CN111534745A - Impact-resistant chain plate steel and manufacturing method thereof - Google Patents
Impact-resistant chain plate steel and manufacturing method thereof Download PDFInfo
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- CN111534745A CN111534745A CN202010364068.3A CN202010364068A CN111534745A CN 111534745 A CN111534745 A CN 111534745A CN 202010364068 A CN202010364068 A CN 202010364068A CN 111534745 A CN111534745 A CN 111534745A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 98
- 239000010959 steel Substances 0.000 title claims abstract description 98
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 53
- 238000005096 rolling process Methods 0.000 claims abstract description 36
- 238000005266 casting Methods 0.000 claims abstract description 24
- 238000003723 Smelting Methods 0.000 claims abstract description 14
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 8
- 239000000956 alloy Substances 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 8
- 238000005098 hot rolling Methods 0.000 claims abstract description 7
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 5
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 238000009749 continuous casting Methods 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 20
- 238000001816 cooling Methods 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 17
- 230000009467 reduction Effects 0.000 claims description 17
- 229910000859 α-Fe Inorganic materials 0.000 claims description 9
- 238000005452 bending Methods 0.000 claims description 8
- 239000000047 product Substances 0.000 claims description 8
- 238000007670 refining Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 238000010791 quenching Methods 0.000 claims description 6
- 230000000171 quenching effect Effects 0.000 claims description 6
- 238000005496 tempering Methods 0.000 claims description 5
- 229910000734 martensite Inorganic materials 0.000 claims description 4
- 229910001562 pearlite Inorganic materials 0.000 claims description 4
- 238000007711 solidification Methods 0.000 claims description 4
- 230000008023 solidification Effects 0.000 claims description 4
- 239000011265 semifinished product Substances 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 claims description 2
- 230000002035 prolonged effect Effects 0.000 abstract description 7
- 239000002245 particle Substances 0.000 description 13
- 239000011572 manganese Substances 0.000 description 12
- 229910001566 austenite Inorganic materials 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 8
- 238000005261 decarburization Methods 0.000 description 8
- 239000006104 solid solution Substances 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 238000005204 segregation Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 229910000677 High-carbon steel Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910000742 Microalloyed steel Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
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- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/466—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a non-continuous process, i.e. the cast being cut before 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
-
- 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
- C21D2211/008—Martensite
-
- 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
- C21D2211/009—Pearlite
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention provides an impact-resistant chain plate steel and a manufacturing method thereof, wherein the steel comprises the following components in percentage by weight: c: 0.3% -0.49%, Si: less than or equal to 0.40 percent, Mn: 0.4% -1.1%, Cr: less than or equal to 0.50 percent, Nb: 0.2% -4.0%; al: 0.015 to 0.1 percent of the total weight of the alloy, less than or equal to 0.0015 percent of O, less than or equal to 0.020 percent of impurity element P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities. The manufacturing method comprises smelting, slab casting and rolling, and hot rolling; after the steel plate produced by the invention is subjected to heat treatment, the impact energy is more than 50J, the impact resistance and the fatigue performance of the processed chain plate are obviously improved, and the service life is prolonged by more than 60%.
Description
Technical Field
The invention belongs to the field of metal materials, and particularly relates to a chain plate hot rolled steel with high impact performance and a manufacturing method thereof.
Background
At present, chain plates are mostly processed by 40Mn and 45Mn steel plates, the surface hardness of raw material steel plates is generally required to be 85 HRB-90 HRB so as to ensure the quality of the parts after stamping, the hardness is 38-42HRC after heat treatment, the impact energy is about 20J, and the problems of chain extension, power system efficiency reduction, short service life, frequent replacement and the like are caused by easy impact wear deformation in the long-term use process. Especially for some automobile power chains, the service life of the chain directly influences the service life of an automobile engine and even the whole automobile.
The invention relates to a low-carbon microalloyed steel and a method for producing a chain link plate by using the same (99100724.7), and the low-carbon microalloyed steel is a cold-rolled sheet containing manganese and vanadium. Low carbon content, low total alloy content, relatively low hardness after heat treatment, insufficient wear resistance, cold rolling requirement and high cost.
The invention discloses a continuous casting process for processing a round chain by a square billet (CN103252466A), belonging to a profile production process, wherein the square billet has small size, the continuous casting billet is easy to produce, and the parameters of a smelting casting billet cooling process and the like are completely different from the continuous casting of a plate blank. And the finished product is a round chain, which has different purposes from the chain plate.
