Hot-rolled wire rod for elevator steel wire rope with high compression ratio and production process

Abstract

The invention discloses a hot-rolled wire rod for a high-compression-ratio elevator steel wire rope and a production process, and belongs to the technical field of steel smelting processing, the hot-rolled wire rod for the high-compression-ratio elevator steel wire rope comprises the following components in percentage by mass: 0.70-0.74% of C, 0.17-0.27% of Si, 0.50-0.55% of Mn, less than or equal to 0.15% of Cr, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.30% of Ni, less than or equal to 0.25% of Cu, less than or equal to 0.007% of Al, less than or equal to 0.0050% of Pb, less than or equal to 0.0050% of Sn, less than or equal to 0.0100% of As, less than or equal to 0.0050% of Sb, by improving the production process of the casting blank, the rolling process with the large compression ratio (277.8) is achieved, that is, a large round blank with the diameter phi being 250 mm is rolled into the steel wire rod for the elevator steel wire rope with the diameter being 15 mm, the density and strength of the wire rod are further improved, meanwhile, the internal quality defects of the wire rod are relieved, and the quality and performance of the wire rod are improved; and the percent of pass of the wire rod reaches 99.7% or above, that is, the uniformity and the strength of the wire rod are effectively improved by improving the core part quality of the wire rod.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting and processing, in particular to a hot-rolled wire rod for a high-compression ratio elevator steel wire rope and a production process. Background Art

[0002] The elevator traction wire rope is an important part of the elevator suspension device and the core safety component of the elevator operation. It bears the weight of the car and counterweight, and relies on the friction between it and the traction wheel rope groove to transmit the power generated by the traction machine to the car and drive it to move up and down. During the operation of the elevator, the traction wire rope reciprocates in both directions around the traction wheel, guide wheel or anti-rope wheel. During this process, the wire rope needs to withstand unidirectional or bidirectional bending stress. Therefore, the quality of the wire rope is directly related to the safety and reliability of the elevator. If there is a problem with the elevator wire rope, it may cause the elevator to lose control or fall, which will bring great threats to people's lives and property safety.

[0003] The existing wire rod rolling is to roll 150×150mm square billet into 15mm wire rod (compression area ratio is 31.85), and the rolling process generally adopts one fire and two fires. The average sorbite rate of the wire rod obtained is 80%, the average tensile strength is 1180MPa, and the average cross-sectional shrinkage is 25%. With the rise of high-rise buildings and high-speed elevators, higher requirements are placed on the safety and reliability of elevator wire ropes. When cooling traditional square billets, the cooling speed of the edges and corners is faster than that of the center, which easily causes internal and external temperature differences and stress concentration, thus affecting the grain size and uniformity of the wire rod, resulting in insufficient product performance and restricting the development of the industry. Summary of the invention

[0004] In order to solve the existing technical problems, the present invention provides a hot-rolled wire rod for elevator wire rope with high compression ratio and a production process. The present application realizes a large compression ratio (277.8) rolling process by improving the production process of the ingot, that is, a φ250mm large round billet is rolled into a 15mm wire rod for elevator wire rope, so that the density and strength of the wire are further improved, while the internal quality defects of the wire are alleviated, the quality and performance of the wire are improved, and the qualified rate of the wire reaches more than 99.7%, that is, by improving the quality of the core of the wire rod, the uniformity and strength of the wire rod are effectively improved.

[0005] The first aspect of the present invention is to provide a hot-rolled wire rod for elevator steel wire rope with a high compression ratio, which adopts the following technical scheme: A hot-rolled wire rod for a high compression ratio elevator steel wire rope, the wire rod comprising the following components in mass percentage: C: 0.70-0.74%, Si: 0.17-0.27%, Mn: 0.50-0.55%, Cr: ≤0.15%, P: ≤0.020%, S: ≤0.015%, Ni: ≤0.30%, Cu: ≤0.25%, Al: ≤0.007%, Pb: ≤0.0050%, Sn: ≤0.0050%, As: ≤0.0100%, Sb: ≤0.0050%, Bi: ≤0.0050%, and the balance being iron and unavoidable impurities.

[0006] In a preferred embodiment, the wire rod has a tensile strength of >980 MPa, an elongation of >10%, and a cross-sectional reduction of >30%.

