hot-rolled steel plate; the sintering at about 850 ℃ in the enamel process is fully utilized, the precipitation strengthening effect of steel type two-phase particles is promoted, the number of the two-phase particles such as TiC, TiN, Ti (CN) and the like is increased, the particle size is increased, and the growth of crystal grains can be inhibited; the purpose of preventing the performance and the strength of the steel plate from being reduced is achieved. The requirements of punch forming and reaming flanging processing are met, the characteristic that the strength of the enameled liner steel plate is reduced a little is also met, and the aim of improving the rigidity of the enameled liner is facilitated.
The hot rolled steel plate provided by the invention fully utilizes the synergistic effect of chemical components of the steel plate and the temperature in the manufacturing process, and simultaneously meets the processing requirement of high-reaming flanging and the performance requirement of high-strength water storage pressure bearing of the enamel liner of the water heater.
The metallographic structure of the hot rolled steel plate with high hole expansibility for the enamel liner of the water heater produced by the method is ferrite and free cementite, the grain size grade of the ferrite is 8-10 grades, and the yield strength R of the hot rolled steel plateP0.2280-340MPa, tensile strength Rm400 to 480MPa, elongation after break A50mm30-40% and 80-140% of reaming property lambda.
Compared with the prior art, the invention has the following positive effects: 1. the high-strength hot-rolled steel plate is adopted to meet the requirement of high rigidity of the enamel liner, and the invention has the advantages of less added amount of alloy elements of the hot-rolled steel plate, low cost and easy realization of production and manufacturing; the component system of the existing hot rolling enamel steel is adopted, and the influence on the matching of the steel plate and the enamel is least. The requirement of the enamel scale explosion resistance of the production steel plate factor of the enamel liner of the water heater is met. 2. The method ensures the enameling performance of the steel plate, improves the reaming and flanging performance of the steel plate through a mode of combining component design and process, and solves the limitation link of reaming and flanging cracking of the sealing head mounting flange in the manufacturing process of the enamel liner of the water heater. 3. The Ti element in the material of the invention with the weight percentage content of 0.03-0.08 percent is an economic addition amount, which can not only reduce the problems of difficult continuous casting of a plurality of furnaces and high breakout risk probability due to overhigh Ti content, but also reduce the steel-making cost. 4. The finish temperature of rough rolling is controlled to be 1020-1060 ℃, the finish temperature of finish rolling is controlled to be 850-900 ℃, the hot rolling coiling temperature is controlled to be 600-680 ℃, the texture and the performance of a steel plate required by the production of a water heater enamel liner blank with excellent reaming performance are obtained, the subsequent processes of cold rolling, annealing and the like can be omitted, the reaming and flanging performance is more excellent, and the requirements of deep drawing forming and reaming and flanging processing of the water heater enamel liner are met. 5. The hot rolled steel plate is suitable for the requirements of deep drawing forming, reaming pipe flanging and enamel processing. And is also suitable for preparing enamel structural parts with good enamel adherence and fish scaling resistance, such as assembled enamel water tanks and the like. 6. Compared with the water heater enamel liner produced by cold rolled sheets, the water heater enamel liner produced by the deep drawing and reaming flanging process prepared by the hot rolled steel sheet has the characteristics of high strength, large volume and better fatigue resistance.
Drawings
FIG. 1 is a photograph of a metallographic structure of a hot rolled steel sheet according to example 1 of the invention.
Detailed Description
The present invention will be further described with reference to examples 1 to 4, which are shown in tables 1 to 3. 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.
Molten steel meeting the chemical composition requirements is obtained through converter smelting, and after the molten steel is refined outside a furnace, slab continuous casting is carried out to obtain a continuous casting slab; the thickness of the continuous casting slab is 210 mm 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 is carried out by a rough rolling and finish rolling continuous rolling unit, controlled cooling is carried out, and then coiling is carried out. The thickness of the hot rolled steel plate is 1.5-4.0 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 with high hole expansion performance for the enamel inner container of the water heater, which is obtained by the method, is shown in figure 1, the metallographic structure of the hot rolled steel plate is ferrite and free cementite, the grain size grade of the ferrite is 8-10 grades, and the yield strength R of the hot rolled steel plateP0.2280-340MPa, tensile strength Rm400 to 480MPa, elongation after break A50mm30-40% and 80-140% of reaming property lambda.
