CN115572910A - High-strength non-quenched and tempered steel for automobile crankshaft and preparation method thereof - Google Patents
High-strength non-quenched and tempered steel for automobile crankshaft and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 108
- 239000010959 steel Substances 0.000 title claims abstract description 108
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 29
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 24
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 22
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 229910052715 tantalum Inorganic materials 0.000 claims abstract description 8
- 229910052796 boron Inorganic materials 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 5
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 4
- 238000005275 alloying Methods 0.000 claims description 57
- 238000010079 rubber tapping Methods 0.000 claims description 49
- 238000005096 rolling process Methods 0.000 claims description 32
- 239000000463 material Substances 0.000 claims description 24
- PGHQEOHSIGPJOC-UHFFFAOYSA-N [Fe].[Ta] Chemical compound [Fe].[Ta] PGHQEOHSIGPJOC-UHFFFAOYSA-N 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 20
- 239000001301 oxygen Substances 0.000 claims description 20
- 239000002893 slag Substances 0.000 claims description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 16
- 238000005266 casting Methods 0.000 claims description 14
- 229910000838 Al alloy Inorganic materials 0.000 claims description 10
- 238000003723 Smelting Methods 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000005728 strengthening Methods 0.000 claims description 8
- 229910000640 Fe alloy Inorganic materials 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 7
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 229910000720 Silicomanganese Inorganic materials 0.000 claims description 5
- OLBVUFHMDRJKTK-UHFFFAOYSA-N [N].[O] Chemical compound [N].[O] OLBVUFHMDRJKTK-UHFFFAOYSA-N 0.000 claims 1
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 230000003647 oxidation Effects 0.000 abstract description 4
- 238000007254 oxidation reaction Methods 0.000 abstract description 4
- 238000010791 quenching Methods 0.000 abstract description 4
- 230000000171 quenching effect Effects 0.000 abstract description 4
- 238000005496 tempering Methods 0.000 abstract description 4
- 238000005336 cracking Methods 0.000 abstract description 3
- 238000009749 continuous casting Methods 0.000 abstract description 2
- 238000005098 hot rolling Methods 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- 239000011572 manganese Substances 0.000 description 13
- 238000007599 discharging Methods 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- PYLLWONICXJARP-UHFFFAOYSA-N manganese silicon Chemical group [Si].[Mn] PYLLWONICXJARP-UHFFFAOYSA-N 0.000 description 5
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- 229910000914 Mn alloy Inorganic materials 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910052582 BN Inorganic materials 0.000 description 2
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910052810 boron oxide Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 206010037660 Pyrexia Diseases 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0025—Adding carbon material
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- 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
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- 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
- C22C33/06—Making ferrous alloys by melting using master alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
- C21C2007/0018—Boron
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- 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
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- Chemical & Material Sciences (AREA)
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- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention discloses a high-strength non-quenched and tempered steel for an automobile crankshaft and a preparation method thereof, wherein the non-quenched and tempered steel comprises the following elements in percentage by mass: 0.35 to 0.45 percent of C, 0.25 to 0.35 percent of Si, 0.50 to 0.80 percent of Mn, 0.015 to 0.03 percent of Ta, 0.001 to 0.003 percent of B, 0.005 to 0.008 percent of S, less than or equal to 0.0013 percent of O, less than or equal to 0.023 percent of N, and the balance of Fe and inevitable impurities. The processing process of the non-quenched and tempered steel adopts the processes of converter → LF furnace → VD furnace → continuous casting → hot rolling. The invention can avoid the problems of large energy consumption, easy oxidation, cracking and the like in the quenching and tempering process and solve the problems of poor hardenability and low strength of non-quenched and tempered steel.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to high-strength non-quenched and tempered steel for an automobile crankshaft and a preparation method thereof.
Background
In recent years, the automobile industry is rapidly developed, and the competition of manufacturing cost among enterprises is intensified day by day. Meanwhile, the requirements of the industry on the safety of automobiles, namely the performance of the structural materials for the automobiles, are higher and higher. At present, the traditional quenched and tempered structural component material with complex production process, high energy consumption and serious heat treatment defects is gradually replaced by non-quenched and tempered steel with simple production process, low energy consumption and few defects. The production of structural steel for automobiles by adopting a non-tempering process becomes an important breakthrough for improving the market competitiveness of automobile production enterprises.
