CN112226673A - Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof - Google Patents
Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof Download PDFInfo
- Publication number
- CN112226673A CN112226673A CN201910581809.0A CN201910581809A CN112226673A CN 112226673 A CN112226673 A CN 112226673A CN 201910581809 A CN201910581809 A CN 201910581809A CN 112226673 A CN112226673 A CN 112226673A
- Authority
- CN
- China
- Prior art keywords
- rolled steel
- equal
- rolling
- hot
- less
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- 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
-
- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- 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
-
- 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
-
- 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
-
- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
Abstract
The invention discloses a hot rolled steel plate with 650 MPa-grade tensile strength and a manufacturing method thereof, and mainly solves the technical problems of high manufacturing cost, low strength and low-temperature impact property of the existing hot rolled steel plate for an automobile beam. The invention relates to a hot rolled steel plate with 650 MPa-level tensile strength, which comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si is less than or equal to 0.1%, Mn: 1.05-1.20%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, Nb: 0.01 to 0.02%, Ti: 0.065-0.085 percent of Ca, 0.0015-0.0045 percent of Ca, 0.02-0.05 percent of Alt, and the balance of Fe and inevitable impurities, wherein the content of the elements is required to meet the requirement that the carbon equivalent is less than or equal to 0.32. The elongation A after fracture of the hot rolled steel plate is 18-24%, and the hot rolled steel plate is mainly used for manufacturing beams, longitudinal beams and other structural parts of trucks.
Description
Technical Field
The invention relates to hot-rolled automobile structural steel, in particular to a hot-rolled steel plate with 650 MPa-level tensile strength and a manufacturing method thereof.
Background
The automobile beam steel is mainly used for manufacturing transverse beams, longitudinal beams and other structural parts of trucks. The automobile beam is formed by cold stamping or rolling, and bears various complex stresses such as impact, torsion and the like in the service process; in addition, the breadth of our country is broad, there are areas with the temperature of about 20 ℃ throughout the year, and also areas with the temperature reaching-30 ℃ to-40 ℃ in winter, and the difference of the temperature requires that the automobile has good low-temperature impact toughness; therefore, the steel for the automobile beam requires high conventional strength, good plasticity and cold bending performance and good low-temperature impact toughness; finally, in order to meet the requirements of aesthetic property and corrosion resistance, the crossbeam is often required to be painted, so the automobile girder steel cannot have rusty red iron oxide skin.
Automobile manufacturers require lower cost and better cost on the premise that the material meets the requirements of strength, toughness and formability. In order to meet the development requirement, a novel automobile beam steel which is low in cost and has strength and impact toughness meeting the requirements of the automobile beam steel needs to be developed.
The Chinese patent application with the application publication number of CN104988392A discloses 610 MPa-level low-cost girder steel, and discloses automobile girder steel with the thickness range of 3-8 mm and the lowest tensile strength Rm610MPa and 18 percent of elongation A after the minimum fracture, which has the defects that the content of Mn is designed to be 1.50 to 1.65 percent, the content of Nb is designed to be 0.02 to 0.04 percent, and the balance is iron, copper, nickel and inevitable impurities; the total content of Mn, Nb and Ti is 1.52-1.72%, and the alloy cost is high; the cooling speed after finish rolling is 80 ℃/S-200 ℃/S, the lower limit and the upper limit of the cooling speed are provided, the production difficulty is high, and the hot rolling production cost is high.
The application publication No. CN102212747A discloses a low-cost steel for automobile beams and a manufacturing method thereof, wherein the content of C is 0.09% -0.15%, the content of Si is 0.30% -0.60%, the content of Mn is 1.25% -1.50%, the content of Nb is 0.015% -0.045%, the total content of Mn + Nb + Ti is 1.265% -1.545%, the alloy cost is high, but the lowest yield strength realized by the steel is 465MPa, and the highest tensile strength is 555 MPa; the content of Si is 0.30-0.60%, according to Si > 0.10%, fayalite is produced at 1180 ℃ in the hot rolling and heating process to form iron scale with an anchor structure, the difficulty of the hot rolling and descaling process is increased, and the surface of the steel plate is subjected to rust red iron scale, so that the coating property of the steel plate is affected, and the surface quality of the steel plate cannot meet the requirement of automobile girder steel; the content of C is 0.09-0.15%, and the low-temperature impact toughness is low.
