CN111286678A - High-sulfur non-quenched and tempered steel for automobile camshaft and production process thereof - Google Patents
High-sulfur non-quenched and tempered steel for automobile camshaft and production process thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 67
- 239000010959 steel Substances 0.000 title claims abstract description 67
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 41
- 239000011593 sulfur Substances 0.000 title claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 238000005096 rolling process Methods 0.000 claims abstract description 44
- 239000000463 material Substances 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 27
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 24
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 19
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 16
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000009749 continuous casting Methods 0.000 claims abstract description 12
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 238000007670 refining Methods 0.000 claims abstract description 12
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910001199 N alloy Inorganic materials 0.000 claims abstract description 6
- SKKMWRVAJNPLFY-UHFFFAOYSA-N azanylidynevanadium Chemical compound [V]#N SKKMWRVAJNPLFY-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 5
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 4
- 238000004925 denaturation Methods 0.000 claims abstract description 3
- 230000036425 denaturation Effects 0.000 claims abstract description 3
- 238000003825 pressing Methods 0.000 claims abstract 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 17
- 239000011575 calcium Substances 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 239000011777 magnesium Substances 0.000 claims description 6
- 229910052749 magnesium Inorganic materials 0.000 claims description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 5
- 229910052760 oxygen Inorganic materials 0.000 claims description 5
- 239000001301 oxygen Substances 0.000 claims description 5
- 238000003723 Smelting Methods 0.000 claims description 4
- 238000009792 diffusion process Methods 0.000 claims description 4
- 238000002791 soaking Methods 0.000 claims description 4
- 229910052729 chemical element Inorganic materials 0.000 claims description 2
- 239000005864 Sulphur Substances 0.000 claims 1
- 229910052739 hydrogen Inorganic materials 0.000 claims 1
- 239000001257 hydrogen Substances 0.000 claims 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 4
- 238000005204 segregation Methods 0.000 abstract description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 abstract description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 abstract 2
- 229910052786 argon Inorganic materials 0.000 abstract 1
- 150000003568 thioethers Chemical class 0.000 abstract 1
- 238000005520 cutting process Methods 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 13
- 238000010791 quenching Methods 0.000 description 8
- 230000000171 quenching effect Effects 0.000 description 8
- 229910000915 Free machining steel Inorganic materials 0.000 description 6
- 150000004763 sulfides Chemical class 0.000 description 5
- 238000005496 tempering Methods 0.000 description 5
- 238000007664 blowing Methods 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005242 forging Methods 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000009489 vacuum treatment Methods 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000006356 dehydrogenation reaction Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 229910000514 dolomite Inorganic materials 0.000 description 2
- 239000010459 dolomite Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910000817 1144 steel Inorganic materials 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000003297 denaturating effect Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- CADICXFYUNYKGD-UHFFFAOYSA-N sulfanylidenemanganese Chemical compound [Mn]=S CADICXFYUNYKGD-UHFFFAOYSA-N 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
- 235000013619 trace mineral Nutrition 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
-
- 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
- C21C7/10—Handling in a vacuum
-
- 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
- C22C33/08—Making cast-iron alloys
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
Abstract
The invention discloses a high-sulfur non-quenched and tempered steel for an automobile camshaft and a production process thereof, wherein the high-sulfur non-quenched and tempered steel comprises the following chemical components: 0.43 to 0.47 percent of C, 0.15 to 0.30 percent of Si, 1.55 to 1.65 percent of Mn, less than or equal to 0.20 percent of Cr, Cu and Ni, 0.24 to 0.33 percent of S, less than or equal to 0.040 percent of P, and the balance of Fe and inevitable impurities. Vanadium-nitrogen alloy is added in the refining process, and RH adopts argon as lifting gas to increase vanadium and nitrogen; carrying out magnesium-calcium denaturation treatment on sulfides in the molten steel after RH is finished; in addition, a soft pressing device is used for continuous casting, and a two-fire finished product rolling process is adopted, so that the segregation of elements such as S, C and the like is reduced, the appearance of sulfide is improved, and the material components and the structure are more uniform; the rolling process adopts a low-temperature controlled rolling and controlled cooling process. The surface quality, machinability, size precision, mechanical properties and other indexes of the final material are greatly improved.