The crankshaft is one of the core parts of an automobile engine, and the performance of the crankshaft determines the reliability and the service life of the engine to a great extent. The crankshaft has very bad service conditions, bears impact load and inertia force for a long time during working, and each part of the crankshaft generates alternating stress such as torsion, bending, tension and compression, shearing and the like. Therefore, the crankshaft should have good appearance quality and microstructure, and ensure sufficient strength, rigidity, toughness, wear resistance and good balance. For the quenched and tempered steel crankshaft, a large amount of energy is consumed in the heat treatment process, and the problems of oxidation, deformation, even cracking and the like in the part heating process are also caused. During heat treatment quenching, the crankshaft is often bent and distorted, the part requirements are difficult to meet through the straightening process, the precision of the processed crankshaft is insufficient, and the noise and vibration phenomena of an engine are caused. Non-quenched and tempered steel is increasingly popular with crankshaft manufacturers due to the advantages of low cost, energy conservation, environmental protection and the like. Among them, hardenability is one of important indexes of non-quenched and tempered steel, and it has a large influence on both the uniformity of structure and the performance. The medium-carbon and low-carbon manganese non-quenched and tempered steel has low hardenability and is not enough to meet the increasing requirements of automobile enterprises on material performance. In view of the above requirements, it is imperative to develop a non-heat treated steel for automobiles having a high hardenability fit. In addition, because the working environment of the crankshaft is very severe, the mechanical property of the material is further improved, which is an internal requirement of the automobile industry for non-quenched and tempered steel.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides the non-quenched and tempered steel for the high-strength automobile crankshaft and the preparation method thereof.
The technical scheme adopted by the invention is as follows:
a high-strength non-quenched and tempered steel for automobile crankshafts comprises the following elements in percentage by mass:
0.35 to 0.45 percent of C, 0.25 to 0.35 percent of Si, 0.50 to 0.80 percent of Mn, 0.015 to 0.03 percent of Ta, 0.001 to 0.003 percent of B, 0.005 to 0.008 percent of S, less than or equal to 0.0013 percent of O, less than or equal to 0.023 percent of N, and the balance of Fe and inevitable impurities.
The preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft comprises the following steps of:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.15-0.25%; controlling the tapping temperature to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking a steel ladle to 1150-1200 ℃ before tapping, adding 1/3-1/2 of the total slagging auxiliary materials into the steel ladle, and continuously baking to 1150-1200 ℃; when tapping to 1/4-1/3 of the liquid level, adding a deoxidizer A; adding a deoxidizer B when tapping to 1/2-3/4;
and (3) alloying low oxygen and nitrogen: removing oxygen in the steel to 30-50 ppm, and adding tantalum-iron alloy for alloying; removing N in the steel to 30-40 ppm, and adding ferroboron for alloying; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 950-1100 ℃, and the deformation is 70-75% of the total deformation; during the second stage rolling: the deformation temperature is 850-900 ℃, and the deformation amount is 25-30% of the total deformation amount; and after rolling, keeping the temperature of the rolled material at 650-700 ℃ for 2-3 h, and after the temperature is kept, air-cooling the rolled material to room temperature to finish the processing.
Preferably, the converter slag control in step (2) is 3 to 5kg/t steel.
Preferably, the deoxidizer A is aluminum alloy ash.
Preferably, the deoxidizer B is a silicon-manganese alloy, wherein the ratio of the Si content to the Mn content is 2 to 4.
Preferably, the alloying temperature of the tantalum iron in the step (3) is 1640-1650 ℃.
Preferably, the tantalum-iron alloying process is performed in an LF furnace.
Preferably, the ferroboron alloying temperature in the step (3) is 1610 to 1620 ℃, and the alloying process is carried out after vacuum breaking by VD.
The invention has the following beneficial effects:
in the non-quenched and tempered steel for the high-strength automobile crankshaft, in order to improve the hardenability of the steel, the B is added in the component design, so that the hardenability of the steel can be obviously improved. In order to improve the strength of the steel, ta is introduced into the steel, and not only can be dissolved in the steel in a solid solution manner to achieve the solid solution strengthening effect, but also is a strong carbonitride forming element; since the mass fraction of Ta is relatively large and the diffusion coefficient thereof in steel is relatively small, the nucleation work of the carbonitride containing Ta is relatively large, and the size of the precipitates is very fine.