Chinese patent application publication No. CN102978511B discloses a method for producing a hot-rolled steel plate for an automobile beam at low cost, wherein the Ti content is 0.05-0.09%, and the Mn content is 1.50-1.80%; the total content of Mn, Nb and Ti is 1.55-1.89%, the alloy cost is high, the tensile strength is 610MPa, and the low-temperature impact is not less than 60J at-20 ℃.
In the prior art, automobile girder steel with low cost, high toughness and good welding performance and with 650 MPa-level tensile strength is lacked.
Disclosure of Invention
The invention aims to provide a hot rolled steel plate with 650 MPa-level tensile strength and a manufacturing method thereof, and mainly solves the technical problems of high manufacturing cost, low strength and low-temperature impact property of the existing hot rolled steel plate for an automobile beam.
The technical idea of the invention is that the advantages of low-cost Ti precipitation strengthening and Ti material welding capability improvement are fully exerted in the component design of the hot-rolled steel plate, the chemical components of the hot-rolled steel plate with the tensile strength of 650MPa are reasonably designed, the hot-rolling control and cooling control process is fully exerted, and the production cost is greatly reduced.
The invention adopts the technical scheme that a hot rolled steel plate with 650 MPa-grade tensile strength comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si is less than or equal to 0.1%, Mn: 1.05-1.20%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, Nb: 0.01-0.02%, Ti: 0.065-0.085 percent of Ca, 0.0015-0.0045 percent of Al, 0.02-0.05 percent of Alt, and the balance of Fe and inevitable impurities, wherein the content of the elements is equal to or less than 0.32, and Ceq is C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15, wherein: C. mn, Cr, Mo, V, Ni, Cu are the weight percentages of the elements in the hot rolled steel sheet.
The metallographic structure of the hot rolled steel plate is fine-grained ferrite and a small amount of pearlite, and the grain size of the ferrite in the structure is 11-13 grades; reH600MPa to 640MPa, tensile strength Rm650-800 MPa, elongation A after fracture of 18-24%, product of strength and elongation of 11700-19200MPa, impact power value Akv at-20 ℃ of 75-95J, and qualified d-a in a 180-degree bending test.
The hot rolled steel plate is mainly used for manufacturing cross beams, longitudinal beams and other structural members of trucks.
The reason why the chemical composition of the hot rolled steel sheet having a tensile strength of 650MPa grade according to the present invention is limited to the above range is as follows:
c: carbon is a main element influencing the obdurability of the automobile girder steel, the strength can be improved by increasing the C percent, but the toughness is reduced, and the C is controlled to be 0.06 percent to 0.08 percent in the invention.
Si: the silicon has strong solid solution strengthening effect after being dissolved in ferrite, and the tensile strength of the hot rolled steel can be improved by 7.8MPa to 8.8MPa and the yield strength can be improved by 3.9MPa to 4.9MPa when 0.1 weight percent of silicon is added into the carbon steel. However, when the silicon content exceeds 0.10%, the adverse effect on the toughness and the surface quality is obviously increased, particularly, a red iron sheet is generated on the hot rolled steel plate, and pits are left on the surface of the steel plate after the steel plate is subjected to continuous pickling to become a crack source of the girder in the service process, so that the set Si content of the invention is less than 0.10%.
Mn: manganese is a basic alloying element of high-strength low-alloy high-strength steel, plays a role through solid solution strengthening, and can reduce the addition of carbon by adding manganese, so that the steel plate has high strength; when the Mn addition amount of the general 650MPa grade high-strength beam steel exceeds 1.6 percent, Mn segregation is easily caused in the continuous casting process by the Mn with high Mn content, the fatigue and bending performance of the beam steel are not good, and particularly when the C content is controlled to be 0.06-0.08 percent, metal Mn is added in the steel making process to enable the Mn content to reach 1.6 percent, so that the cost is greatly increased. The invention adopts the medium manganese design, eliminates the possibility of Mn segregation in the material design, designs the Mn range to be 1.05-1.20%, and realizes high-strength beam steel products with lower cost and low segregation tendency.
