CN116676534A - Hot-rolled wear-resistant steel plate and manufacturing method thereof - Google Patents
Hot-rolled wear-resistant steel plate and manufacturing method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 59
- 239000010959 steel Substances 0.000 title claims abstract description 59
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 39
- 238000005452 bending Methods 0.000 claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 11
- 238000012797 qualification Methods 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims description 84
- 238000005096 rolling process Methods 0.000 claims description 69
- 238000010438 heat treatment Methods 0.000 claims description 22
- 238000005496 tempering Methods 0.000 claims description 18
- 229910001563 bainite Inorganic materials 0.000 claims description 14
- 239000002244 precipitate Substances 0.000 claims description 14
- 239000002105 nanoparticle Substances 0.000 claims description 7
- 230000009467 reduction Effects 0.000 claims description 7
- 238000009749 continuous casting Methods 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 4
- 238000010079 rubber tapping Methods 0.000 claims description 4
- 238000003723 Smelting Methods 0.000 claims description 3
- 230000001186 cumulative effect Effects 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- 238000013000 roll bending Methods 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 40
- 230000008569 process Effects 0.000 abstract description 32
- RMLPZKRPSQVRAB-UHFFFAOYSA-N tris(3-methylphenyl) phosphate Chemical compound CC1=CC=CC(OP(=O)(OC=2C=C(C)C=CC=2)OC=2C=C(C)C=CC=2)=C1 RMLPZKRPSQVRAB-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 25
- 238000005728 strengthening Methods 0.000 description 25
- 238000001556 precipitation Methods 0.000 description 20
- 230000000694 effects Effects 0.000 description 16
- 229910000859 α-Fe Inorganic materials 0.000 description 15
- 229910045601 alloy Inorganic materials 0.000 description 12
- 239000000956 alloy Substances 0.000 description 12
- 229910001566 austenite Inorganic materials 0.000 description 12
- 238000010791 quenching Methods 0.000 description 10
- 230000000171 quenching effect Effects 0.000 description 10
- 238000010587 phase diagram Methods 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 230000009286 beneficial effect Effects 0.000 description 6
- 238000005266 casting Methods 0.000 description 6
- 238000000227 grinding Methods 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 229910000734 martensite Inorganic materials 0.000 description 5
- 238000004321 preservation Methods 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- 238000005299 abrasion Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 238000000137 annealing Methods 0.000 description 3
- 238000011217 control strategy Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000006004 Quartz sand Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000004781 supercooling Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 208000020442 loss of weight Diseases 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
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- 229910052698 phosphorus Inorganic materials 0.000 description 1
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- 230000003014 reinforcing effect Effects 0.000 description 1
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- 229910052717 sulfur Inorganic materials 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
-
- 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
- C21D8/0236—Cold 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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0242—Flattening; Dressing; Flexing
-
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention discloses a hot-rolled wear-resistant steel plate and a manufacturing method thereof, wherein the chemical components of the hot-rolled wear-resistant steel plate comprise C, si, mn, B, ti, als, fe, and the chemical components simultaneously satisfy the following requirements: ti-3.42 x N-3*S-B is more than or equal to 0.040% and less than or equal to 0.14%; the invention adopts a heat-treatment-free TMCP process, the tensile strength of the material is more than or equal to 1050MPa, the wear resistance reaches NM300 level, the yield ratio is less than or equal to 0.70, the cold bending performance reaches 180 degrees, D=1a is qualified, the plate shape qualification rate is more than or equal to 95%, the material has the advantages of high strength, high hardness, low yield ratio, easy forming, low production cost and the like, and can be applied to manufacturing high-strength wear-resistant parts such as special vehicles, engineering machinery and the like.
Description
Technical Field
The invention belongs to the technical field of wear-resistant steel, and particularly relates to a hot-rolled wear-resistant steel plate and a manufacturing method thereof.
Background
Regarding the wear-resistant steel plate, the main production process at present is tempering heat treatment, the structure type is martensite, and the tempering heat treatment product has the advantages of high strength, high wear resistance, stable plate shape and the like, but has long process flow and high production cost, and the product has limited forming performance, and the cold bending performance can only ensure 90 degrees, and D=6a is qualified. The other process is quenching and tempering-free heat treatment on-line quenching, the structure type is martensite and ferrite, as in the patent published under the publication number CN103233161A, CN104532126A, CN108411203A, CN110760752A, CN111334720A, the wear-resistant grade of the product is NM300, and the wear-resistant steel plate has the advantages of high strength, high wear resistance, easy forming and the like, but is influenced by the thin product specification, high cooling rate, narrow cooling process window, low-temperature coiling and the like, the plate shape qualification rate of the wear-resistant steel plate produced by the on-line quenching process is lower, and the plate shape control is always an industrial problem.