According to the preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft, the oxygen content in the steel can be effectively reduced by adopting high-tensile carbon smelting, and the burden of subsequent deoxidation is reduced; the oxygen content in the steel is reduced, the added deoxidizer is relatively reduced, the amount of non-metallic inclusions generated by deoxidation in the steel is reduced, and the purification of molten steel is facilitated. The reduction of the oxygen blowing amount can bring the shortage of the molten steel temperature, so a certain molten steel temperature is ensured in the high-carbon-drawing smelting process. The slag charge added into the steel can cause the temperature of the molten steel to be reduced, and the carbon pulling operation is carried outTherefore, the slag should be roasted. Baking the steel ladle to 1150-1200 ℃, adding part of slagging auxiliary materials after the temperature is reached, and baking again to prevent the slag from heating along with the steel ladle for a long time to corrode refractory materials of the steel ladle; another benefit of baking the slag charge to 1150-1200 ℃ is that the slag can be melted quickly, and the slagging speed is the key point of smelting. The aluminum alloy ash contains a large amount of metal aluminum, partial fluoride and oxide, has a low melting point, and can be added into molten steel to effectively reduce the oxygen content in the molten steel and serve as a fluxing agent to accelerate the melting of other additives. Deoxidation of aluminium results in the production of large size Al 2 O 3 The impurities, fluorides and oxides in the aluminum alloy ash can rapidly remove Al 2 O 3 And large-size impurities remained in the steel are avoided by adsorption. The silicon-manganese deoxidation can form complex silicate, and the liquid-phase oxide in the molten steel is easier to remove. The purpose of carrying out the aluminum alloy ash deoxidation before the silicon-manganese deoxidation is also to improve the yield of the silicon-manganese alloy. Tantalum is an important rare metal, and the property of the tantalum is very active to combine with oxygen in steel to form oxide; the alloying after controlling the oxygen in the steel to a low level is to prevent oxidation thereof, and the present invention expects that it exists in the steel in the form of an alloy. The chemical property of boron is very active, boron oxide can be combined with oxygen in steel to generate boron oxide, boron nitride can be combined with nitrogen in steel to generate boron nitride, the performance of the steel can be deteriorated by the oxide and the nitride of the boron, and the hardenability of the steel can be effectively improved only by boron element which is dissolved in the steel in a solid mode and exists as interstitial atoms, so that the corresponding process design is carried out. The reason why the two-stage rolling is performed is as follows: the first stage rolling is to change the size of the steel, the second stage rolling is to strain-induce nucleation of tantalum carbonitride, and the heat-retention treatment is performed after rolling to sufficiently precipitate tantalum-containing carbonitride in the steel and improve the overall performance of the steel.
Detailed Description
The present invention will be further described with reference to the following examples.
The non-quenched and tempered steel for the high-strength automobile crankshaft comprises the following elements in percentage by mass:
0.35 to 0.45 percent of C, 0.25 to 0.35 percent of Si, 0.50 to 0.80 percent of Mn, 0.015 to 0.03 percent of Ta, 0.001 to 0.003 percent of B, 0.005 to 0.008 percent of S, less than or equal to 0.0013 percent of O, less than or equal to 0.023 percent of N, and the balance of Fe and inevitable impurities.
The preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft adopts the process of converter → LF furnace → VD furnace → continuous casting → hot rolling in the whole scheme, and comprises the following steps:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.15% -0.25%; the tapping temperature is controlled to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking the steel ladle to 1150-1200 ℃ before tapping, adding 1/3-1/2 of the total slagging auxiliary materials into the steel ladle, and continuously baking to 1150-1200 ℃; when tapping to 1/4-1/3 of the liquid level, adding a deoxidizer A (adopting aluminum alloy ash); when tapping to 1/2-3/4, adding deoxidizer B (silicon-manganese alloy is adopted, wherein the ratio of Si content to Mn content is 2-4); the slag discharging amount of the converter is controlled to be 3-5 kg/t steel;
and (3) alloying low oxygen and nitrogen: oxygen in steel is removed to 30-50 ppm, tantalum-iron alloy is added for alloying, the tantalum-iron alloying temperature is 1640-1650 ℃, and the tantalum-iron alloying process is carried out in an LF furnace; removing N in the steel to 30-40 ppm, adding ferroboron for alloying, wherein the ferroboron alloying temperature is 1610-1620 ℃, and the alloying process is carried out after vacuum breaking by VD; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 950-1100 ℃, and the deformation is 70-75% of the total deformation; and during the second stage of rolling: the deformation temperature is 850-900 ℃, and the deformation amount is 25-30% of the total deformation amount; and after rolling, keeping the temperature of the rolled material at 650-700 ℃ for 2-3 h, and after the temperature is kept, air-cooling the rolled material to room temperature to finish the processing.
Example 1
In the non-quenched and tempered steel for the high-strength automobile crankshaft, the non-quenched and tempered steel comprises the following elements in percentage by mass:
0.35% of C, 0.25% of Si, 0.50% of Mn, 0.015% of Ta, 0.001% of B, 0.005% of S, 0.0012% of O, 0.023% of N, and the balance of Fe and inevitable impurities.
The preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft comprises the following steps:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.15%; controlling the tapping temperature to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking the steel ladle to 1150 ℃ before tapping, adding 1/3 of the total slagging auxiliary materials into the steel ladle, and continuously baking to 1150 ℃; when tapping to 1/3 of the liquid level, adding deoxidizer aluminum alloy ash; adding a deoxidizer, namely a silicomanganese alloy when tapping to 1/2, wherein the ratio of the content of Si to the content of Mn is 2; the slag discharging amount of the converter is controlled to be 3kg/t steel;
and (3) alloying low oxygen and nitrogen: removing oxygen in steel to 30ppm, adding a tantalum-iron alloy for alloying, wherein the tantalum-iron alloying temperature is 1640-1650 ℃, and the tantalum-iron alloying process is carried out in an LF furnace; removing N in the steel to 40ppm, adding ferroboron for alloying, wherein the ferroboron alloying temperature is 1610-1620 ℃, and the alloying process is carried out after vacuum is broken by VD; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 980-1100 ℃, and the deformation amount is 75 percent of the total deformation amount; and during the second stage of rolling: the deformation temperature is 850-890 ℃, and the deformation amount is 25 percent of the total deformation amount; and after rolling, keeping the temperature of the rolled material at 650 ℃ for 3h, and after keeping the temperature, air-cooling to room temperature to finish the processing.
Example 2
In the non-quenched and tempered steel for the high-strength automobile crankshaft, the element composition comprises the following components in percentage by mass:
0.45% of C, 0.35% of Si, 0.80% of Mn, 0.03% of Ta, 0.003% of B, 0.008% of S, 0.0009% of O, 0.020% of N, and the balance of Fe and inevitable impurities.
The preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft comprises the following steps:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.25%; controlling the tapping temperature to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking the steel ladle to 1200 ℃ before tapping, adding 1/2 of the total slagging auxiliary materials into the steel ladle, and continuously baking to 1200 ℃; when tapping to 1/4 of the liquid level, adding deoxidizer aluminum alloy ash; adding a deoxidizer, namely a silicomanganese alloy when tapping to 3/4, wherein the ratio of the content of Si to the content of Mn is 4; the slag discharging amount of the converter is controlled at 5kg/t steel;
and (3) alloying low oxygen and nitrogen: oxygen in steel is removed to 50ppm, tantalum-iron alloy is added for alloying, the temperature of the tantalum-iron alloying is 1640-1650 ℃, and the tantalum-iron alloying process is carried out in an LF furnace; removing N in the steel to 30ppm, adding ferroboron for alloying, wherein the ferroboron alloying temperature is 1610-1620 ℃, and the alloying process is carried out after vacuum breaking by VD; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 950-1080 ℃, and the deformation amount is 70 percent of the total deformation amount; during the second stage rolling: the deformation temperature is 860-900 ℃, and the deformation amount is 30 percent of the total deformation amount; and after rolling is finished, keeping the temperature of the rolled material at 700 ℃ for 2h, and after the temperature is kept, air-cooling the rolled material to room temperature to finish processing.
