Microalloyed steel for lead screw guide rail and manufacturing method of microalloyed steel

Abstract

The invention provides microalloyed steel for a lead screw guide rail and a manufacturing method of the microalloyed steel. The manufacturing method comprises the steps of converter smelting, external refining, RH vacuum degassing, continuous casting, continuous rolling, cooling, flaw detection, finishing, warehousing and the like. According to the method, the chemical components of the steel are reasonably designed, the gas content and non-metallic inclusions in the steel are reduced through the converter smelting and external refining processes, and the purity and quality of the steel are improved; according to the continuous casting process, by controlling the superheat degree and adopting the double-electromagnetic stirring technology, the component segregation problem of a continuous casting blank is remarkably solved, and the density of the casting blank is improved. According to the method, the strength, hardness, toughness, wear resistance, hardenability and other properties of the steel are comprehensively improved, meanwhile, the size and number of non-metallic inclusions and center carbon segregation are reduced, the requirements for the purity and structure uniformity of the steel are met, and a high-quality and high-performance steel product is provided for the high-end field.

Description

Technical Field

[0001] The invention belongs to the technical field of special steel smelting, and in particular relates to a micro-alloyed steel for a lead screw guide rail and a manufacturing method thereof. Background Art

[0002] Screw guides are widely used in precision manufacturing fields such as machine tools, automation equipment, and semiconductor devices. Their precision and rigidity have a significant impact on the performance and processing accuracy of the equipment. With the continuous development of machining and precision manufacturing technologies, the performance requirements for screw guides are becoming increasingly higher. Accordingly, the performance of the raw steel used to process screw guides must also be improved to meet the requirements of technicians, especially the material's wear resistance, hardenability, purity, and structural uniformity. The steel used for screw guides must possess the following properties: high fatigue strength, elastic strength, yield strength, and toughness, high wear resistance, high and uniform hardness, and a certain degree of corrosion resistance. In addition, because users need to surface harden the screw guides during material processing, the hardenability of the steel must also meet the requirements for use.

[0003] At present, the guide rail steels used at home and abroad are mostly 55, S55C and other products. Due to the limitations of product quality, they cannot fully meet the needs of high-end users for screw guide rail steel. Summary of the Invention

[0004] The present invention addresses the technical problem that the strength and hardenability of guide rail steel in the prior art cannot meet the requirements of high-end screw guide rail processing, and proposes a micro-alloyed screw guide rail steel with high strength, high wear resistance and high hardenability and a manufacturing method thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A micro-alloyed steel for a lead screw guide rail comprises the following main components by weight: C 0.45-0.55%, Si 0.20-0.35%, Mn 0.90-1.00%, Cr 0.35-0.45%, P ≤ 0.020%, S ≤ 0.010%, Mo ≤ 0.2%, Ni ≤ 0.2%, Al 0.01%-0.05%, Cu ≤ 0.2%, Ca ≤ 0.0008%, Ti ≤ 0.002%, O ≤ 0.0012%, and the balance is Fe and unavoidable impurities.

[0007] Preferably, its main components in weight percentage are: C 0.51%, Si 0.24%, Mn 0.98%, Cr0.39%, P≤0.013%, S≤0.004%, Mo≤0.01%, Ni≤0.02%, Al 0.018%, Cu≤0.01%, Ca≤0.0001%, Ti≤0.0008%, O≤0.00058%, and the balance is Fe and unavoidable impurities.

[0008] The present invention also provides a method for manufacturing micro-alloyed lead screw guide rail steel, comprising the following steps:

[0009] (1) A converter is used to smelt molten iron. During the blowing process, the main blowing time is 14-16 minutes and the secondary blowing time is 1-2 minutes. During the blowing process, an audio device is used to monitor the sound in the furnace in real time, and the gun position and blowing volume are adjusted according to the sound. The carbon content is controlled to be ≥0.10% during steel tapping. During the steel tapping process, deoxidizer and alloy material are added to the ladle for deoxidation and alloying. At the same time, a slide plate is used to block slag. After steel tapping, a special pre-melted synthetic slag material for refining is added to the surface of the ladle to use the converter tapping temperature to melt the slag in advance.