Compared with martensite and ferrite structures, the bainite structure has better matching of strength, hardness and plasticity and toughness, and is also applied to the production of wear-resistant steel in recent years. The structure types of the composite material are granular bainite and acicular ferrite, the chemical components of the composite material are added with high content Ti (the content of Ti is up to 0.5-0.8%), so that Ti cannot be completely dissolved into a matrix in the heating process, a large number of micron-sized TiC precipitates can be formed by combining the chemical components through the design of medium C content, and the wear resistance of the composite material can be improved to a certain extent, but a large number of micron-sized TiC hard particles are not beneficial to the plasticity and toughness of the composite material, the tensile strength of the composite material is only 900MPa at most, and the strength level is not high.
The structure type of the patent disclosed by the publication No. CN 109234612B is bainite, the tensile strength of the material reaches 900MPa at the highest, the strength level of the material is not high, the yield ratio is 0.89-0.90, and the yield ratio is high.
The structure type of the patent disclosed by the publication number CN114908291A, CN114892080A is bainite, the tensile strength of the material is up to 1000MPa, but one alloy component is added with noble alloy elements Mo, cu, ni and rare earth elements with higher content, so that the alloy cost is higher; on the other hand, the material has a yield ratio larger than 0.87 and higher yield ratio, which is unfavorable for the cold bending forming performance of the material.
The structure type of the patent disclosed by the publication No. CN114058945A, CN107747056A, CN110747405A, CN106636899A is mainly bainite, the tensile strength of the material reaches 1000MPa, but the production process of the material needs tempering or quenching, tempering or cold rolling and annealing heat treatment, the material strength is improved mainly through tempering or quenching, tempering or annealing procedures, the process flow is long, and the production cost is high.
The thin-gauge 1400MPa grade bainitic steel and the manufacturing method thereof disclosed in the publication No. CN113430467A are produced by adopting a thin strip continuous casting and rolling process flow, and are different from the traditional hot continuous rolling process flow in that (1) a fine-grain as-cast structure obtained under the condition of rapid solidification of double-roller thin strip continuous casting is utilized, and a gas mist cooling system is combined for rapid cooling to form a bainitic structure with very fine grain size, so that higher strength is easy to realize, the alloy addition amount is lower, and the rolling cooling process parameters are not applicable to the traditional hot continuous rolling process flow; (2) Because the edge of the casting strip has a casting structure with the depth of about 2mm, the edge of the thin casting strip has poor quality and needs to be cut.
In summary, the disclosed patent has been searched for about wear-resistant steel, and the prior art that the structure type is martensite is adopted by a quenching and tempering heat treatment process has the defects of long process flow, high production cost, limited material forming performance and the like. The prior art with martensite and ferrite as the structure types and adopting the heat-treatment-free online quenching process has the problems of low plate shape qualification rate and difficult plate shape control. By adopting the prior art of hot continuous rolling technology and bainite structure type, on one hand, the tensile strength of the material is only 900MPa at most, the strength level is not high, and the yield ratio is high; on the other hand, the tensile strength of the material reaches 1000MPa, but the alloy components are added with noble alloy elements Mo, cu, ni and rare earth elements with higher content, so that the alloy cost is higher, the yield ratio is higher, or the production process needs tempering or quenching, tempering or cold rolling and annealing heat treatment, and the process flow is long and the production cost is high; on the other hand, the tensile strength of the material reaches 1000MPa, and the alloy composition and the technological parameters of the material are not suitable for the traditional hot continuous rolling technological process by adopting the thin strip continuous casting and rolling technological process.