P, S: p is liable to cause segregation and deteriorate the toughness in the structural steel for automobiles, and P causes the steel to be "cold brittle". S is easy to form MnS inclusions with Mn, the low-temperature toughness of steel is reduced, the wide cold bending qualification rate is reduced, and S can cause hot brittleness. Therefore, the P, S content in the high-grade automobile girder steel is reduced as much as possible. In the invention, P is controlled to be less than or equal to 0.015 percent, and S is controlled to be 0.003 percent. And feeding Ca wire and other inclusion modifying treatment technology to spheroidize and distribute the inclusions uniformly and reduce the adverse effect on low-temperature impact toughness.
Nb: niobium is a micro-adjusting microalloying element belonging to the invention and plays a role in fine grain strengthening. On one hand, Nb can remarkably improve the recrystallization temperature Tnr of steel, so that large deformation in the hot rolling process can be carried out below the recrystallization temperature Tnr, thereby obtaining a fine austenite structure containing a large number of deformation zones and refining the austenite structure before phase transformation as much as possible; on the other hand, fine Nb (C, N) is separated out in the controlled rolling and controlled cooling process in the controlled cooling process, so that the precipitation strengthening effect is achieved, and the strength of the steel is improved. Because the Nb alloy is expensive, the Nb in the invention only needs to be realized by increasing the recrystallization temperature, and the control is as follows: 0.01 to 0.02 percent.
Ti: the Ti is added into the low-carbon microalloyed steel, so that the grain refinement and precipitation strengthening can be realized, and the yield strength and the toughness of the steel can be improved. The improvement of the performance is mainly related to that Ti can increase austenite recrystallization temperature and austenite coarsening temperature, thereby increasing the grain size in the continuous casting and heating processes, and meanwhile, the addition of Ti into Nb steel can prolong the precipitation incubation period of NbC, so that the precipitation starting time of carbide in Nb-Ti composite steel is later than that of Nb steel, thereby leading the precipitate to be finer and more dispersed. Because Ti can form TiN high-temperature refractory particles with N at high temperature, the addition of Ti can also improve the grain size of the welding heat affected zone, thereby improving the toughness of the welding heat affected zone. In the invention, Ti is controlled to be 0.065-0.085%.
Ca: after Ca treatment is carried out on the steel, inclusions in the steel are converted from flocculent alumina into spherical calcium aluminate inclusions, the stress concentration tendency of the inclusions is greatly reduced, fatigue premature failure caused by stress concentration of a hot-rolled steel plate at the inclusions in the fatigue process is prevented, and the fatigue performance of the hot-rolled steel plate is greatly improved, wherein the content of Ca is limited to be 0.0015-0.0045%.
Aluminum: the aluminum plays a role in deoxidation in the present invention, and is a strong oxidizing forming element, and forms Al with oxygen in steel2O3Is removed during steel making. Too high an aluminum content can lead to excessive Al formation2O3Inclusion of Al2O3Inclusions are extremely detrimental to the fatigue properties of hot rolled steel sheets, which must be treated with Al2O3The inclusion is controlled, and the content of Alt is limited to be 0.02-0.05 percent.
