WO2024051758A1 - Method for preparing steel 50crva for transmission chain of engine - Google Patents

Method for preparing steel 50crva for transmission chain of engine Download PDF

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Publication number
WO2024051758A1
WO2024051758A1 PCT/CN2023/117357 CN2023117357W WO2024051758A1 WO 2024051758 A1 WO2024051758 A1 WO 2024051758A1 CN 2023117357 W CN2023117357 W CN 2023117357W WO 2024051758 A1 WO2024051758 A1 WO 2024051758A1
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Prior art keywords
steel
rolling
50crva
preparing
engine transmission
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PCT/CN2023/117357
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French (fr)
Chinese (zh)
Inventor
徐晓春
王攀峰
马兆红
韩菱
韩玉梅
丁世磊
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南京钢铁股份有限公司
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Publication of WO2024051758A1 publication Critical patent/WO2024051758A1/en

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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
    • 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
    • C21C7/072—Treatment with gases
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—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
    • C22C38/18—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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • 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

Definitions

  • the present invention relates to a method for preparing hot-rolled steel strips for automobiles, and in particular to a method for preparing 50CrVA steel for engine transmission chains.
  • Automotive engine chains can be divided into timing chains, oil pump chains, high-pressure pump chains, common rail pump chains, balance shaft chains, etc. according to their uses; according to their structures, they can be divided into roller chains, bushing chains, and toothed chains; according to their row numbers It can be divided into: single-row chain, double-row chain, multi-row chain; according to the meshing mechanism, the toothed chain can be divided into internal meshing, external meshing, internal-external composite meshing toothed chain and variable pitch Hy-Vo chain, etc.
  • the steel 50CrVA used in the engine transmission chain is a medium carbon steel.
  • it is difficult to control the oxygen content of the molten steel during tapping which makes the yield of alloy elements during deoxidation and alloying of the tapping unstable.
  • the composition of the molten steel entering the LF refining process The large fluctuations increase the difficulty of adjusting LF refining according to the target composition of the molten steel.
  • the initial oxygen content of the molten steel is high, and the inclusion content of the initial molten steel is also high.
  • 50CrVA alloy structural steel is prone to decarburization during the heating process of the billet.
  • the present invention aims to provide a transmission chain steel 50CrVA with stable chemical composition, low non-metallic inclusion content in the steel, fine and uniform structure, and less surface decarburization layer, so as to improve the service life of the engine transmission chain.
  • the preparation method of 50CrVA steel for engine transmission chain according to the present invention includes the following steps:
  • VD vacuum treatment vacuum degree ⁇ 1mbar, processing time more than 10 minutes, after breaking the vacuum, feed pure calcium rod cored wire 50-100m, soft blowing Ar time more than 15 minutes;
  • a three-stage continuous push-steel heating furnace is used to heat billets and rectangular billets;
  • the initial composition of the molten steel reaches 70% to the lower limit of the target composition. 90%.
  • the initial composition of the molten steel reaches 80% to 85% of the lower limit of the target composition.
  • the target components of molten steel are calculated in terms of weight percentage: C: 0.50% ⁇ 0.54%, Si: 0.18% ⁇ 0.30%, Mn: 0.70% ⁇ 0.80%, P ⁇ 0.015%, S ⁇ 0.010%, Cr: 0.95 %-1.10%, Ni ⁇ 0.20%, Cu ⁇ 0.20%, Ti ⁇ 0.20%, Alt: 0.020% ⁇ 0.050%, V: 0.12%-0.20%, the rest are iron and trace elements.
  • the LF refining in step (2) is fine-tuned according to the target composition of the molten steel.
  • the alloy added in step (2) is high carbon ferromanganese alloy, silicon manganese alloy and fervanadium alloy.
  • the carburizing agent added in step (2) is high-purity graphite carbon material.
  • the deoxidizer added in step (2) is high-purity silicon carbide.
  • the refining time in step (2) is 40 to 70 minutes, and the white residue holding time is 30 to 50 minutes.
  • step (4) the long nozzle Ar is sealed for full protection casting, and the tundish is blown with Ar before the big ladle is poured; medium carbon steel molding slag is used, the superheat of the tundish is 10-30°C, and the 150*150mm continuous casting
  • the casting speed is 2.0-2.2m/min
  • the casting speed of 150*220mm is 1.3-1.5m/min
  • the crystallizer and terminal electromagnetic stirring are adopted, the crystallizer liquid level is automatically controlled, and the liquid level fluctuation is ⁇ 6mm.
  • the heating atmosphere in step (5) is a reducing atmosphere, and the residual oxygen content of the flue gas is controlled to be ⁇ 3%.
  • the heating process adopts slow burning at low temperature and fast burning at high temperature under a reducing atmosphere, and the residual oxygen content of the flue gas is controlled to ⁇ 3% to reduce decarburization on the surface of the cast slab.
  • step (6) reciprocating multi-pass rolling is used for rough rolling, with an opening rolling temperature of 1030-1140°C; for mid-finishing rolling, the opening temperature is 960-1030°C, and the thickness tolerance is controlled by the AGC system to be less than 0.05mm; The rolling temperature is 890 ⁇ 950°C.
  • step (1) of the present invention a deoxidizing furnace protective agent is added at the end of the smelting process of the electric furnace to reduce the oxygen content of the molten steel, and an eccentric furnace bottom tapping operation is adopted to retain steel and slag, which greatly reduces the amount of slag and greatly reduces the oxidation of the molten steel, which not only improves the The yield of alloying elements reduces the amount of carburizing agent, reduces production costs, reduces the content of inclusions in steel, and improves the purity of molten steel; in step (2), LF refining uses ferrosilicon manganese, high carbon ferrochrome, ferrovanadium alloys and high Pure graphite carbon material is used for alloying of molten steel, high-purity silicon carbide is used for diffusion deoxidation, lime and fluorite slag systems are used to achieve the effect of rapid desulfurization of molten steel, and foamed slag is produced to realize slag submerged arc operation to reduce the amount of N absorbed
  • step (4) the continuous casting process adopts billet and rectangular billet continuous casting, and uses a five-machine and five-stream billet continuous casting machine for constant casting speed to reduce the fluctuation of the crystallizer liquid level and promote the effective floating of inclusions, thereby Improve the purity of cast steel billet.
  • the significant advantages of the present invention are: 1.
  • the non-metallic inclusion content of the finished steel strip produced by the present invention is lower than 0.5 levels, the chemical composition has small fluctuations, and the performance of different batches of materials is stable; 2.
  • the finished steel strip produced by the present invention has less surface decarburization, a fine and uniform structure, a grain size of 7.0, good toughness, and a long service life of the engine transmission chain.
  • a method for preparing 50CrVA steel for engine transmission chains which sequentially includes electric furnace smelting, LF refining, VD vacuum treatment, continuous casting, heating, descaling, rolling, cooling and coiling. The specific steps are as follows:
  • (1) Electric furnace smelting 45 tons of scrap steel and 65 tons of molten iron are added to the electric furnace. During the smelting process, 7040kg of active lime is added, and the oxygen supply is controlled to 5200m3. At the end of the smelting, 260kg of deoxidizing furnace protective agent is added, and the stay is 1 minute, and then passes through the eccentric furnace bottom
  • control the C content in the molten steel to 0.11%, the P content to 0.009%, and the oxygen content of the molten steel to 270 ppm
  • 240kg of modified refining slag 110kg of aluminum pellets, 650kg of lime, and the initial composition of molten steel reaches 80% of the lower limit of the target composition.
  • (2) LF refining Add 75kg of fervanadium, 160kg of silicon-manganese, 550kg of high-carbon ferrochromium alloy, and 180kg of high-purity graphite carbon material into the LF refining furnace for alloying of molten steel. Add 80kg of high-purity silicon carbide in small quantities and in batches for diffusion deoxidation.
  • the target components of the molten steel are calculated in terms of weight percentage: C: 0.51%, Si: 0.22%, Mn: 0.72%, P: 0.010%, S: 0.002%, Cr: 1.03%, Ni: 0.03%, Cu: 0.06%, Alt: 0.038%, Ti0.004%, V0.13%, the rest is iron and trace elements.