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
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 (4)
1. A high-hole-expansion-performance hot rolled steel plate for an enamel inner container of a water heater comprises the following chemical components in percentage by weight: c: 0.02-0.10%, Si is less than or equal to 0.03%, Mn: 0.2-0.8%, P is less than or equal to 0.02%, S is less than or equal to 0.006%, Als: 0.01-0.05%, N: 0.004-0.007%, Cu: 0.01-0.08%, Ti: 0.03-0.08% of Ca, 0.004-0.008% of Ca, and the balance of iron and inevitable impurities.
2. The hot rolled steel plate with high hole expansibility for the enamel liner of a water heater as claimed in claim 1, wherein the metallographic structure of the hot rolled steel plate is ferrite + free cementite, the grain size of the ferrite is 8-10 grade, and the yield strength R of the hot rolled steel plate with the thickness of 1.5-4.0 mmP0.2280-340MPa, tensile strength Rm400 to 480MPa, elongation after break A50mm30-40% and 80-140% of reaming property lambda.
3. A manufacturing method of a hot rolled steel plate with high hole expansion performance for an enamel inner container of a water heater is characterized by comprising the following steps:
continuously casting molten steel to obtain a continuous casting plate blank, wherein the molten steel comprises the following components in percentage by weight: c: 0.02-0.10%, Si is less than or equal to 0.03%, Mn: 0.2-0.8%, P is less than or equal to 0.02%, S is less than or equal to 0.006%, Als: 0.01-0.05%, N: 0.004-0.007%, Cu: 0.01-0.08%, Ti: 0.03-0.08 percent of Ca, 0.004-0.008 percent of Ca, and the balance of iron and inevitable impurities;
heating the continuous casting plate blank to 1180-1220 ℃, and then carrying out hot rolling, wherein the hot rolling is a two-section type rolling process, the rough rolling is 6-pass continuous rolling, the rolling is carried out at the temperature above the austenite recrystallization temperature, and the finish temperature of the rough rolling is 1020-1060 ℃; the finish rolling is 7-pass continuous rolling, the rolling is carried out in an austenite non-recrystallization temperature region, the finish rolling temperature is 850-900 ℃, the finish rolling reduction rate is not less than 75%, the laminar cooling after the finish rolling adopts a three-section cooling mode, the first section adopts water cooling, the cooling speed is 20-50 ℃/s, the final cooling temperature of the first section is 650-700 ℃/s, the second section adopts air cooling, the air cooling time is 4-15s, the third section adopts water cooling, the cooling speed is 30-60 ℃/s, and the coiling temperature is 600-680 ℃, so that the hot rolled steel coil is obtained.
4. The method for manufacturing the hot rolled steel plate with high hole expansibility for the enamel liner of the water heater as set forth in claim 3, wherein after the hot rolling and finish rolling, the thickness of the hot rolled steel plate is controlled to be 1.5-4.0 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810979189.1A CN110863136A (en) | 2018-08-27 | 2018-08-27 | High-hole-expansion-performance hot rolled steel plate for enamel liner of water heater and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810979189.1A CN110863136A (en) | 2018-08-27 | 2018-08-27 | High-hole-expansion-performance hot rolled steel plate for enamel liner of water heater and manufacturing method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114318126A (en) * | 2020-09-30 | 2022-04-12 | 上海梅山钢铁股份有限公司 | Hot-rolled pickled steel plate for acid corrosion resistant enamel heat exchanger and manufacturing method thereof |
| CN115369329A (en) * | 2022-09-30 | 2022-11-22 | 武汉钢铁有限公司 | Wide-width thin-specification high-surface-quality hot-rolled deep-drawing enamel steel and production method thereof |
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| CN114318126A (en) * | 2020-09-30 | 2022-04-12 | 上海梅山钢铁股份有限公司 | Hot-rolled pickled steel plate for acid corrosion resistant enamel heat exchanger and manufacturing method thereof |
| CN115369329A (en) * | 2022-09-30 | 2022-11-22 | 武汉钢铁有限公司 | Wide-width thin-specification high-surface-quality hot-rolled deep-drawing enamel steel and production method thereof |
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Application publication date: 20200306 |