[0010] (2) The molten steel is hoisted to the LF refining equipment for refining, refining agent is added and argon is used for stirring. The argon flow rate is 200-500NL / min in the early stage and 50-200NL / min in the later stage;

[0011] (3) Removing gases and inclusions from molten steel under vacuum conditions;

[0012] (4) The refined molten steel is cast in a protective manner, with a continuous casting superheat of 25-40°C and a casting speed of 0.70-0.80 m / min. Electromagnetic stirring of the crystallizer is used to improve the uniformity of alloy element precipitation, and the remaining steel in the ladle is ≥5 tons;

[0013] (5) The continuous casting billet is hot fed into a heating furnace at a temperature of ≥550°C, and then heated at a temperature of 1180-1250°C for 2.0-3.0 hours. After heating, the billet is fed into a continuous rolling mill for multiple passes;

[0014] (6) The rolled steel is transported to the cooling bed and slowly cooled using an insulation cover. The temperature entering the slow cooling pit is ≥400℃.

[0015] Preferably, the cooling step further includes flaw detection and finishing steps, wherein the cooled steel is flaw detected by a flaw detector, and the steel that passes the flaw detection is ground and punched to obtain a qualified finished product.

[0016] Preferably, in step (1), audio slagging technology is used to monitor the sound intensity in the furnace in real time. When the audio trend curve exceeds the splashing line, the gun position is lowered or the blowing volume is reduced to control the splashing; when the audio trend curve is lower than the return line, the gun position is raised to increase the oxygen flow and contact area, and / or iron-containing oxides are added to increase the iron oxide content in the slag.

[0017] Preferably, the composition and weight content of the slag in step (1) are CaO 40%-50%, Al2O3 10%-30%, and SiO2 10%-30%.

[0018] Preferably, in step (4), a dual electromagnetic stirring technology combining mold electromagnetic stirring (M-EMS) and solidification end electromagnetic stirring (F-EMS) is adopted, wherein the M-EMS parameter is 300-400A / 2Hz and the F-EMS parameter is 300-500A / 8Hz.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are:

[0020] This invention improves the purity and quality of steel by rationally designing its chemical composition and reducing the gas content and non-metallic inclusions in the steel through converter smelting and refining processes. The continuous casting process significantly improves the compositional segregation of the continuous casting ingot by controlling superheat and employing dual electromagnetic stirring technology, thereby increasing the density of the ingot. This achieves comprehensive improvements in steel properties such as strength, hardness, toughness, wear resistance, and hardenability, while also reducing the size and number of non-metallic inclusions and central carbon segregation, ensuring the required purity and structural uniformity of the steel, and providing high-quality, high-performance steel products for high-end applications. DETAILED DESCRIPTION

[0021] In order to better understand the present invention, the following is a detailed description with reference to the embodiments.

[0022] Example 1

[0023] A method for manufacturing micro-alloyed lead screw guide rail steel comprises the following steps:

[0024] (1) Converter smelting

[0025] During the blowing process of molten iron produced in a converter (BOF), the main blowing operation (i.e., the main blowing time) lasts 15 minutes. After the main blowing, an additional blowing time (i.e., the re-blowing time) is performed for 2 minutes to further optimize the blowing effect. The blowing process utilizes audio slag removal technology. During the converter steelmaking process, the state of the slag is crucial for dephosphorization and desulfurization, as well as for preventing splashing and backwash. Traditionally, determining slag state relies primarily on operator experience, which is subject to significant uncertainty. Audio slag removal technology uses audio acquisition equipment to monitor the sound intensity within the furnace in real time. Based on the sound trend, the system automatically determines whether the current blowing state is in the optimal state between splashing and backwash. When the audio trend curve exceeds the splashing line, the slag is too thin and splashing may occur. In this case, the operator should immediately take measures to lower the gun position or reduce the air blow volume to reduce the oxygen flow and impact depth, thereby controlling splashing. When the audio frequency curve falls below the dry-out line, the slag is too viscous and may dry out. Operators should raise the lance position to increase oxygen flow and contact area. They can also consider adding an appropriate amount of iron oxides, such as iron scale or iron ore, to increase the iron oxide content in the slag, thereby improving the slag condition and eliminating dry-out. Audio frequency slagging technology effectively avoids quality issues such as unacceptable endpoint temperature and substandard carbon, sulfur, and phosphorus content caused by poor slag condition.

