CN117089772A - High-quality sulfur-containing cold heading steel wire rod and preparation method thereof - Google Patents

High-quality sulfur-containing cold heading steel wire rod and preparation method thereof Download PDF

Info

Publication number
CN117089772A
CN117089772A CN202311364847.3A CN202311364847A CN117089772A CN 117089772 A CN117089772 A CN 117089772A CN 202311364847 A CN202311364847 A CN 202311364847A CN 117089772 A CN117089772 A CN 117089772A
Authority
CN
China
Prior art keywords
equal
components
continuous casting
steel
slag
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202311364847.3A
Other languages
Chinese (zh)
Other versions
CN117089772B (en
Inventor
蔡小锋
赵家七
李宁
马建超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Institute Of Research Of Iron & Steel shagang jiangsu Province
Jiangsu Shagang Group Co Ltd
Zhangjiagang Rongsheng Special Steel Co Ltd
Original Assignee
Institute Of Research Of Iron & Steel shagang jiangsu Province
Jiangsu Shagang Group Co Ltd
Zhangjiagang Rongsheng Special Steel Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Institute Of Research Of Iron & Steel shagang jiangsu Province, Jiangsu Shagang Group Co Ltd, Zhangjiagang Rongsheng Special Steel Co Ltd filed Critical Institute Of Research Of Iron & Steel shagang jiangsu Province
Priority to CN202311364847.3A priority Critical patent/CN117089772B/en
Publication of CN117089772A publication Critical patent/CN117089772A/en
Application granted granted Critical
Publication of CN117089772B publication Critical patent/CN117089772B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • 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

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses a high-quality sulfur-containing cold heading steel wire rod and a preparation method thereof, belonging to the technical field of steelmaking. The wire rod comprises the following components in percentage by mass: s:0.015-0.05%, al:0.010-0.060%, T.O less than or equal to 0.0025%, fe and impurities. The preparation method comprises the following steps: converter-LF refining-continuous casting-cogging-high-speed wire rolling. The converter tapping and refining process adopts a medium-low alkalinity calcium aluminosilicate ternary slag system, ensures the yield of sulfur and aluminum elements in steel, and reduces inclusions in steel. Controlling the alkalinity of refining slag system and the balance of Ca, S, al, ca, O elements in molten steel, and avoiding nozzle nodulation. The continuous casting adopts a high superheat process, combines the cooling water quantity of a crystallizer and a secondary cooling section and the sectional reduction, and reduces element segregation in a casting blank and continuous casting blank cracks. The rolling temperature is controlled, the grain size is refined, a cooling process of quick cooling and slow cooling is adopted, the spheroidizing annealing time is shortened, the MnS inclusion morphology is controlled, and the high-quality wire rod is comprehensively obtained.