Disclosure of Invention
The invention aims to provide a hot-rolled wear-resistant steel plate and a manufacturing method thereof, wherein a heat-treatment-free TMCP process is adopted, the tensile strength of the material is more than or equal to 1050MPa, the wear resistance reaches NM300 level, the yield ratio is less than or equal to 0.70, the cold bending performance reaches 180 degrees, D=1a is qualified, the plate shape qualification rate is more than or equal to 95%, and the material has the advantages of high strength, high hardness, low yield ratio, easiness in forming, low production cost and the like, and can be applied to manufacturing high-strength wear-resistant parts such as special vehicles, engineering machinery and the like.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the hot-rolled wear-resistant steel plate comprises the following chemical components in percentage by weight: c:0.08 to 0.13 percent; si:0.60 to 1.40 percent; mn:1.60 to 2.40 percent; ti:0.050 to 0.15 percent; b:0.0008 to 0.0030 percent; als: 0.020-060 percent; p: less than or equal to 0.012%; s: less than or equal to 0.005%; n: less than or equal to 0.0050%; o: less than or equal to 0.0030 percent; the balance of Fe and unavoidable impurities; and needs to satisfy simultaneously: ti-3.42 x N-3*S-B is more than or equal to 0.040% and less than or equal to 0.14%.
The metallographic structure of the hot-rolled wear-resistant steel plate is granular bainite and nano-sized precipitates, the size of the nano-sized precipitates is less than or equal to 20nm, and the volume fraction of the nano-sized precipitates is 0.15-0.22%.
The yield strength of the hot-rolled wear-resistant steel plate is more than or equal to 700MPa, the tensile strength is more than or equal to 1050MPa, the yield ratio is less than or equal to 0.70, and the elongation A is equal to 50 More than or equal to 16 percent, the hardness is more than or equal to 310HB, the cold bending performance reaches 180 degrees, D=1a is qualified, the open plate unevenness is controlled to be less than or equal to 5mm/m, and the plate shape qualification rate is more than or equal to 95 percent.
The manufacturing method of the hot-rolled wear-resistant steel plate provided by the invention comprises the following steps: smelting, continuous casting, heating, rolling, cooling, coiling, flattening and flattening.
In the heating step, the end temperature of the secondary section is more than or equal to 1200 ℃, the soaking time is more than or equal to 30min, the tapping temperature of the slab is 1230-1280 ℃, and the heat preservation time of the slab temperature is more than or equal to 1230 ℃ is more than or equal to 40min.
In the rolling step, rolling is carried out by adopting a hot continuous rolling unit with 2 frames of rough rolling and 7 frames of finish rolling, and the final rolling temperature R of rough rolling 2 DT is 1080-1130 ℃, and the cumulative rolling reduction of rough rolling is more than or equal to 80%; finish rolling finishing temperature FDT is 850-900 ℃, and finish rolling accumulated rolling reduction is more than or equal to 85%; rolling at a constant speed; the rolling speed v of the finish rolling F7 frame is more than or equal to 6.5m/s; convexity C of F7 frame 40 Is 10-30 mu m, wedge-shaped W 40 Is-10 to 10 mu m.
In the cooling step, the strip steel is subjected to sectional cooling after being discharged from the F7 rack; the first section adopts concentrated cooling, and is cooled to 620-680 ℃ at a cooling rate of more than or equal to 100 ℃/s; then performing second-stage air cooling for 8-12 s; cooling in the air, cooling to 490-550 deg.c at cooling rate not lower than 30 deg.c/s, coiling, unloading, covering with heat insulating cover, tempering, heat insulating for 60-90 min, cooling in the air to room temperature.
In the cooling step, the strip steel is subjected to sectional cooling after being discharged from the F7 rack; the first section adopts concentrated cooling, and is cooled to 620-680 ℃ at a cooling rate of 110-120 ℃/s; then performing second-stage air cooling for 8-12 s; cooling in air, cooling to 490-550 deg.c at 30-60 deg.c/s, coiling, unloading, covering with heat insulating cover, tempering, heat insulating for 60-90 min, cooling in air to room temperature.
In the leveling step, the rolling force of the leveling machine is 500-800t, the bending force is 70-100t, and the leveling speed is 50-100m/min.
In the hot-rolled wear-resistant steel plate provided by the invention, the actions and the control of each component are as follows:
c:0.08% -0.13%, C is taken as a basic element in steel, plays a very important role in improving the strength and hardness of the steel, and in order to obtain higher strength and hardness, the content of C must be ensured to be more than 0.08%, but the content of C cannot be high, and when the content of C is more than or equal to 0.13%, the size of a Mao island in the formed bainite is larger, the proportion is more, and the toughness of the material is not improved.