[0007] The second aspect of the present invention is to provide a production process for hot-rolled wire rods for high compression ratio elevator steel wire ropes, including S1, converter smelting, S2, LF furnace refining, S3, continuous casting, S4, rolling, wherein in step S1, constant gun variable pressure operation is adopted, and the oxygen pressure during oxygen blowing smelting is: 0-6min oxygen pressure is 0.7-0.9MPa, 7-10min oxygen pressure is 1.2-1.4MPa, 11-15min oxygen pressure is 1.0-1.2MPa, 16-18min oxygen pressure is 1.3-1.5MPa; oxygen flow rate: bottom blowing flow rate is 0.1-0.2m 3 / (min·t).

[0008] The continuous casting process parameters in step S3 are superheat 18-40°C, casting speed 0.8-1.05m / min, secondary cooling water volume 0.6L / kg, surface crystallizer electromagnetic stirring current 480A, frequency 3Hz, solidification end electromagnetic stirring current 500A, stirring frequency 10Hz.

[0009] In a preferred embodiment, the installation position of the electromagnetic stirring at the end of solidification is determined by the following criteria: the solid phase fraction fsc at the center of the ingot is 0.1-0.2, the solidification fraction Ds of the ingot is 0.7-0.8, and the width of the two-phase zone of the liquid phase hole is 40-50 mm.

[0010] In a preferred embodiment, the electromagnetic stirring installation position at the end of solidification is 9.75m away from the meniscus of the crystallizer.

[0011] In a preferred embodiment, the surface crystallizer electromagnetic stirring adopts continuous stirring, and the solidification end electromagnetic stirring adopts alternating stirring, and the conditions are 10s-3s-10s.

[0012] In a preferred embodiment, in the rolling process of step S4, the temperature of the billet heating section is 1080±10°C, the temperature of the soaking section is 1060±10°C, the heating time is 80-120min, the opening temperature is 980-1020°C, and the finishing rolling temperature is 920-940°C.

[0013] In a preferred embodiment, in the rolling process of step S4, the spinning temperature is 860-880°C, the first roller speed of the Stelmore air-cooled line is 0.90m / s, and the roller speeds of each section are set to 0.98m / s, 1.07m / s, 1.17m / s, 1.27m / s, 1.38m / s, 1.41m / s, 1.44m / s, 1.47m / s, 1.50m / s, 1.38m / s, 1.22m / s, and 1.22m / s respectively.

[0014] In summary, the present invention has the following beneficial effects: In the wire rolling process, the present application improves the quality and stability of the billet by improving the production process of the billet, meets the requirements of the large-section high compression ratio rolling process, and thus improves the quality and performance of the wire. The preparation process in the present application has the following advantages: first, the large-section high compression ratio rolling process can greatly compress the diameter of the billet, improve the density of the material, and improve the strength and toughness of the wire; second, in the large-section high compression ratio rolling process, multiple rolling processes are required, and each rolling process will refine the grains of the wire, further improving the strength and toughness of the wire. In addition, the large-section high compression ratio rolling process adopts high compression ratio technology, which can shorten the time of each rolling process, improve production efficiency, and reduce production costs. In the rolling process, if the compression ratio is too small, the defects such as pores and inclusions inside the wire will not be effectively improved, thereby affecting the quality and performance of the wire. The large-section high compression ratio rolling process can greatly compress the diameter of the billet, further improve the density and strength of the wire, and thus effectively alleviate the internal quality defects of the wire.

[0015] The constant gun variable pressure operation in the converter solves the technical difficulties such as low blowing efficiency and poor dephosphorization effect under the conventional operation mode. Moreover, the constant gun variable pressure operation mode can improve the slag making and slag melting efficiency, avoid splashing and reduce metal loss.

[0016] The large-flow double-blowing process of the converter can quickly oxidize impurities and gases in molten steel, thereby improving the quality and purity of the molten steel. It can also effectively control the temperature and composition of the molten steel, improving the uniformity and stability of the molten steel. In addition, the large-flow double-blowing process can quickly and accurately complete the oxygen blowing process, thereby shortening the steelmaking time, increasing the output and efficiency of molten steel, and reducing energy consumption and costs in the steelmaking process. At the same time, it can also reduce waste gas emissions and oxidation reactions in the steelmaking process, reducing environmental pollution.