Description
Technical Field
The invention belongs to the field of metallurgy, and relates to high-sulfur non-quenched and tempered steel for an automobile camshaft and a production process thereof.
Background
The non-quenched and tempered steel is a novel material developed from foreign countries in the early 70s, and has the advantages of simplifying the production process of mechanical parts, canceling quenching and tempering, saving energy, improving the utilization rate of materials, improving the internal quality of parts, reducing the cost and the like. The method is widely popularized and applied in automobile, agricultural machinery and machinery manufacturing industries in developed countries such as the United states, Japan, Germany and the like.
The high-strength high-toughness non-quenched and tempered steel developed in recent years has gradually replaced low-alloy structural steel and carbon-bonded steel. Such as 40MnV, 45MnVS, 1144, 44SMn28, C70S6, 38MnSiVS and the like, gradually replace 42CrMo, 40Cr, 40MnB, 35, 45 and the like, and are used for manufacturing automobile spline shafts, crankshafts, connecting rods, camshafts and other parts. Because the non-quenched and tempered steel omits the quenching and tempering process (namely, the quenching and high-temperature tempering process), a large amount of energy is saved, the straightening and partial machining process caused by quenching deformation can be omitted, the utilization rate and the production efficiency of materials are improved, the production period is shortened, the consumption of cutters is reduced, the labor condition is improved, and the environment is protected.
The non-quenched and tempered steel is generally classified into 2 types, one type is medium-low sulfur free-cutting non-quenched and tempered steel, the sulfur content of the medium-low sulfur free-cutting non-quenched and tempered steel is 0.025-0.10%, and the non-quenched and tempered steel is generally used by mechanical processing after being forged; the other type is high-sulfur free-cutting non-quenched and tempered steel, the sulfur content of the steel is 0.15-0.40%, and the high-sulfur free-cutting steel has high sulfur content (0.15-0.40%), so that the shape control difficulty of sulfides is high, and the defects of nonuniform sulfides, high grade and the like are easy to occur. Generally, the C content is required to be low, for example, "CN 1718828A low-carbon high-sulfur free-cutting steel" and "CN 103966531A production method of low-carbon high-sulfur free-cutting steel with excellent sulfide form" require that the carbon content of finished product is low, the cutting performance is reduced by too high carbon content, but the mechanical property of too low carbon content far does not meet the use requirement of users, in the field, the research on medium-carbon high-sulfur free-cutting steel is less, in "CN 110777244A medium-carbon high-sulfur free-cutting steel and preparation process thereof", relates to S1144 steel, solves the problem of quenching cracking by solving the controlled rolling and controlled cooling process, and also needs forging heat treatment (quenching) to achieve the mechanical requirement and the cutting performance.
For medium-carbon high-sulfur cutting steel (such as 1144 steel), if forging and quenching and tempering are not carried out, the hot rolled state is the final use state of the material, and the material is directly used by cutting, so that the processing cost of the downstream industry can be obviously reduced. However, because the forging and the quenching and tempering treatment are not carried out, the method has extremely high requirements on the surface quality of steel and the mechanical property of the hot-rolled state, and has the disadvantages of complex processing and large cutting amount, so the requirements on the cutting property and the dimensional precision of the material are also very high, and how to consider the hot-rolled state mechanical property and the cutting property of medium-carbon high-sulfur non-quenched and tempered steel becomes a big difficulty of the industry.
Disclosure of Invention
The method aims to solve the defects that the strength index of the high-sulfur non-quenched and tempered steel for direct and easy cutting processing is lower than that of the quenched and tempered steel, is unstable and has large fluctuation, and in addition, the high-sulfur non-quenched and tempered steel is easy to have uneven sulfides, high grade and the like. In order to improve the cutting performance and stably improve the mechanical property, the invention provides high-sulfur non-quenched and tempered steel for an automobile camshaft and a production process thereof, the obtained steel is high-sulfur non-quenched and tempered steel, and the high-sulfur non-quenched and tempered steel has better cutting performance and stable mechanical property in a hot rolling state: high strength and hardness.