The invention relates to a chain steel material (CN103422034A) and a chain plate material of a pipeline chain plate conveyor (CN109881128A), which are added with unconventional compounds or elements, need a special production method, have high cost and complex production process.
The invention relates to a steel for circular chain and a manufacturing method thereof (CN102653834A), a mining large-size high-strength chain steel and a preparation method thereof (CN201410800419.5), and a 90-grade chain steel (CN201811242708.2), which are all made of section bars, the steel for chain has low carbon content, high alloy contents of Ni, Cr, Mo and the like and high cost, and the conventional heat treatment process can not meet the requirements of high hardness, high wear resistance and high impact property of the chain plate.
The outer chain plate of chain (CN 2206868Y) is a special utility model patent, which introduces the improvement of the shape of chain plate, and does not mention the material.
The invention relates to a caterpillar track steel with high strength, high wear resistance and long fatigue life and a production process thereof (CN201610507885.3), which is a round bar rolled by a continuous casting square billet and is not suitable for being used as a chain plate. And the content of C is 0.28-0.32%, which is lower, the hardness after heat treatment is difficult to reach more than 37HRC, the content of Mn is more than 1.45%, segregation is easy to form, the structure is uneven, and the fatigue performance is influenced.
The documents of 18MnZL hot rolled strip steel for bicycle chains, chemical component design of steel for racing chains, development and application of steel for cold rolled chain of Wu steel and the like all introduce cold rolled steel plate steel. The 16Mn chain steel introduced in the 16Mn steel chain plate fracture analysis has low carbon content, can meet the hardness requirement after carburization, and has complex process.
The steel grades mentioned in the above documents and inventions are not suitable for directly processing the high-wear-resistant chain plate by using the hot rolled plate. Therefore, the hot rolled steel strip is suitable for directly processing various chain plates, and has good impact resistance and long service life.
Disclosure of Invention
The invention aims to overcome the problems and the defects and provide the anti-impact chain plate steel and the manufacturing method thereof, the steel for the chain plate adopts a plate rolling process of continuous casting and continuous production, the impact performance of the steel plate is more than 200J, and the wear-resisting life of the manufactured chain is prolonged by more than 60 percent compared with that of a common chain.
The purpose of the invention is realized as follows:
an impact-resistant chain plate steel comprises the following components in percentage by weight: c: 0.3% -0.49%, Si: less than or equal to 0.40 percent, Mn: 0.4% -1.1%, Cr: less than or equal to 0.50 percent, Nb: 0.2% -4.0%; al: 0.015 to 0.1 percent of the total weight of the alloy, less than or equal to 0.0015 percent of O, less than or equal to 0.020 percent of impurity element P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities.
The steel structure of the shock-resistant chain plate is uniform and fine ferrite and pearlite, the volume percentage of the ferrite is below 30%, the grain size is above 10 grade, the surface roughness is below 1.8um, various non-metal inclusions are less than 1.5 grade, and the depth of a single-surface decarburized layer is less than 1.0 percent of the plate thickness.
The invention has the following design reasons:
c is a main solid solution strengthening element in the steel, if the carbon content is higher than 0.50%, the toughness and the plasticity of the steel and the brittleness of the chain are easy to be reduced to be lower than 0.3%, and the hardness after heat treatment is insufficient. Therefore, the C content is controlled to be 0.3-0.49%.
Mn is a good deoxidizer and desulfurizer, and is an essential element for ensuring the strength and toughness of steel. Manganese and iron form a solid solution, which can increase the hardness and strength of ferrite and austenite in steel. Mn and S are combined to form MnS, so that the influence of hot cracks caused by FeS formed at the grain boundary on the hot formability of the steel for the saw blade is avoided. Meanwhile, Mn is also a good deoxidizer and increases hardenability. The Mn content is too low to meet the requirement of high strength and hardness after heat treatment, and the Mn content is too high to form segregation zones to influence the welding performance and increase the production cost, so the Mn content should be controlled to be 0.4-1.1% by comprehensively considering the factors of cost, performance requirements and the like.