  • VD vacuum treatment After the composition and temperature of the molten steel refined by LF are qualified, VD vacuum degassing is carried out, the vacuum degree is 0.48mbar, the processing time is 19 minutes, after the vacuum is broken, the covering agent is added, soft blowing of argon gas is performed for 39 minutes, and static stirring is carried out. During this time, the slag surface moves slightly and is not exposed to light to ensure that inclusions are fully floated and removed.
  • the specific water content is 0.60L/kg, the electromagnetic stirring frequency of the crystallizer is 3.00Hz, the current is 300A; the terminal electromagnetic stirring frequency is 8Hz, the current is 350A; the center segregation, center shrinkage cavity and center porosity of the slab are all lower than level 1.0.
  • Implementing constant pulling speed casting can avoid slag entrainment, and at the same time, non-metallic inclusions can fully collide, grow, float and be removed.
  • Heating Put the 150mm ⁇ 220mm small rectangular billet into a three-stage continuous push steel heating furnace and heat it in a reducing atmosphere.
  • the residual oxygen content of the flue gas is 2.2%.
  • the temperature of the heating section of the heating furnace is controlled at 1130°C
  • the temperature of the soaking section is controlled at 1080°C
  • the temperature difference across the billet section is less than 30°C.
  • the opening temperature of mid-finish rolling is 995°C;
  • the final rolling temperature is controlled by controlling the final rolling speed, the final rolling temperature is 880°C, the final rolling speed is 6m/s, and then it is twisted, snake-shaped oscillated and transported to the flat chain for transportation and cooling.
  • Cooling and coiling Air-cool the rolled steel strip, check the surface quality and dimensional tolerance, coil, pack and put it into storage.
  • the coiling temperature is 690°C.
  • a method for preparing 50CrVA steel for engine transmission chains which sequentially includes electric furnace smelting, LF refining, VD vacuum treatment, continuous casting, heating, descaling, rolling, cooling and coiling. The specific steps are as follows:
  • (1) Electric furnace smelting 43 tons of scrap steel and 65 tons of molten iron are added to the electric furnace. During the smelting process, 6520kg of active lime is added, and the oxygen supply is controlled to 5100m3. At the end of the smelting, 250kg of deoxidizing furnace protective agent is added, and the stay is 1 minute, and then passes through the eccentric furnace bottom When tapping steel, control the C content in the molten steel to 0.09%, the P content to 0.007%, and the oxygen content of the molten steel to 285ppm; during the tapping process of the electric furnace, add 200kg of ferrovanadium, 600kg of silicon manganese, 245kg of high carbon ferromanganese, and 1,400kg of high carbon ferrochrome. , 250kg of modified refining slag, 120kg of aluminum pellets, 650kg of lime, and the initial composition of molten steel reaches 85% of the lower limit of the target composition.
  • (2) LF refining Add 75kg of fervanadium, 130kg of silicon-manganese, 500kg of high-carbon ferrochromium alloy, and 140kg of high-purity graphite carbon material into the LF refining furnace for alloying of molten steel. Add 80kg of high-purity silicon carbide in small quantities and in batches for diffusion deoxidation.
  • the target components of the molten steel are calculated in terms of weight percentage: C: 0.51%, Si: 0.23%, Mn: 0.73%, P: 0.010%, S: 0.002%, Cr: 1.01%, Ni: 0.02%, Cu: 0.06%, Alt: 0.030%, Ti0.005%, V0.13%, the rest is iron and trace elements.
  • VD vacuum treatment After the composition and temperature of the molten steel refined by LF are qualified, VD vacuum degassing is carried out, the vacuum degree is 0.71mbar, the processing time is 19 minutes, after the vacuum is broken, increase the covering agent, blow argon softly and stir for 24 minutes, and stir quietly When the slag surface moves slightly, no light can be seen.
  • the specific water content is 0.60L/kg, the electromagnetic stirring frequency of the crystallizer is 3.00Hz, the current is 300A; the terminal electromagnetic stirring frequency is 8Hz, the current is 350A; the center segregation, center shrinkage cavity and center porosity of the slab are all lower than level 1.0.
  • Implementing constant pulling speed casting can avoid slag entrainment, and at the same time, non-metallic inclusions can fully collide, grow, float and be removed.
  • Heating Put the 150mm ⁇ 220mm small rectangular billet into a three-stage continuous push steel heating furnace and heat it in a reducing atmosphere.
  • the residual oxygen content of the flue gas is 2.1%.
  • the temperature of the heating section of the heating furnace is controlled at 1125°C
  • the temperature of the soaking section is controlled at 1087°C
  • the temperature difference across the billet section is less than 30°C.
  • the opening temperature of intermediate finishing rolling is 985°C; the final rolling temperature is controlled by controlling the final rolling speed, the final rolling temperature is 886°C, the final rolling speed is 6m/s, and then it is twisted, snake-shaped oscillated, flat chain transported and cooled.
  • Cooling and coiling Air-cool the rolled steel strip, check the surface quality and dimensional tolerance, coil, pack and put it into storage.
  • the coiling temperature is 675°C.
  • a method for preparing 50CrVA steel for engine transmission chains which sequentially includes electric furnace smelting, LF refining, VD vacuum treatment, continuous casting, heating, descaling, rolling, cooling and coiling. The specific steps are as follows:
  • (1) Electric furnace smelting 42 tons of scrap steel and 66 tons of molten iron are added to the electric furnace. During the smelting process, 6850kg of active lime is added, and the oxygen supply is controlled to 4950m3. At the end of the smelting, 260kg of deoxidizing furnace protective agent is added, and the stay is 1 minute, and then passes through the eccentric furnace bottom
  • control the C content in the molten steel to 0.08%, the P content to 0.007%, and the oxygen content of the molten steel to 277 ppm
  • 240kg of modified refining slag 110kg of aluminum pellets, 600kg of lime, and the initial composition of molten steel reaches 80% of the lower limit of the target composition.
  • (2) LF refining Add 75kg of fervanadium, 145kg of silicon-manganese, 530kg of high-carbon ferrochromium alloy, and 150kg of high-purity graphite carbon material into the LF refining furnace for alloying of molten steel, and add 80kg of high-purity silicon carbide in small quantities and in batches for diffusion deoxidation.
  • the target components of the molten steel are calculated in terms of weight percentage: C: 0.51%, Si: 0.25%, Mn: 0.75%, P: 0.008%, S: 0.002%, Cr: 1.02%, Ni: 0.02%, Cu: 0.05%, Alt: 0.036%, Ti0.005%, V0.14%, the rest is iron and trace elements.
  • VD vacuum treatment After the composition and temperature of the molten steel refined by LF are qualified, VD vacuum degassing is carried out, the vacuum degree is 0.60mbar, the processing time is 21 minutes, after the vacuum is broken, the covering agent is increased, soft blowing of argon gas is performed for 37 minutes, and static stirring is carried out When the slag surface moves slightly, no light can be seen.
  • the specific water content is 0.60L/kg, the electromagnetic stirring frequency of the crystallizer is 3.00Hz, the current is 300A; the terminal electromagnetic stirring frequency is 8Hz, the current is 350A; the center segregation, center shrinkage cavity and center porosity of the slab are all lower than level 1.0.
  • Implementing constant pulling speed casting can avoid slag entrainment, and at the same time, non-metallic inclusions can fully collide, grow, float and be removed.
  • Heating Put the 150mm ⁇ 220mm small rectangular billet into a three-stage continuous push-steel heating furnace and heat it in a reducing atmosphere.
  • the residual oxygen content of the flue gas is 2.4%.
  • the temperature of the heating section of the heating furnace is controlled at 1128°C, the temperature of the soaking section is controlled at 1090°C, and the temperature difference across the billet section is less than 30°C.
  • the starting rolling temperature of intermediate and finishing rolling is 990°C; the final rolling temperature is controlled by controlling the final rolling speed, the final rolling temperature is 905°C, the final rolling speed 6m/s, and then twisted and vibrated in a serpentine shape against flat chains for transportation and cooling.
  • Cooling and coiling Air-cool the rolled steel strip, check the surface quality and dimensional tolerance, coil, pack and put it into storage.
  • the coiling temperature is 685°C.
  • composition characteristics of the 50CrVA hot-rolled steel strips for engine transmission chains prepared in Examples 1 to 3 of the present invention are shown in Table 1.