Description

High-quality sulfur-containing cold heading steel wire rod and preparation method thereof
Technical Field
The invention relates to a high-quality sulfur-containing cold heading steel wire rod and a preparation method thereof, belonging to the technical field of steelmaking.
Background
The cold heading steel is mainly used for various structural members and fasteners, is convenient to machine and cut, prolongs the service life of a cutter, reduces cutting resistance, improves the finish of a machined surface, and is easy to remove chips and the like. Because of extremely high requirements on processing performance and product quality, the method has strict control on the morphology, the composition and the uniformity of tissues, the surface quality and the internal quality of sulfides in the product. The good sulfide morphology is beneficial to improving the processing performance of cold heading steel, sulfide inclusions with smaller spherical or spindle-shaped length-width ratio are expected to be obtained in production, and the larger length-width ratio can not only destroy the continuity of a matrix, but also cause the adhesion of cutting scraps, reduce the surface quality of a workpiece and increase the loss of a cutter. In addition, the wire rod has good tissue and internal and external quality, and simultaneously, the cold heading performance and the cutting performance can be better considered.
At present, cold heading steel is mainly produced by adopting an electric furnace/converter, LF refining, VD refining, RH refining and continuous casting process. Only a small part of iron and steel enterprises have the capacity of stable production, the product quality is unstable, and high-end products still depend on foreign import.
The cold heading steel is mainly prepared by adding sulfur element into steel and combining with the morphological control of sulfide inclusion. Although elemental sulfur is one of the main factors that cause hot shortness of steel, free-cutting steel forms more spherical or spindle-shaped MnS, which contributes to improvement of machinability of steel. The control of sulfur in free-cutting cold-heading steel is one of the difficulties in its production. The main adding modes at present are as follows: adding pyrite and feeding sulfur line. The traditional production process is that white slag is produced in the tapping and refining processes of a converter, so that a large amount of molten steel is easily desulfurized, the yield of sulfur element is seriously influenced, and the stability of sulfur element control is not facilitated.
The castability of sulfur-containing cold forging steel is another major difficulty in its production stability. The steel is usually aluminum deoxidized steel, and calcium treatment is needed after smelting to lead Al in the steel 2 O 3 Inclusion denaturation improves the castability of molten steel, but the steel contains higher sulfur content, ca and S in the molten steel are easy to combine to form high-melting-point CaS during calcium treatment, so that a water gap is nodulated, the production smooth operation and the product quality are influenced, and the production efficiency is influenced; secondly, the sulfur content of the sulfur-containing cold forging steel is high, the viscosity of molten steel is high, the fluidity is poor, and the casting temperature must be increased to ensure the castability of the sulfur-containing cold forging steel; and the sulfur-containing cold heading steel is also a crack sensitive steel grade, cold heading cracking is caused in the subsequent rolling process, a weak cooling system is required to be adopted, and the control of a continuous casting process is extremely important.
Patent application CN111254254a provides a method for preparing steel for sulfur-containing engineering machinery, wherein the steel mainly comprises the following components: 0.32-0.36%, si:0.15-0.35%, mn:0.90-1.40%, P < 0.040%, S:0.005-0.035%, cr:0.05-0.30%, B:0.0008-0.0030%, al:0.015-0.040%, ti:0.025-0.050%. The molten iron pre-desulfurization procedure is not carried out before the converter smelting, the mass percent of the end point C of the converter is controlled to be more than or equal to 0.06 percent or the tapping oxygen level is controlled to be less than or equal to 400ppm, and the tapping temperature is controlled to be more than or equal to 1560 ℃; adding carburant to pre-deoxidize in the early stage of tapping, then sequentially adding alloy, deoxidizing agent and slag to deoxidize and alloy, and keeping argon blowing in the whole process of deoxidizing and alloying, and tapping in a double-gear mode in the later stage of tapping. Controlling the alkalinity of refining slag to be 4-7, adopting silicon carbide, aluminum particles, silicon aluminum calcium or calcium carbide to carry out composite diffusion deoxidation, controlling the superheat degree of a continuous casting tundish in continuous casting according to a target feeding sulfur line, and improving the quality of products. However, the converter does not use high-sulfur molten iron and high-sulfur scrap steel, and the subsequent sulfur increment is large and the cost is high. In addition, the alkalinity of refining slag is controlled to be 4-7, the relative height is relatively high, the desulfurization amount in the refining process is large, the amount of sulfur fed into the refining process is large, the sulfur content of molten steel is controlled unstably, the production efficiency of sulfur-containing steel is affected, and the cost is increased.
Patent application CN114737105A discloses a smelting method for producing sulfur-containing steel by low-sulfur molten iron, which comprises the following steps: aluminum deoxidizing molten steel in the tapping process of a primary smelting furnace (electric furnace/converter), adding alloys such as sulfur and iron for alloying, and adding quartz sand, premelted refining slag and lime to prepare low-alkalinity slag; and carrying out slag surface composite diffusion deoxidation operation in the LF refining process. According to the method, sulfur content of molten steel is improved by adding sulfur and iron in the tapping process, the problem of low initial sulfur content of molten steel caused by low sulfur content of molten steel is solved, meanwhile, aluminum is adopted for strong deoxidation, low-alkalinity furnace slag is produced, and the desulfurization amount in the LF refining process is less than 0.010%, so that the sulfur content of the molten steel is ensured to be stable. However, in the tapping process of the primary smelting furnace (electric furnace/converter), aluminum deoxidation is carried out on molten steel, alloys such as sulfur and iron are added for alloying, low-alkalinity slag is produced by adding quartz sand, premelted refining slag and lime, the low-alkalinity slag system has poor desulfurization capability, but strong oxidizing property, and is remarkable in oxidizing Al in the molten steel, so that alumina inclusions are increased, and meanwhile, when the acid slag system is subjected to calcium treatment, the Ca oxidation on metal is very serious, the calcium treatment effect is poor, and the problem of nozzle nodulation is easily caused.
Patent application CN113201620A discloses a method for smelting sulfur-containing steel by using desulfurization slag, wherein 4-6kg/t of desulfurization slag is added into a ladle in advance before tapping of a converter, and 0.030-0.050% of S element can be recovered; the deoxidized alloy is added when tapping is finished for 3/4-tapping; LF furnace utilizes lime and is rich in SiO 2 Low-alkalinity slag is produced from the silicon slag, and the alkalinity of the slag is controlled to be 0.7-1.0; the slag surface is deoxidized by SiC, and the FeO of the slag is controlled to be 4-6%; soft stirring is carried out in the whole refining process, and the ventilation flow rate of ladle bottom blowing is 100-200L/min; the patentThe method effectively utilizes the waste resource desulfurization slag for secondary use, can save the lime consumption of the slag former of the LF furnace, saves the consumption of the chalcogenide alloy, can directly recycle Fe in the desulfurization slag, and improves the molten steel yield. However, the desulfurization slag is added into the ladle in advance before tapping of the converter, and the LF furnace utilizes lime and is rich in SiO 2 The alkalinity of the silicon slag is 0.7-1.0, but the FeO content of the slag reaches 4-6%, the oxidizing property of the slag is strong, the alkalinity is low, if aluminum is contained, the aluminum oxide inclusion in the molten steel is easily increased, and the casting property of the molten steel is affected. If the steel is Si-Mn deoxidized steel, the molten steel is not deoxidized thoroughly, the total oxygen content is high, and the defect of casting blank bubbles is easily caused.
Patent application CN116716547A discloses a medium carbon cold heading steel for racks and a smelting method thereof, which utilize Al, lime, premelted slag and deoxidizing slag-making agent to carry out quick deoxidization and white slag making in the converter tapping process so as to ensure the produced Al 2 O 3 The impurities and the floating in the morning are removed, and the cleanliness is improved. The continuous casting adopts low superheat degree and dynamic soft reduction, and ensures that the low-power tissue of the casting blank is uniform and compact. However, the tapping process of the converter by utilizing Al, lime, premelting slag and deoxidizing slag former is used for making white slag, so that the alkalinity is high and the desulfurization capability is strong. After the VD process is broken, adding the sulfur iron, controlling the S content to be unstable, and obtaining lower sulfur element yield, wherein alumina inclusion in molten steel may influence the pouring property of the molten steel.