Si is one of common elements in steel and is used as a reducing agent and a deoxidizing agent in the steelmaking process, and Si in a solid solution form can improve the yield strength and the ductile-brittle transition temperature, but if the content of Si exceeds the upper limit, the toughness and the welding performance are reduced. On the other hand, Si is a ferrite forming element, and the high content of Si can cause serious decarburization on the steel surface, so that the content of Si is not easy to be too high, and the content of Si is less than or equal to 0.40 percent.
Cr is an element for remarkably improving the hardenability of steel, a proper amount of Cr is added into the steel to enable a C curve to move to the right, and the spacing between pearlite pieces obtained at the same cooling speed is more refined. For high carbon steel, Cr can increase the activation energy of carbon diffusion and reduce the decarburization tendency of steel. On the other hand, Cr can also increase the ferrite electrode potential, promote the formation of a dense oxide film on the surface of steel, and improve the corrosion resistance. The Cr content is too high, the alloy cost is increased, and the shape of the steel plate is poor and difficult to level, so the Cr content is controlled to be less than or equal to 0.50 percent.
Nb is a micro-alloy element for fine grain strengthening and precipitation strengthening, and the toughness and plasticity of the hot-rolled steel plate and the strength and toughness of the steel after heat treatment can be improved by adding a proper amount of Nb into the steel. Usually, the microalloyed Nb content in the steel is 0.01-0.05%, and 0.2-4.0% of Nb is added in the invention. By adding Nb to steel, fine carbonitride two-phase particles such as NbC and NbCN can be precipitated during hot working, thereby suppressing the deformation recrystallization of austenite, preventing the growth of austenite grains, and refining the grains. The type and size of the generated particles directly influence the service performance of the steel, such as wear resistance and the like. For example, NbC particles smaller than 30um are produced, the effect of grain refinement is obvious, the hardness after heat treatment is obviously improved, the wear resistance is enhanced, and the service life is prolonged. When the length of a timing chain in an engine extends by 50% due to severe wear after a current automobile is used for several years, the engine is judged to be useless. After 0.2% -4% of Nb is added into the chain steel, the impact resistance and wear resistance are obviously improved, when a common engine is scrapped due to other reasons, the length of the chain is only extended by 20% to the maximum extent, namely, the scrapping of the engine due to the abrasion extension problem of the timing chain is avoided, and the service life of the engine is prolonged. On the other hand, Nb can suppress the oxidation and decarburization of the steel surface.
Al: 0.015-0.1%, Al is generally used as deoxidizer during smelting, crystal grains can be refined, the strength is improved, but Al-containing oxide inclusion is easily formed at the same time, and the fatigue performance of steel is influenced. Therefore, the Al content is controlled to be 0.015-0.10%.
O: o is less than or equal to 0.0015 percent, oxygen is a residual element in steel making, the oxygen content is high, a large amount of non-metallic inclusions exist, and the fatigue performance is seriously influenced. In order to ensure the strength and hardness of the steel for the chain plate after heat treatment, the steel for the chain plate has medium C content and overhigh oxygen content in high-carbon steel, and non-metallic inclusions are not easy to float up during smelting, so that the inclusions in the steel are excessive, and the fatigue life is influenced, therefore, the invention requires that O in a finished steel plate is less than or equal to 0.0015 percent.
P and S are inevitable harmful impurities in steel, and the existence of P and S can seriously deteriorate the toughness of the steel, influence the fatigue performance and shorten the service life. Measures are therefore taken to keep the P and S contents in the steel as low as possible. According to the invention, the maximum P content is limited to 0.020% and the maximum S content to 0.010%.
The composition design adopts the medium carbon content, and alloy elements such as Mn, Cr, Si and the like are added, so that the hardenability and hardenability of the steel plate are ensured. 0.2 to 4 percent of Nb is added into the steel, the steel plate structure is uniform and fine, the austenite grain size is ensured to be more than 10 grade, and the shock resistance is improved to be more than 50J. Meanwhile, the content of impurity elements such as P, S, O and the like is strictly controlled, the fatigue property of steel is improved, and the service life of the chain plate is further prolonged.