The purpose of the invention is realized by the following technical scheme:
the non-quenched and tempered steel for the automobile camshaft spare and accessory parts comprises the following chemical element components in percentage by weight: 0.43 to 0.47 percent of C, 0.15 to 0.30 percent of Si, 1.55 to 1.65 percent of Mn, less than or equal to 0.20 percent of Cr, Cu and Ni, 0.24 to 0.33 percent of S, less than or equal to 0.040 percent of P, and the balance of Fe and inevitable impurities.
More preferably: 0.43 to 0.47 percent of C, 0.15 to 0.30 percent of Si, 1.55 to 1.65 percent of Mn, less than or equal to 0.20 percent of Cr, Cu and Ni, 0.24 to 0.33 percent of S, less than or equal to 0.040 percent of P, 0.025 to 0.035 percent of V, 0.0060 to 0.0100 percent of N, and the balance of Fe and inevitable impurities.
The production process of the high-sulfur non-quenched and tempered steel for the automobile camshaft comprises the following steps of converter smelting, LF refining, RH vacuum refining, continuous casting and rolling, and the process flow is as follows:
(1) smelting in a converter, adding iron and steel materials: molten iron, scrap steel and ore; slagging materials: lime and dolomite; blowing oxygen for decarburization and dephosphorizing; adjusting the temperature of the molten steel; initially adjusting components and pre-deoxidizing;
(2) LF refining, namely deoxidizing, heating and finely adjusting components in an LF furnace, and adding 0.35-0.5 kg/ton vanadium-nitrogen alloy to increase V and N, so that the mechanical property of the material is stably improved through fine crystallization and precipitation strengthening.
(3) RH vacuum refining, dehydrogenation, oxygen removal and impurity removal, and nitrogen increase by adopting nitrogen as lifting gas. By adding vanadium-nitrogen alloy and RH in the LF refining process, nitrogen is used as lifting gas, and the nitrogen content requirement of the molten steel can be met without additionally increasing nitrogen for the molten steel; after the vacuum treatment is finished, performing denaturation treatment on molten steel by using a magnesium-calcium wire at an RH station, wherein the magnesium-calcium wire for magnesium-calcium treatment comprises the following elements: mg and Ca contents are 10-13 percent, Si content is 25-30 percent, the rest is industrial pure iron, the feeding amount is 2m/t steel, the wire feeding speed is controlled to be 150-180m/min, wire feeding is divided into four times, each time is 60-70 meters, each time interval is 15-20 seconds, the target magnesium content is 9-13ppm, and the Ca content is 7-11ppm, and through magnesium-calcium treatment, sulfides can be attached to the periphery of oxide cores such as magnesium oxide, calcium oxide and the like, so that the desired spindle-shaped sulfides can be obtained, and the cutting performance of the material is improved.
(4) And (3) continuously casting a continuous casting billet with a 280 x 320mm section on a continuous casting machine, putting a light reduction device, and adopting a light reduction mode with the reduction of 15mm so as to break the sulfide and reduce the segregation of elements such as C, S and the like, thereby improving the appearance of the sulfide and laying a foundation for obtaining a uniform and consistent material structure after rolling.
(5) The first cogging rolling is carried out, rolling is carried out in a cogging mill set, a 280 x 320 section continuous casting billet is cogging into a 160 x 160mm section, and the cogging heating adopts a high-temperature diffusion process, which specifically comprises the following steps: the heating temperature of the soaking section is controlled to be 1210-.
(6) Rolling the second finished product in a continuous rolling mill, forming by a KOCKS finishing mill, adopting a brand new roll collar, cleaning and replacing a rolling groove guide, controlling the dimensional precision of the finished product to +/-0.20 mm, refining material grains by controlled rolling and controlled cooling in the rolling process, achieving the purpose of fine grain strengthening, and obviously improving the surface quality of the material, wherein the controlled rolling and controlled cooling process parameters are as follows: the initial rolling temperature is 1080-.