  • the thickness of the hot-rolled steel strip for the circlip engine transmission chain prepared in Examples 1 to 3, the thickness of the total decarburization layer on one side, the inclusion type grade, and the mechanical properties of the cold-rolled finished steel strip after quenching and tempering were tested. , the results obtained are shown in Table 2.
  • the industry control standard for the thickness of the decarburization layer is that when the steel strip thickness is ⁇ 3.00mm, the total decarburization layer on one side is ⁇ 0.08mm; when the steel strip thickness is >3.00mm, the total decarburization layer on one side is ⁇ 2.5% of the actual thickness. It can be seen from Table 2 that when the thickness of the steel strip produced by the present invention is ⁇ 3.00mm, the total decarburization layer on one side is 0.03mm and 0.03mm; when the steel strip thickness is >3.00mm, the total decarburization layer on one side is 0.03mm and 0.03mm respectively. 0.03mm and 0.04, 0.04mm, it can be seen that the finished product hot-rolled steel strip for engine transmission chain prepared by the present invention has less surface decarburization layer, which is better than the existing protocol control standard.
  • Inclusion types are divided into Type A sulfides, Type B oxides, Type C silicates, Type D spherical oxides and Type DS large particle inclusions, among which Type A, Type B, Type C and Type D inclusions are further divided into For fine series and coarse series, the lower the inclusion level, the higher the purity of the steel.
  • the specific protocol control standards are shown in Table 3. It can be seen from the inspection results in Table 2 that the inclusions in the steel strip prepared by the present invention are only Class A fine series, Class D fine series and thick series, and the others are all Class 0, indicating that the engine transmission chain prepared by the present invention
  • the finished product of hot-rolled steel strip has low inclusion content, and the material structure and grain size are fine and stable between different batches. It can be widely used in automobile engines and other fields.

Abstract

Disclosed in the present invention is a method for preparing steel 50CrVA for a transmission chain of an engine, the method comprising the procedures of electric furnace smelting, LF refining, a VD vacuum treatment, continuous casting, heating, rolling, cooling and coiling. In the present invention, a deoxidizing furnace-protecting agent is added at the end point of the electric furnace smelting for deoxidation to guarantee that the oxygen content of molten steel is 400 ppm or less during tapping, such that the inclusion content is reduced; and at the end, the contents of the initial components of the molten steel reach 70-90% of the lower limits of the contents of target components; during the LF refining, the molten steel is alloyed by using ferrosilicomanganese, a high-carbon ferrochrome, a ferrovanadium alloy and a high-purity graphite carbon material, and is deoxidized by using a high-purity graphite carbon material and a high-purity silicon carbide; and in the continuous casting procedure, the continuous casting of a small square billet and a small rectangular billet is used, and constant-pulling-speed casting is carried out by using a five-machine five-strand small square billet continuous casting machine, thereby improving the purity of a cast steel billet. The inclusion content of the finished product prepared in the present invention is as low as grade 0.5 or below, the fluctuation of chemical components is small, and the performance of different batches of materials is stable; a finished steel strip product has less surface decarburization, a fine and uniform structure, a grain size of grade 7.0 and a good toughness; and an engine transmission chain processed therefrom has a long service life.

Description

一种发动机传动链用钢50CrVA的制备方法A preparation method of 50CrVA steel for engine transmission chain 技术领域Technical field
本发明涉及汽车用热轧钢带的制备方法，尤其涉及一种发动机传动链用钢50CrVA的制备方法。The present invention relates to a method for preparing hot-rolled steel strips for automobiles, and in particular to a method for preparing 50CrVA steel for engine transmission chains.
背景技术Background technique
目前，各大汽车公司的轿车产品均采用链传动作为其发动机正时传动***和机油泵传动***，常见的有三缸、四缸直列发动机和V6、V8、V10等V型发动机。汽车发动机链条按照用途可分为正时链、机油泵链、高压泵链、共轨泵链、平衡轴链等；按照结构可分为滚子链、套筒链、齿形链；按照排数可分为：单排链、双排链、多排链；按照啮合机制齿形链又可分为内啮合、外啮合、内一外复合啮合齿形链和变节距的Hy-Vo链等。At present, the sedan products of major automobile companies all use chain drive as their engine timing transmission system and oil pump transmission system. Common three-cylinder and four-cylinder inline engines and V-type engines such as V6, V8, and V10 are common. Automotive engine chains can be divided into timing chains, oil pump chains, high-pressure pump chains, common rail pump chains, balance shaft chains, etc. according to their uses; according to their structures, they can be divided into roller chains, bushing chains, and toothed chains; according to their row numbers It can be divided into: single-row chain, double-row chain, multi-row chain; according to the meshing mechanism, the toothed chain can be divided into internal meshing, external meshing, internal-external composite meshing toothed chain and variable pitch Hy-Vo chain, etc.
发动机传动链用钢50CrVA是中碳钢，在电炉冶炼工序中，出钢时的钢水氧含量控制困难，使得出钢脱氧合金化时合金元素的收得率不稳定，进入LF精炼工序的钢水成分波动大，增加了LF精炼根据钢水的目标成分进行调整的难度，再则，钢水初始氧含量高，初始钢水的夹杂物含量也高。除此之外，在钢坯加热过程中50CrVA合金结构钢易发生脱碳。The steel 50CrVA used in the engine transmission chain is a medium carbon steel. In the electric furnace smelting process, it is difficult to control the oxygen content of the molten steel during tapping, which makes the yield of alloy elements during deoxidation and alloying of the tapping unstable. The composition of the molten steel entering the LF refining process The large fluctuations increase the difficulty of adjusting LF refining according to the target composition of the molten steel. Furthermore, the initial oxygen content of the molten steel is high, and the inclusion content of the initial molten steel is also high. In addition, 50CrVA alloy structural steel is prone to decarburization during the heating process of the billet.
发明内容Contents of the invention
发明目的：本发明旨在提供一种化学成分稳定、钢中非金属夹杂物含量低、组织细小均匀、表面脱碳层少的传动链用钢50CrVA，提高发动机传动链的使用寿命的传动链用钢的制备方法。Purpose of the invention: The present invention aims to provide a transmission chain steel 50CrVA with stable chemical composition, low non-metallic inclusion content in the steel, fine and uniform structure, and less surface decarburization layer, so as to improve the service life of the engine transmission chain. Methods of Preparing Steel.
技术方案：本发明所述的发动机传动链用钢50CrVA的制备方法，包括如下步骤：Technical solution: The preparation method of 50CrVA steel for engine transmission chain according to the present invention includes the following steps:
(1)电炉冶炼：在冶炼终点加入脱氧护炉剂，偏心炉底出钢，出钢时钢水中C含量≥0.08％，P含量≤0.010％，氧含量≤400ppm；(1) Electric furnace smelting: Add deoxidizing furnace protective agent at the end of smelting, and tap the steel at the eccentric furnace bottom. When tapping, the C content in the molten steel is ≥0.08%, the P content is ≤0.010%, and the oxygen content is ≤400ppm;
(2)LF精炼：采用合金和增碳剂进行钢水合金化，加入脱氧剂进行扩散脱氧，渣系采用CaO-SiO2-Al2O3，二元碱度控制在2.0-3.0；(2) LF refining: alloy and carburizing agent are used to alloy the molten steel, and deoxidizer is added for diffusion deoxidation. CaO-SiO 2 -Al 2 O 3 is used as the slag system, and the binary basicity is controlled at 2.0-3.0;
(3)VD真空处理：真空度≤1mbar，处理时间10min以上，破真空后喂纯钙棒包心线50-100m，软吹Ar时间大于15min；(3) VD vacuum treatment: vacuum degree ≤ 1mbar, processing time more than 10 minutes, after breaking the vacuum, feed pure calcium rod cored wire 50-100m, soft blowing Ar time more than 15 minutes;
(4)连铸：采用五机五流小方坯连铸机恒拉速浇铸得到小方坯、小矩坯；(4) Continuous casting: Use a five-machine, five-stream billet continuous casting machine to cast billets and rectangular billets at constant casting speed;
(5)加热：采用三段连续推钢式加热炉加热小方坯、小矩坯；(5) Heating: A three-stage continuous push-steel heating furnace is used to heat billets and rectangular billets;
(6)轧制：除鳞后小方坯、小矩坯进行粗轧、中精轧和终轧；(6) Rolling: After descaling, the billets and rectangular billets are subjected to rough rolling, medium finishing rolling and final rolling;
(7)冷却和卷取。(7) Cooling and coiling.