The second technical scheme of the invention provides a manufacturing method of the anti-impact chain plate steel, which comprises smelting, plate blank continuous casting and continuous rolling and hot rolling;
(1) smelting:
converter smelting and LF or RH external refining are carried out, and the refining treatment time is required to be more than 30min so that nonmetallic inclusions can float sufficiently, the quality of molten steel is ensured, and the fatigue performance of a finished steel plate is improved; the O content of the middle package is required to be less than or equal to 0.0020 percent so as to ensure that the O content of a finished product is less than or equal to 0.0015 percent;
converter smelting and LF or RH external refining treatment are adopted, the treatment time is more than 30min, the floating of nonmetallic inclusions is facilitated to be sufficient, the purity of molten steel is ensured, and the fatigue performance of a finished steel plate is improved; the O content in the medium package is required to be less than or equal to 0.0020 percent so as to ensure that the O content in the finished product is less than or equal to 0.0015 percent and various nonmetallic inclusions are less than 1.5 grade.
(2) Slab continuous casting and rolling:
adopting a vertical bending or vertical continuous casting machine for continuous casting, carrying out soft reduction at the position with the solidification rate of 45-65% of a slab, wherein the temperature of the casting blank is more than 930 ℃ when the vertical bending casting machine carries out continuous casting and secondary cooling, and the thickness of the slab is not more than 230 mm;
the vertical bending or vertical continuous casting machine is adopted for continuous casting, and soft reduction is carried out at the position with the solidification rate of 45% -65% of a casting blank in the continuous casting so as to control segregation and inclusion. The continuous casting process is too early in reduction, the liquid core is too small in thickness, inclusion floating is not facilitated, the reduction is too late, the liquid core at the reduction position is too large in thickness, and the casting blank is prone to crack, segregation and other defects. The casting blank temperature is above 930 ℃ during the continuous casting secondary cooling of the vertical bending type casting machine, and cracks are avoided when the casting blank is bent and cooled.
In order to control the size of the two-phase particles, the thickness of the slab cannot be larger than 230mm, so that the cooling of the slab is promoted, the storage energy is reduced, and the growth of the two-phase particles is inhibited. On the other hand, the slab is put into a heating furnace at a temperature of more than 650 ℃, so that serious surface decarburization and oxidation caused by long-time secondary heating are avoided, and meanwhile, the solid solution of two-phase particles in the casting blank is promoted, so that fine two-phase particles are generated again in the rolling process, crystal grains are refined, the hardness and the wear resistance after heat treatment are improved, and the service life of the chain plate is prolonged. Directly putting the plate blank into a heating furnace for heating without going down a roller way after the plate blank is cut off, and waiting for rolling;
(3) hot rolling:
(a) the heating furnace adopts a reducing atmosphere stepping heating furnace, the heating temperature of the casting blank is 1100-1250 ℃, and the surface decarburization is reduced as much as possible while the uniform heating of the casting blank is ensured, and the surface grain boundary oxidation is inhibited in the furnace for 2-4 h;
rolling by a hot continuous rolling mill group. The heating temperature of the casting blank is 1100-1250 ℃, the furnace time is 4-5 hours, the solid solution speed of Nb particles is obviously increased at the temperature of more than 1100 ℃, the solid solution amount is obviously increased, and more than 70 percent of Nb is solid-dissolved in the steel after the temperature reaches 1200 ℃. According to the characteristics of the walking beam furnace, the casting blank is calculated to have enough time to promote the solid solution of Nb at 1100-1250 ℃ after being put into the furnace at 800 ℃ for more than 4 hours. After the furnace time exceeds 4 hours, the surface of the casting blank is seriously oxidized and decarburized, and the impact and fatigue performance after heat treatment is influenced. And removing the surface iron scale by adopting a high-pressure water descaling technology, thereby reducing the surface decarburization oxidation of the finished steel plate, ensuring that the depth of a single-surface decarburized layer is less than 1.0 percent of the plate thickness and avoiding grain boundary oxidation.
(b) The fine and rough rolling adopts high-pressure water for descaling, and the water pressure is more than 15MPa, so that the surface quality of the finished steel plate is ensured;
(c) the first pass reduction rate of rough rolling is more than 40 percent, and the rolling temperature is 1050-1150 ℃;
(d) the total reduction rate of finish rolling is more than 85 percent, and the finish rolling temperature of the finish rolling is 750-950 ℃;
the large reduction rate of more than 40 percent in the first pass, the rolling temperature of 1050-1150 ℃, the final rolling temperature of 750-950 ℃, the austenite zone rolling and the large reduction rate in the first pass are adopted, the segregation of the casting blank tissues is broken, the banding of the finished product is reduced, and the tissue uniformity of the finished product is improved. The total reduction rate of the Nb-containing steel in finish rolling is more than 85%, recrystallization is promoted, a new austenite grain zone is formed, and grains are refined.