[0017] By determining the parameters of electromagnetic stirring of the surface crystallizer and electromagnetic stirring at the end of solidification as well as the installation position of electromagnetic stirring at the end of solidification, the V-shaped segregation in the center of the ingot and the white bright band on the edge are basically eliminated. At the same time, the quality of the center of the ingot is improved, and internal defects such as shrinkage cavity, central shrinkage and central segregation are effectively controlled. The equiaxed crystal rate of the ingot is increased, the central carbon segregation index is reduced, and the quality of the continuous casting ingot is significantly improved.

[0018] When the opening temperature is controlled within the range of 975-1000℃, the grains can be quickly refined and homogenized, and the grain coarsening behavior caused by excessively high temperature during the rolling deformation process can be suppressed. The higher the opening temperature, the larger the austenite grain size. After the wire rod enters the finishing mill, the speed is fast and the deformation rate is large, so the effect of temperature on the grain size of the wire rod is more obvious. Therefore, lowering the wire rod temperature when entering the finishing mill is beneficial to grain refinement.

[0019] After the spinning temperature increases, the starting temperature of the pearlite phase transformation decreases. This is because from the end of fine rolling to the spinning process, due to the increase in temperature, the dislocations in the deformed austenite grains recover more completely, resulting in increased austenite stability, increased phase transformation supercooling, and a lower starting point of the phase transformation temperature. These changes will be beneficial to the refinement of the troostite lamellae.

[0020] The electromagnetic stirring condition at the end of solidification is to stir for 10 seconds, stop for 3 seconds, and then stir for 10 seconds. This can optimize the fluidity of molten steel during continuous casting and help improve the microstructure of the casting, such as refining the grains, reducing center segregation and defects, thereby improving the overall quality and performance of the casting. Moreover, this alternating stirring method provides a more suitable fluid mechanics environment by breaking the excessive mixing that may be caused by continuous stirring, which helps to promote the uniform distribution of internal components of the material, while reducing energy consumption and avoiding the adverse effects that may be caused by excessive stirring. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the embodiments.

[0022] The inventors have found through a large number of experiments that rolling round billets into wire rods has a series of advantages over rolling square billets into wire rods, which are mainly reflected in the following aspects: 1. Forming efficiency and energy saving: Since the shape of the round billet is closer to the final circular cross-section of the wire, the degree of deformation required during the rolling process is smaller, which not only reduces the number of rolling passes and shortens the processing path, but also saves a lot of energy consumption; compared with the square billet, the round billet can reach the required size faster and more energy-efficiently when entering the rolling mill in the initial hot state.

[0023] 2. Surface quality and internal structure: Due to its uniform shape, the cooling rate of the round billet is relatively consistent across the entire cross section, which helps to obtain better internal structure and external surface quality. However, the cooling rate of the edges and corners of the square billet is faster than that of the center, which can easily cause internal and external temperature differences and stress concentration, affecting the performance of the final product. In contrast, the temperature distribution of the round billet is more uniform during the entire cooling process, which can reduce internal stress and improve the mechanical properties of the product.

[0024] 3. Dimensional accuracy and geometric consistency: The round billet is easier to maintain dimensional consistency during subsequent processing, which is especially important for precision wires that require strict tolerance control. The round billet is not prone to flattening or twisting during heat treatment and cold processing, and maintains a good geometric shape, ensuring the dimensional accuracy and straightness of the product.

[0025] 4. Raw material utilization and cost efficiency: Since round billets can be directly produced by continuous casting machines, the process of billet remelting and secondary casting is omitted, which reduces the generation of waste. In addition, the conversion loss from round billets to wire rods is less, which reduces material waste and improves the overall utilization of raw materials, thereby reducing unit costs.

[0026] 5. Flexibility and diversity: Round billets are suitable for the production of wires of various specifications and materials. The diameter can be easily adjusted to meet different market and customer needs. This flexibility provides manufacturers with greater choice to meet diverse product needs.