A manufacturing method of a hot rolled steel plate with 650MPa tensile strength comprises the following steps:
continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si is less than or equal to 0.1%, Mn: 1.05-1.20%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, Nb: 0.01-0.02%, Ti: 0.065-0.085 percent of Ca, 0.0015-0.0045 percent of Al, 0.02-0.05 percent of Alt, and the balance of Fe and inevitable impurities, wherein the content of the elements is equal to or less than 0.32, and Ceq is C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15, wherein: C. mn, Cr, Mo, V, Ni, Cu are the weight percentages of the elements in the hot rolled steel plate;
heating the continuous casting plate blank at 1230-1260 ℃ for 180-240 min, and then carrying out hot rolling, wherein the hot rolling is a two-stage 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 1000-1015 ℃; after rough rolling, controlling the thickness of the intermediate blank to be 43-47 mm; the finish rolling is 7-pass continuous rolling, rolling is carried out in an austenite non-recrystallization temperature area, and the finish rolling temperature is 860-890 ℃; after finish rolling, controlling the thickness of the steel plate to be 8.0-10.0 mm, adopting front-stage cooling for laminar cooling, wherein the laminar cooling speed is more than or equal to 35 ℃/s, and coiling when the coiling temperature is 585-620 ℃ to obtain a hot-rolled steel coil;
and slowly cooling the coiled hot rolled steel coil to 100 ℃ for more than or equal to 48 hours, wherein the slow cooling speed of the hot rolled steel coil is less than or equal to 20 ℃/h, and the finishing slow cooling temperature is less than or equal to 50 ℃.
The reason of the hot rolling process system adopted by the invention is as follows:
1. setting of heating temperature and heating time of continuous casting slab
The temperature and the time of the continuous casting slab discharging furnace are set to ensure the dissolution of coarse Nb and Ti microalloy carbon and nitride particles in the continuous casting slab, and the Nb and Ti microalloy carbon and nitride particles can be separated out in the cooling process of the continuous casting slab according to the content of Nb and Ti in the technical scheme of the invention, and the separated Nb and Ti microalloy carbon and nitride particles are coarse and have no strengthening effect; when a plate blank before hot rolling is heated, coarse Nb and Ti microalloy carbon and nitride are fully dissolved, so that the combined Nb and Ti elements can be dissolved into austenite in a solid solution mode, interphase precipitation is formed during phase change in the subsequent hot rolling and cooling processes, and ferrite is strengthened, which is very important for the technical scheme of the invention; the temperature is too low and the heating time is too short, original coarse Nb and Ti microalloy carbon and nitride particles in the continuous casting slab cannot be fully dissolved, the temperature is too high, the heating time is too long, the surface of the slab is seriously oxidized and decarburized, the final performance and the surface quality of a steel plate are not facilitated, and energy is also consumed. The method is mainly used for strengthening Ti, and the dissolution temperature of the alloy carbonitride of Ti is higher than that of the carbonitride of Nb, so that the heating temperature of the continuous casting slab is set to be 1230-1260 ℃, and the heating time is set to be 180-240 min.
2. Setting of roughing finishing temperature
The rough rolling process is controlled to roll above the austenite recrystallization temperature, so that austenite is ensured to obtain uniform and fine austenite grains after repeated deformation and recrystallization. Through theoretical calculation, the recrystallization temperature under the component design of the invention is about 1000 ℃, so the rough rolling finishing temperature is set to be 1000-1015 ℃.
3. Intermediate blank thickness setting
The thickness of the finish rolling intermediate billet determines the capacity of converting non-recrystallized austenite into fine ferrite in the finish rolling stage, and the larger the thickness of the intermediate billet is, the finer the ferrite after phase transformation is, and the better the toughness of the material is. The thickness of the intermediate blank is 43-47 mm
4. Setting of finish Rolling finishing temperature
The setting of the finishing temperature according to the invention has two effects, on the one hand, byRolling the austenite non-recrystallization region to obtain flat austenite grains with deformation zones inside, and converting the flat austenite grains into fine ferrite grains in the subsequent laminar cooling process to play a role of fine grain strengthening. The grain refinement of the invention is important, and the fine grain strengthening can realize high toughness without reducing the strength. On the other hand, the finish rolling temperature cannot be too low, and the excessively low finish rolling temperature easily induces austenite state precipitation of Nb and Ti microalloy carbon and nitride during rolling, so that sufficient precipitates are not generated in the subsequent phase transformation process, and the precipitation strengthening effect is influenced. Ar in the invention3The temperature is 835 ℃, so the finish rolling temperature is set to 860 ℃ to 890 ℃.