[0026] During the tapping process, deoxidizers and alloying materials are added to the ladle for deoxidation and alloying. Slag blocks are also used. After tapping, pre-melted synthetic slag, specifically designed for refining, is added to the ladle surface to pre-melt the slag at the converter tapping temperature, creating conditions for refining, deoxidation, and inclusion removal. The slag composition and weight percentages are 40%-50% CaO, 10%-30% Al2O3, and 10%-30% SiO2, with an addition rate of 800-1200 kg per ladle. The final molten steel has a C content of 0.16% and a P content of 0.011%.

[0027] (2) Refining outside the furnace

[0028] Molten steel from the converter is hoisted into the LF refining facility, where it is deoxidized with ferrosilicon powder and carbon powder. Argon is blown throughout the refining process to further remove impurities and gases from the molten steel. The argon flow rate is set at 300 NL / min for the first 20 minutes to accelerate slagging, and 70 NL / min for the last 20 minutes to reduce contact between the molten steel and air and improve its purity.

[0029] (3) RH vacuum refining

[0030] Under vacuum conditions, gases and inclusions in the molten steel are removed by blowing oxygen, etc. In this embodiment, the vacuum degree is 67 Pa, maintained for 25 minutes, and the soft blowing time is 21 minutes, ensuring that the molten steel reaches 6 cycles in the vacuum chamber to fully remove gases and inclusions in the steel.

[0031] (4) Continuous casting

[0032] After refining, the molten steel is cast in a protective casting process at a casting speed of 0.77 m / min and a continuous casting superheat of 32-33°C. This superheat ensures sufficient fluidity for smooth casting into the mold while avoiding internal defects caused by excessive superheat and cracking caused by excessive superheat. It also meets the requirements of soft reduction and end-of-solidification electromagnetic stirring (EMS) technologies, ensuring their optimal performance. Electromagnetic stirring (EMS) in the mold is used during continuous casting to improve the uniformity of alloying element precipitation, with a bulk steel reserve of ≥5 tons. This implementation utilizes a dual electromagnetic stirring technology combining mold electromagnetic stirring (M-EMS) and end-of-solidification electromagnetic stirring (F-EMS), with M-EMS parameters of 300A / 2Hz and F-EMS parameters of 500A / 8Hz. This technology significantly improves compositional segregation in the continuous casting ingot, increases density, and reduces defects such as central porosity and shrinkage cavities. It also refines grain size, increases the equiaxed grain ratio, and significantly enhances ingot quality.

[0033] (5) Heating

[0034] The continuous casting billet is sent hot into the heating furnace with a temperature of 605℃ and a soaking temperature of 1201℃. The heating time in the furnace is 2.3h. The heating temperature and sufficient heating time can improve the segregation of the steel, further improve the segregation problem of the steel, and improve the structural uniformity and performance stability of the steel.

[0035] (6) Rolling

[0036] After heating, the steel is put into a continuous rolling mill for multiple rolling passes to obtain a screw guide rail steel with a specification of Φ45mm, wherein the starting rolling temperature is 1050℃ and the finishing rolling temperature is 831℃;

[0037] (7) Cooling

[0038] The rolled steel is transported to the cooling bed and slowly cooled using an insulation cover. The temperature entering the slow cooling pit is 403°C.

[0039] (8) Flaw detection and finishing

[0040] The cooled steel is inspected with a flaw detector, and the qualified steel is ground and punched to obtain qualified finished products.

[0041] The component contents of the screw guide steel smelted by the above steps are C 0.50%, Si 0.35%, Mn 0.98%, P 0.013%, S 0.004%, Cr 0.40%, Mo 0.01%, Ni 0.02%, Al 0.015%, Cu 0.01%, Ca 0.0001%, Ti 0.0007%, O 0.00058%, and the balance is Fe and unavoidable impurities.