进一步地，步骤(1)中冶炼工序结束时，钢水的初始成分达到目标成分下限的70％～ 90％。优选地，钢水的初始成分达到目标成分下限的80％～85％。其中，钢水的目标成分以重量百分比含量计为：C：0.50％～0.54％，Si：0.18％～0.30％，Mn：0.70％～0.80％，P≤0.015％，S≤0.010％，Cr:0.95％-1.10％，Ni≤0.20％，Cu≤0.20％，Ti≤0.20％，Alt：0.020％～0.050％，V：0.12％-0.20％，其余为铁和微量元素。Further, at the end of the smelting process in step (1), the initial composition of the molten steel reaches 70% to the lower limit of the target composition. 90%. Preferably, the initial composition of the molten steel reaches 80% to 85% of the lower limit of the target composition. Among them, the target components of molten steel are calculated in terms of weight percentage: C: 0.50% ~ 0.54%, Si: 0.18% ~ 0.30%, Mn: 0.70% ~ 0.80%, P ≤ 0.015%, S ≤ 0.010%, Cr: 0.95 %-1.10%, Ni≤0.20%, Cu≤0.20%, Ti≤0.20%, Alt: 0.020%~0.050%, V: 0.12%-0.20%, the rest are iron and trace elements.
优选地，步骤(2)中LF精炼根据钢水的目标成分进行微调。Preferably, the LF refining in step (2) is fine-tuned according to the target composition of the molten steel.
优选地，步骤(2)中加入的合金为高碳锰铁合金、硅锰合金和钒铁合金。Preferably, the alloy added in step (2) is high carbon ferromanganese alloy, silicon manganese alloy and fervanadium alloy.
优选地，步骤(2)中加入的增碳剂为高纯石墨碳材。Preferably, the carburizing agent added in step (2) is high-purity graphite carbon material.
优选地，步骤(2)中加入的脱氧剂为高纯碳化硅。Preferably, the deoxidizer added in step (2) is high-purity silicon carbide.
优选地，步骤(2)中精炼时间40～70min，白渣保持时间30～50min。Preferably, the refining time in step (2) is 40 to 70 minutes, and the white residue holding time is 30 to 50 minutes.
进一步地，步骤(4)中，长水口Ar封全保护浇铸，同时大包开浇前中间包吹Ar处理；使用中碳钢保护渣，中包过热度10-30℃，150*150mm连铸拉速2.0-2.2m/min、150*220mm连铸拉速1.3-1.5m/min，采用结晶器和末端电磁搅拌，结晶器液面自动控制，液面波动≤±6mm。Further, in step (4), the long nozzle Ar is sealed for full protection casting, and the tundish is blown with Ar before the big ladle is poured; medium carbon steel molding slag is used, the superheat of the tundish is 10-30°C, and the 150*150mm continuous casting The casting speed is 2.0-2.2m/min, the casting speed of 150*220mm is 1.3-1.5m/min, the crystallizer and terminal electromagnetic stirring are adopted, the crystallizer liquid level is automatically controlled, and the liquid level fluctuation is ≤±6mm.
优选地，步骤(5)中加热气氛为还原性气氛，控制烟气残氧量≤3％。加热工序采用还原性气氛下低温慢烧、高温快烧，控制烟气残氧量≤3％，减少铸坯表面脱碳。Preferably, the heating atmosphere in step (5) is a reducing atmosphere, and the residual oxygen content of the flue gas is controlled to be ≤3%. The heating process adopts slow burning at low temperature and fast burning at high temperature under a reducing atmosphere, and the residual oxygen content of the flue gas is controlled to ≤3% to reduce decarburization on the surface of the cast slab.
优选地，步骤(6)中粗轧采用往复式多道次轧制，开轧温度1030～1140℃；中精轧开轧温度960～1030℃，并通过AGC***控制厚度公差小于0.05mm；终轧温度890～950℃。Preferably, in step (6), reciprocating multi-pass rolling is used for rough rolling, with an opening rolling temperature of 1030-1140°C; for mid-finishing rolling, the opening temperature is 960-1030°C, and the thickness tolerance is controlled by the AGC system to be less than 0.05mm; The rolling temperature is 890~950℃.
本发明步骤(1)中电炉冶炼工序冶炼终点加入脱氧护炉剂降低钢水氧含量，采用偏心炉底出钢留钢留渣操作，极大地减少下渣量，使钢水氧化性大大降低，既提高合金元素收得率，减少增碳剂用量，降低生产成本，又减少钢中夹杂物含量，提高钢水纯净度；步骤(2)中LF精炼采用硅锰铁、高碳铬铁、钒铁合金和高纯石墨碳材进行钢水合金化，以高纯碳化硅进行扩散脱氧，采用石灰和萤石渣系达到钢水快速脱S的效果，同时造泡沫渣实现渣埋弧操作，减少钢液的吸N量；步骤(4)中连铸工序采用小方坯、小矩坯连铸，采用五机五流小方坯连铸机恒拉速浇铸，减少结晶器液面波动，促进夹杂物有效上浮，进而提高浇铸钢坯的纯净度。In the step (1) of the present invention, a deoxidizing furnace protective agent is added at the end of the smelting process of the electric furnace to reduce the oxygen content of the molten steel, and an eccentric furnace bottom tapping operation is adopted to retain steel and slag, which greatly reduces the amount of slag and greatly reduces the oxidation of the molten steel, which not only improves the The yield of alloying elements reduces the amount of carburizing agent, reduces production costs, reduces the content of inclusions in steel, and improves the purity of molten steel; in step (2), LF refining uses ferrosilicon manganese, high carbon ferrochrome, ferrovanadium alloys and high Pure graphite carbon material is used for alloying of molten steel, high-purity silicon carbide is used for diffusion deoxidation, lime and fluorite slag systems are used to achieve the effect of rapid desulfurization of molten steel, and foamed slag is produced to realize slag submerged arc operation to reduce the amount of N absorbed by the molten steel. ; In step (4), the continuous casting process adopts billet and rectangular billet continuous casting, and uses a five-machine and five-stream billet continuous casting machine for constant casting speed to reduce the fluctuation of the crystallizer liquid level and promote the effective floating of inclusions, thereby Improve the purity of cast steel billet.
有益效果：本发明与现有技术相比，其显著优点是：1、本发明所制得的钢带成品非金属夹杂物含量低0.5级以内，化学成分波动小，不同批次材料性能稳定；2、本发明所制得的钢带成品表面脱碳少，组织细小均匀晶粒度7.0级，韧性好，加工发动机传动链寿命高。Beneficial effects: Compared with the existing technology, the significant advantages of the present invention are: 1. The non-metallic inclusion content of the finished steel strip produced by the present invention is lower than 0.5 levels, the chemical composition has small fluctuations, and the performance of different batches of materials is stable; 2. The finished steel strip produced by the present invention has less surface decarburization, a fine and uniform structure, a grain size of 7.0, good toughness, and a long service life of the engine transmission chain.
具体实施方式Detailed ways
下面结合实施例对本发明作进一步说明。 The present invention will be further described below in conjunction with examples.