[0027] In addition, the present application adopts a φ250mm large-section, large-compression ratio, one-fire material production process. Compared with the two-fire material production process of square billets, the rolling process of the present application can significantly save more than 30% of gas consumption, and the comprehensive energy consumption index is at the international leading level.

[0028] Example 1 A production process for hot-rolled wire rod for high compression ratio elevator wire rope, comprising the following steps: S1. Converter smelting 95t of molten iron and 30t of scrap steel are added to the converter. The temperature of the molten iron entering the converter is ≥1280℃, P≤0.100%, S≤0.020%, Ti≤0.065%, and then the constant gun voltage control system is started to start oxygen blowing smelting. The oxygen pressure from 0 to 6 minutes is 0.7MPa, the oxygen pressure from 7 to 10 minutes is 1.2MPa, the oxygen pressure from 11 to 15 minutes is 1.0MPa, and the oxygen pressure from 16 to 18 minutes is 1.3MPa; the oxygen bottom blowing flow rate is 0.1-0.2m 3 / (min·t), endpoint control C ≥ 0.10%, P ≤ 0.015%, S ≤ 0.012%, oxygen content ≤ 550ppm, tapping temperature is 1600-1620℃, pour the molten steel into the ladle; S2, LF refining The ladle inlet temperature is controlled to be ≥1480℃, the ladle hanging temperature is 1525±5℃, the molten steel is poured into the LF refining furnace, argon is blown online during the steel-making process, the argon flow rate is 100L / min, the pressure is 0.3MPa, and white ash is added in 2-3 batches to make white slag under the conditions of voltage level 6 and current of 25000A. The amount of white ash added is ≥5.33kg / ton of steel, and fluorite is added according to the fluidity of the slag. The white slag refining time is >15min. According to the amount of slag, the progress basicity is adjusted to make the total slag amount reach 10kg / ton of steel, and the basicity is 1.8-2.5. According to the target composition, alloy is added to adjust the molten steel composition, and then silicon carbide is used for slag surface deoxidation. The amount of silicon carbide is 0.4kg / ton of steel, and the whole refining cycle is 45±5min; S3, continuous casting The specification of the ingot is a round ingot with a diameter of 250mm. The casting control is as follows: from the ladle to the tundish during the continuous casting process, the tundish adopts plasma heating technology, and the tundish to the crystallizer adopts a protective casing to protect the casting throughout the process to prevent the secondary oxidation of the molten steel and ensure the purity of the molten steel. The superheat is 18°C, the constant pulling speed is 0.8m / min, the secondary cooling water volume is 0.6L / kg, the electromagnetic stirring of the surface crystallizer adopts a continuous stirring mode, the stirring current is 480A, and the frequency is 3Hz. The electromagnetic stirring at the end of solidification adopts an alternating stirring mode, the alternating conditions are 10s-3s-10s, the stirring current is 500A, and the stirring frequency is 10Hz. The installation position of the electromagnetic stirring at the end of solidification is determined as follows: the solid phase ratio fsc at the center of the ingot is 0.1-0.2, the solidification ratio Ds of the ingot is 0.7-0.8, and the width of the two-phase zone of the liquid phase hole is 40-50mm. Therefore, the installation position of the electromagnetic stirring at the end of solidification is determined to be 9.75m away from the meniscus of the crystallizer. The calculation formula of the solid phase fraction fsc at the center of the ingot is fsc=(T L -T) / (T L -T S ), where T L is the liquidus temperature, T S is the solidus temperature, T is the center temperature of the ingot; The calculation formula of the solidification rate Ds of the ingot is: Ds = A / A0, where A is the solidified area of ​​the ingot cross section, and A0 is the area of ​​the ingot cross section; S4, rolling The round billet with a diameter of 250 mm obtained in the above step S3 is subjected to heating, rough rolling, finish rolling, sizing, spinning and cooling to obtain a wire rod with a diameter of 15 mm, wherein C: 0.70%, Si: 0.17%, Mn: 0.50%, Cr: ≤0.15%, P: ≤0.020%, S: ≤0.015%, Ni: ≤0.30%, Cu: ≤0.25%, Al: ≤0.007%, Pb: ≤0.0050%, Sn: ≤0.0050%, As: ≤0.0100%, Sb: ≤0.0050%, Bi: ≤0.0050%, and the balance is iron and unavoidable impurities; The temperature of the billet heating section is 1070℃, the temperature of the soaking section is 1050℃, the heating time is 80min, the rolling start temperature is 980℃, the finishing rolling start temperature is 920℃, and the wire laying temperature is 860℃; The entire process adopts the Stelmore air cooling line to achieve large air volume controlled cooling. The speed of the first roller section is 0.90m / s, and the speeds of each roller section are set to 0.98m / s, 1.07m / s, 1.17m / s, 1.27m / s, 1.38m / s, 1.41m / s, 1.44m / s, 1.47m / s, 1.50m / s, 1.38m / s, 1.22m / s, and 1.22m / s respectively. The fan air volume is 90% for 1#-5# fans and 80% for 6# fan.