The invention has the beneficial effects that: the high-sulfur non-quenched and tempered steel for direct cutting processing has high requirements on the hot-rolled mechanical property, the sulfide grade and the appearance of the material, and has strict requirements on the dimensional precision and the surface quality of the material. The invention makes the following efforts:
①, adding vanadium-nitrogen alloy in the LF refining process to increase V and N, simultaneously adopting nitrogen as bottom blowing to increase nitrogen in the RH vacuum treatment process, adding additional alloy to increase N is not needed, and the V and N are combined to separate out, so that the effects of fine grains and precipitation strengthening are achieved, the strength of the material is stably improved, and the V content of the steel grade is 0.025-0.035%, the expected strength can be met without too high V content, because the invention also improves the strength by implementing the controlled cooling control process in the rolling process, the fluctuation of elements can be reduced, and additional operation is saved.
② and RH vacuum treatment, the magnesium-calcium wire is used for denaturating the sulfide in the molten steel, so that the manganese sulfide is wrapped around the oxide of magnesium and calcium, the generation of elongated sulfide inclusions is reduced, the proportion of spindle-shaped sulfide is increased, and the cutting performance of the material is improved.
③, the S content of the invention is 0.24-0.33%, the invention combines the two-fire material forming process, the first cogging adopts the high temperature diffusion heating process, the segregation of S, C is reduced, the rolling reduction parameter is optimized after a large number of tests through the soft rolling technology of the continuous casting billet, at the same time, the slender sulfide can be broken through 2 rolling, the sulfide appearance is optimized, and the sulfide grade is reduced.
④, when rolling the second product, the controlled rolling and cooling process is adopted to refine the grain size of the material, the strength and toughness of the material are stably improved by the fine-grain strengthening effect, and the scratch defect can be prevented by low-temperature rolling and low-temperature cooling, thereby improving the surface quality of the material.
⑤, the size precision and the surface quality are effectively controlled by adopting KOCKS finish rolling and cleaning and replacing the roll collar and the groove guide.
The steel of the invention belongs to the steel for direct cutting processing, and through the efforts, the appearance of sulfide in a hot rolling state is effectively improved, the cutting processing performance is improved, the mechanical property and the surface quality of the material are also stably improved, and the yield strength of the mechanical property in the hot rolling state is more than or equal to 460 MPa; the tensile strength is more than or equal to 720 Mpa.
Detailed Description
The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified. In the following process, unpublished conditions are known methods commonly used in steelmaking and have a negligible effect on the final properties of the steel.
According to the chemical composition of the steel, the following production process steps are adopted:
(1) smelting in a converter, adding iron and steel materials: molten iron, scrap steel and ore; slagging materials: lime and dolomite; blowing oxygen for decarburization and dephosphorizing; adjusting the temperature of the molten steel; initially adjusting components and pre-deoxidizing;
(2) LF refining, namely deoxidizing, heating and finely adjusting components in an LF furnace, and adding 0.35-0.5 kg/ton of vanadium-nitrogen alloy to increase nitrogen and vanadium;
(3) RH vacuum refining, dehydrogenation, oxygen and inclusion removal, nitrogen is used as bottom blowing gas, after vacuum is finished, magnesium and calcium wires are used for processing molten steel at an RH station, and the magnesium and calcium wires comprise the following elements: the contents of Mg and Ca are 10-13%; si content is 25-30%, the rest is industrial pure iron, the feeding amount is 2m/t steel, the wire feeding speed is controlled to be 150-;
(4) and (3) continuously casting a continuous casting billet with a 280 x 320mm section on a continuous casting machine, and applying a light reduction device in the casting process, wherein the light reduction adopts a mode of 15mm reduction.
(5) The first cogging rolling is carried out, a 280 x 320mm section casting blank is cogging into a 160 x 160mm section through a cogging mill, a high-temperature diffusion process is adopted for cogging heating, and the specific heating process parameters are set as follows: the heating temperature of the soaking section is 1210-1250 ℃, and the total heating time is 240-300 min.