实施例1Example 1
一种发动机传动链用钢50CrVA的制备方法，依次包括电炉冶炼、LF精炼、VD真空处理、连铸、加热、除鳞、轧制、冷却和卷取工序，具体步骤如下：A method for preparing 50CrVA steel for engine transmission chains, which sequentially includes electric furnace smelting, LF refining, VD vacuum treatment, continuous casting, heating, descaling, rolling, cooling and coiling. The specific steps are as follows:
(1)电炉冶炼：电炉中加入45吨废钢和65吨铁水，冶炼钢水的过程中加入活性石灰7040kg，控制供氧量为5200m3，冶炼终点加入脱氧护炉剂260kg，停留1min，通过偏心炉底出钢，控制出钢时钢水中C含量0.11％，P含量0.009％，钢水的氧含量270ppm；电炉出钢过程中加入钒铁200kg、硅锰600kg、高碳锰铁250kg、高碳铬铁1400kg、改性精炼渣240kg、铝丸110kg、石灰650kg、钢水的初始成分达到目标成分下限的80％。(1) Electric furnace smelting: 45 tons of scrap steel and 65 tons of molten iron are added to the electric furnace. During the smelting process, 7040kg of active lime is added, and the oxygen supply is controlled to 5200m3. At the end of the smelting, 260kg of deoxidizing furnace protective agent is added, and the stay is 1 minute, and then passes through the eccentric furnace bottom When tapping steel, control the C content in the molten steel to 0.11%, the P content to 0.009%, and the oxygen content of the molten steel to 270 ppm; during the tapping process of the electric furnace, add 200kg of ferrovanadium, 600kg of silicon manganese, 250kg of high carbon ferromanganese, and 1,400kg of high carbon ferrochromium. , 240kg of modified refining slag, 110kg of aluminum pellets, 650kg of lime, and the initial composition of molten steel reaches 80% of the lower limit of the target composition.
(2)LF精炼：向LF精炼炉内加入钒铁75kg、硅锰160kg、高碳铬铁合金550kg、高纯石墨碳材180kg进行钢水合金化，少量多批次加入高纯碳化硅80kg进行扩散脱氧，加入石灰200kg，萤石130kg进行造渣，控制精炼时间55min，白渣保持时间在40min，控制炉渣二元碱度2.84；钢水的目标成分以重量百分比含量计为：C：0.51％、Si：0.22％、Mn：0.72％、P：0.010％、S：0.002％、Cr：1.03％、Ni：0.03％、Cu：0.06％，Alt：0.038％、Ti0.004％、V0.13％其余为铁和微量元素。(2) LF refining: Add 75kg of fervanadium, 160kg of silicon-manganese, 550kg of high-carbon ferrochromium alloy, and 180kg of high-purity graphite carbon material into the LF refining furnace for alloying of molten steel. Add 80kg of high-purity silicon carbide in small quantities and in batches for diffusion deoxidation. , add 200kg of lime and 130kg of fluorite to make slag, control the refining time to 55min, the white slag retention time to 40min, and control the binary alkalinity of the slag to 2.84; the target components of the molten steel are calculated in terms of weight percentage: C: 0.51%, Si: 0.22%, Mn: 0.72%, P: 0.010%, S: 0.002%, Cr: 1.03%, Ni: 0.03%, Cu: 0.06%, Alt: 0.038%, Ti0.004%, V0.13%, the rest is iron and trace elements.
(3)VD真空处理：LF精炼的钢水成分、温度合格后，进行VD真空脱气，真空度0.48mbar，处理时间19min，破真空后加大包覆盖剂，软吹氩气搅拌39min，静搅时渣面微动不见光，保证夹杂物充分上浮去除。(3) VD vacuum treatment: After the composition and temperature of the molten steel refined by LF are qualified, VD vacuum degassing is carried out, the vacuum degree is 0.48mbar, the processing time is 19 minutes, after the vacuum is broken, the covering agent is added, soft blowing of argon gas is performed for 39 minutes, and static stirring is carried out. During this time, the slag surface moves slightly and is not exposed to light to ensure that inclusions are fully floated and removed.
(4)连铸：钢水VD真空处理后，吊包到小方坯连铸机浇铸，连铸采用五机五流整体水口中间包，长水口Ar封全保护浇铸，同时大包开浇前中间包吹Ar处理，防止钢水二次氧化。过热度25℃，拉速1.40m/min恒拉速进行浇铸制得尺寸150mm×220mm的小矩坯。其中比水量为0.60L/kg，结晶器电磁搅拌频率3.00Hz、电流300A；末端电磁搅拌频率8Hz、电流350A；铸坯中心偏析、中心缩孔和中心疏松均低于1.0级。实施恒拉速浇铸，可避免卷渣，同时非金属夹杂物能够充分碰撞长大上浮去除。(4) Continuous casting: After the VD vacuum treatment of the molten steel, the ladle is transferred to the billet continuous casting machine for casting. The continuous casting adopts a five-machine five-flow integral nozzle tundish, and the long nozzle Ar is sealed for full protection casting. At the same time, the big ladle is opened in the middle before pouring. Ar treatment is included to prevent secondary oxidation of molten steel. The superheat degree is 25°C, and the casting speed is constant at 1.40m/min to obtain a small rectangular billet with a size of 150mm×220mm. The specific water content is 0.60L/kg, the electromagnetic stirring frequency of the crystallizer is 3.00Hz, the current is 300A; the terminal electromagnetic stirring frequency is 8Hz, the current is 350A; the center segregation, center shrinkage cavity and center porosity of the slab are all lower than level 1.0. Implementing constant pulling speed casting can avoid slag entrainment, and at the same time, non-metallic inclusions can fully collide, grow, float and be removed.
(5)加热：将150mm×220mm的小矩坯装入三段连续推钢式加热炉中，在还原性气氛中加热，烟气残氧量2.2％。加热炉加热段温度控制在1130℃，均热段温度控制在1080℃，钢坯断面温差小于30℃。(5) Heating: Put the 150mm×220mm small rectangular billet into a three-stage continuous push steel heating furnace and heat it in a reducing atmosphere. The residual oxygen content of the flue gas is 2.2%. The temperature of the heating section of the heating furnace is controlled at 1130°C, the temperature of the soaking section is controlled at 1080°C, and the temperature difference across the billet section is less than 30°C.
(6)轧制：将加热后的150mm×220mm小矩坯经高压水除鳞后送入轧制工序，包括粗轧、中精轧和终轧。其中粗轧采用往复式Φ650和Φ500粗轧机组多道次轧制，开轧温度1096℃，经过6道次粗轧后中精轧；中精轧全线共计10架轧机，前3架中轧，后7架精轧，其形式为立-平-平-立-平-平-平-平-平-平，配备AGC全自动测厚仪，控制厚度公差，中精轧开轧温度995℃；通过控制终轧速度来控制终轧温度，终轧温度880℃，终轧速度6m/s，然后经扭转，蛇形震荡抵平板链运输和冷却。 (6) Rolling: The heated 150mm×220mm rectangular billet is descaled by high-pressure water and then sent to the rolling process, including rough rolling, medium-finish rolling and final rolling. Among them, rough rolling adopts reciprocating Φ650 and Φ500 rough rolling mill units with multi-pass rolling. The rolling temperature is 1096°C. After 6 passes of rough rolling, intermediate and finishing rolling are performed. The entire intermediate and finishing rolling line has a total of 10 rolling stands, with the first three intermediate rolling stands. The last 7 stands of finishing rolling are in the form of vertical-flat-flat-vertical-flat-flat-flat-flat-flat-flat. They are equipped with AGC fully automatic thickness gauge to control the thickness tolerance. The opening temperature of mid-finish rolling is 995°C; The final rolling temperature is controlled by controlling the final rolling speed, the final rolling temperature is 880°C, the final rolling speed is 6m/s, and then it is twisted, snake-shaped oscillated and transported to the flat chain for transportation and cooling.
(7)冷却和卷取：将轧制后的钢带空冷，检查表面质量和尺寸公差，进行卷取、打包和入库，卷取温度690℃。(7) Cooling and coiling: Air-cool the rolled steel strip, check the surface quality and dimensional tolerance, coil, pack and put it into storage. The coiling temperature is 690°C.