(e) After the strip steel is taken out of the finishing mill, the strip steel is cooled to below 700 ℃ at a cooling speed of more than 10 ℃/S and coiled so as to control the size of two-phase particles.
After rolling, rapidly cooling to below 700 ℃ at a cooling rate of more than 10 ℃/S for coiling, on one hand, the growth of Nb-containing particles can be inhibited, the particle size is controlled to be below 50um, austenite grains are refined to be above 10 grade, and the impact energy after heat treatment is above 50J. On the other hand, the surface oxidation and decarburization can be suppressed, and the surface hardness and fatigue property can be controlled. The cooling speed is lower than 10 ℃/S, the formed particles are large, and the particles grow obviously after being coiled at the temperature of more than 700 ℃. The grain is larger than 50um, not only can austenite grain not be refined, but also can influence the mechanical property of steel, and the surface of the steel plate is easy to be oxidized and decarburized, the surface grain boundary is seriously oxidized, surface microcracks are easily formed, and the impact and fatigue properties are seriously influenced.
A heat treatment process of impact-resistant chain plate steel is characterized in that after the chain plate steel is processed into a chain plate semi-finished product, heat treatment is carried out, and the specific process is as follows:
heating at 835 and 870 ℃, preserving heat for 20-45min, performing oil quenching, cooling the quenching oil to below 80 ℃, tempering at 280 and 380 ℃, and forming a tempered martensite structure after heat treatment, wherein the impact energy is more than 50J.
The chain plate structure is tempered martensite, and the impact energy is more than 50J.
The invention has the beneficial effects that: the steel plate produced by applying the technical scheme disclosed by the invention adopts a continuous casting production process, so that the yield is high and the production cost is low; the hot rolled plate structure is uniform and fine ferrite and pearlite, the volume ratio of the ferrite is below 30%, and the toughness is ensured; austenite grains are fine and uniform, and the grain size is more than 10 grades; the non-metallic inclusions are less than 1.5 grade, the depth of the single-side surface decarburization layer is less than 1.0 percent of the thickness of the plate, and no crystal boundary oxidation exists. After heat treatment, the impact energy is more than 50J, the impact resistance and fatigue performance of the processed chain plate are obviously improved, and the service life is prolonged by more than 60%.
Detailed Description
The present invention is further illustrated by the following examples.
According to the embodiment of the invention, smelting, continuous casting and continuous rolling and hot rolling are carried out according to the component proportion of the technical scheme.
(1) Smelting:
converter smelting, LF or RH external refining, wherein the refining treatment time is required to be more than 30min, and the middle package O is required to be less than or equal to 0.0020% so as to ensure that the finished product O is less than or equal to 0.0015%;
(2) continuous casting and rolling:
carrying out soft reduction at the position with the solidification rate of 45-65% of the plate blank, wherein the casting blank temperature is more than 930 ℃ when the vertical bending type casting machine carries out continuous casting and secondary cooling, and the plate blank thickness is not more than 230 mm; directly feeding the plate blank into a heating furnace for heating without falling off a roller way after cutting off the plate blank, and feeding the plate blank into the heating furnace for rolling at the temperature of more than 650 ℃;
(3) hot rolling:
(a) the heating furnace adopts a reducing atmosphere heating furnace, the heating temperature of a casting blank is 1100-1250 ℃, and the casting blank is heated in the furnace for 2-4 h;
(b) the fine and rough rolling adopts high-pressure water to remove scale, and the water pressure is more than 15 MPa;
(c) the first pass reduction rate of rough rolling is more than 40 percent, and the rolling temperature is 1050-1150 ℃;
(d) the total reduction rate of finish rolling is more than 85 percent, and the finish rolling temperature of the finish rolling is 750-950 ℃;
(e) after the strip steel is taken out of the finishing mill, the strip steel is cooled to below 700 ℃ at a cooling speed of more than 10 ℃/S and coiled.
Furthermore, a vertical bending type or vertical type continuous casting machine is adopted for continuous casting.
Further, the heating furnace is a stepping heating furnace.