[0042] Example 2

[0043] A method for manufacturing micro-alloyed lead screw guide rail steel comprises the following steps:

[0044] (1) Converter smelting

[0045] Molten iron is smelted in a converter, with a main blowing time of 15 minutes and a secondary blowing time of 2 minutes. During the tapping process, deoxidizers and alloying materials are added to the ladle for deoxidation and alloying. A sliding plate is used to block slag. After tapping, a pre-melted synthetic slag specifically designed for refining is added to the ladle surface to pre-melt the slag at the converter tapping temperature, creating conditions for refining, deoxidation, and inclusion removal. The slag composition and weight percentages are 40%-50% CaO, 10%-30% Al2O3, and 10%-30% SiO2, with an addition rate of 800-1200 kg per furnace. The final molten steel contains 0.13% C and 0.010% P.

[0046] (2) Refining outside the furnace

[0047] Molten steel from the converter is hoisted into the LF refining facility, where it is deoxidized with ferrosilicon powder and carbon powder. Argon is blown throughout the refining process to further remove impurities and gases from the molten steel. The argon flow rate is set at 350 NL / min for the first 20 minutes to accelerate slagging, and 65 NL / min for the last 20 minutes to reduce contact between the molten steel and air and improve its purity.

[0048] (3) RH vacuum refining

[0049] Under vacuum conditions, gases and inclusions in the molten steel are removed by blowing oxygen, etc. In this embodiment, the vacuum degree is 67 Pa, maintained for 23 minutes, and the soft blowing time is 25 minutes, ensuring that the molten steel reaches 6 cycles in the vacuum chamber to fully remove gases and inclusions in the steel.

[0050] (4) Continuous casting

[0051] The refined molten steel is cast in a protective casting process with a casting speed of 0.75m / min and a continuous casting superheat of 27-29°C. During the continuous casting process, electromagnetic stirring of the crystallizer is used to improve the uniformity of alloy element precipitation, and the remaining steel in the bulk ladle is ≥5 tons. This implementation adopts a dual electromagnetic stirring technology that combines crystallizer electromagnetic stirring (M-EMS) and solidification end electromagnetic stirring (F-EMS), where the M-EMS parameters are 350A / 2Hz and the F-EMS parameters are 450A / 8Hz. This can significantly improve the composition segregation problem of the continuous casting billet, improve the density of the billet, reduce defects such as central porosity and shrinkage, and at the same time refine the grain size, increase the equiaxed crystal ratio, and significantly improve the billet quality.

[0052] (5) Heating

[0053] The continuous casting billet is sent hot into the heating furnace with a temperature of 610℃, a soaking temperature of 1199℃ and a heating time of 2.2h in the furnace. The heating temperature and sufficient heating time can improve the segregation of the steel, further improve the segregation problem of the steel and improve the structural uniformity and performance stability of the steel.

[0054] (6) Rolling

[0055] After heating, the steel is put into a continuous rolling mill for multiple rolling passes to obtain a screw guide rail steel with a specification of Φ50mm, wherein the starting rolling temperature is 1045℃ and the finishing rolling temperature is 837℃;

[0056] (7) Cooling

[0057] The rolled steel is transported to the cooling bed and slow-cooled using a heat preservation cover. The temperature entering the slow-cooling pit is 407°C.

[0058] (8) Flaw detection and finishing

[0059] The cooled steel is inspected with a flaw detector, and the qualified steel is ground and punched to obtain qualified finished products.

[0060] The component contents of the screw guide steel smelted by the above steps are C 0.49%, Si 0.28%, Mn 0.99%, P 0.011%, S 0.004%, Cr 0.41%, Mo 0.02%, Ni 0.01%, Al 0.017%, Cu 0.02%, Ca 0.0002%, Ti 0.0008%, O 0.00059%, and the balance is Fe and unavoidable impurities.

[0061] Example 3

[0062] A method for manufacturing micro-alloyed lead screw guide rail steel comprises the following steps:

[0063] (1) Converter smelting

[0064] Molten iron is smelted in a converter, with a main blowing time of 15 minutes and a secondary blowing time of 2 minutes. During the tapping process, deoxidizers and alloying materials are added to the ladle for deoxidation and alloying. A sliding plate is used to block slag. After tapping, a pre-melted synthetic slag specifically designed for refining is added to the ladle surface to pre-melt the slag at the converter tapping temperature, creating conditions for refining, deoxidation, and inclusion removal. The slag composition and weight percentages are 40%-50% CaO, 10%-30% Al2O3, and 10%-30% SiO2, with an addition rate of 800-1200 kg per furnace. The final molten steel contains 0.13% C and 0.010% P.