[0029] Example 2 A production process for hot-rolled wire rod for high compression ratio elevator wire rope, comprising the following steps: S1. Converter smelting 95t of molten iron and 30t of scrap steel are added to the converter. The temperature of the molten iron entering the converter is ≥1280℃, P≤0.100%, S≤0.020%, Ti≤0.065%, and then the constant gun voltage control system is started to start oxygen blowing smelting. The oxygen pressure from 0 to 6 minutes is 0.8MPa, the oxygen pressure from 7 to 10 minutes is 1.3MPa, the oxygen pressure from 11 to 15 minutes is 1.1MPa, and the oxygen pressure from 16 to 18 minutes is 1.4MPa; the oxygen bottom blowing flow rate is 0.1-0.2m 3 / (min·t), endpoint control C ≥ 0.10%, P ≤ 0.015%, S ≤ 0.012%, oxygen content ≤ 550ppm, tapping temperature is 1600-1620℃, pour the molten steel into the ladle; S2, LF refining The ladle inlet temperature is controlled to be ≥1480℃, the ladle hanging temperature is 1525±5℃, the molten steel is poured into the LF refining furnace, argon is blown online during the steel-making process, the argon flow rate is 100L / min, the pressure is 0.3MPa, and white ash is added in 2-3 batches to make white slag under the conditions of voltage level 6 and current of 25000A. The amount of white ash added is ≥5.33kg / ton of steel, and fluorite is added according to the fluidity of the slag. The white slag refining time is >15min. According to the amount of slag, the progress basicity is adjusted to make the total slag amount reach 10kg / ton of steel, and the basicity is 1.8-2.5. According to the target composition, alloy is added to adjust the molten steel composition, and then silicon carbide is used for slag surface deoxidation. The amount of silicon carbide is 0.4kg / ton of steel, and the whole refining cycle is 45±5min; S3, continuous casting The specification of the ingot is a round ingot with a diameter of 250mm. The casting control is as follows: from the ladle to the tundish during the continuous casting process, the tundish adopts plasma heating technology, and the tundish to the crystallizer adopts a protective casing to protect the casting throughout the process to prevent the secondary oxidation of the molten steel and ensure the purity of the molten steel. The superheat is 30°C, the constant pulling speed is 0.92m / min, the secondary cooling water volume is 0.6L / kg, the electromagnetic stirring of the surface crystallizer adopts a continuous stirring mode, the stirring current is 480A, and the frequency is 3Hz. The electromagnetic stirring at the end of solidification adopts an alternating stirring mode, the alternating conditions are 10s-3s-10s, the stirring current is 500A, and the stirring frequency is 10Hz. The installation position of the electromagnetic stirring at the end of solidification is determined as follows: the solid phase ratio fsc at the center of the ingot is 0.1-0.2, the solidification ratio Ds of the ingot is 0.7-0.8, and the width of the two-phase zone of the liquid phase hole is 40-50mm. Therefore, the installation position of the electromagnetic stirring at the end of solidification is determined to be 9.75m away from the meniscus of the crystallizer. The calculation formula of the solid phase fraction fsc at the center of the ingot is fsc=(T L -T) / (T L -T S ), where T L is the liquidus temperature, T S is the solidus temperature, T is the center temperature of the ingot; The calculation formula of the solidification rate Ds of the ingot is: Ds = A / A0, where A is the solidified area of ​​the ingot cross section, and A0 is the area of ​​the ingot cross section; S4, rolling The round billet with a diameter of 250 mm obtained in the above step S3 is heated, roughly rolled, finely rolled, sizing, spinning and cooled to obtain a wire rod with a diameter of 15 mm, wherein C: 0.73%, Si: 0.23%, Mn: 0.53%, Cr: ≤0.15%, P: ≤0.020%, S: ≤0.015%, Ni: ≤0.30%, Cu: ≤0.25%, Al: ≤0.007%, Pb: ≤0.0050%, Sn: ≤0.0050%, As: ≤0.0100%, Sb: ≤0.0050%, Bi: ≤0.0050%, and the balance is iron and unavoidable impurities; The temperature of the billet heating section is 1080℃, the temperature of the soaking section is 1060℃, the heating time is 100min, the rolling start temperature is 1000℃, the finishing rolling start temperature is 930℃, and the wire laying temperature is 870℃; The entire process adopts the Stelmore air cooling line to achieve large air volume controlled cooling. The speed of the first roller section is 0.90m / s, and the speeds of each roller section are set to 0.98m / s, 1.07m / s, 1.17m / s, 1.27m / s, 1.38m / s, 1.41m / s, 1.44m / s, 1.47m / s, 1.50m / s, 1.38m / s, 1.22m / s, and 1.22m / s respectively. The fan air volume is 90% for 1#-5# fans and 80% for 6# fan.