Si:0.60% -1.40%, si has stronger solid solution strengthening effect, can improve the strength of the material, can inhibit cementite from forming, is favorable for obtaining a bainite structure with fine grains after rolling and cooling, but has high Si content, serious red rust on the surface of the strip steel, is difficult to remove, and is unfavorable for controlling the surface quality.
Mn:1.60 to 2.40 percent of Mn is taken as a reinforcing element of steel, can obviously improve the hardenability of the steel and the strength of the steel, and in order to ensure that the tensile strength of the material is more than or equal to 1050MPa, the Mn content is controlled to be more than 1.60 percent, but the Mn content is more than 2.40 percent, the center segregation of a casting blank is easy to cause, and the welding performance and the forming performance of the material are not facilitated.
Ti:0.05 to 0.15 percent, ti is used as an important element of the invention, and the purpose of adding higher content is to refine the original austenite grain refining effect in the heating process; on the other hand, ti which is dissolved in the matrix in the heating process can separate out a large amount of nano TiC after cooling and air-cooling sections and coiling and heat preservation, thereby playing the role of precipitation strengthening and improving the strength and hardness of the material; in addition, ti can fix excessive B, so that the quantity of FeB and the like precipitated in a grain boundary can be reduced, and the FeB is dispersed and distributed on a ferrite matrix, thereby being beneficial to improving the strength, the hardness and the wear resistance of the material. However, the Ti content cannot be too high, and considering that the C content is 0.08-0.15 percent, ti which cannot be completely dissolved in a matrix in a heating process when the Ti content is more than 0.15 percent forms a large amount of hard micron-sized TiC after rolling and cooling according to a solid solubility product formula, and the micron-sized TiC becomes a crack initiation source, which is unfavorable for the plasticity and toughness of the material and the cold roll forming property. In order to fully exert the precipitation strengthening effect of Ti, ti-3.42N-3*S-B is not less than 0.040%, when the content of Ti-3.42N-3*S-B is more than 0.14% according to the solid solubility product formula analysis, the total solid solution temperature of TiC is more than 1278 ℃, a large amount of hard micron-sized TiC is formed after rolling and cooling in the heating process, and the micron-sized TiC becomes a crack initiation source, which is unfavorable for the plasticity and toughness of materials and the cold bending forming performance.
B:0.0008% -0.0030%, B is used as another important element of the invention, can improve the austenite stability, can avoid cooling the air cooling section and form the pearlitic structure on the one hand; on the other hand, the transformation from austenite to ferrite can be delayed, and the problems of formation of a large amount of soft-phase ferrite structure, material strength and hardness reduction caused by the increase of TiC precipitation quantity and the increase of precipitation strengthening effect in the cooling air cooling section and the need of prolonging air cooling time are avoided. The addition of a certain amount of B can properly prolong the air cooling time, control the ferrite proportion, improve the quantity and proportion of TiC precipitates and improve the precipitation strengthening effect.
Als:0.020% -0.060%, als is mainly used as deoxidizer, and can react with N to generate AlN pinning grain boundary, and plays a role of refining grains.
P, S as an impurity element adversely affects the properties of steel such as plasticity, forming, welding, etc., and the lower the content thereof, the better the production cost factor is considered, and P is controlled in actual production: less than or equal to 0.012 percent, S: less than or equal to 0.005 percent.
O, N as a harmful gas element, since Ti is extremely active, it preferentially reacts with O, N to precipitate, which affects the yield of Ti, the precipitation amount of TiC and the precipitation strengthening effect, and N: less than or equal to 0.0050%; o: less than or equal to 0.0030 percent.
The chemical components of the invention adopt the low-C medium-Si high-Mn high-Ti and B microalloying design, no expensive alloy elements such as Mo, ni, nb, V and the like are added, and the alloy cost is low.
In the manufacturing method of the hot-rolled wear-resistant steel plate, in the heating process, the smaller austenite grain size and the higher Ti solid solution are comprehensively considered, high-temperature heating is adopted, the heat preservation time of a high-temperature section is emphasized to be prolonged instead of the total furnace time, the purposes of high-temperature heating and the tapping temperature of a casting blank to be 1230-1280 ℃ are mainly to improve the atomic proportion of Ti solid solution in a matrix, and conditions are created for separating TiC precipitates in the cooling and coiling process; the heat preservation time of the casting blank temperature of more than or equal to 1230 ℃ is controlled to be 30-50 min, so that Ti atoms can be fully dissolved into a matrix for enough time, and meanwhile, the defects that the strength is not improved due to too thick austenite grains and the surface quality is not controlled due to too thick scale.