实施例2Example 2
一种发动机传动链用钢50CrVA的制备方法，依次包括电炉冶炼、LF精炼、VD真空处理、连铸、加热、除鳞、轧制、冷却和卷取工序，具体步骤如下：A method for preparing 50CrVA steel for engine transmission chains, which sequentially includes electric furnace smelting, LF refining, VD vacuum treatment, continuous casting, heating, descaling, rolling, cooling and coiling. The specific steps are as follows:
(1)电炉冶炼：电炉中加入43吨废钢和65吨铁水，冶炼钢水的过程中加入活性石灰6520kg，控制供氧量为5100m3，冶炼终点加入脱氧护炉剂250kg，停留1min，通过偏心炉底出钢，控制出钢时钢水中C含量0.09％，P含量0.007％，钢水的氧含量285ppm；电炉出钢过程中加入钒铁200kg、硅锰600kg、高碳锰铁245kg、高碳铬铁1400kg、改性精炼渣250kg、铝丸120kg、石灰650kg、钢水的初始成分达到目标成分下限的85％。(1) Electric furnace smelting: 43 tons of scrap steel and 65 tons of molten iron are added to the electric furnace. During the smelting process, 6520kg of active lime is added, and the oxygen supply is controlled to 5100m3. At the end of the smelting, 250kg of deoxidizing furnace protective agent is added, and the stay is 1 minute, and then passes through the eccentric furnace bottom When tapping steel, control the C content in the molten steel to 0.09%, the P content to 0.007%, and the oxygen content of the molten steel to 285ppm; during the tapping process of the electric furnace, add 200kg of ferrovanadium, 600kg of silicon manganese, 245kg of high carbon ferromanganese, and 1,400kg of high carbon ferrochrome. , 250kg of modified refining slag, 120kg of aluminum pellets, 650kg of lime, and the initial composition of molten steel reaches 85% of the lower limit of the target composition.
(2)LF精炼：向LF精炼炉内加入钒铁75kg、硅锰130kg、高碳铬铁合金500kg、高纯石墨碳材140kg进行钢水合金化，少量多批次加入高纯碳化硅80kg进行扩散脱氧，加入石灰200kg，萤石130kg进行造渣，控制精炼时间62min，白渣保持时间在50min，控制炉渣二元碱度2.80；钢水的目标成分以重量百分比含量计为：C：0.51％、Si：0.23％、Mn：0.73％、P：0.010％、S：0.002％、Cr：1.01％、Ni：0.02％、Cu：0.06％，Alt：0.030％、Ti0.005％、V0.13％其余为铁和微量元素。(2) LF refining: Add 75kg of fervanadium, 130kg of silicon-manganese, 500kg of high-carbon ferrochromium alloy, and 140kg of high-purity graphite carbon material into the LF refining furnace for alloying of molten steel. Add 80kg of high-purity silicon carbide in small quantities and in batches for diffusion deoxidation. , add 200kg of lime and 130kg of fluorite to make slag, control the refining time to 62min, the white slag retention time to 50min, and control the binary alkalinity of the slag to 2.80; the target components of the molten steel are calculated in terms of weight percentage: C: 0.51%, Si: 0.23%, Mn: 0.73%, P: 0.010%, S: 0.002%, Cr: 1.01%, Ni: 0.02%, Cu: 0.06%, Alt: 0.030%, Ti0.005%, V0.13%, the rest is iron and trace elements.
(3)VD真空处理：LF精炼的钢水成分、温度合格后，进行VD真空脱气，真空度0.71mbar，处理时间19min，破真空后加大包覆盖剂，软吹氩气搅拌24min，静搅时渣面微动不见光。(3) VD vacuum treatment: After the composition and temperature of the molten steel refined by LF are qualified, VD vacuum degassing is carried out, the vacuum degree is 0.71mbar, the processing time is 19 minutes, after the vacuum is broken, increase the covering agent, blow argon softly and stir for 24 minutes, and stir quietly When the slag surface moves slightly, no light can be seen.
(4)连铸：钢水VD真空处理后，吊包到小方坯7#连铸机浇铸，连铸采用五机五流整体水口中间包，长水口Ar封全保护浇铸，同时大包开浇前中间包吹Ar处理，防止钢水二次氧化。过热度23℃，拉速1.40m/min恒拉速进行浇铸制得尺寸150mm×220mm的小矩坯。其中比水量为0.60L/kg，结晶器电磁搅拌频率3.00Hz、电流300A；末端电磁搅拌频率8Hz、电流350A；铸坯中心偏析、中心缩孔和中心疏松均低于1.0级。实施恒拉速浇铸，可避免卷渣，同时非金属夹杂物能够充分碰撞长大上浮去除。(4) Continuous casting: After the VD vacuum treatment of the molten steel, the ladle is transferred to the billet 7# continuous casting machine for casting. The continuous casting adopts a five-machine five-flow integral nozzle tundish, and the long nozzle Ar is fully protected for casting. At the same time, the large ladle is cast. The front tundish is treated with Ar blowing to prevent secondary oxidation of molten steel. The superheat degree is 23°C and the casting speed is constant at 1.40m/min to obtain a small rectangular billet with a size of 150mm×220mm. The specific water content is 0.60L/kg, the electromagnetic stirring frequency of the crystallizer is 3.00Hz, the current is 300A; the terminal electromagnetic stirring frequency is 8Hz, the current is 350A; the center segregation, center shrinkage cavity and center porosity of the slab are all lower than level 1.0. Implementing constant pulling speed casting can avoid slag entrainment, and at the same time, non-metallic inclusions can fully collide, grow, float and be removed.
(5)加热：将150mm×220mm的小矩坯装入三段连续推钢式加热炉中，在还原性气氛中加热，烟气残氧量2.1％。加热炉加热段温度控制在1125℃，均热段温度控制在1087℃，钢坯断面温差小于30℃。(5) Heating: Put the 150mm×220mm small rectangular billet into a three-stage continuous push steel heating furnace and heat it in a reducing atmosphere. The residual oxygen content of the flue gas is 2.1%. The temperature of the heating section of the heating furnace is controlled at 1125°C, the temperature of the soaking section is controlled at 1087°C, and the temperature difference across the billet section is less than 30°C.
(6)轧制：将加热后的150mm×220mm小矩坯经高压水除鳞后送入轧制工序，包括粗轧、中精轧和终轧。其中粗轧采用往复式Φ650和Φ500粗轧机组多道次轧制，开轧温度1090℃，经过6道次粗轧后中精轧；中精轧全线共计10架轧机，前3架中轧，后7架精轧，其形式为立-平-平-立-平-平-平-平-平-平，配备AGC全自动测厚仪，控制厚 度公差，中精轧开轧温度985℃；通过控制终轧速度来控制终轧温度，终轧温度886℃，终轧速度6m/s，然后经扭转，蛇形震荡抵平板链运输和冷却。(6) Rolling: The heated 150mm×220mm rectangular billet is descaled by high-pressure water and then sent to the rolling process, including rough rolling, medium-finish rolling and final rolling. Among them, rough rolling adopts multi-pass rolling of reciprocating Φ650 and Φ500 rough rolling mill units, with an opening rolling temperature of 1090°C. After 6 passes of rough rolling, intermediate and finishing rolling are performed; the entire intermediate and finishing rolling line has a total of 10 rolling stands, with the first three intermediate rolling stands. The last 7 stands of finishing rolling are in the form of vertical-flat-flat-vertical-flat-flat-flat-flat-flat-flat. They are equipped with AGC fully automatic thickness gauge to control the thickness. Tolerance, the opening temperature of intermediate finishing rolling is 985°C; the final rolling temperature is controlled by controlling the final rolling speed, the final rolling temperature is 886°C, the final rolling speed is 6m/s, and then it is twisted, snake-shaped oscillated, flat chain transported and cooled.
(7)冷却和卷取：将轧制后的钢带空冷，检查表面质量和尺寸公差，进行卷取、打包和入库，卷取温度675℃。(7) Cooling and coiling: Air-cool the rolled steel strip, check the surface quality and dimensional tolerance, coil, pack and put it into storage. The coiling temperature is 675°C.