[0030] Example 3 A production process for hot-rolled wire rod for high compression ratio elevator wire rope, comprising the following steps: S1. Converter smelting 95t of molten iron and 30t of scrap steel are added to the converter. The temperature of the molten iron entering the converter is ≥1280℃, P≤0.100%, S≤0.020%, Ti≤0.065%, and then the constant gun voltage control system is started to start oxygen blowing smelting. The oxygen pressure from 0 to 6 minutes is 0.9MPa, the oxygen pressure from 7 to 10 minutes is 1.4MPa, the oxygen pressure from 11 to 15 minutes is 1.2MPa, and the oxygen pressure from 16 to 18 minutes is 1.5MPa; the oxygen bottom blowing flow rate is 0.1-0.2m 3 / (min·t), endpoint control C ≥ 0.10%, P ≤ 0.015%, S ≤ 0.012%, oxygen content ≤ 550ppm, tapping temperature is 1600-1620℃, pour the molten steel into the ladle; S2, LF refining The ladle inlet temperature is controlled to be ≥1480℃, the ladle hanging temperature is 1525±5℃, the molten steel is poured into the LF refining furnace, argon is blown online during the steel-making process, the argon flow rate is 100L / min, the pressure is 0.3MPa, and white ash is added in 2-3 batches to make white slag under the conditions of voltage level 6 and current of 25000A. The amount of white ash added is ≥5.33kg / ton of steel, and fluorite is added according to the fluidity of the slag. The white slag refining time is >15min. According to the amount of slag, the progress basicity is adjusted to make the total slag amount reach 10kg / ton of steel, and the basicity is 1.8-2.5. According to the target composition, alloy is added to adjust the molten steel composition, and then silicon carbide is used for slag surface deoxidation. The amount of silicon carbide is 0.4kg / ton of steel, and the whole refining cycle is 45±5min; S3, continuous casting The specification of the ingot is a round ingot with a diameter of 250mm. The casting control is as follows: from the ladle to the tundish during the continuous casting process, the tundish adopts plasma heating technology, and the tundish to the crystallizer adopts a protective casing to protect the casting throughout the process to prevent the secondary oxidation of the molten steel and ensure the purity of the molten steel. The superheat is 40℃, the constant pulling speed is 1.05m / min, the secondary cooling water volume is 0.6L / kg, the electromagnetic stirring of the surface crystallizer adopts a continuous stirring mode, the stirring current is 480A, and the frequency is 3Hz. The electromagnetic stirring at the end of solidification adopts an alternating stirring mode, the alternating conditions are 10s-3s-10s, the stirring current is 500A, and the stirring frequency is 10Hz. The installation position of the electromagnetic stirring at the end of solidification is determined as follows: the solid phase ratio fsc at the center of the ingot is 0.1-0.2, the solidification ratio Ds of the ingot is 0.7-0.8, and the width of the two-phase zone of the liquid phase hole is 40-50mm. Therefore, the installation position of the electromagnetic stirring at the end of solidification is determined to be 9.75m away from the meniscus of the crystallizer. The calculation formula of the solid phase fraction fsc at the center of the ingot is fsc=(T L -T) / (T L -T S ), where T L is the liquidus temperature, T S is the solidus temperature, T is the center temperature of the ingot; The calculation formula of the solidification rate Ds of the ingot is: Ds = A / A0, where A is the solidified area of ​​the ingot cross section, and A0 is the area of ​​the ingot cross section; S4, rolling The round billet with a diameter of 250 mm obtained in the above step S3 is heated, roughly rolled, finely rolled, sizing, spinning and cooled to obtain a wire rod with a diameter of 15 mm, wherein C: 0.74%, Si: 0.27%, Mn: 0.55%, Cr: ≤0.15%, P: ≤0.020%, S: ≤0.015%, Ni: ≤0.30%, Cu: ≤0.25%, Al: ≤0.007%, Pb: ≤0.0050%, Sn: ≤0.0050%, As: ≤0.0100%, Sb: ≤0.0050%, Bi: ≤0.0050%, and the balance is iron and unavoidable impurities; The temperature of the billet heating section is 1090℃, the temperature of the soaking section is 1070℃, the heating time is 120min, the rolling start temperature is 1020℃, the finishing rolling start temperature is 940℃, and the wire laying temperature is 880℃; The entire process adopts the Stelmore air cooling line to achieve large air volume controlled cooling. The speed of the first roller section is 0.90m / s, and the speeds of each roller section are set to 0.98m / s, 1.07m / s, 1.17m / s, 1.27m / s, 1.38m / s, 1.41m / s, 1.44m / s, 1.47m / s, 1.50m / s, 1.38m / s, 1.22m / s, and 1.22m / s respectively. The fan air volume is 90% for 1#-5# fans and 80% for 6# fan.