[0065] (2) Refining outside the furnace

[0066] Molten steel from the converter is hoisted into the LF refining facility, where it is deoxidized with ferrosilicon powder and carbon powder. Argon is blown throughout the refining process to further remove impurities and gases from the molten steel. The argon flow rate is set at 350 NL / min for the first 20 minutes to accelerate slagging, and 65 NL / min for the last 20 minutes to reduce contact between the molten steel and air and improve its purity.

[0067] (3) RH vacuum refining

[0068] Under vacuum conditions, gases and inclusions in the molten steel are removed by blowing oxygen, etc. In this embodiment, the vacuum degree is 67 Pa, maintained for 23 minutes, and the soft blowing time is 25 minutes, ensuring that the molten steel reaches 6 cycles in the vacuum chamber to fully remove gases and inclusions in the steel.

[0069] (4) Continuous casting

[0070] The refined molten steel is cast in a protective casting process with a casting speed of 0.75m / min and a continuous casting superheat of 27-29°C. During the continuous casting process, electromagnetic stirring of the crystallizer is used to improve the uniformity of alloy element precipitation, and the remaining steel in the bulk ladle is ≥5 tons. This implementation adopts a dual electromagnetic stirring technology that combines crystallizer electromagnetic stirring (M-EMS) and solidification end electromagnetic stirring (F-EMS), where the M-EMS parameters are 350A / 2Hz and the F-EMS parameters are 450A / 8Hz. This can significantly improve the composition segregation problem of the continuous casting billet, improve the density of the billet, reduce defects such as central porosity and shrinkage, and at the same time refine the grain size, increase the equiaxed crystal ratio, and significantly improve the billet quality.

[0071] (5) Heating

[0072] The continuous casting billet is sent hot into the heating furnace with a temperature of 610℃, a soaking temperature of 1199℃ and a heating time of 2.2h in the furnace. The heating temperature and sufficient heating time can improve the segregation of the steel, further improve the segregation problem of the steel and improve the structural uniformity and performance stability of the steel.

[0073] (6) Rolling

[0074] After heating, the steel is put into a continuous rolling mill for multiple rolling passes to obtain a screw guide rail steel with a specification of Φ50mm, wherein the starting rolling temperature is 1045℃ and the finishing rolling temperature is 837℃;

[0075] (7) Cooling

[0076] The rolled steel is transported to the cooling bed and slow-cooled using a heat preservation cover. The temperature entering the slow-cooling pit is 407°C.

[0077] (8) Flaw detection and finishing

[0078] The cooled steel is inspected with a flaw detector, and the qualified steel is ground and punched to obtain qualified finished products.

[0079] The component contents of the screw guide steel smelted by the above steps are C 0.51%, Si 0.24%, Mn 0.98%, P 0.013%, S 0.004%, Cr 0.39%, Mo 0.01%, Ni 0.02%, Al 0.018%, Cu 0.01%, Ca 0.0001%, Ti 0.0008%, O 0.00058%, and the balance is Fe and unavoidable impurities.

[0080] Comparative Example 1

[0081] This embodiment adopts existing technology to produce 55 steel, and its specific steps are as follows:

[0082] (1) Converter smelting process: Molten steel C: 0.09%, P: 0.009%.

[0083] (2) LF refining process: Calcium carbide and carbon powder are used for deoxidation, and argon is blown throughout the refining process. The argon flow rate is 40NL / min 20 minutes before refining and 250NL / min after 20 minutes.

[0084] (3) Continuous casting process: The tundish superheat is 20-22°C, and the pouring speed is controlled at 0.75 m / min. A dual electromagnetic stirring technology combining mold electromagnetic stirring (M-EMS) and end-of-solidification electromagnetic stirring (F-EMS) is adopted, where the M-EMS parameter is 300 A / 2 Hz and the F-EMS parameter is 500 A / 8 Hz.

[0085] (4) Heating process: The soaking temperature is 1211°C and the heating time in the furnace is 1.5 hours.