实施例3Example 3
一种发动机传动链用钢50CrVA的制备方法，依次包括电炉冶炼、LF精炼、VD真空处理、连铸、加热、除鳞、轧制、冷却和卷取工序，具体步骤如下：A method for preparing 50CrVA steel for engine transmission chains, which sequentially includes electric furnace smelting, LF refining, VD vacuum treatment, continuous casting, heating, descaling, rolling, cooling and coiling. The specific steps are as follows:
(1)电炉冶炼：电炉中加入42吨废钢和66吨铁水，冶炼钢水的过程中加入活性石灰6850kg，控制供氧量为4950m3，冶炼终点加入脱氧护炉剂260kg，停留1min，通过偏心炉底出钢，控制出钢时钢水中C含量0.08％，P含量0.007％，钢水的氧含量277ppm；电炉出钢过程中加入钒铁200kg、硅锰600kg、高碳锰铁240kg、高碳铬铁1350kg、改性精炼渣240kg、铝丸110kg、石灰600kg、钢水的初始成分达到目标成分下限的80％。(1) Electric furnace smelting: 42 tons of scrap steel and 66 tons of molten iron are added to the electric furnace. During the smelting process, 6850kg of active lime is added, and the oxygen supply is controlled to 4950m3. At the end of the smelting, 260kg of deoxidizing furnace protective agent is added, and the stay is 1 minute, and then passes through the eccentric furnace bottom When tapping steel, control the C content in the molten steel to 0.08%, the P content to 0.007%, and the oxygen content of the molten steel to 277 ppm; during the tapping process of the electric furnace, add 200kg of ferrovanadium, 600kg of silicon manganese, 240kg of high carbon ferromanganese, and 1350kg of high carbon ferrochromium. , 240kg of modified refining slag, 110kg of aluminum pellets, 600kg of lime, and the initial composition of molten steel reaches 80% of the lower limit of the target composition.
(2)LF精炼：向LF精炼炉内加入钒铁75kg、硅锰145kg、高碳铬铁合金530kg、高纯石墨碳材150kg进行钢水合金化，少量多批次加入高纯碳化硅80kg进行扩散脱氧，加入石灰200kg，萤石130kg进行造渣，控制精炼时间58min，白渣保持时间在45min，控制炉渣二元碱度2.75；钢水的目标成分以重量百分比含量计为：C：0.51％、Si：0.25％、Mn：0.75％、P：0.008％、S：0.002％、Cr：1.02％、Ni：0.02％、Cu：0.05％，Alt：0.036％、Ti0.005％、V0.14％其余为铁和微量元素。(2) LF refining: Add 75kg of fervanadium, 145kg of silicon-manganese, 530kg of high-carbon ferrochromium alloy, and 150kg of high-purity graphite carbon material into the LF refining furnace for alloying of molten steel, and add 80kg of high-purity silicon carbide in small quantities and in batches for diffusion deoxidation. , add 200kg of lime and 130kg of fluorite to make slag, control the refining time to 58min, the white slag retention time to 45min, and control the binary alkalinity of the slag to 2.75; the target components of the molten steel are calculated in terms of weight percentage: C: 0.51%, Si: 0.25%, Mn: 0.75%, P: 0.008%, S: 0.002%, Cr: 1.02%, Ni: 0.02%, Cu: 0.05%, Alt: 0.036%, Ti0.005%, V0.14%, the rest is iron and trace elements.
(3)VD真空处理：LF精炼的钢水成分、温度合格后，进行VD真空脱气，真空度0.60mbar，处理时间21min，破真空后加大包覆盖剂，软吹氩气搅拌37min，静搅时渣面微动不见光。(3) VD vacuum treatment: After the composition and temperature of the molten steel refined by LF are qualified, VD vacuum degassing is carried out, the vacuum degree is 0.60mbar, the processing time is 21 minutes, after the vacuum is broken, the covering agent is increased, soft blowing of argon gas is performed for 37 minutes, and static stirring is carried out When the slag surface moves slightly, no light can be seen.
(4)连铸：钢水VD真空处理后，吊包到小方坯7#连铸机浇铸，连铸采用五机五流整体水口中间包，长水口Ar封全保护浇铸，同时大包开浇前中间包吹Ar处理，防止钢水二次氧化。过热度28℃，拉速1.40m/min恒拉速进行浇铸制得尺寸150mm×220mm的小矩坯。其中比水量为0.60L/kg，结晶器电磁搅拌频率3.00Hz、电流300A；末端电磁搅拌频率8Hz、电流350A；铸坯中心偏析、中心缩孔和中心疏松均低于1.0级。实施恒拉速浇铸，可避免卷渣，同时非金属夹杂物能够充分碰撞长大上浮去除。(4) Continuous casting: After the VD vacuum treatment of the molten steel, the ladle is transferred to the billet 7# continuous casting machine for casting. The continuous casting adopts a five-machine five-flow integral nozzle tundish, and the long nozzle Ar is fully protected for casting. At the same time, the large ladle is cast. The front tundish is treated with Ar blowing to prevent secondary oxidation of molten steel. The superheat degree is 28°C and the casting speed is constant at 1.40m/min to obtain a small rectangular billet with a size of 150mm×220mm. The specific water content is 0.60L/kg, the electromagnetic stirring frequency of the crystallizer is 3.00Hz, the current is 300A; the terminal electromagnetic stirring frequency is 8Hz, the current is 350A; the center segregation, center shrinkage cavity and center porosity of the slab are all lower than level 1.0. Implementing constant pulling speed casting can avoid slag entrainment, and at the same time, non-metallic inclusions can fully collide, grow, float and be removed.
(5)加热：将150mm×220mm的小矩坯装入三段连续推钢式加热炉中，在还原性气氛中加热，烟气残氧量2.4％。加热炉加热段温度控制在1128℃，均热段温度控制在1090℃，钢坯断面温差小于30℃。(5) Heating: Put the 150mm×220mm small rectangular billet into a three-stage continuous push-steel heating furnace and heat it in a reducing atmosphere. The residual oxygen content of the flue gas is 2.4%. The temperature of the heating section of the heating furnace is controlled at 1128°C, the temperature of the soaking section is controlled at 1090°C, and the temperature difference across the billet section is less than 30°C.
(6)轧制：将加热后的150mm×220mm小矩坯经高压水除鳞后送入轧制工序，包括粗轧、中精轧和终轧。其中粗轧采用往复式Φ650和Φ500粗轧机组多道次轧制，开轧 温度1075℃，经过6道次粗轧后中精轧；中精轧全线共计10架轧机，前3架中轧，后7架精轧，其形式为立-平-平-立-平-平-平-平-平-平，配备AGC全自动测厚仪，控制厚度公差，中精轧开轧温度990℃；通过控制终轧速度来控制终轧温度，终轧温度905℃，终轧速度6m/s，然后经扭转，蛇形震荡抵平板链运输和冷却。(6) Rolling: The heated 150mm×220mm rectangular billet is descaled by high-pressure water and then sent to the rolling process, including rough rolling, medium-finish rolling and final rolling. Among them, rough rolling adopts reciprocating Φ650 and Φ500 rough rolling mill units with multi-pass rolling. The temperature is 1075°C. After 6 passes of rough rolling, there are intermediate and finishing rolling. There are 10 rolling mills in the entire intermediate and finishing rolling line. The first 3 intermediate rolling stands and the last 7 finishing rolling stands are in the form of vertical-flat-flat-vertical-flat-flat. - Flat-flat-flat-flat, equipped with AGC fully automatic thickness gauge to control the thickness tolerance, the starting rolling temperature of intermediate and finishing rolling is 990℃; the final rolling temperature is controlled by controlling the final rolling speed, the final rolling temperature is 905℃, the final rolling speed 6m/s, and then twisted and vibrated in a serpentine shape against flat chains for transportation and cooling.
(7)冷却和卷取：将轧制后的钢带空冷，检查表面质量和尺寸公差，进行卷取、打包和入库，卷取温度685℃。(7) Cooling and coiling: Air-cool the rolled steel strip, check the surface quality and dimensional tolerance, coil, pack and put it into storage. The coiling temperature is 685°C.
本发明实施例1～3制得的发动机传动链用钢50CrVA热轧钢带的组分特征见表1。检测实施例1～3所制得弹性挡圈发动机传动链用热轧钢带的厚度、其单面总脱碳层厚度、夹杂物类型等级以及钢带冷轧成品淬火回火处理后的力学性能，所得结果见表2。The composition characteristics of the 50CrVA hot-rolled steel strips for engine transmission chains prepared in Examples 1 to 3 of the present invention are shown in Table 1. The thickness of the hot-rolled steel strip for the circlip engine transmission chain prepared in Examples 1 to 3, the thickness of the total decarburization layer on one side, the inclusion type grade, and the mechanical properties of the cold-rolled finished steel strip after quenching and tempering were tested. , the results obtained are shown in Table 2.