The sulfur-containing cold forging steel has strict requirements on inclusion types, components, structural uniformity, surface quality and the like in order to ensure cutting processability. Therefore, the control of inclusion types, component structure uniformity, casting blank segregation, cracks and the like is a key for subsequently obtaining high-quality free-cutting cold heading steel wire rods. Analysis shows that the inclusion is mainly researched from the aspect of sulfide inclusion control, and mainly considers how to economically and stably control the content of S element, and meanwhile, the uniform distribution of C element and alloy element in the wire rod needs to be ensured.
The sulfur-containing cold heading steel contains metal aluminum and C besides high S element content, so that molten steel and slag are thoroughly deoxidized, the low-oxidability slag has good desulfurization effect, and the sulfur content of the molten steel is not easy to control stably; meanwhile, aluminum oxide is mainly used as the inclusion of the aluminum deoxidized steel, so that the pouring property of molten steel is poor. In the calcium treatment process, a large amount of S element exists in molten steel and reacts with Ca element to form CaS, so that a water gap is formed. Therefore, the design of the refining slag system of the sulfur-containing cold forging steel and the balance of S, al, ca, O elements are very important to the stable control of the components and the pouring performance of molten steel in the production process.
In addition, the sensitivity of the high-sulfur cold heading steel is very high, so that the requirements on the continuous casting superheat degree, the cooling process, the subsequent rolling process and the like are very high, and the surface or internal cracks are avoided, so that the wire rod with low defect rate is obtained.
In order to overcome the technical problems, the system comprehensively designs a steelmaking continuous casting and rolling process scheme.
Disclosure of Invention
In order to solve the problems, the invention discloses a high-quality sulfur-containing cold heading steel wire rod and a preparation method thereof, wherein the content of molten iron S is controlled, high-quality stable molten steel is obtained in a converter and a refining process, meanwhile, the quantity and the size of oxide inclusions in the steel are reduced, and in addition, the components and the structure of the wire rod are homogenized and the surface and internal quality are improved by combining with the optimization design of continuous casting and a steel rolling process. The specific technical scheme is as follows:
the high-quality sulfur-containing cold heading steel wire rod comprises the following chemical components in percentage by mass: c:0.45-0.55%, si:0.20-0.50%, mn:0.65-1.85%, cr:0.1-0.3%, S:0.015-0.05%, al:0.010-0.060 percent, P is less than or equal to 0.015 percent, T.O is less than or equal to 0.0025 percent, N is less than or equal to 0.0045 percent, and the balance is Fe and other unavoidable impurity components.
Further, the rolling diameter specification of the cold heading steel wire rod is 5.5-20mm.
The method for preparing the high-quality sulfur-containing cold heading steel wire rod is produced according to the process flow of converter-LF refining-continuous casting-cogging-high-line rolling, and specifically comprises the following steps:
step 1: the working procedure before iron: the molten iron comprises the following chemical components in percentage by mass: c:4.0-4.5%, si:0.2-0.5%, P is less than or equal to 0.13%, S:0.03-0.07%, wherein the temperature is 1380-1450 ℃, molten iron is directly conveyed to a converter for smelting without pretreatment;
step 2: converter process: the converter scrap steel ratio is 15-25%, clean scrap steel is selected for smelting, when converter blowing is finished, the S mass percentage content is 0.010-0.035%, the molten steel temperature is more than or equal to 1610 ℃, then tapping is carried out, and a slide plate is adopted for slag blocking for the next smelting;
step 3: tapping the converter: firstly, sequentially adding metal aluminum, silicon alloy, manganese alloy, carbon powder and ferrochrome alloy into a steel ladle to carry out deoxidization alloying, wherein the bottom blowing flow is 100-300NL/min, when 85% of steel is tapped, adding calcium aluminosilicate synthetic slag and lime to carry out slag making, controlling the slag alkalinity to be 1.5-2.5, and after the steel tapping is finished, the bottom blowing flow is 400-800NL/min, stirring for 3-5min, and then conveying to an LF furnace to carry out treatment;
step 4: refining process of LF furnace: argon is blown from the bottom in the whole process, the maximum flow rate of the air brick argon is 400-500NL/min during charging and alloying, the maximum flow rate of the air brick argon is 200-400NL/min during heating, and the maximum flow rate of the air brick argon is 100-150NL/min in the rest time; adding lime and calcium aluminosilicate to synthesize slag in the refining process, and controlling the alkalinity of ladle slag at CaO/SiO 2 =2.0-3.5，Al 2 O 3 15-25% of the weight percentage, wherein T.Fe+MnO is not less than 1.5 and not more than 3.5%; firstly adding 2-4kg/t of pyrite, then adding silicon alloy, manganese alloy, ferrochrome alloy and aluminum feeding wires, electrifying to regulate the components and the temperature of molten steel to reach the standards, then performing calcium treatment, feeding 50-120m pure calcium wires, tapping, performing soft stirring and calm treatment, and conveying the molten steel with Ca content of 3-8ppm to continuous casting pouring;
step 5: continuous casting process: pouring by a bloom continuous casting machine, protecting and pouring in the whole continuous casting process, adopting a high-alkalinity high-alumina tundish covering agent, controlling the superheat degree of the tundish molten steel to be 30-50 ℃, using a low-melting-point crystallizer covering slag, and using a crystallizer for electromagnetic stirring; the water quantity of the crystallizer is 2600-3200NL/min; the secondary cooling section adopts a weak cooling mode, and the water quantity of the secondary cooling section is respectively from zone 1 to zone 4: 1 section 60-100 NL/min, 2 section 20-50 NL/min, 3 section 20-40 NL/min, 4 section 10-30 NL/min; lightly rolling the continuous casting blank in a withdrawal and straightening machine, wherein the total rolling reduction is 8-15mm, the rolling pressure is 30-40bar, and the specification of the obtained continuous casting blank is 300mm multiplied by 390mm;
step 6: cogging process: the cogging heating temperature is 1140-1180 ℃, the heating time is 180-250min, and the specification of the intermediate billet obtained by cogging is 140mm multiplied by 140mm;
step 7: high-line rolling process: the heating temperature is 1040-1080 ℃, the initial rolling temperature is 940-960 ℃, the finish rolling inlet temperature is 860-890 ℃, the spinning temperature is 820-840 ℃, the speed of a roller way of a Siteur inlet section is 0.4-0.8m/s, the high-line rolling process is provided with 1-5# fans, the fans are sequentially arranged according to the rolling sequence, the air quantity of the 1-4# fans is 40-90%, and the rest fans are closed; and the heat preservation cover corresponding to the No. 5 fan and the subsequent heat preservation cover are all closed.
Further, the clean scrap steel used in the converter in the step 2 comprises less than or equal to 0.015% of P, less than or equal to 0.05% of S, and the balance of conventional C, si, al, mn, fe elements and other unavoidable impurity elements in percentage by mass.
Further, when the converter tapping in the step 3 reaches 20-30%, 70-85% of aluminum ingot, 50-70% of manganese alloy, 50-80% of silicon alloy, total ferrochrome alloy and 60-80% of carbon powder are added.
Further, the aluminum ingot components in the converter tapping process comprise Al more than or equal to 98%, P less than or equal to 0.010%, S less than or equal to 0.01%, and the balance of Fe and other unavoidable impurity components; the manganese alloy comprises Mn not less than 98%, P not more than 0.010%, ti not more than 0.0025% and Fe and other unavoidable impurity components as the rest; the silicon alloy comprises 75% -80% of Si, less than or equal to 0.015% of P, less than or equal to 0.0035% of Ti, and the balance of Fe and other unavoidable impurity components; the ferrochrome comprises 55-65% of Cr, less than or equal to 0.015% of P, and the balance of Fe and other unavoidable impurity components; the addition amount of the calcium aluminosilicate synthetic slag is 6-10kg/t, and the main components comprise 25-40% of CaO and SiO 2 18-28%、Al 2 O 3 30-40% of other unavoidable components, wherein CaAl 2 SiO 7 The phase ratio is more than 75%; lime content is CaO more than or equal to 97%, and the balance is other unavoidable components.
Further, lime with CaO content more than or equal to 97% is added in the refining process of the step 4 LF furnace, and the balance is other unavoidable components; the addition amount of the calcium aluminosilicate synthetic slag is 0-0.5kg/t, and the components comprise 25-40% of CaO and SiO 2 18-28%、Al 2 O 3 30-40% of other unavoidable components, wherein CaAl 2 SiO 7 The component accounts for more than 80 percent; adding pyrite in refining processThe component is FeS 2 More than or equal to 50 percent, and the balance is unavoidable impurity components; the components are regulated to reach the standard, and the refining tapping temperature is controlled between 1550 ℃ and 1570 ℃.
Further, in the continuous casting process in the step 5, the argon flow of the long ladle nozzle is 250-350NL/min; the adopted high alkalinity high alumina tundish covering agent comprises the following components: caO 45-55%, al 2 O 3 25-35%、MnO 2-5%、SiO 2 Less than or equal to 5 percent, mgO 3-6 percent and other unavoidable components; the thickness of the mold flux layer of the crystallizer is maintained to be 15-22mm, and the addition amount is 0.25-0.35kg/t.