Specific properties are shown in table 1.
Example 3
In the non-quenched and tempered steel for the high-strength automobile crankshaft, the non-quenched and tempered steel comprises the following elements in percentage by mass:
0.40% of C, 0.30% of Si, 0.65% of Mn, 0.020% of Ta, 0.002% of B, 0.0065% of S, less than or equal to 0.0013% of O, less than or equal to 0.023% of N, and the balance of Fe and inevitable impurities.
The preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft comprises the following steps:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.20%; controlling the tapping temperature to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking the steel ladle to 1180 ℃ before tapping, adding 2/5 of the total slagging auxiliary material into the steel ladle, and continuously baking to 1170 ℃; when tapping to 7/12 liquid level, adding deoxidizer aluminum alloy ash; when tapping reaches 5/8, adding a deoxidizer silicomanganese alloy, wherein the ratio of the Si content to the Mn content is 4; the slag discharging amount of the converter is controlled to be 4kg/t steel;
and (3) alloying low oxygen and nitrogen: removing oxygen in steel to 45ppm, adding a tantalum-iron alloy for alloying, wherein the tantalum-iron alloying temperature is 1640-1650 ℃, and the tantalum-iron alloying process is carried out in an LF furnace; removing N in the steel to 36ppm, adding ferroboron for alloying, wherein the ferroboron alloying temperature is 1610-1620 ℃, and the alloying process is carried out after vacuum breaking by VD; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 960-1090 ℃, and the deformation amount is 74 percent of the total deformation amount; during the second stage rolling: the deformation temperature is 852-897 ℃, and the deformation amount is 26 percent of the total deformation amount; and after rolling, keeping the temperature of the rolled material at 680 ℃ for 2.6h, and after keeping the temperature, air-cooling the rolled material to room temperature to finish the processing.
Specific properties are shown in table 1.
Example 4
In the non-quenched and tempered steel for the high-strength automobile crankshaft, the element composition comprises the following components in percentage by mass:
0.42% of C, 0.33% of Si, 0.68% of Mn, 0.025% of Ta, 0.0025% of B, 0.0075% of S, 0.0010% of O, 0.019% of N, and the balance Fe and inevitable impurities.
The preparation method of the non-quenched and tempered steel for the high-strength automobile crankshaft comprises the following steps:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.23%; the tapping temperature is controlled to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking the steel ladle to 1180 ℃ before tapping, adding 1/2 of the total slagging auxiliary materials into the steel ladle, and continuously baking to 1175 ℃; when tapping to 1/3 of the liquid level, adding deoxidizer aluminum alloy ash; adding a deoxidizer, namely a silicomanganese alloy when tapping to 3/4, wherein the ratio of the content of Si to the content of Mn is 3.5; the slag discharging amount of the converter is controlled to be 4.3kg/t steel;
and (3) alloying low oxygen and nitrogen: removing oxygen in steel to 38ppm, adding a tantalum-iron alloy for alloying, wherein the tantalum-iron alloying temperature is 1640-1650 ℃, and the tantalum-iron alloying process is carried out in an LF furnace; removing N in the steel to 36ppm, adding ferroboron for alloying, wherein the ferroboron alloying temperature is 1610-1620 ℃, and the alloying process is carried out after vacuum breaking by VD; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 950-1100 ℃, and the deformation amount is 73 percent of the total deformation amount; during the second stage rolling: the deformation temperature is 850-900 ℃, and the deformation amount is 27 percent of the total deformation amount; and after rolling is finished, keeping the temperature of the rolled material at 675 ℃ for 2.6h, and after the temperature is kept, cooling the rolled material to room temperature in air, thus finishing the processing.
Specific performance parameters of the non-heat treated steels prepared in the examples are shown in Table 1.
TABLE 1
As can be seen from Table 1, the non-quenched and tempered steel for the high-strength automobile crankshaft, which is prepared by the invention, can effectively avoid the problems of high energy consumption, easy oxidation, cracking and the like caused by quenching and tempering without quenching and tempering treatment, the crankshaft steel has excellent hardenability, and the depth of a complete hardenability area is 4627-5153 mu m; high mechanical property, microhardness of 340-366 HV, yield strength of 871-890 MPa, tensile strength of 997-1117 MPa and elongation of 23-27%.