In the rolling process, the rough rolling stage fully plays the characteristic of high-temperature large deformation so as to fully recrystallize the austenite. The method improves the accumulated deformation of the non-recrystallized region in the finish rolling stage and combines with lower finish rolling temperature, is favorable for generating larger accumulated strain energy, increases nucleation positions, refines the austenite grain size and the grain size of converting austenite into ferrite or bainite, and improves the fine grain strengthening effect. The main purpose of controlling the finish rolling speed to be more than or equal to 6.5m/s is to reduce the precipitation of micron-sized TiC in austenite as much as possible and improve the precipitation quantity of nano-sized TiC in the cooling air cooling section and the coiling process. Meanwhile, in order to control the quality of the finish rolling outlet plate shape, a control strategy of small convexity, small wedge shape and constant speed rolling is adopted.
According to the invention, on the cooling process, a control strategy of sectional cooling and online tempering after coiling is adopted, so that the synergistic effect of three strengthening modes of fine grain strengthening, precipitation strengthening and phase change strengthening is fully exerted, and the problem that precipitation strengthening (high coiling temperature requirement) and phase change strengthening (low coiling temperature requirement) cannot be achieved by adopting a one-stage continuous cooling process after rolling is avoided.
The first section adopts concentrated cooling and improves the cooling speed to be more than 100 ℃/s, mainly aims at improving the phase transformation supercooling degree and increasing the nucleation position, refines the ferrite grain size formed by austenite transformation and the bainite grain size formed by residual austenite transformation, and is beneficial to improving the material strength and the cold-bending forming performance. The main purpose of rapid cooling to 620-680 ℃ is that the temperature range is near the temperature of the nose tip of the PTT curve, so that a large proportion of nano TiC precipitates can be rapidly formed, and the precipitation strengthening effect and the effect of improving the wear resistance of the hard TiC on the material are fully exerted.
The air cooling time of the second stage is controlled to be 8-12 s, the air cooling time is less than 8s, and the TiC precipitation quantity is small; the air cooling time is more than 12s, the ferrite proportion is gradually increased, the grain size is increased, the TiC precipitate proportion is large, but the increment of the precipitation strengthening to the material strength is smaller than the decrement of the ferrite proportion to the transformation strengthening, the improvement of the material strength, the hardness and the wear resistance is not facilitated, and the laminar cooling line is limited in length and does not have the condition of long-time air cooling. The second stage of air cooling is controlled at 620-680 ℃, if the air cooling is controlled at 680 ℃ or higher, the supercooling degree is small, the phase change driving force is low, on one hand, austenite is difficult to transform into ferrite under the condition that the B element can obviously inhibit the formation of ferrite tissue, and the formed tissue after cooling is lath bainite, and the strength and the hardness are ensured, but the cold bending performance is not facilitated; on the other hand, when the ferrite proportion is smaller, the amount of TiC precipitated in the crystal is smaller, and the TiC precipitate is not in the optimal precipitation temperature range, so that the TiC precipitate proportion is lower, and the improvement effect of precipitation strengthening on the material strength is not facilitated; if the air cooling start temperature is too low, especially <600 ℃, the bainitic structure and the phase change strengthening effect are better, but the quantity of TiC precipitates and the precipitation strengthening effect are reduced at the same time, which is unfavorable for improving the strength and the wear resistance of the final material.
The third section is cooled to 490-550 ℃ at a cooling rate of more than or equal to 30 ℃/s, and then medium-temperature coiling is carried out, on one hand, a fine bainitic structure can be obtained, and the effect of phase change reinforcement on material strength improvement is fully exerted; on the other hand, compared with low-temperature coiling at the temperature of less than or equal to 300 ℃, the medium-temperature coiling has obvious advantages in the aspect of controlling the shape of the thin high-strength hot rolled strip steel, and the shape qualification rate can be improved. Meanwhile, on-line tempering is carried out by matching with a coiling and heat-preserving process, on one hand, tiC which is not precipitated in a cooling air cooling section can be continuously precipitated, and the precipitation strengthening effect is further improved; on the other hand, the uniformity control of the length, the width direction temperature, the mechanical property and the residual stress of the hot coil is facilitated, the plate shape quality is further facilitated, and the plate shape flatness is improved.