Further, the pouring tonnage of the continuous casting tundish in the step 5 is more than or equal to 25t, the tonnage of the continuous casting tundish in normal pouring is more than or equal to 40t, and the tonnage of the continuous casting tundish in large ladle replacement is more than or equal to 30t; the immersion nozzle insertion depth is 120-180mm, the continuous casting pulling speed is controlled at 0.6-0.7m/min, the electromagnetic stirring current of the crystallizer is 550-750A, and the frequency is 2-3Hz.
Further, the continuous casting billet from the continuous casting machine enters a cooling bed, the surface temperature of the cooling bed is more than or equal to 650 ℃, the corner temperature of the cooling bed is more than or equal to 500 ℃, hot charging and hot feeding rolling are carried out, and the casting billet is fed to the next rolling step without cooling to the room temperature.
The high-quality sulfur-containing cold heading steel wire rod prepared by the method for preparing the high-quality sulfur-containing cold heading steel wire rod.
Further, in the high-quality sulfur-containing free-cutting steel wire rod, class B inclusions are less than or equal to 1 grade, class C inclusions are less than or equal to 1 grade, class Ds inclusions are less than or equal to 0.5 grade, the proportion of MnS inclusions with the length-width ratio of less than or equal to 4 is more than 80 percent, the grain size is more than or equal to 8 grades, the spheroidization rating is more than or equal to 6 grades, the rating of net-shaped cementite is less than or equal to 1 grade, and the surface vibration mark, pit, lug, fold and pore defect height or depth is less than or equal to 2mm.
The principle of the invention is as follows:
the sulfur-containing cold heading steel is mainly used for various connecting pieces and fasteners. The requirements for the method are as follows: the cutting tool is convenient for machining and cutting, reduces cutting resistance, improves the finish of a machined surface, and prolongs the service life of the tool. Because of extremely high requirements on processability and product quality, the shape control of sulfides, the purity of blanks, the blank shape of a casting blank, the surface quality and the internal quality are strictly controlled.
In order to obtain the high-quality wire rod, the multi-dimensional comprehensive control is required from the aspects of stable control of S element in steel, control of molten steel cleanliness, control of casting blank segregation and cracks, production efficiency and cost control and the like. The S element is a key for ensuring the cutting processing performance of cold heading steel, and stable control of the S element is required to be ensured when a smelting process is designed, and meanwhile, the production efficiency and the cost are controlled.
The conventional process for producing sulfur-containing cold heading steel comprises the steps of adding alloy and carbon powder into converter tapping for full deoxidation to produce a high-alkalinity slag system, carrying out slag diffusion deoxidation and calcium treatment in an LF refining process to cause a large amount of desulfurization of molten steel, and then adding a large amount of sulfur wires or sulfur irons in the LF refining process, wherein the S element has poor control stability. The continuous casting process adopts a low superheat degree and medium-low strength cooling process, the temperature control of continuous casting molten steel is low, the floating removal of inclusions is not facilitated, and the control of the pouring performance of the molten steel is not facilitated.
The system comprehensively designs the converter tapping, refining, deoxidizing, alloying and slagging processes, adopts the calcium aluminosilicate ternary slag system for smelting, ensures weaker slag desulfurization capability and lower oxidizing property, can reduce aluminum oxidation, is beneficial to calcium treatment of molten steel, and obtains high-pouring molten steel.
The continuous casting adopts a high-superheat process mode, the secondary cooling water distribution and pressing down process is controlled through accurate sectional control, the electromagnetic stirring of a crystallizer and the casting blank heat preservation slow cooling process are reasonably controlled, the rolling process controls proper rolling temperature, the cooling process of quick cooling and slow cooling after quick cooling is controlled, the grain size is refined, the spheroidizing annealing time is shortened, the MnS inclusion morphology and the like are controlled, and the wire rod with high surface quality and internal quality is obtained.
The beneficial effects of the invention are as follows:
(1) In the tapping process of the converter, lime and calcium aluminosilicate synthetic slag are adopted to manufacture a middle-low alkalinity slag system, and firstly, a calcium aluminosilicate ternary slag system with the middle-low alkalinity of 1.5-2.5 is formed, so that slag desulfurization in the process from tapping to LF refining can be inhibited.
(2) In the LF refining process, after molten steel components are adjusted in place, fine-tuning slag basicity such as lime is added, the control is in the range of 2.0-3.5, and middle and small bottom blowing is controlled, so that severe slag-gold reaction and a large amount of desulfurization are avoided, and the stable and efficient control of the S content of molten steel is realized.
(3) After the refined components reach the target requirements, feeding 50-120m pure calcium wires for calcium treatment, controlling the Ca content in steel within the range of 3-8ppm, not only ensuring the modification of Ca element on alumina inclusion, but also reducing the generation of CaS inclusion to cause nozzle nodulation.
(4) Finally, the continuous casting process adopts a high-superheat pouring process, and the high-alkalinity high-alumina tundish covering agent is combined, so that the melting effect of the tundish covering agent can be improved, the desulfurization of ladle slag in the pouring process is reduced, the floating of inclusions is facilitated, and the cleanliness is improved.
(5) Precisely controlling the temperature of a casting blank out of a crystallizer in the continuous casting process, the temperature, the rolling reduction and the like in the secondary cooling stage, and obtaining the casting blank with low segregation index.
(6) By controlling the processes of cogging, rolling and stelmor air cooling, the wire rod with uniform structure and crystal grain is obtained, and sulfide inclusions with smaller spherical or spindle-shaped length-width ratio are obtained. The spinning temperature is too low, the growth driving force of austenite grains is insufficient, and the spinning temperature is too high, so that huge grains are easy to appear to deteriorate the cold workability of the wire rod. The cooling process of quick cooling and slow cooling is adopted, so that the spheroidizing annealing time is shortened, and the form of MnS inclusions is properly controlled.
The core improvement point of the invention is as follows:
(1) The converter tapping and refining process adopts a medium-low alkalinity calcium aluminosilicate ternary slag system, ensures the yield of sulfur and aluminum elements in steel, reduces the formation of inclusions in steel, and improves the cleanliness of molten steel.
(2) The accurate calcium treatment technology prevents nozzle nodulation by accurately controlling Ca content of molten steel and designing and controlling alkalinity of refining slag system and balance of S, al, ca, O elements in molten steel.
(3) The continuous casting adopts a high superheat process, and the problems of segregation of various elements in a casting blank and continuous casting blank cracks can be alleviated by combining the precise control of cooling water quantity of a crystallizer and a secondary cooling section and the precise sectional pressing control technology.
(4) And (3) controlling proper rolling temperature, refining grain size, adopting a cooling process of quick cooling and then slow cooling, shortening spheroidizing annealing time, properly controlling MnS inclusion morphology, and comprehensively obtaining the high-quality wire rod.
Drawings
FIG. 1 is a photograph showing a low magnification of a cast slab according to the present invention.
Detailed Description
The invention is further elucidated below in connection with the specific embodiments. It should be understood that the following detailed description is merely illustrative of the invention and is not intended to limit the scope of the invention.
Example 1
(1) Pre-iron process, molten iron C:4.1%, si:0.26%, P:0.11%, S:0.03 percent of molten iron at the temperature of 1397 ℃ is directly conveyed to a converter for smelting without pretreatment.
(2) A converter process, wherein the ratio of the waste steel of the converter is 18%, clean waste steel is selected for smelting, and the clean waste steel used by the converter comprises the following components: 0.014%, S:0.05%, the balance of conventional C, si, al, mn, fe elements and other unavoidable impurity elements. And after finishing the blowing of the converter, the S content is 0.015%, the temperature of molten steel is 1621 ℃, then tapping is carried out, and a sliding plate is adopted to stop slag for carrying out the next smelting.