5. Method of laminar cooling after finish rolling and setting of cooling rate
In the hot-rolled steel sheet of the present invention, the cooling after the finish rolling is performed in order to suppress the growth of crystal grains and the precipitation of Nb and Ti microalloy carbonitride in a high temperature zone by a high laminar cooling rate, and therefore, the cooling method is a front-stage cooling. The precipitation of Nb and Ti microalloy carbonitride particles in austenite is inhibited through rapid cooling, and solid-solution Nb and Ti elements are retained in deformed austenite, so that the precipitation of fine and dispersed Nb and Ti microalloy carbonitride in a ferrite region at a lower temperature becomes possible; the cooling rate was too slow to prevent early precipitation of Nb and Ti microalloy carbonitride in the high temperature deformation austenite. Therefore, the invention sets that the laminar cooling stage adopts front-section forced cooling, and the cooling speed is more than or equal to 35 ℃/S.
6. Setting of coiling temperature in Hot Rolling
The hot rolling coiling temperature mainly influences the structure and the performance of the material. The invention contains Nb and Ti, and the coiling temperature is designed to be 585-620 ℃ according to the optimal precipitation temperature of Nb-Ti microalloy elements. If the coiling temperature is lower than 585 ℃, the precipitation of Nb and Ti microalloy carbon and nitride is inhibited, and the strength is insufficient; if the coiling temperature is higher than 620 ℃, precipitates of carbon and nitride of the Nb and Ti microalloy are coarsened to cause insufficient toughness, and the cracking problem occurs after subsequent bending, punching and the like by users.
7. Setting of slow cooling time, slow cooling speed and slow cooling end temperature of hot rolled coil
The slow cooling of the hot plate coil is mainly to ensure that Ti is continuously precipitated in the invention and the precipitation strengthening effect of Ti is fully exerted. The precipitation strengthening effect is related to slow cooling speed which is more than or equal to 20 ℃/h, Ti precipitation power is fast insufficient, and the precipitation strengthening effect of Ti can not be fully exerted; the slow cooling speed is less than or equal to 20 ℃/h, the Ti precipitation power can be kept for a long time, and the precipitation strengthening effect of Ti is exerted. Comprehensively considered, the time of slowly cooling a hot rolled steel coil obtained by coiling the hot rolled steel plate to 100 ℃ is more than or equal to 48 hours, the slow cooling speed of the hot rolled steel coil is less than or equal to 20 ℃/h, and the finishing slow cooling temperature is less than or equal to 50 ℃.
The metallographic structure of the hot rolled steel plate produced by the method is fine-grained ferrite and a small amount of pearlite, and the grain size of the ferrite in the structure is 11-13 grades; upper yield strength R of 8.0-10.0 mm hot rolled steel plateeH600MPa to 640MPa, tensile strength Rm650-800 MPa, elongation A after fracture of 18-24%, product of strength and elongation of 11700-19200MPa, impact power value Akv at-20 ℃ of 75-95J, and qualified d-a in a 180-degree bending test.
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 hot rolled steel plate produced by the method has low cost and high strength, and has lower cost and good low-temperature impact toughness after being manufactured into the girder, thereby meeting the requirements of girder manufacturing enterprises on high-strength reduction, low cost and high-low-temperature impact toughness of the hot rolled steel plate. 2. The invention adopts a low-C, medium-Mn, Nb and Ti component system, and can obtain fine-grain ferrite and a small amount of pearlite by matching with a conventional steelmaking process and a TMCP process, thereby ensuring that the high-strength and high-toughness performance is obtained: upper yield strength ReH600MPa to 640MPa, tensile strength Rm650 Mpa-800 Mpa, elongation A after fracture is 18% -24%, product of strength and elongation is 11700-. 3. The invention adopts a component system with low C, medium Mn, Nb and Ti to have good welding performance and cold bending performance, and the welding carbon equivalent Ceq is 0.24-0.28; the cold bending d is qualified as 1 a; 4. the invention leads the aluminum oxide inclusion and the manganese sulfide inclusion to be mixed through a proper inclusion treatment process,the steel plate has small size and is distributed in a dispersion way, so that the possibility of crack initiation from inclusion in the impact test process is reduced, and the low-temperature impact toughness of the steel plate is greatly improved, and the-20 ℃ impact work value Akv is 75J-95J.