Claims (8)
1. The non-quenched and tempered steel for the high-strength automobile crankshaft is characterized by comprising the following elements in percentage by mass:
0.35 to 0.45 percent of C, 0.25 to 0.35 percent of Si, 0.50 to 0.80 percent of Mn, 0.015 to 0.03 percent of Ta, 0.001 to 0.003 percent of B, 0.005 to 0.008 percent of S, less than or equal to 0.0013 percent of O, less than or equal to 0.023 percent of N, and the balance of Fe and inevitable impurities.
2. The method for preparing the non-quenched and tempered steel for the high-strength automobile crankshaft as recited in claim 1, comprising the steps of:
step (1), high-tension carbon smelting: controlling the carbon content of the converter tapping at 0.15% -0.25%; the tapping temperature is controlled to be 1620-1650 ℃;
step (2), tapping pretreatment: controlling the slag discharge amount of the converter during tapping; baking a steel ladle to 1150-1200 ℃ before tapping, adding 1/3-1/2 of the total slagging auxiliary materials into the steel ladle, and continuously baking to 1150-1200 ℃; when tapping to 1/4-1/3 of the liquid level, adding a deoxidizer A; adding a deoxidizer B when tapping to 1/2-3/4;
step (3), low oxygen nitrogen alloying: removing oxygen in the steel to 30-50 ppm, and adding tantalum-iron alloy for alloying; removing N in the steel to 30-40 ppm, and adding ferroboron for alloying; preparing a casting blank after alloying;
step (4), deformation strengthening treatment: rolling a casting blank, wherein the rolling is divided into two stages, and when the first stage is rolled: the deformation temperature is 950-1100 ℃, and the deformation amount is 70-75% of the total deformation amount; and during the second stage of rolling: the deformation temperature is 850-900 ℃, and the deformation amount is 25-30% of the total deformation amount; and after rolling, keeping the temperature of the rolled material at 650-700 ℃ for 2-3 h, and after keeping the temperature, air-cooling to room temperature to finish the processing.
3. The method for preparing non-heat treated steel for high strength automobile crankshafts according to claim 2, characterized in that the converter slag amount in the step (2) is controlled to 3 to 5kg/t steel.
4. The method for producing a high-strength non-heat-treated steel for an automobile crankshaft as claimed in claim 2, wherein the deoxidizer A is aluminum alloy ash.
5. The method of claim 2, wherein the deoxidizer B is a silicomanganese alloy, wherein the ratio of the Si content to the Mn content is 2 to 4.
6. The method for preparing the non-quenched and tempered steel for the high-strength automobile crankshaft according to claim 2, wherein the alloying temperature of the tantalum iron in the step (3) is 1640-1650 ℃.
7. The method for manufacturing a high-strength non-quenched and tempered steel for an automobile crankshaft according to claim 6, wherein the tantalum-iron alloying process is performed in an LF furnace.
8. The method for preparing the non-quenched and tempered steel for the high-strength automobile crankshaft according to claim 2, wherein the ferroboron alloying temperature in the step (3) is 1610 to 1620 ℃, and the alloying process is performed after vacuum breaking by VD.
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| CN112823217A (en) * | 2018-10-10 | 2021-05-18 | 杰富意钢铁株式会社 | High-strength steel sheet and method for producing same |
| CN114182162A (en) * | 2021-12-21 | 2022-03-15 | 广东韶钢松山股份有限公司 | Smelting method of non-quenched and tempered steel, non-quenched and tempered steel and connecting rod |
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| CN107208239A (en) * | 2015-01-27 | 2017-09-26 | 新日铁住金株式会社 | Micro Alloying mechanical part wire rod, Micro Alloying mechanical part steel wire and Micro Alloying mechanical part |
| CN112823217A (en) * | 2018-10-10 | 2021-05-18 | 杰富意钢铁株式会社 | High-strength steel sheet and method for producing same |
| CN114182162A (en) * | 2021-12-21 | 2022-03-15 | 广东韶钢松山股份有限公司 | Smelting method of non-quenched and tempered steel, non-quenched and tempered steel and connecting rod |
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