The invention performs a leveling process after coiling, and is mainly based on the consideration of improving the strip shape and the uniformity of the width direction performance of the strip steel. Under the condition of ensuring the strip shape of the strip steel, a control strategy with small leveling force and large bending force is preferably adopted, and the main purpose is to avoid the aggravation of the work hardening degree of the strip steel and not to be beneficial to the uniformity of the performance of the strip steel in the width direction. Meanwhile, in order to control the strip shape stability in the flattening process, the flattening speed of the strip steel is not too fast, and the flattening speed is controlled to be 50-100m/min.
Compared with the prior art, the invention has the following beneficial effects:
1) Compared with the existing 1000 MPa-level bainite structure type wear-resistant steel, on one hand, the low-temperature and high-Mn and high-Ti microalloying design is adopted for chemical components, and no expensive alloy elements such as Mo, ni, nb, V and the like are added, so that the alloy cost is low, and the TMCP process is adopted, so that the quenching and tempering heat treatment process is omitted, the process flow is short, and the process cost is reduced by 1000-1200 yuan/t compared with the quenching and tempering heat treatment process.
2) The invention adopts a sectional cooling process, can fully exert the effect of two strengthening modes of precipitation strengthening and phase change strengthening on the improvement of the material strength, and solves the problem that the high precipitation strengthening and high phase change strengthening effect are difficult to obtain simultaneously when bainitic steel is produced by a continuous cooling process. Compared with bainitic steel produced by a traditional hot continuous rolling production line, the material has the advantages of tensile strength of more than or equal to 1050MPa, hardness of more than or equal to 310HB, high strength and hardness, yield ratio of less than or equal to 0.70, cold bending performance of 180 degrees, D=1a being qualified, and lower yield ratio (more than 0.87) than the existing bainitic steel, and is beneficial to improving the cold bending performance of the material.
3) The unevenness of the heat wear-resistant steel plate produced by the invention after transverse cutting and leveling is controlled to be less than or equal to 5mm/m, the plate shape qualification rate is more than or equal to 95%, and the use requirements of downstream users are better met.
Drawings
FIG. 1 is a typical golden phase diagram of the hot rolled wear resistant steel of example 1;
FIG. 2 is a typical golden phase diagram of the hot rolled wear resistant steel of example 2;
FIG. 3 is a typical golden phase diagram of the hot rolled wear resistant steel of example 3;
FIG. 4 is a typical golden phase diagram of the hot rolled wear resistant steel of comparative example 1;
FIG. 5 is a typical golden phase diagram of the hot rolled wear resistant steel of comparative example 2;
FIG. 6 is a typical golden phase diagram of the hot rolled wear resistant steel of comparative example 3;
FIG. 7 is a typical golden phase diagram of the hot rolled wear resistant steel in comparative example 5;
FIG. 8 is a typical golden phase diagram of the hot rolled wear resistant steel of comparative example 6;
Detailed Description
The invention provides a hot-rolled wear-resistant steel plate, which comprises the following chemical components in percentage by weight: c:0.08 to 0.13 percent; si:0.60 to 1.40 percent; mn:1.60 to 2.40 percent; ti:0.050 to 0.15 percent; b:0.0008 to 0.0030 percent; als: 0.020-060 percent; p: less than or equal to 0.012%; s: less than or equal to 0.005%; n: less than or equal to 0.0050%; o: less than or equal to 0.0030 percent; the balance of Fe and unavoidable impurities; and needs to satisfy simultaneously: ti-3.42 x N-3*S-B is more than or equal to 0.040% and less than or equal to 0.14%.
The manufacturing method of the hot-rolled wear-resistant steel plate comprises the following steps: smelting, continuous casting, heating, rolling, cooling, coiling, flattening and flattening.
In the heating step, the end temperature of the secondary section is more than or equal to 1200 ℃, the soaking time is more than or equal to 30min, the tapping temperature of the slab is 1230-1280 ℃, and the heat preservation time of the slab temperature is more than or equal to 1230 ℃ is more than or equal to 40min.