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 is further illustrated with reference to examples 1 to 3, which are shown in tables 1 to 3; table 1 shows the chemical composition (in weight%) of the steels of the examples of the invention, 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.
The carbon equivalent Ceq of the steels of the examples 1 to 5 of the present invention were 0.259, 0.258, 0.260, 0.260, and 0.260, respectively.
Smelting in a converter to obtain molten steel meeting the requirements of chemical components, blowing Ar to the molten steel in an LF ladle refining furnace refining process, carrying out vacuum cyclic degassing treatment and component fine adjustment in an RH furnace, and then carrying out slab continuous casting to obtain a continuous casting slab; the thickness of the continuous casting slab is 210-230 mm, the width is 900-1600 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. Controlling rolling by a rough rolling and finish rolling continuous rolling unit, coiling after laminar cooling, performing front-section cooling by laminar cooling, slowly cooling to room temperature, and warehousing to produce qualified hot-rolled steel coils; the thickness of the hot rolled steel plate is 8.0-10.0 mm. The hot rolling process control parameters are shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
The hot rolled steel sheet obtained by the above method has a metallographic structure of fine-grained ferrite + a small amount of pearlite, a grain size of the ferrite in the structure being in the range of 11 to 13, and an upper yield strength R of the hot rolled steel sheet, see FIG. 1eH600MPa to 640MPa, tensile strength Rm650-800 MPa, elongation A after fracture of 18-24%, product of strength and elongation of 11700-19200MPa, and impact power value Akv at-20 ℃ of 75-100J.
The hot rolled steel plate obtained by the invention is sampled, a transverse sample is obtained by tensile and bending tests, a longitudinal sample is obtained by impact tests, and the tensile test is carried out according to the part 1 of the GB/T228.1-2010 metal material tensile test: room temperature test method for tensile test; performing a bending test according to GB/T232-2010 bending test method for metal materials; the impact test is carried out according to GB/T229-2007 method for testing charpy pendulum impact of metal materials, 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 hot rolled steel plate with 650 MPa-grade tensile strength comprises the following chemical components in percentage by weight: the weight percentage of the chemical components is as follows: c: 0.06-0.08%, Si is less than or equal to 0.1%, Mn: 1.05-1.20%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, Nb: 0.01-0.02%, Ti: 0.065-0.085 percent of Ca, 0.0015-0.0045 percent of Al, 0.02-0.05 percent of Alt, and the balance of Fe and inevitable impurities, wherein the content of the elements is equal to or less than 0.32, and Ceq is C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15, wherein: C. mn, Cr, Mo, V, Ni, Cu are the weight percentages of the elements in the hot rolled steel plate; upper yield strength R of 8.0-10.0 mm hot rolled steel plateeH600MPa to 640MPa, tensile strength Rm650 Mpa-800 Mpa, cutThe post-elongation A is 18-24%, the product of strength and elongation is 11700-19200MPa, the impact power value Akv at-20 ℃ is 75J-100J, and the d-a is qualified in a 180-degree bending test.
2. A hot-rolled steel sheet for a wheel having a tensile strength of 630MPa according to claim 1, wherein said hot-rolled steel sheet has a metallographic structure comprising fine-grained ferrite and a small amount of pearlite, and the grain size of the ferrite in said structure is in the range of 11 to 13.