[0031] Comparative Example 1 A production process for hot-rolled wire rods for high compression ratio elevator steel wire ropes, which differs from Example 1 in that, in step S1 converter smelting, the pressure of oxygen during oxygen blowing smelting is 1.0 MPa, and the rest is the same as Example 1.

[0032] Comparative Example 2 A production process for hot-rolled wire rods for high compression ratio elevator wire ropes, which is different from Example 1 in that in step S3 continuous casting, the electromagnetic stirring at the end of solidification adopts a continuous stirring method, and the rest is the same as Example 1.

[0033] Comparative Example 3 A production process for hot-rolled wire rods for high compression ratio elevator wire ropes, which differs from Example 1 in that, in step S3 continuous casting, the electromagnetic stirring installation position at the end of solidification is 11.1 m away from the meniscus of the crystallizer, and the rest is the same as Example 1.

[0034] Performance Testing 1. According to GB / T228.1-2021 "Tensile Test of Metallic Materials Part 1: Room Temperature Test Method", the wire rods obtained in the embodiment and the comparative example were tested for elongation after fracture, shrinkage of cross section and tensile strength. The test results are shown in Table 1; 2. The detection standard of decarburized layer shall be based on the relevant provisions of GB / T224, and the microstructure shall be tested in accordance with the relevant provisions of GB / T13298.

[0035] Table 1 Wire rod performance test results The non-metallic inclusions in the wire rod were determined according to the relevant provisions of GB / T10561-2005 "Standard Rating Chart Microscopic Examination Method for Determination of Non-Metallic Inclusion Content in Steel", among which Class A, Class B, Class C and Class D inclusions were all controlled at ≤1.0 level.

[0036] The present application adjusts the oxygen blowing pressure, oxygen blowing flow rate in the converter smelting and various parameters in the continuous casting, so that the troostite rate of the wire rod obtained in Examples 1-3 of the present application reaches 92% or more, and the obtained microstructure contains only troostite, ferrite and pearlite, without harmful structures such as martensite, network cementite and network ferrite, and the depth of the decarburization layer is stably controlled to be below 0.05mm, that is, the depth is less than 0.8%D (diameter), and after the wire rod obtained in the present application is further processed into steel wire, the wire yield rate is greater than 97.7%, and the wire qualification rate is ≥99.9%.