(3) A converter tapping process, namely, sequentially adding 85% aluminum ingot, 70% manganese alloy, 80% silicon alloy, all ferrochrome alloy and 75% carbon powder into a steel ladle to carry out deoxidization alloying when the converter taps 20%, wherein the bottom blowing flow is 300NL/min, adding calcium aluminosilicate to synthesize slag and lime to carry out slag making when the converter taps 85%, controlling the slag alkalinity to be 1.5, and carrying out LF treatment after the tapping finishes the bottom blowing flow of 800NL/min, stirring for 5 min; the main components of the aluminum ingot in the tapping process of the converter include Al:98.1%, P:0.008% of Fe and other unavoidable impurity components; the main components of the manganese alloy comprise Mn:98.0%, P:0.006%, ti:0.002% of Fe and other unavoidable impurity components; silicon alloy Si:78%, P:0.011%, ti:0.008% of Fe and other unavoidable impurity components; ferrochrome Cr:60%, P:0.011%, the balance being Fe and other unavoidable impurity components; the addition amount of the calcium aluminosilicate synthetic slag is 8.9kg/t, and the main components comprise CaO:38%, siO 2 ：19%、Al 2 O 3 :38% and other unavoidable components, wherein CaAl 2 SiO 7 Phase ratio 75%; the lime comprises the following components: 98% and the rest are other unavoidable components.
(4) In the LF furnace refining process, argon is blown at the bottom in the whole process, the maximum air brick argon flow is 400-500NL/min during charging and alloying, the maximum air brick argon flow is 200-400NL/min during heating, and the maximum air brick argon flow is 100-150NL/min during the rest time; adding lime and calcium aluminosilicate to synthesize slag in the refining process, and controlling the alkalinity of ladle slag at CaO/SiO 2 ：2.2、Al 2 O 3 25% of the content of T.Fe+MnO:3.1%; firstly adding 3.7kg/t of pyrite, then adding silicon alloy, manganese alloy, ferrochrome alloy and aluminum feeding wires, electrifying to completely regulate the components and the temperature of molten steel to reach the standards, then performing calcium treatment, feeding 60m pure calcium wires, regulating the components to reach the standards, controlling the refining tapping temperature to 1565 ℃, then tapping to perform soft stirring and calm treatment, and transporting the molten steel to continuous casting pouring after the Ca content of the molten steel is 5 ppm; lime is added in the refining process, wherein the lime comprises 98% of CaO, and the balance of other unavoidable components; the addition amount of the calcium aluminosilicate synthetic slag is 0, and the main components comprise CaO:38%, siO 2 ：19%、Al 2 O 3 :38% and other unavoidable components, wherein CaAl 2 SiO 7 The component accounts for 75 percent; the pyrite component added in the refining process is FeS 2 :55% and the balance of unavoidable impurity components.
(5) A continuous casting procedure, namely casting by adopting a bloom continuous casting machine, wherein the whole casting process is protected and casting, and the argon flow of a ladle long nozzle is 300NL/min; the pouring basket has a pouring tonnage of 25t, the tonnage of the pouring basket is more than or equal to 40t during normal pouring, and the tonnage of the pouring basket is more than or equal to 30t during continuous pouring and ladle replacement; the immersion nozzle insertion depth is 160mm, and the continuous casting pulling speed is controlled to be 0.65m/min; adopting a high-alkalinity high-alumina tundish covering agent, and controlling the superheat degree of the tundish molten steel to be 48 ℃; using a low-melting-point crystallizer casting powder, maintaining the thickness of a slag layer of the crystallizer casting powder at 20mm, adding 0.31kg/t, using a crystallizer for electromagnetic stirring, wherein the electromagnetic stirring current of the crystallizer is 650A, the frequency is 2Hz, and the water quantity of the crystallizer is 2800NL/min; the secondary cooling section adopts a weak cooling mode, and the water quantity of the secondary cooling section is respectively from zone 1 to zone 4: 1 section 92 NL/min, 2 section 45 NL/min, 3 section 36 NL/min, 4 section 26 NL/min; the continuous casting blank is lightly pressed by a withdrawal and straightening machine, and the total pressing amount is 1The pressure of a pressing roller is 35bar, the specification of the obtained continuous casting billet is 300mm multiplied by 390mm, the surface temperature of a cooling bed is 660 ℃, the temperature of a corner is 505 ℃, and the hot charging hot feeding rolling is carried out. The main components of the adopted high alkalinity high alumina tundish covering agent comprise: caO:52%, al 2 O 3 ：34%、MnO：4.3%、SiO 2 :1.4%, mgO:4.5%, and other unavoidable components.
(6) And a cogging step, wherein the cogging heating temperature is 1145 ℃, the heating time is 244min, and the specification of the intermediate billet obtained by cogging is 140mm multiplied by 140mm.
(7) A high-speed line rolling process, wherein the heating temperature is 1077 ℃, the initial rolling temperature is 958 ℃, the finish rolling inlet temperature is 887 ℃, the spinning temperature is 820 ℃, the speed of a roller way of a Siteur inlet section is 0.62m/s, the air quantity of 1 # fan and 4# fan is 90%, 80% and 80% in sequence, and the rest fans are closed; and the heat preservation cover corresponding to the No. 5 fan and the subsequent heat preservation cover are all closed.
(8) The rolling specification of the cold heading steel wire rod is 6.5mm, and the cold heading steel wire rod comprises the following chemical components in percentage by mass: c:0.48%, si:0.23%, mn:0.75%, cr:0.25%, S:0.018%, al:0.025%, P:0.01%, T.O.: 0.0010%, N:0.0040% and the balance of Fe and other unavoidable impurity components. The high-quality sulfur-containing free-cutting steel wire rod has the defects of class B inclusion level 0, class C inclusion level 1, class Ds inclusion level 0.5, mnS inclusion proportion 92% with the length-width ratio less than or equal to 4, grain size level 9, spheroidization grade 8, network cementite grade 0.5, surface vibration mark, pit, convex block, folding, air hole and the like with the height or depth less than or equal to 2mm.
Example 2
(1) Pre-iron process, molten iron C:4.5%, si:0.35%, P:0.09%, S:0.05 percent of molten iron at 1410 ℃ without pretreatment, and directly conveyed to a converter for smelting.
(2) A converter process, wherein the ratio of the waste steel of the converter is 20%, clean waste steel is selected for smelting, and the clean waste steel used by the converter comprises the following components: 0.013%, S:0.03%, the balance of conventional C, si, al, mn, fe elements and other unavoidable impurity elements. After finishing converting, the S content of the converter is 0.021%, the temperature of molten steel is 1645 ℃, then tapping is carried out, and a sliding plate is adopted to stop slag for carrying out the next smelting.
(3) A converter tapping process, namely, sequentially adding 80% of aluminum ingot, 65% of manganese alloy, 70% of silicon alloy, all ferrochrome alloy and 80% of carbon powder into a steel ladle to deoxidize and alloy when the converter taps 20%, wherein the bottom blowing flow is 230NL/min, adding calcium aluminosilicate to synthesize slag and lime to slag when the converter taps 85%, controlling the slag alkalinity to be 1.9, and after tapping, the bottom blowing flow is 600NL/min, stirring for 4.8min, and then conveying to LF for treatment; the main components of the aluminum ingot in the tapping process of the converter include Al:98.3%, P:0.008% of Fe and other unavoidable impurity components; the main components of the manganese alloy comprise Mn:98.8%, P:0.006%, ti:0.0021%, the balance being Fe and other unavoidable impurity components; silicon alloy Si:75%, P:0.01%, ti:0.009%, the balance being Fe and other unavoidable impurity components; ferrochrome Cr:58%, P:0.015% of Fe and other unavoidable impurity components; the addition amount of the calcium aluminosilicate synthetic slag is 8.4kg/t, and the main components comprise CaO:40% of SiO 2 ：20%、Al 2 O 3 :35% and other unavoidable components, wherein CaAl 2 SiO 7 Phase ratio 79%; the lime comprises the following components: 98% and the rest are other unavoidable components.
(4) In the LF furnace refining process, argon is blown at the bottom in the whole process, the maximum air brick argon flow is 400-500NL/min during charging and alloying, the maximum air brick argon flow is 200-400NL/min during heating, and the maximum air brick argon flow is 100-150NL/min during the rest time; adding lime and calcium aluminosilicate to synthesize slag in the refining process, and controlling the alkalinity of ladle slag at CaO/SiO 2 ：2.6，Al 2 O 3 22% of the content, T.Fe+MnO:1.6%; firstly adding 3.1kg/t of pyrite, then adding silicon alloy, manganese alloy, ferrochrome alloy and aluminum feeding wires, electrifying to completely regulate the components and the temperature of molten steel to reach the standards, then performing calcium treatment, feeding 70m pure calcium wires, regulating the components to reach the standards, controlling the refining tapping temperature to 1560 ℃, then tapping to perform soft stirring and calm treatment, and transporting the molten steel to continuous casting pouring after the Ca content of the molten steel is 6 ppm; lime is added in the refining process, wherein the lime comprises 98% of CaO, and the balance of other unavoidable components; the addition amount of the calcium aluminosilicate synthetic slag is 0.2 kg/t, and the main components comprise CaO:40% of SiO 2 ：20%、Al 2 O 3 :35% and other unavoidableWherein CaAl 2 SiO 7 Phase ratio 79%; the pyrite component added in the refining process is FeS 2 :58% and the balance of unavoidable impurity components.