3. A manufacturing method of a hot rolled steel plate with 650MPa tensile strength comprises the following steps:
continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si is less than or equal to 0.1%, Mn: 1.05-1.20%, P is less than or equal to 0.015%, S is less than or equal to 0.003%, Nb: 0.01-0.02%, Ti: 0.065-0.085 percent of Ca, 0.0015-0.0045 percent of Al, 0.02-0.05 percent of Alt, and the balance of Fe and inevitable impurities, wherein the content of the elements is equal to or less than 0.32, and Ceq is C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15, wherein: C. mn, Cr, Mo, V, Ni, Cu are the weight percentages of the elements in the hot rolled steel plate;
heating the continuous casting plate blank at 1230-1260 ℃ for 180-240 min, and then carrying out hot rolling, wherein the hot rolling is a two-stage 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 1000-1015 ℃; after rough rolling, controlling the thickness of the intermediate blank to be 43-47 mm; the finish rolling is 7-pass continuous rolling, rolling is carried out in an austenite non-recrystallization temperature area, and the finish rolling temperature is 860-890 ℃; after finish rolling, adopting front-stage cooling for laminar cooling, wherein the laminar cooling speed is more than or equal to 35 ℃/s, and obtaining a hot-rolled steel coil by coiling when the coiling temperature is 585-620 ℃;
and slowly cooling the coiled hot rolled steel coil to 100 ℃ for more than or equal to 48 hours, wherein the slow cooling speed of the hot rolled steel coil is less than or equal to 20 ℃/h, and the finishing slow cooling temperature is less than or equal to 50 ℃.
4. The method for producing a hot-rolled steel sheet for a wheel having a tensile strength of 630MPa according to claim 3, wherein the thickness of the steel sheet is controlled to 8.0 to 10.0mm after the hot rolling and finish rolling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910581809.0A CN112226673A (en) | 2019-06-30 | 2019-06-30 | Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910581809.0A CN112226673A (en) | 2019-06-30 | 2019-06-30 | Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112226673A true CN112226673A (en) | 2021-01-15 |
Family
ID=74111031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910581809.0A Pending CN112226673A (en) | 2019-06-30 | 2019-06-30 | Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112226673A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114875337A (en) * | 2022-05-31 | 2022-08-09 | 东风商用车有限公司 | Method for obtaining high-strength steel roll-formed rim |
| CN114959480A (en) * | 2022-05-31 | 2022-08-30 | 本钢板材股份有限公司 | High-strength hot-rolled coil for 650 MPa-level thin and wide tank and production method thereof |
| CN115505836A (en) * | 2021-06-23 | 2022-12-23 | 上海梅山钢铁股份有限公司 | 500 MPa-grade yield strength hot-rolled steel plate for automobile chassis suspension |
| CN115572902A (en) * | 2022-09-30 | 2023-01-06 | 吉林建龙钢铁有限责任公司 | Steel for integrated wheel hub and preparation method thereof |
| CN116065103A (en) * | 2021-11-01 | 2023-05-05 | 上海梅山钢铁股份有限公司 | High-reaming hot-rolled pickled steel plate with low cost and 550MPa yield strength |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101565794A (en) * | 2008-04-22 | 2009-10-28 | 宝山钢铁股份有限公司 | High-strength hot rolling automotive frame steel plate and manufacturing method thereof |
| CN104694822A (en) * | 2013-12-06 | 2015-06-10 | 上海梅山钢铁股份有限公司 | High-strength hot rolled steel plate with 700 MPa grade yield strength and manufacturing method thereof |
| CN107868911A (en) * | 2016-09-26 | 2018-04-03 | 上海梅山钢铁股份有限公司 | A kind of yield strength 600MPa level hot rolled steel plates and its manufacture method |
-
2019
- 2019-06-30 CN CN201910581809.0A patent/CN112226673A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101565794A (en) * | 2008-04-22 | 2009-10-28 | 宝山钢铁股份有限公司 | High-strength hot rolling automotive frame steel plate and manufacturing method thereof |
| CN104694822A (en) * | 2013-12-06 | 2015-06-10 | 上海梅山钢铁股份有限公司 | High-strength hot rolled steel plate with 700 MPa grade yield strength and manufacturing method thereof |