A heat treatment process of impact-resistant chain plate steel is characterized in that after the chain plate steel is processed into a chain plate semi-finished product, heat treatment is carried out, and the specific process is as follows:
heating at 835-870 ℃, preserving heat for 20-45min, performing oil quenching, cooling to the temperature of not higher than 80 ℃, cooling to the temperature of below 200 ℃, tempering at 280-380 ℃, forming a tempered martensite structure at room temperature after heat treatment, and performing impact of more than 50J after heat treatment.
The compositions of the steels of the examples of the invention are shown in table 1. The main process parameters of the steel of the embodiment of the invention are shown in Table 2. The heat treatment process of the steel of the examples of the present invention is shown in Table 3. The properties of the steels of the examples of the invention are shown in Table 4.
TABLE 1 composition (wt%) of steels of examples of the present invention
| Examples | C | Si | Mn | P | S | Cr | Nb | Al | Finished product O |
| 1 | 0.35 | 0.25 | 0.40 | 0.015 | 0.005 | 0.02 | 1.10 | 0.015 | 0.0015 |
| 2 | 0.46 | 0.27 | 0.92 | 0.004 | 0.009 | 0.15 | 0.32 | 0.058 | 0.0012 |
| 3 | 0.38 | 0.08 | 0.91 | 0.008 | 0.02 | 0.22 | 2.5 | 0.029 | 0.0011 |
| 4 | 0.40 | 0.16 | 0.55 | 0.010 | 0.018 | 0.10 | 1.9 | 0.025 | 0.0005 |
| 5 | 0.45 | 0.40 | 0.60 | 0.012 | 0.004 | 0.45 | 1.0 | 0.078 | 0.0007 |
| 6 | 0.47 | 0.15 | 0.75 | 0.014 | 0.003 | 0.39 | 0.5 | 0.018 | 0.0008 |
| 7 | 0.32 | 0.16 | 0.88 | 0.013 | 0.008 | 0.50 | 3.5 | 0.055 | 0.00012 |
| 8 | 0.31 | 0.27 | 0.82 | 0.014 | 0.004 | 0.48 | 2.0 | 0.029 | 0.0008 |
| 9 | 0.39 | 0.30 | 0.99 | 0.012 | 0.007 | 0.25 | 1.5 | 0.038 | 0.00010 |
| 10 | 0.47 | 0.08 | 0.68 | 0.010 | 0.01 | 0.14 | 0.4 | 0.045 | 0.0008 |
| 11 | 0.36 | 0.09 | 0.70 | 0.008 | 0.007 | 0.48 | 0.6 | 0.098 | 0.0003 |
| 12 | 0.45 | 0.07 | 0.82 | 0.013 | 0.006 | 0.35 | 1.0 | 0.033 | 0.0009 |
| 13 | 0.44 | 0.16 | 1.08 | 0.013 | 0.008 | 0.25 | 2.5 | 0.035 | 0.0002 |
| 14 | 0.39 | 0.06 | 0.82 | 0.014 | 0.004 | 0.08 | 2.0 | 0.040 | 0.0009 |
| 15 | 0.43 | 0.10 | 0.79 | 0.012 | 0.007 | 0.15 | 1.8 | 0.058 | 0.00010 |
| 16 | 0.40 | 0.18 | 0.88 | 0.030 | 0.01 | 0.46 | 3.6 | 0.055 | 0.00013 |
| 17 | 0.32 | 0.15 | 0.80 | 0.025 | 0.025 | 0.32 | 0.5 | 0.049 | 0.00010 |
| 18 | 0.48 | 0.27 | 0.72 | 0.004 | 0.009 | 0.45 | 0.9 | 0.048 | 0.00012 |
TABLE 2 Main Process parameters of the steels of the examples of the invention
TABLE 3 Heat treatment Process for steels of examples of the invention
| Numbering | Heating temperature of | Holding time min | Cooling to a temperature of | Tempering temperature DEG C | Quenching oil temperature DEG C |
| 1 | 835 | 20 | 180 | 350 | 55 |
| 2 | 850 | 30 | 195 | 320 | 45 |
| 3 | 865 | 25 | 150 | 330 | 50 |
| 4 | 848 | 29 | 170 | 360 | 65 |
| 5 | 850 | 45 | 180 | 300 | 55 |
| 6 | 835 | 42 | 160 | 380 | 44 |
| 7 | 860 | 30 | 180 | 355 | 56 |
| 8 | 843 | 40 | 178 | 358 | 59 |
| 9 | 840 | 35 | 180 | 350 | 65 |
| 10 | 860 | 33 | 150 | 290 | 75 |
| 11 | 840 | 43 | 150 | 320 | 80 |
| 12 | 850 | 40 | 145 | 340 | 55 |
| 13 | 846 | 25 | 180 | 320 | 20 |
| 14 | 855 | 30 | 165 | 305 | 55 |
| 15 | 840 | 28 | 180 | 350 | 35 |
| 16 | 855 | 27 | 170 | 325 | 45 |
| 17 | 868 | 30 | 180 | 300 | 55 |
| 18 | 845 | 40 | 165 | 280 | 50 |
TABLE 4 Properties of steels of examples of the invention
In order to express the present invention, the above embodiments are properly and fully described by way of examples, and the above embodiments are only used for illustrating the present invention and not for limiting the present invention, and those skilled in the relevant art can make various changes and modifications without departing from the spirit and scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made by the persons skilled in the relevant art should be included in the protection scope of the present invention, and the protection scope of the present invention should be defined by the claims.