(5) A continuous casting procedure, namely casting by adopting a bloom continuous casting machine, protecting and casting in the whole continuous casting process, wherein the argon flow of a ladle long nozzle is 300NL/min; the pouring basket has a pouring tonnage 28 t, the tonnage is more than or equal to 40t during normal pouring, and the tonnage is more than or equal to 30t during continuous pouring and ladle replacement; the immersion nozzle insertion depth is 160mm, and the continuous casting pulling speed is controlled to be 0.65m/min; adopting a high-alkalinity high-alumina tundish covering agent, and controlling the superheat degree of the tundish molten steel to be 42 ℃; using a low-melting-point crystallizer casting powder, maintaining the thickness of a slag layer of the crystallizer casting powder at 22mm, adding 0.35kg/t, using a crystallizer for electromagnetic stirring, wherein the electromagnetic stirring current of the crystallizer is 650A, the frequency is 2Hz, and the water quantity of the crystallizer is 2800NL/min; the secondary cooling section adopts a weak cooling mode, and the water quantity of the secondary cooling section is respectively from zone 1 to zone 4: 1 section 89 NL/min, 2 section 41 NL/min, 3 section 33 NL/min, 4 section 22 NL/min; the continuous casting blank is lightly pressed by a withdrawal and straightening machine, the total pressing amount is 12mm, the pressing roller pressure is 36bar, the specification of the obtained continuous casting blank is 300mm multiplied by 390mm, the surface temperature of a cooling bed is 680 ℃, the temperature of a corner is 524 ℃, and hot charging and hot feeding rolling are carried out. The main components of the adopted high alkalinity high alumina tundish covering agent comprise: caO:50% of Al 2 O 3 ：33%、MnO：3.7%、SiO 2 :2.1%, mgO:5.3%, and other unavoidable components.
(6) And a cogging step, wherein the cogging heating temperature is 1156 ℃, the heating time is 220min, and the specification of the intermediate billet obtained by cogging is 140mm multiplied by 140mm.
(7) A high-speed line rolling process, wherein the heating temperature is 1056 ℃, the initial rolling temperature is 951 ℃, the finish rolling inlet temperature is 874 ℃, the spinning temperature is 824 ℃, the speed of a roller way of a Siteur inlet section is 0.57m/s, the air quantity of 1-4# fans is 90%, 80%, 70% and 70% in sequence, and the rest fans are closed; and the heat preservation cover corresponding to the No. 5 fan and the subsequent heat preservation cover are all closed.
(8) The rolling specification of the cold heading steel wire rod is 8mm, and the chemical components of the cold heading steel wire rod comprise the following components in percentage by mass: c:0.51%, si:0.23%, mn:0.85%, cr:0.25%, S:0.028%, al:0.022%, P:0.01%, T.O.: 0.0018%, N:0.0035% of Fe and other unavoidable impurity components. The high-quality sulfur-containing free-cutting steel wire rod has the defects of 0.5 level of B-type inclusions, 0.5 level of C-type inclusions, 0 level of Ds-type inclusions, 89 percent of MnS inclusion with the length-width ratio less than or equal to 4, 9 grade of grain size, 8 grade of spheroidization rating, 0 grade of net cementite rating, less than or equal to 2mm in height or depth of surface vibration marks, pits, bumps, folds, pores and the like.
Example 3
(1) Pre-iron process, molten iron C:4.3%, si:0.5%, P:0.12%, S:0.04 percent, the temperature is 1432 ℃, and the molten iron is directly conveyed to a converter for smelting without pretreatment.
(2) A converter process, wherein the ratio of the waste steel of the converter is 21%, clean waste steel is selected for smelting, and the clean waste steel used by the converter comprises the following components: 0.011%, S:0.04%, the balance of conventional C, si, al, mn, fe elements, and other unavoidable impurity elements. After finishing the blowing of the converter, the S content is 0.026%, the temperature of molten steel is 1635 ℃, then tapping is carried out, and a sliding plate is adopted to stop slag for carrying out the next smelting.
(3) A converter tapping step, namely, 80% of aluminum ingot, 70% of manganese alloy, 65% of silicon alloy, all ferrochrome alloy and 70% of carbon powder are sequentially added into a steel ladle to carry out deoxidization alloying when the converter taps 25%, the bottom blowing flow is 220NL/min, calcium aluminosilicate synthetic slag and lime are added to carry out slag making when the converter taps 85%, the slag alkalinity is controlled to 2.2, the bottom blowing flow is 500NL/min after tapping is finished, and the steel ladle is stirred for 4.1min and then conveyed to LF for treatment; the main components of the aluminum ingot in the tapping process of the converter include Al:98.4%, P:0.01% of Fe and other unavoidable impurity components; the main components of the manganese alloy comprise Mn:98.6%, P:0.007%, ti:0.0018% of Fe and other unavoidable impurity components; silicon alloy Si:80%, P:0.009%, ti:0.01% of Fe and other unavoidable impurity components; ferrochrome Cr:61%, P:0.014%, the balance being Fe and other unavoidable impurity components; the addition amount of the calcium aluminosilicate synthetic slag is 8.2kg/t, and the main components comprise CaO:39, siO 2 ：23%，Al 2 O 3 :33% of other unavoidable components, wherein CaAl 2 SiO 7 The phase ratio is 82%; the lime comprises the following components: 98% and the rest are other unavoidable components.
(4) In the LF furnace refining process, argon is blown at the bottom in the whole process, the maximum air brick argon flow is 400-500NL/min during charging and alloying, the maximum air brick argon flow is 200-400NL/min during heating, and the maximum air brick argon flow is 100-150NL/min during the rest time; adding lime and calcium aluminosilicate to synthesize slag in the refining process, and controlling the alkalinity of ladle slag at CaO/SiO 2 ：2.9，Al 2 O 3 Content 19%, t.fe+mno:1.9%; firstly adding 2.6kg/t of pyrite, then adding silicon alloy, manganese alloy, ferrochrome alloy and aluminum feeding wires, electrifying to completely regulate the components and the temperature of molten steel to reach the standard, then performing calcium treatment, feeding 50m pure calcium wires, regulating the components to reach the standard, controlling the refining tapping temperature to reach 1554 ℃, then tapping to perform soft stirring and calm treatment, and conveying the molten steel with the Ca content of 4ppm to continuous casting pouring; lime is added in the refining process, and the lime comprises CaO:98%, the rest is other unavoidable components; the addition amount of the calcium aluminosilicate synthetic slag is 0, and the main components comprise CaO:39%, siO 2 ：23%、Al 2 O 3 :33% of other unavoidable components, wherein CaAl 2 SiO 7 The phase ratio is 82%; the pyrite component added in the refining process is FeS 2 :56% and the balance of unavoidable impurity components.
(5) A continuous casting procedure, namely casting by adopting a bloom continuous casting machine, wherein the whole casting process is protected and casting, and the argon flow of a ladle long nozzle is 280NL/min; the pouring basket has a pouring tonnage of 30t, the tonnage of the pouring basket is more than or equal to 40t during normal pouring, and the tonnage of the pouring basket is more than or equal to 30t during continuous pouring and ladle replacement; the immersion nozzle insertion depth is 160mm, and the continuous casting pulling speed is controlled at 0.66m/min; adopting a high-alkalinity high-alumina tundish covering agent, and controlling the superheat degree of the tundish molten steel to be 36 ℃; using a low-melting-point crystallizer casting powder, maintaining the thickness of a slag layer of the crystallizer casting powder at 18mm, adding 0.26kg/t, using a crystallizer for electromagnetic stirring, wherein the electromagnetic stirring current of the crystallizer is 650A, the frequency is 3Hz, and the water quantity of the crystallizer is 3000NL/min; the secondary cooling section adopts a weak cooling mode, and the water quantity of the secondary cooling section is respectively from zone 1 to zone 4: 1 section 80NL/min, 2 section 36 NL/min, 3 section 29 NL/min, 4 section 18 NL/min; the continuous casting blank is lightly pressed by a withdrawal and straightening machine, the total pressing amount is 13mm, the pressing roller pressure is 38bar, the specification of the obtained continuous casting blank is 300mm multiplied by 390mm, the surface temperature of a cooling bed is 700 ℃, and the angle is the same as that of the continuous casting blankThe temperature of the hot charging and hot rolling is 541 ℃. The main components of the adopted high alkalinity high alumina tundish covering agent comprise: caO:48%, al 2 O 3 ：30%、MnO：4.9%、SiO 2 :2.3%, mgO:5.6%, and other unavoidable components.
(6) And a cogging step, wherein the cogging heating temperature is 1164 ℃, the heating time is 201min, and the specification of the intermediate billet obtained by cogging is 140mm multiplied by 140mm.
(7) A high-speed line rolling process, wherein the heating temperature is 1048 ℃, the initial rolling temperature is 945 ℃, the finish rolling inlet temperature is 868 ℃, the spinning temperature is 829 ℃, the roller way speed of a Siteur inlet section is 0.53m/s, the air quantity of 1-4# fans is 80%, 60% and 60% in sequence, and the rest fans are closed; and the heat preservation cover corresponding to the No. 5 fan and the subsequent heat preservation cover are all closed.
(8) The rolling specification of the cold heading steel wire rod is 6.5mm, and the cold heading steel wire rod comprises the following chemical components in percentage by mass: c:0.51%, si:0.26%, mn:1.45%, cr:0.26%, S:0.038%, al:0.018%, P:0.009%, T.O.: 0.0015%, N:0.0030% and the balance of Fe and other unavoidable impurity components. The high-quality sulfur-containing free-cutting steel wire rod has the defects of class B inclusion 1, class C inclusion 0.5, class Ds inclusion 0.5, mnS inclusion proportion less than or equal to 4, grain size 8.5, spheroidization rating 7, mesh cementite rating 0.5, surface vibration mark, pit, lug, fold, air hole and the like with the height or depth less than or equal to 2mm.
The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the technical means, and also comprises the technical scheme formed by any combination of the technical features.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.