| CN107868911A (en) * | 2016-09-26 | 2018-04-03 | 上海梅山钢铁股份有限公司 | A kind of yield strength 600MPa level hot rolled steel plates and its manufacture method |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115505836A (en) * | 2021-06-23 | 2022-12-23 | 上海梅山钢铁股份有限公司 | 500 MPa-grade yield strength hot-rolled steel plate for automobile chassis suspension |
| CN116065103A (en) * | 2021-11-01 | 2023-05-05 | 上海梅山钢铁股份有限公司 | High-reaming hot-rolled pickled steel plate with low cost and 550MPa yield strength |
| CN114875337A (en) * | 2022-05-31 | 2022-08-09 | 东风商用车有限公司 | Method for obtaining high-strength steel roll-formed rim |
| CN114959480A (en) * | 2022-05-31 | 2022-08-30 | 本钢板材股份有限公司 | High-strength hot-rolled coil for 650 MPa-level thin and wide tank and production method thereof |
| CN115572902A (en) * | 2022-09-30 | 2023-01-06 | 吉林建龙钢铁有限责任公司 | Steel for integrated wheel hub and preparation method thereof |
| CN115572902B (en) * | 2022-09-30 | 2023-08-22 | 吉林建龙钢铁有限责任公司 | Integrated steel for wheel hub and preparation method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110484827B (en) | Hot-rolled pickled steel plate with tensile strength of 600MPa and low yield ratio | |
| CN109536846B (en) | High-toughness hot-rolled steel plate with yield strength of 700MPa and manufacturing method thereof | |
| CN112226673A (en) | Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof | |
| CN109778069B (en) | One-steel multi-stage cold-rolled low-alloy high-strength steel with yield strength covering 240-270 Mpa and manufacturing method thereof | |
| CN111378896B (en) | High-strength weather-resistant steel plate for building bridge and manufacturing method thereof | |
| WO2022022066A1 (en) | Steel board for polar marine engineering and preparation method therefor | |
| CN111172466B (en) | Plasticity-enhanced cold-rolled dual-phase steel with tensile strength of 590MPa and production method thereof | |
| CN111455269A (en) | Yield strength 960MPa grade very high strength marine steel plate and manufacturing method thereof | |
| CN111926234B (en) | Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame | |
| CN110791702A (en) | Marine steel plate with good welding performance and low yield ratio and manufacturing method thereof | |
| CN114369764B (en) | High-performance thick hot-rolled H-shaped steel with yield strength of 460MPa and production method thereof | |
| CN114807750A (en) | Thin 500 MPa-grade low-yield-ratio high-toughness bridge steel plate and manufacturing method thereof | |
| CN112553524A (en) | Hot rolled steel plate with yield strength of 360MPa for pipeline and manufacturing method thereof | |
| CN102418047B (en) | Non-quenched and tempered fatigue-resistant steel plate and manufacturing method thereof | |
| CN113802054A (en) | Hot rolled steel plate with yield strength of 420MPa and manufacturing method thereof | |
| CN110938771A (en) | Hot-rolled steel plate for wheel with tensile strength of 630MPa and manufacturing method thereof | |
| CN114231826B (en) | Production method of Q420qE bridge structural steel plate | |
| CN111321340A (en) | Hot rolled steel plate with yield strength of 450MPa and manufacturing method thereof | |
| CN114000068B (en) | Low-nitrogen ultrahigh-strength hot-rolled steel strip with thickness of 4-10mm and production method thereof | |
| CN114480976A (en) | High-temperature rolled Q420qE bridge structural steel plate and production method thereof | |
| CN113846269A (en) | Cold-rolled high-weather-resistance steel plate with high strength and plasticity and preparation method thereof | |
| CN111334721A (en) | Normalized rolling medium-thick ship plate steel and production method thereof for eliminating banded structure | |
| CN115369328B (en) | Low-temperature-resistant rolled steel and production method thereof | |
| CN115386783B (en) | Ultrahigh-strength steel plate with yield strength of 1000MPa and preparation method thereof | |
| CN114480951B (en) | Hot-rolled dual-phase steel plate with 700 MPa-level tensile strength and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210115 |
|
| RJ01 | Rejection of invention patent application after publication |