In the rolling step, a 2-frame rough rolling machine and a 7-machine are adoptedRolling by a frame finish rolling hot continuous rolling unit; finishing temperature R of rough rolling 2 DT is 1080-1130 ℃, and the cumulative rolling reduction of rough rolling is more than or equal to 80%; finish rolling finishing temperature FDT is 850-900 ℃, and finish rolling accumulated rolling reduction is more than or equal to 85%; rolling at a constant speed; the rolling speed v of the finish rolling F7 frame is more than or equal to 6.5m/s; convexity C of F7 frame 40 Is 10-30 mu m, wedge-shaped W 40 Is-10 to 10 mu m.
In the cooling step, the strip steel is subjected to sectional cooling after being discharged from the F7 rack; the first section adopts concentrated cooling, and is cooled to 620-680 ℃ at a cooling rate of 110-120 ℃/s; then performing second-stage air cooling for 8-12 s; cooling in air, cooling to 490-550 deg.c at 30-60 deg.c/s, coiling, unloading, covering with heat insulating cover, tempering, heat insulating for 60-90 min, cooling in air to room temperature.
In the leveling step, the rolling force of the leveling machine is 500-800t, the bending force is 70-100t, and the leveling speed is 50-100m/min.
The present invention will be described in detail with reference to examples.
The chemical compositions of the examples and the comparative examples are shown in Table 1, the rolling process parameters are shown in Table 2, the cooling process parameters are shown in Table 3, the leveling process parameters and the unevenness of the flat plate are shown in Table 4, the structure types are shown in Table 5, the mechanical properties are shown in Table 6, and the wear resistance is shown in Table 7.
Table 1 chemical Components (weight percent, wt%) of examples and comparative examples
Table 2 rolling process parameters of examples and comparative examples
Table 3 cooling process parameters for examples and comparative examples
Table 4 leveling process parameters, open panel yield for examples and comparative examples
Remarks: the unevenness of the open plate is less than or equal to 8mm/m, and the plate shape percent of pass is equal to the weight of the open plate qualified product/the weight of the hot coil.
TABLE 5 tissue types for examples and comparative examples
Table 6 mechanical properties of examples and comparative examples
Table 7 abrasion resistance properties of examples and comparative examples
| Numbering device | Loss of weight of mill (g) | Relative wear resistance |
| Example 1 | 2.6804 | 1.24 |
| Example 2 | 2.6631 | 1.25 |
| Example 3 | 2.6534 | 1.26 |
| Comparative example 1 | 3.3321 | 1.00 |
| Comparative example 2 | 3.1277 | 1.07 |
| Comparative example 3 | 3.4403 | 0.97 |
| Comparative example 4 | 2.7413 | 1.21 |
| Comparative example 5 | 2.7089 | 1.23 |
| Comparative example 6 | 2.8388 | 1.17 |
| Comparative example 7 | 2.2608 | 1.47 |
| Comparative example 8 | 2.8912 | 1.15 |
| Comparative example 9 | 2.4956 | 1.34 |
Note that: the abrasive wear test was performed on an MLS-225 wet rubber wheel tester, and the sample size of the abrasive wear test was: 57mm (length). Times.25.5 mm (width). Times.2.5 mm (thickness), wherein the 57 mm.times.25.5 mm face is a wear face, the wear face is polished. The test parameters were as follows: the hardness of the rubber wheel is 60HS, the rotating speed of the rubber wheel is 240r/min, the abrasive is a solution formed by mixing quartz sand and water according to the proportion of 1:1, the particle size of the quartz sand is 20-40 meshes, and the load is 170N. Firstly, the abrasion surface of a sample is subjected to 1000r pre-grinding, the weight m1 of the sample after the pre-grinding is recorded, then the sample is subjected to 60min fine grinding, the weight m2 of the sample after the fine grinding is recorded, the sample after the pre-grinding and the sample after the fine grinding are subjected to ultrasonic cleaning, and the weight is measured by adopting an electronic balance (the precision is 0.1 mg). The wear loss weight Deltam (m 1-m 2) is taken as a main parameter for evaluating the wear resistance of the material, and the smaller the wear loss weight is, the better the wear resistance of the material is. 3 pieces of each test material were respectively selected under the same test conditions for the abrasive wear test, and the average value of the abrasion loss weights of 3 pieces of the test materials was taken as the final abrasion loss weight.