[0037] Compared with Example 1, when the argon pressure in the converter smelting process is only set to 1.0 MPa or the electromagnetic stirring at the end of solidification adopts continuous stirring or the installation position of the electromagnetic stirring at the end of solidification is 11.1 mm away from the meniscus of the crystallizer, the tensile strength, elongation after fracture and cross-sectional shrinkage of the wire rod obtained in Comparative Examples 1-3 are reduced, the austenite grain size grade is reduced, and the depth of the decarburization layer is increased. This shows that the preparation method of the present application can effectively ensure the mechanical properties of the wire rod while improving the uniformity of the wire rod.

[0038] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A hot-rolled wire rod for elevator steel wire rope with high compression ratio, characterized in that: The wire rod includes the following components in mass percentage: C: 0.70-0.74%, Si: 0.17-0.27%, Mn: 0.50-0.55%, Cr: ≤0.15%, P: ≤0.020%, S: ≤0.015%, Ni: ≤0.30%, Cu: ≤0.25%, Al: ≤0.007%, Pb: ≤0.0050%, Sn: ≤0.0050%, As: ≤0.0100%, Sb: ≤0.0050%, Bi: ≤0.0050%, and the balance is iron and unavoidable impurities.

2. The hot-rolled wire rod for elevator steel wire rope with high compression ratio according to claim 1, characterized in that: The wire rod has a tensile strength greater than 980 MPa, an elongation greater than 10%, and a cross-sectional shrinkage greater than 30%.

3. A production process for the hot-rolled wire rod for elevator steel wire rope with high compression ratio as claimed in claim 1 or 2, comprising S1, converter smelting, S2, LF furnace refining, S3, continuous casting, S4, rolling, characterized in that: In step S1, constant gun variable pressure operation is adopted, and the oxygen pressure during oxygen blowing smelting is: 0.7-0.9MPa for 0-6min, 1.2-1.4MPa for 7-10min, 1.0-1.2MPa for 11-15min, and 1.3-1.5MPa for 16-18min; oxygen flow rate: bottom blowing flow rate is 0.1-0.2m 3 / (min·t).

4. The continuous casting process parameters in step S3 are superheat 18-40°C, casting speed 0.8-1.05m / min, secondary cooling water volume 0.6L / kg, surface crystallizer electromagnetic stirring current 480A, frequency 3Hz, solidification end electromagnetic stirring current 500A, stirring frequency 10Hz.

5. The production process of hot-rolled wire rod for high compression ratio elevator steel wire rope according to claim 3, characterized in that: The installation position of the electromagnetic stirring at the end of solidification is determined by the following criteria: the solid phase ratio fsc at the center of the ingot is 0.1-0.2, the solidification ratio Ds of the ingot is 0.7-0.8, and the width of the two-phase zone of the liquid phase hole is 40-50 mm.

6. The production process of hot-rolled wire rod for high compression ratio elevator wire rope according to claim 4, characterized in that: The electromagnetic stirring installation position at the end of solidification is 9.75m away from the meniscus of the crystallizer.

7. The production process of hot-rolled wire rod for high compression ratio elevator wire rope according to claim 3, characterized in that: The surface crystallizer electromagnetic stirring adopts a continuous stirring mode, and the solidification end electromagnetic stirring adopts an alternating stirring mode, and the conditions are 10s-3s-10s.

8. The production process of hot-rolled wire rod for high compression ratio elevator steel wire rope according to claim 3, characterized in that: In the rolling process of step S4, the temperature of the billet heating section is 1080±10°C, the temperature of the soaking section is 1060±10°C, the heating time is 80-120min, the rolling opening temperature is 980-1020°C, and the finishing rolling temperature is 920-940°C.

9. The production process of hot-rolled wire rod for high compression ratio elevator steel wire rope according to claim 3, characterized in that: In the rolling process of step S4, the spinning temperature is 860-880°C, the roller speed of the first section of the Stelmore air-cooled line is 0.90m / s, and the roller speeds of each section are set to 0.98m / s, 1.07m / s, 1.17m / s, 1.27m / s, 1.38m / s, 1.41m / s, 1.44m / s, 1.47m / s, 1.50m / s, 1.38m / s, 1.22m / s, and 1.22m / s respectively.

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