表1实施例1～3制得的发动机传动链用热轧钢带各组分的重量百分比
Table 1 Weight percentage of each component of the hot-rolled steel strip for engine transmission chain prepared in Examples 1 to 3
表2实施例1～3所制得弹性挡圈用热轧钢带的综合性能
Table 2 Comprehensive properties of hot-rolled steel strips for elastic retaining rings prepared in Examples 1 to 3
表3夹杂物类型及等级的协议控制标准
Table 3 Protocol control standards for inclusion types and levels
由表1可以看出，本发明所制备的发动机传动链用钢热轧钢带成品的化学成分波动小。It can be seen from Table 1 that the chemical composition of the finished hot-rolled steel strip for engine transmission chains prepared by the present invention has small fluctuations.
脱碳层厚度的行业控制标准为钢带厚度≤3.00mm时，单面总脱碳层≤0.08mm；钢带厚度＞3.00mm时，单面总脱碳层≤实际厚度的2.5％。由表2可以看出，本发明制得的钢带厚度≤3.00mm时，单面总脱碳层为0.03mm和0.03mm；钢带厚度＞3.00mm时，单面总脱碳层为0.03、0.03mm和0.04、0.04mm，可见本发明制备的发动机传动链用钢热轧钢带成品的表面脱碳层少，优于现有的协议控制标准。The industry control standard for the thickness of the decarburization layer is that when the steel strip thickness is ≤3.00mm, the total decarburization layer on one side is ≤0.08mm; when the steel strip thickness is >3.00mm, the total decarburization layer on one side is ≤2.5% of the actual thickness. It can be seen from Table 2 that when the thickness of the steel strip produced by the present invention is ≤3.00mm, the total decarburization layer on one side is 0.03mm and 0.03mm; when the steel strip thickness is >3.00mm, the total decarburization layer on one side is 0.03mm and 0.03mm respectively. 0.03mm and 0.04, 0.04mm, it can be seen that the finished product hot-rolled steel strip for engine transmission chain prepared by the present invention has less surface decarburization layer, which is better than the existing protocol control standard.
夹杂物类型分为A类硫化物、B类氧化物、C类硅酸盐、D类球状氧化物及DS类大颗粒夹杂物，其中A类、B类、C类和D类夹杂物又分为细系和粗系，夹杂物级别越低，钢的纯净度越高，具体的协议控制标准见表3。从表2的检验结果可以看出，本发明制备的钢带夹杂物只有A类细系、D类细系和粗系为0.5级，其余都是0级，说明本发明所制备的发动机传动链用热轧钢带成品的夹杂物含量低，不同批次间材料的组织、晶粒度细小性能稳定，可广泛地应用于汽车发动机等领域。 Inclusion types are divided into Type A sulfides, Type B oxides, Type C silicates, Type D spherical oxides and Type DS large particle inclusions, among which Type A, Type B, Type C and Type D inclusions are further divided into For fine series and coarse series, the lower the inclusion level, the higher the purity of the steel. The specific protocol control standards are shown in Table 3. It can be seen from the inspection results in Table 2 that the inclusions in the steel strip prepared by the present invention are only Class A fine series, Class D fine series and thick series, and the others are all Class 0, indicating that the engine transmission chain prepared by the present invention The finished product of hot-rolled steel strip has low inclusion content, and the material structure and grain size are fine and stable between different batches. It can be widely used in automobile engines and other fields.

Claims (10)

  1. 一种发动机传动链用钢50CrVA的制备方法，其特征在于，包括如下步骤：A method for preparing 50CrVA steel for engine transmission chains, which is characterized by including the following steps:
    (1)电炉冶炼：在冶炼终点加入脱氧护炉剂，偏心炉底出钢，出钢时钢水中C含量≥0.08％，P含量≤0.010％，氧含量≤400ppm；(1) Electric furnace smelting: Add deoxidizing furnace protective agent at the end of smelting, and tap the steel at the eccentric furnace bottom. When tapping, the C content in the molten steel is ≥0.08%, the P content is ≤0.010%, and the oxygen content is ≤400ppm;
    (2)LF精炼：采用合金和增碳剂进行钢水合金化，加入脱氧剂进行扩散脱氧，渣系采用CaO-SiO2-Al2O3，二元碱度控制在2.0-3.0；(2) LF refining: alloy and carburizing agent are used to alloy the molten steel, and deoxidizer is added for diffusion deoxidation. CaO-SiO 2 -Al 2 O 3 is used as the slag system, and the binary basicity is controlled at 2.0-3.0;
    (3)VD真空处理：真空度≤1mbar，处理时间10min以上，破真空后喂纯钙棒包心线50-100m，软吹Ar时间大于15min；(3) VD vacuum treatment: vacuum degree ≤ 1mbar, processing time more than 10 minutes, after breaking the vacuum, feed pure calcium rod cored wire 50-100m, soft blowing Ar time more than 15 minutes;
    (4)连铸：采用五机五流小方坯连铸机恒拉速浇铸得到小方坯、小矩坯；(4) Continuous casting: Use a five-machine, five-stream billet continuous casting machine to cast billets and rectangular billets at constant casting speed;
    (5)加热：采用三段连续推钢式加热炉加热小方坯、小矩坯；(5) Heating: A three-stage continuous push-steel heating furnace is used to heat billets and rectangular billets;
    (6)轧制：除鳞后小方坯、小矩坯进行粗轧、中精轧和终轧；(6) Rolling: After descaling, the billets and rectangular billets are subjected to rough rolling, medium finishing rolling and final rolling;
    (7)冷却和卷取。(7) Cooling and coiling.
  2. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(1)中冶炼工序结束时，钢水的初始成分达到目标成分下限的70％～90％。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that at the end of the smelting process in step (1), the initial composition of the molten steel reaches 70% to 90% of the lower limit of the target composition.
  3. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(2)中LF精炼根据钢水的目标成分进行微调。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that in step (2), LF refining is fine-tuned according to the target composition of the molten steel.
  4. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(2)中加入的合金为高碳锰铁合金、硅锰合金和钒铁合金。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that the alloy added in step (2) is high carbon ferromanganese alloy, silicon manganese alloy and ferrovanadium alloy.
  5. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(2)中加入的增碳剂为高纯石墨碳材。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that the carburizing agent added in step (2) is high-purity graphite carbon material.
  6. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(2)中加入的脱氧剂为高纯碳化硅。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that the deoxidizer added in step (2) is high-purity silicon carbide.
  7. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(2)中精炼时间40～70min，白渣保持时间30～50min。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that in step (2), the refining time is 40 to 70 minutes, and the white slag holding time is 30 to 50 minutes.
  8. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(4)中，长水口Ar封全保护浇铸，同时大包开浇前中间包吹Ar处理；使用中碳钢保护渣，中包过热度10-30℃，150*150mm连铸拉速2.0-2.2m/min、150*220mm连铸拉速1.3-1.5m/min，采用结晶器和末端电磁搅拌，结晶器液面自动控制，液面波动≤±6mm。The preparation method of engine transmission chain steel 50CrVA according to claim 1, characterized in that, in step (4), the long nozzle Ar is sealed for full protection casting, and at the same time, the tundish is blown with Ar before the big ladle is opened and poured; medium carbon steel is used Mold powder, middle package superheat degree 10-30℃, 150*150mm continuous casting speed 2.0-2.2m/min, 150*220mm continuous casting speed 1.3-1.5m/min, using crystallizer and terminal electromagnetic stirring, crystallizer The liquid level is automatically controlled, and the liquid level fluctuation is ≤±6mm.
  9. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(5)中加热气氛为还原性气氛，控制烟气残氧量≤3％。The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that in step (5), the heating atmosphere is a reducing atmosphere, and the residual oxygen content of the flue gas is controlled to be ≤3%.
  10. 根据权利要求1所述发动机传动链用钢50CrVA的制备方法，其特征在于，步骤(6)中，粗轧采用往复式多道次轧制，开轧温度1030～1140℃；中精轧开轧温度960～1030℃，并通过AGC***控制厚度公差小于0.05mm；终轧温度890～950℃。 The method for preparing 50CrVA steel for engine transmission chains according to claim 1, characterized in that in step (6), rough rolling adopts reciprocating multi-pass rolling, and the opening rolling temperature is 1030-1140°C; the medium and finishing rolling is opened The temperature is 960~1030℃, and the thickness tolerance is controlled by the AGC system to be less than 0.05mm; the final rolling temperature is 890~950℃.
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