Relative wear resistance = wear loss weight of example or comparative example/loss weight of comparative example 1, with loss weight of comparative example 1 as a reference standard.
The foregoing detailed description of a hot rolled wear resistant steel sheet and method of manufacturing the same has been given by way of illustration and not limitation, and several embodiments may be enumerated in accordance with the limited scope, and therefore variations and modifications may be considered to be within the scope of the present invention without departing from the general inventive concept.
Claims (9)
1. The hot-rolled wear-resistant steel plate is characterized by comprising the following chemical components in percentage by weight: c:0.08 to 0.13 percent; si:0.60 to 1.40 percent; mn:1.60 to 2.40 percent; ti:0.050 to 0.15 percent; b:0.0008 to 0.0030 percent; als: 0.020-060 percent; p: less than or equal to 0.012%; s: less than or equal to 0.005%; n: less than or equal to 0.0050%; o: less than or equal to 0.0030 percent; the balance of Fe and unavoidable impurities; and needs to satisfy simultaneously: ti-3.42 x N-3*S-B is more than or equal to 0.040% and less than or equal to 0.14%.
2. The hot-rolled wear-resistant steel sheet according to claim 1, wherein the metallographic structure of the hot-rolled wear-resistant steel sheet is granular bainite and nano-sized precipitates, the nano-sized precipitates are not more than 20nm in size, and the volume fraction of the nano-sized precipitates is 0.15 to 0.22%.
3. The hot-rolled wear-resistant steel sheet according to claim 1, wherein the hot-rolled wear-resistant steel sheet has a yield strength of not less than 700MPa, a tensile strength of not less than 1050MPa, a yield ratio of not more than 0.70, and an elongation A 50 More than or equal to 16 percent, the hardness is more than or equal to 310HB, the cold bending performance reaches 180 degrees, D=1a is qualified, the open plate unevenness is controlled to be less than or equal to 5mm/m, and the plate shape qualification rate is more than or equal to 95 percent.
4. A method of manufacturing a hot rolled wear resistant steel sheet as claimed in any one of claims 1 to 3, wherein said method of manufacturing comprises the steps of: smelting, continuous casting, heating, rolling, cooling, coiling, flattening and flattening.
5. The method according to claim 4, wherein in the heating step, the end temperature of the secondary section is not less than 1200 ℃, the soaking time is not less than 30min, the tapping temperature of the slab is 1230-1280 ℃, and the holding time of the slab temperature not less than 1230 ℃ is not less than 40min.
6. The method according to claim 4, wherein in the rolling step, rolling is performed by using a 2-stand rough rolling mill and a 7-stand finish rolling hot continuous rolling mill; finishing temperature R of rough rolling 2 DT is 1080-1130 ℃, and the cumulative rolling reduction of rough rolling is more than or equal to 80%; finish rolling finishing temperature FDT is 850-900 ℃, and finish rolling accumulated rolling reduction is more than or equal to 85%; rolling at a constant speed; the rolling speed v of the finish rolling F7 frame is more than or equal to 6.5m/s; convexity C of F7 frame 40 Is 10-30 mu m, wedge-shaped W 40 Is-10 to 10 mu m.
7. The method according to claim 4, wherein in the cooling step, the strip steel is cooled in sections after being discharged from the F7 frame; the first section adopts concentrated cooling, and is cooled to 620-680 ℃ at a cooling rate of more than or equal to 100 ℃/s; then performing second-stage air cooling for 8-12 s; cooling in the air, cooling to 490-550 deg.c at cooling rate not lower than 30 deg.c/s, coiling, unloading, covering with heat insulating cover, tempering, heat insulating for 60-90 min, cooling in the air to room temperature.
8. The method according to claim 5, wherein in the cooling step, the strip steel is cooled in sections after being discharged from the F7 frame; the first section adopts concentrated cooling, and is cooled to 620-680 ℃ at a cooling rate of 110-120 ℃/s; then performing second-stage air cooling for 8-12 s; cooling in air, cooling to 490-550 deg.c at 30-60 deg.c/s, coiling, unloading, covering with heat insulating cover, tempering, heat insulating for 60-90 min, cooling in air to room temperature.
9. The method according to claim 5, wherein in the flattening step, the flattening machine has a rolling force of 500 to 800t, a roll bending force of 70 to 100t, and a flattening rate of 50 to 100m/min.
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