(6) And rolling the second finished product in a continuous rolling unit, forming the finished product by a KOCKS finishing mill, cleaning and replacing a groove guide by adopting a brand-new roll collar, controlling the dimensional accuracy of the finished product to +/-0.20 mm, and realizing a rolling and cooling control process in the steel rolling process: the initial rolling temperature is 1080-.
Five-furnace steel is prepared by adopting the process, and the steel components are shown in table 1.
Comparative example 1
Comparative example 1 is different from example 1 in that: the same procedure as in example 1 was carried out except that the trace elements V and N were not added.
Comparative example 2
Comparative example 2 differs from example 1 in that: the magnesium-calcium treatment of the sulfide in the molten steel was not performed, and the other conditions and operations were the same as those in example 1.
Comparative example 3
Comparative example 3 differs from example 1 in that: the cogging process is omitted, the two-shot forming process is not adopted, and other conditions and operations are the same as those of example 1.
The rolling is as follows: the heating process comprises the steps of soaking section heating temperature of 1210-1250 ℃, total heating time of 240-300min, and then primary rolling is carried out on the casting blank with the 280-320 mm section to be rolled into the phi-35 mm specification.
Comparative example 4
Comparative example 4 is different from example 1 in that: the controlled rolling and controlled cooling process is not adopted, the finish rolling temperature is 920-950 ℃, the temperature of an upper cooling bed is 900-930 ℃, and other operations are performed in the same embodiment.
Examples 1 to 5 of the present invention and comparative examples 1 to 4.
(1) Chemical composition pairs such as table 1 below
TABLE 1 chemical composition of steel (% by weight)
| Item | C | Si | Mn | Cr | P | S | Cu | Ni | V | N | Mg | Ca |
| Example 1 | 0.45 | 0.23 | 1.59 | 0.02 | 0.012 | 0.275 | 0.016 | 0.003 | 0.030 | 0.0083 | 0.0011 | 0.0008 |
| Example 2 | 0.45 | 0.20 | 1.60 | 0.01 | 0.013 | 0.280 | 0.020 | 0.002 | 0.030 | 0.0078 | 0.0009 | 0.0009 |
| Example 3 | 0.46 | 0.22 | 1.58 | 0.02 | 0.014 | 0.278 | 0.019 | 0.002 | 0.029 | 0.0076 | 0.0010 | 0.0010 |
| Example 4 | 0.45 | 0.22 | 1.61 | 0.02 | 0.013 | 0.276 | 0.022 | 0.004 | 0.031 | 0.0092 | 0.0012 | 0.0011 |
| Example 5 | 0.46 | 0.21 | 1.60 | 0.03 | 0.012 | 0.278 | 0.013 | 0.005 | 0.029 | 0.0085 | 0.0011 | 0.0009 |
| Comparative example 1 | 0.44 | 0.20 | 1.62 | 0.03 | 0.015 | 0.277 | 0.017 | 0.004 | 0.001 | 0.0045 | 0.0009 | 0.0008 |
| Comparative example 2 | 0.45 | 0.24 | 1.60 | 0.02 | 0.012 | 0.274 | 0.015 | 0.005 | 0.028 | 0.0075 | 0.0002 | 0.0003 |
| Comparative example 3 | 0.47 | 0.22 | 1.58 | 0.03 | 0.013 | 0.281 | 0.023 | 0.003 | 0.030 | 0.0069 | 0.0010 | 0.0007 |
| Comparative example 4 | 0.45 | 0.20 | 1.61 | 0.01 | 0.013 | 0.279 | 0.020 | 0.002 | 0.030 | 0.0089 | 0.0010 | 0.0009 |
(2) The hot rolled mechanical properties and sulfide grade are given in Table 2 below
TABLE 2 comparison of mechanical properties and sulfide grades of hot rolled steels
The detection standard of the sulfide grade is as follows: microscopic comparison image array detection method of nonmetallic sulfide inclusion in DIN SEP 1572 free-cutting steel. The sulfide grade is not allowed to exceed 4.0.
Wherein the tool life (h) is obtained by processing the same part at the same cutting speed.
The results show that: by adding V, N element, magnesium calcium wire denaturalizes sulfide, continuous casting adopts soft reduction, rolling adopts a two-fire forming process: the first cogging rolling is performed at high temperature, and the second finished product rolling is performed by adopting a low-temperature controlled rolling and cooling technology, so that the surface quality and the final service performance of the high-sulfur non-quenched and tempered steel for the automobile camshaft are as follows: the cutting performance and the mechanical property in a hot rolling state are greatly improved, and the cutting performance and the mechanical property reach the international advanced level, do not need heat treatment and can be directly used.
Claims (7)
1. The utility model provides a non quenched and tempered steel of high sulphur for automobile camshaft which characterized in that: the high-sulfur non-quenched and tempered steel comprises the following chemical element components in percentage by weight: 0.43 to 0.47 percent of C, 0.15 to 0.30 percent of Si, 1.55 to 1.65 percent of Mn, less than or equal to 0.20 percent of Cr, Cu and Ni, 0.24 to 0.33 percent of S, less than or equal to 0.040 percent of P, and the balance of Fe and inevitable impurities.
2. The high-sulfur non-quenched and tempered steel for an automotive camshaft according to claim 1, wherein: the high-sulfur non-quenched and tempered steel comprises, by weight, 0.43-0.47% of C, 0.15-0.30% of Si, 1.55-1.65% of Mn, less than or equal to 0.20% of Cr, Cu and Ni, 0.24-0.33% of S, less than or equal to 0.040% of P, 0.025-0.035% of V, 0.0060-0.0100% of N, and the balance of Fe and inevitable impurities.
3. The production process of the high-sulfur non-quenched and tempered steel for the automobile camshaft according to claim 2, characterized by comprising the steps of: the production process comprises the following steps:
(1) smelting in a converter;
(2) LF refining, namely deoxidizing, heating and finely adjusting components in an LF furnace, and adding vanadium-nitrogen alloy to increase V and N;
(3) RH vacuum refining, namely, removing hydrogen, oxygen and impurities, increasing nitrogen by using nitrogen as lifting gas, and performing denaturation treatment on molten steel by using a magnesium-calcium wire at an RH station after vacuum is finished;
(4) continuous casting, namely casting a continuous casting blank on a continuous casting machine, and casting by using a soft reduction device;
(5) the first cogging rolling, rolling in a cogging mill, heating by adopting a high-temperature diffusion process, controlling the heating temperature of a soaking section to be 1210-;
(6) and rolling the second finished product in a continuous rolling mill set, forming the finished product by a KOCKS finishing mill, controlling the dimensional precision of the finished product to be +/-0.20 mm, and improving the strength of the material by adopting a controlled rolling and cooling process in the steel rolling process.
4. The method for producing the high-sulfur non-quenched and tempered steel for an automobile camshaft according to claim 3, comprising the steps of: and (3) adding a magnesium-calcium line for treatment, and controlling the magnesium content to be 9-13ppm and the Ca content to be 7-11ppm of the target finished product.
5. The method for producing the high-sulfur non-quenched and tempered steel for an automobile camshaft according to claim 3, comprising the steps of: the magnesium-calcium wire used for magnesium-calcium treatment in the step (3) comprises the following elements: mg and Ca content is 10-13%, Si content is 25-30%, the rest is industrial pure iron, the feeding amount is 2m/t steel, the wire feeding speed is controlled to be 150-70 m/min, wire feeding is divided into four times, each time is 60-70 m, and the interval is 15-20 seconds.
6. The method for producing the high-sulfur non-quenched and tempered steel for an automobile camshaft according to claim 3, comprising the steps of: and (4) casting continuously by using a light pressing device, and adopting a light pressing mode with the pressing amount of 15mm so as to break the sulfide.
7. The method for producing the high-sulfur non-quenched and tempered steel for an automobile camshaft according to claim 3, comprising the steps of: and (6) rolling at 1080-.
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