Claims (10)

1. The high-quality sulfur-containing cold heading steel wire rod is characterized by comprising the following chemical components in percentage by mass: c:0.45-0.55%, si:0.20-0.50%, mn:0.65-1.85%, cr:0.1-0.3%, S:0.015-0.05%, al:0.010-0.060 percent, P is less than or equal to 0.015 percent, T.O is less than or equal to 0.0025 percent, N is less than or equal to 0.0045 percent, and the balance is Fe and other unavoidable impurity components.
2. The high quality sulfur-containing cold heading steel wire rod of claim 1, wherein the cold heading steel wire rod has a rolled diameter gauge of 5.5-20mm.
3. A method for preparing the high-quality sulfur-containing cold heading steel wire rod as defined in claim 1 or 2, which is characterized by comprising the following steps of converter-LF refining-continuous casting-cogging-high-line rolling:
step 1: the working procedure before iron: the molten iron comprises the following chemical components in percentage by mass: c:4.0-4.5%, si:0.2-0.5%, P is less than or equal to 0.13%, S:0.03-0.07%, wherein the temperature is 1380-1450 ℃, molten iron is directly conveyed to a converter for smelting without pretreatment;
step 2: converter process: the converter scrap steel ratio is 15-25%, clean scrap steel is selected for smelting, when converter blowing is finished, the S mass percentage content is 0.010-0.035%, the molten steel temperature is more than or equal to 1610 ℃, then tapping is carried out, and a slide plate is adopted for slag blocking for the next smelting;
step 3: tapping the converter: firstly, sequentially adding metal aluminum, silicon alloy, manganese alloy, carbon powder and ferrochrome alloy into a steel ladle to carry out deoxidization alloying, wherein the bottom blowing flow is 100-300NL/min, when 85% of steel is tapped, adding calcium aluminosilicate synthetic slag and lime to carry out slag making, controlling the slag alkalinity to be 1.5-2.5, and after the steel tapping is finished, the bottom blowing flow is 400-800NL/min, stirring for 3-5min, and then conveying to an LF furnace to carry out treatment;
step 4: refining process of LF furnace: argon is blown from the bottom in the whole process, the maximum flow rate of the air brick argon is 400-500NL/min during charging and alloying, the maximum flow rate of the air brick argon is 200-400NL/min during heating, and the maximum flow rate of the air brick argon is 100-150NL/min in the rest time; adding lime and calcium aluminosilicate to synthesize slag in the refining process, and controlling the alkalinity of ladle slag at CaO/SiO 2 =2.0-3.5，Al 2 O 3 Mass percent15-25% of Fe+MnO less than or equal to 1.5% and less than or equal to 3.5%; firstly adding 2-4kg/t of pyrite, then adding silicon alloy, manganese alloy, ferrochrome alloy and aluminum feeding wires, electrifying to regulate the components and the temperature of molten steel to reach the standards, then performing calcium treatment, feeding 50-120m pure calcium wires, tapping, performing soft stirring and calm treatment, and conveying the molten steel with Ca content of 3-8ppm to continuous casting pouring;
step 5: continuous casting process: pouring by a bloom continuous casting machine, protecting and pouring in the whole continuous casting process, adopting a high-alkalinity high-alumina tundish covering agent, controlling the superheat degree of the tundish molten steel to be 30-50 ℃, using a low-melting-point crystallizer covering slag, and using a crystallizer for electromagnetic stirring; the water quantity of the crystallizer is 2600-3200NL/min; the secondary cooling section adopts a weak cooling mode, and the water quantity of the secondary cooling section is respectively from zone 1 to zone 4: 1 section 60-100 NL/min, 2 section 20-50 NL/min, 3 section 20-40 NL/min, 4 section 10-30 NL/min; lightly rolling the continuous casting blank in a withdrawal and straightening machine, wherein the total rolling reduction is 8-15mm, and the rolling pressure is 30-40bar;
step 6: cogging process: the cogging heating temperature is 1140-1180 ℃, and the heating time is 180-250min;
step 7: high-line rolling process: the heating temperature is 1040-1080 ℃, the initial rolling temperature is 940-960 ℃, the finish rolling inlet temperature is 860-890 ℃, the spinning temperature is 820-840 ℃, the speed of a roller way of a Siteur inlet section is 0.4-0.8m/s, the high-line rolling process is provided with 1-5# fans, the fans are sequentially arranged according to the rolling sequence, the air quantity of the 1-4# fans is 40-90%, and the rest fans are closed; and the heat preservation cover corresponding to the No. 5 fan and the subsequent heat preservation cover are all closed.
4. The method for preparing high-quality sulfur-containing cold heading steel wire rods according to claim 3, wherein the clean scrap steel used in the converter in the step 2 comprises the following components in percentage by mass of P less than or equal to 0.015%, S less than or equal to 0.05%, and the balance of conventional C, si, al, mn, fe elements and other unavoidable impurity elements.
5. The method for preparing high-quality sulfur-containing cold heading steel wire rods according to claim 3, wherein 70-85% of aluminum ingots, 50-70% of manganese alloys, 50-80% of silicon alloys, total ferrochrome alloys and 60-80% of carbon powders are added when 20-30% of steel is tapped from the converter in the step 3.
6. The method for preparing the high-quality sulfur-containing cold heading steel wire rod according to claim 5, wherein the aluminum ingot component in the converter tapping process comprises Al not less than 98%, P not more than 0.010%, S not more than 0.01%, and the balance of Fe and other unavoidable impurity components; the manganese alloy comprises Mn not less than 98%, P not more than 0.010%, ti not more than 0.0025% and Fe and other unavoidable impurity components as the rest; the silicon alloy comprises 75% -80% of Si, less than or equal to 0.015% of P, less than or equal to 0.0035% of Ti, and the balance of Fe and other unavoidable impurity components; the ferrochrome comprises 55-65% of Cr, less than or equal to 0.015% of P, and the balance of Fe and other unavoidable impurity components; the addition amount of the calcium aluminosilicate synthetic slag is 6-10kg/t, and the main components comprise 25-40% of CaO and SiO 2 18-28%、Al 2 O 3 30-40% of other unavoidable components, wherein CaAl 2 SiO 7 The phase ratio is more than 75%; lime content is CaO more than or equal to 97%, and the balance is other unavoidable components.
7. The method for preparing high-quality sulfur-containing cold heading steel wire rods according to claim 3, wherein lime with CaO content more than or equal to 97% and other unavoidable components is added in the refining process of the step 4 LF furnace; the addition amount of the calcium aluminosilicate synthetic slag is 0-0.5kg/t, and the components comprise 25-40% of CaO and SiO 2 18-28%、Al 2 O 3 30-40% of other unavoidable components, wherein CaAl 2 SiO 7 The component accounts for more than 80 percent; the pyrite component added in the refining process is FeS 2 More than or equal to 50 percent, and the balance is unavoidable impurity components; the components are regulated to reach the standard, and the refining tapping temperature is controlled between 1550 ℃ and 1570 ℃.
8. The method for preparing the high-quality sulfur-containing cold heading steel wire rod according to claim 3, wherein in the continuous casting process of the step 5, the argon flow of a ladle long nozzle is 250-350NL/min; the adopted high alkalinity high alumina tundish covering agent comprises the following components: caO 45-55%, al 2 O 3 25-35%、MnO 2-5%、SiO 2 Less than or equal to 5 percent, mgO 3-6 percent, andother unavoidable components; the thickness of the mold flux layer of the crystallizer is maintained to be 15-22mm, and the addition amount is 0.25-0.35kg/t.
9. The method for preparing the high-quality sulfur-containing cold heading steel wire rod according to claim 3, wherein the pouring tonnage of the continuous casting tundish in the step 5 is more than or equal to 25t, the tonnage of the continuous casting tundish is more than or equal to 40t in normal pouring, and the tonnage of the continuous casting tundish is more than or equal to 30t; the immersion nozzle insertion depth is 120-180mm, the continuous casting pulling speed is controlled at 0.6-0.7m/min, the electromagnetic stirring current of the crystallizer is 550-750A, and the frequency is 2-3Hz.
10. The method for preparing the high-quality sulfur-containing cold heading steel wire rod according to claim 3, wherein the continuous casting billet from the continuous casting machine enters a cooling bed, the surface temperature of the cooling bed is more than or equal to 650 ℃, the corner temperature of the cooling bed is more than or equal to 500 ℃, hot charging and hot feeding are carried out for rolling, and the casting billet is carried out for next rolling without cooling to room temperature.
CN202311364847.3A 2023-10-20 2023-10-20 High-quality sulfur-containing cold heading steel wire rod and preparation method thereof Active CN117089772B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311364847.3A CN117089772B (en) 2023-10-20 2023-10-20 High-quality sulfur-containing cold heading steel wire rod and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311364847.3A CN117089772B (en) 2023-10-20 2023-10-20 High-quality sulfur-containing cold heading steel wire rod and preparation method thereof