Claims (7)
1. The impact-resistant chain plate steel is characterized by comprising the following components in percentage by weight: c: 0.3% -0.49%, Si: less than or equal to 0.40 percent, Mn: 0.4% -1.1%, Cr: less than or equal to 0.50 percent, Nb: 0.2% -4.0%; al: 0.015 to 0.1 percent of the total weight of the alloy, less than or equal to 0.0015 percent of O, less than or equal to 0.020 percent of impurity element P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities.
2. The impact-resistant chain plate steel as claimed in claim 1, wherein the structure of the impact-resistant chain plate steel is ferrite and pearlite, the volume percentage of ferrite is less than 30%, the grain size is more than 10 grade, various non-metallic inclusions are less than 1.5 grade, and the depth of the decarburized layer on the single-side surface of the steel plate is less than 1.0% of the plate thickness.
3. A method for manufacturing an impact-resistant chain plate steel as defined in claim 1 or 2, comprising smelting, slab casting and rolling, hot rolling; it is characterized in that the preparation method is characterized in that,
(1) smelting:
converter smelting, LF or RH external refining, wherein the refining treatment time is required to be more than 30min, and the middle package O is required to be less than or equal to 0.0020% so as to ensure that the finished product O is less than or equal to 0.0015%;
(2) slab continuous casting and rolling:
carrying out soft reduction at the position where the solidification rate of the plate blank is 45-65%, wherein the thickness of the plate blank is not more than 230 mm; directly feeding the plate blank into a heating furnace for heating without falling off a roller way after cutting off the plate blank, and feeding the plate blank into the heating furnace for rolling at the temperature of more than 650 ℃;
(3) hot rolling:
(a) the heating furnace adopts a reducing atmosphere heating furnace, the heating temperature of a casting blank is 1100-1250 ℃, and the casting blank is heated in the furnace for 2-4 hours;
(b) the fine and rough rolling adopts high-pressure water to remove scale, and the water pressure is more than 15 MPa;
(c) the first pass reduction rate of rough rolling is more than 40%, and the initial rolling temperature is 1050-1150 ℃;
(d) the total reduction rate of finish rolling is more than 85%, and the finish rolling temperature is 750-950 ℃;
(e) after the strip steel is taken out of the finishing mill, the strip steel is cooled to below 700 ℃ at a cooling speed of more than 10 ℃/s and coiled.
4. The method of claim 3, wherein the slab is continuously cast by a vertical bending or vertical continuous casting machine, and the slab temperature is 930 ℃ or higher when the slab is continuously cast by the vertical bending casting machine and cooled secondarily.
5. The method for manufacturing impact-resistant chain plate steel as claimed in claim 3, wherein the heating furnace is a walking beam furnace.
6. A heat treatment process for impact-resistant link plate steel as claimed in claim 1, wherein the link plate steel is heat-treated after being processed into a link plate semi-finished product;
the specific process comprises the following steps:
heating at 835-870 ℃, preserving heat for 20-45min, and performing oil quenching, wherein the temperature of quenching oil is not higher than 80 ℃, cooling to below 200 ℃, and putting into a furnace for tempering, wherein the tempering temperature is 280-380 ℃.
7. A link plate manufactured by the heat treatment process of claim 6, wherein the structure of the link plate is tempered martensite, and the impact energy is more than 50J.
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