[0086] (5) Rolling process: After heating, the steel is put into the continuous rolling mill for multiple rolling to obtain 55 steel for screw guide rails with a specification of Φ40 mm, wherein the starting rolling temperature is 1055°C and the finishing rolling temperature is 801°C.

[0087] (6) Cooling process: Cooling bed cover insulation cover, slow cooling temperature 315℃.

[0088] The 55 steel for the screw guide rail smelted by the above steps has the following component contents: C 0.55%, Si 0.27%, Mn 0.60%, P 0.012%, S 0.001%, Cr 0.03%, Mo 0.01%, Ni 0.01%, Al 0.020%, Cu 0.01%, Ca 0.0004%, Ti 0.0006%, O 0.0015%, and the balance is Fe and unavoidable impurities.

[0089] Comparative Example 2

[0090] This embodiment adopts the existing technology to produce S55C steel, and its specific steps are as follows:

[0091] (1) Converter smelting process: Molten steel C: 0.01%, P: 0.010%.

[0092] (2) LF refining process: Calcium carbide and carbon powder are used for deoxidation. Argon is blown throughout the refining process. The argon flow rate is 550 NL / min 20 minutes before refining and 185 NL / min after 20 minutes.

[0093] (3) RH vacuum refining process: vacuum degree 133Pa, maintain for 10 minutes; soft blowing time 15 minutes.

[0094] (4) Continuous casting process: The tundish superheat is 15-20°C, and the pouring speed is controlled at 0.70 m / min. A dual electromagnetic stirring technology combining mold electromagnetic stirring (M-EMS) and end-of-solidification electromagnetic stirring (F-EMS) is adopted, where the M-EMS parameters are 150 A / 2 Hz and the F-EMS parameters are 550 A / 8 Hz.

[0095] (5) Heating process: The soaking temperature is 1220°C and the heating time in the furnace is 1.8 hours.

[0096] (6) Rolling process: After heating, the steel is put into a continuous rolling mill for multiple rolling passes to obtain S55C steel for screw guide rails with a specification of Φ55 mm. The starting rolling temperature is 1071°C and the finishing rolling temperature is 811°C.

[0097] (7) Cooling bed cover insulation cover, slow cooling temperature 355℃.

[0098] The S55C steel for the screw guide smelted by the above steps has the following component contents: C 0.56%, Si 0.28%, Mn 0.75%, P 0.010%, S 0.002%, Cr 0.10%, Mo 0.01%, Ni 0.01%, Al 0.020%, Cu 0.01%, Ca 0.0003%, Ti 0.0010%, O 0.0018%, and the balance is Fe and unavoidable impurities.

[0099] The steels prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to mechanical property tests, and the test results are shown in Table 2. It can be seen from Table 2 that the micro-alloyed screw guide rail steels prepared in Examples 1-3 have significantly improved tensile strength, hardness and hardenability compared with the 55 and S55C screw guide rail steels commonly used in the prior art.

[0100] Table 2 Mechanical properties

[0101]

[0102] The steels prepared in Examples 1-3 and Comparative Examples 1-2 were scanned for inclusions larger than 5μm. The results are shown in Table 3. As can be seen from Table 3, the microalloyed lead screw guide rail steels prepared in Examples 1-3 exhibit superior inclusion counts and maximum inclusion sizes compared to the 55 and S55C steels commonly used for lead screw guide rails in the prior art. With fewer and smaller inclusions, the fatigue life of the steel is correspondingly extended, and the risk of fatigue failure when subjected to cyclic stress is also reduced.

[0103] Table 3 Inclusion scanning results

[0104] Example Scanning area Number of inclusions Maximum inclusion size / μm Example 1 <![CDATA[150mm 3 ]]> 103 21 Example 2 <![CDATA[150mm 3 ]]> 118 33 Example 3 <![CDATA[150mm 3 ]]> 74 17 Comparative Example 1 <![CDATA[150mm 3 ]]> 699 53 Comparative Example 2 <![CDATA[150mm 3 ]]> 662 44

[0105] In addition, it was detected that the carbon content in the central carbon segregation area of ​​the steel prepared in Examples 1-3 of the present invention did not exceed 5% of the normal smelting carbon content, and the central carbon segregation was significantly limited, thereby ensuring the structural uniformity of the steel.

[0106] The above description is merely a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any person skilled in the art may utilize the technical contents disclosed above to change or modify them into equivalent embodiments with equivalent changes for application in other fields. However, any simple modification, equivalent change, and modification of the above embodiments made in accordance with the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A micro-alloyed steel for a lead screw guide rail, characterized in that: Its main components are as follows in weight percentage: C 0.45-0.55%, Si 0.20-0.35%, Mn 0.90-1.00%, Cr 0.35-0.45%, P≤0.020%, S≤0.010%, Mo≤0.2%, Ni≤0.2%, Al0.01%-0.05%, Cu≤0.2%, Ca≤0.0008%, Ti≤0.002%, O≤0.0012%, and the balance is Fe and unavoidable impurities.

2. The microalloyed steel for lead screw guide rail according to claim 1, characterized in that: Its main components in weight percentage are: C 0.51%, Si 0.24%, Mn 0.98%, Cr0.39%, P≤0.013%, S≤0.004%, Mo≤0.01%, Ni≤0.02%, Al 0.018%, Cu≤0.01%, Ca≤0.0001%, Ti≤0.0008%, O≤0.00058%, and the balance is Fe and unavoidable impurities.

3. A method for manufacturing micro-alloyed screw guide steel, characterized in that: The following steps are involved: (1) A converter is used to smelt molten iron. During the blowing process, the main blowing time is 14-16 minutes and the secondary blowing time is 1-2 minutes. During the blowing process, an audio device is used to monitor the sound in the furnace in real time, and the gun position and blowing volume are adjusted according to the sound. The carbon content is controlled to be ≥0.10% during steel tapping. During the steel tapping process, deoxidizer and alloy material are added to the ladle for deoxidation and alloying. At the same time, a slide plate is used to block slag. After steel tapping, a special pre-melted synthetic slag material for refining is added to the surface of the ladle to use the converter tapping temperature to melt the slag in advance. (2) The molten steel is hoisted to the LF refining equipment for refining, refining agent is added and argon is used for stirring. The argon flow rate is 200-500NL / min in the early stage and 50-200NL / min in the later stage; (3) Removing gases and inclusions from molten steel under vacuum conditions; (4) The refined molten steel is cast in a protective manner, with a continuous casting superheat of 25-40°C and a casting speed of 0.70-0.80 m / min. Electromagnetic stirring of the crystallizer is used to improve the uniformity of alloy element precipitation, and the remaining steel in the ladle is ≥5 tons; (5) The continuous casting billet is hot fed into a heating furnace at a temperature of ≥550°C, and then heated at a temperature of 1180-1250°C for 2.0-3.0 hours. After heating, the billet is fed into a continuous rolling mill for multiple passes; (6) The rolled steel is transported to the cooling bed and slowly cooled using an insulation cover. The temperature entering the slow cooling pit is ≥400℃.

4. The method for manufacturing microalloyed lead screw guide rail steel according to claim 1, wherein: After the cooling step, the process also includes flaw detection and finishing steps, in which the cooled steel is inspected with a flaw detector, and the steel that passes the flaw detection is ground and punched to obtain a qualified finished product.

5. The method for manufacturing microalloyed lead screw guide rail steel according to claim 1, wherein: In step (1), the audio slagging technology is used to monitor the sound intensity in the furnace in real time. When the audio trend curve exceeds the splashing line, the gun position is lowered or the blowing volume is reduced to control the splashing; when the audio trend curve is lower than the return line, the gun position is raised to increase the oxygen flow and contact area, and / or iron-containing oxides are added to increase the iron oxide content in the slag.

6. The method for manufacturing microalloyed lead screw guide rail steel according to claim 1, wherein: The composition and weight content of the slag in step (1) are CaO 40%-50%, Al2O3 10%-30%, and SiO2 10%-30%.

7. The method for manufacturing microalloyed lead screw guide rail steel according to claim 1, wherein: In step (4), a dual electromagnetic stirring technology combining mold electromagnetic stirring (M-EMS) and solidification end electromagnetic stirring (F-EMS) is adopted, wherein the M-EMS parameter is 300-400A / 2Hz, and the F-EMS parameter is 300-500A / 8Hz.

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