Publications (2)

Publication Number Publication Date
CN117089772A true CN117089772A (en) 2023-11-21
CN117089772B CN117089772B (en) 2023-12-19

Family

ID=88771950

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311364847.3A Active CN117089772B (en) 2023-10-20 2023-10-20 High-quality sulfur-containing cold heading steel wire rod and preparation method thereof

Country Status (1)

Country Link
CN (1) CN117089772B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117327883A (en) * 2023-12-01 2024-01-02 张家港荣盛特钢有限公司 Non-quenched and tempered steel wire rod and production method thereof
CN117840394A (en) * 2024-03-07 2024-04-09 江苏省沙钢钢铁研究院有限公司 High-quality casting blank and continuous casting method thereof

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103469050A (en) * 2013-09-22 2013-12-25 中天钢铁集团有限公司 Aluminum-containing cold forging steel smelting process
CN105543675A (en) * 2015-12-21 2016-05-04 中天钢铁集团有限公司 Cold heading steel with refined crystalline grains and production process thereof
CN109913738A (en) * 2019-03-19 2019-06-21 江阴华西钢铁有限公司 The production technology of high-performance 35K cold-forging steel continuous casting square billet
CN112359279A (en) * 2020-10-20 2021-02-12 中天钢铁集团有限公司 Alloy structure steel wire rod for shaft and preparation method thereof
CN114231840A (en) * 2021-11-24 2022-03-25 邯郸钢铁集团有限责任公司 Wire rod for high-hardenability medium-carbon cold heading steel and production process thereof
CN114871397A (en) * 2022-03-28 2022-08-09 本钢板材股份有限公司 High-quality steel wire rod for cold heading and preparation method thereof
CN114990437A (en) * 2022-05-25 2022-09-02 张家港荣盛特钢有限公司 Cold heading steel wire rod and production method thereof
CN115232917A (en) * 2022-07-18 2022-10-25 中天钢铁集团有限公司 Smelting deoxidation process of aluminum-containing cold forging steel
CN116497261A (en) * 2023-06-19 2023-07-28 张家港荣盛特钢有限公司 Vulcanizing cold heading steel wire rod and preparation method and application thereof

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103469050A (en) * 2013-09-22 2013-12-25 中天钢铁集团有限公司 Aluminum-containing cold forging steel smelting process
CN105543675A (en) * 2015-12-21 2016-05-04 中天钢铁集团有限公司 Cold heading steel with refined crystalline grains and production process thereof
CN109913738A (en) * 2019-03-19 2019-06-21 江阴华西钢铁有限公司 The production technology of high-performance 35K cold-forging steel continuous casting square billet
CN112359279A (en) * 2020-10-20 2021-02-12 中天钢铁集团有限公司 Alloy structure steel wire rod for shaft and preparation method thereof
CN114231840A (en) * 2021-11-24 2022-03-25 邯郸钢铁集团有限责任公司 Wire rod for high-hardenability medium-carbon cold heading steel and production process thereof
CN114871397A (en) * 2022-03-28 2022-08-09 本钢板材股份有限公司 High-quality steel wire rod for cold heading and preparation method thereof
CN114990437A (en) * 2022-05-25 2022-09-02 张家港荣盛特钢有限公司 Cold heading steel wire rod and production method thereof
CN115232917A (en) * 2022-07-18 2022-10-25 中天钢铁集团有限公司 Smelting deoxidation process of aluminum-containing cold forging steel
CN116497261A (en) * 2023-06-19 2023-07-28 张家港荣盛特钢有限公司 Vulcanizing cold heading steel wire rod and preparation method and application thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117327883A (en) * 2023-12-01 2024-01-02 张家港荣盛特钢有限公司 Non-quenched and tempered steel wire rod and production method thereof
CN117327883B (en) * 2023-12-01 2024-02-20 张家港荣盛特钢有限公司 Non-quenched and tempered steel wire rod and production method thereof
CN117840394A (en) * 2024-03-07 2024-04-09 江苏省沙钢钢铁研究院有限公司 High-quality casting blank and continuous casting method thereof
CN117840394B (en) * 2024-03-07 2024-05-03 江苏省沙钢钢铁研究院有限公司 High-quality casting blank and continuous casting method thereof

Also Published As

Publication number Publication date
CN117089772B (en) 2023-12-19

Similar Documents

Publication Publication Date Title
CN117089772B (en) High-quality sulfur-containing cold heading steel wire rod and preparation method thereof
CN103160729B (en) Medium-carbon microalloyed steel for engineering machinery caterpillar chain piece and production process thereof
CN104946972B (en) Steel disc strip for diode lead and production technology of steel disc strip
CN109988972B (en) Round steel for low-carbon sulfur-containing air conditioning pipe and production process thereof
CN107699796B (en) A kind of low-carbon compound automatic steel and its production method
CN113025879B (en) Weather-resistant bridge steel and smelting method thereof
CN109706404B (en) Titanium-containing carbon steel and production method thereof
CN109457183A (en) A kind of low-sulfur free-cutting pinion steel and preparation method thereof
CN110541114B (en) Smelting method of high-nitrogen high-sulfur low-aluminum steel
JP2011530004A (en) Environmentally friendly lead-free free-cutting steel and method for producing the same
CN114892094B (en) Pre-hardened mirror plastic die steel and production method thereof
CN114959415A (en) Manufacturing method of microalloyed wind power transmission gear steel
CN111334718A (en) European standard R260Mn steel rail and production method thereof
CN104357761A (en) Sulfur-containing free-cutting die steel smelting technique
CN115896634B (en) High-temperature-resistant nonferrous metal die-casting forming die steel material and preparation method thereof
CN114875334B (en) Pre-hardened mirror plastic die steel and smelting method thereof
CN111074159A (en) Low-yield-ratio spiral welded pipe steel A139Gr.E and preparation method thereof
CN114231849B (en) Steel for offshore wind power turntable bearing and smelting method thereof
CN109913739A (en) The production technology of the high-quality Q195 continuous casting square billet of aircraft industry fastener
CN109778073B (en) Free-cutting steel for automobile synchronizer and preparation method thereof
CN109913755B (en) Peritectic steel and preparation method thereof
CN113462971A (en) Hot-working die large round billet and preparation method thereof
CN107058880B (en) A kind of automobile daming piston bar steel and its production method
CN112126743B (en) Production method of low-aluminum-content Cr5 steel ingot for supporting roll
CN115976396B (en) High-strength corrosion-resistant hot rolled steel strip Q550NQR1 for container and production method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant