CN115874109A - Alloy cold forging steel and manufacturing method thereof - Google Patents

Alloy cold forging steel and manufacturing method thereof Download PDF

Info

Publication number
CN115874109A
CN115874109A CN202111146953.5A CN202111146953A CN115874109A CN 115874109 A CN115874109 A CN 115874109A CN 202111146953 A CN202111146953 A CN 202111146953A CN 115874109 A CN115874109 A CN 115874109A
Authority
CN
China
Prior art keywords
steel
alloy cold
equal
cold heading
alloy
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
CN202111146953.5A
Other languages
Chinese (zh)
Other versions
CN115874109B (en
Inventor
郑宏光
徐超
黄宗泽
杨宝权
李树贵
陈志平
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.)
Baoshan Iron and Steel Co Ltd
Original Assignee
Baoshan Iron and 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 Baoshan Iron and Steel Co Ltd filed Critical Baoshan Iron and Steel Co Ltd
Priority to CN202111146953.5A priority Critical patent/CN115874109B/en
Publication of CN115874109A publication Critical patent/CN115874109A/en
Application granted granted Critical
Publication of CN115874109B publication Critical patent/CN115874109B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Landscapes

  • Heat Treatment Of Steel (AREA)

Abstract

The invention discloses alloy cold forging steel, which contains Fe and inevitable impurity elements, and also contains the following chemical elements in percentage by mass: c:0.05-0.12%, si:1.0-1.5%, mn:1.5-2.0%, V:0.01-0.04%, al:0.018 to 0.05%, sm:0.02-0.05%, ca:0.001-0.005%, more than 0 and less than or equal to 0.005% of N, more than 0 and less than or equal to 0.001% of O, less than or equal to 0.025% of P, and more than 0 and less than or equal to 0.015% of S. In addition, the invention also discloses a manufacturing method of the alloy cold forging steel, which comprises the following steps: smelting and refining; (2) continuous casting of a bloom; (3) primary hot rolling and cogging; (4) performing secondary hot rolling to obtain a finished product; (5) quenching and tempering: wherein the quenching heating temperature is 855-890 ℃, and the quenching cooling speed is 50-90 ℃/s; the tempering heating temperature is 645-670 ℃, and the tempering cooling speed is 50-90 ℃/min. The alloy cold forging steel has excellent mechanical property, can be used for producing standard parts such as bolts, screws, pins, nuts and the like, and is widely applied to various industries.

Description

Alloy cold forging steel and manufacturing method thereof
Technical Field
The invention relates to a steel material and a manufacturing method thereof, in particular to cold forging steel and a manufacturing method thereof.
Background
The cold heading process is a process which adopts one-time or multi-time impact loading forming at room temperature, can be used for producing cold heading steel, and is widely used for producing standard parts (fasteners) such as bolts, screws, pins, nuts and the like.
The cold heading steel is generally selected from low-medium carbon high-quality structural steel and high-quality alloy structural steel, and various mechanical standard parts and fasteners can be manufactured by adopting the steel for cold heading forming so as to be used in the industries of automobiles, shipbuilding, equipment manufacturing, electronics, household appliances, bicycles, tools, light steel structures, buildings and the like.
Because the cold heading steel has very good cold forming performance, in recent years, in the machining industry, cold drawing is often adopted to replace hot rolled material cold cutting machining. The method is an advanced machining process which is started in recent years, and the product manufactured by the method has high dimensional precision, good surface smoothness and high productivity, and can reduce 10-30% of metal consumption while saving a large amount of labor.
In the prior art, 07Mn2SiV belongs to steel for forming cold forging steel, and according to the content disclosed by the standard of alloy structural steel, the chemical element composition range of the 07Mn2SiV is as follows: c:0.05 to 0.12 percent; si:1.0 to 1.5 percent; mn:1.5 to 2.0 percent; s is less than or equal to 0.035%; p is less than or equal to 0.035%; v:0.01 to 0.04 percent; al is more than or equal to 0.015 percent. The mechanical property of the steelCan be as follows: yield strength (sigma) s ) More than or equal to 385MPa; tensile strength (σ) b ) Not less than 625MPa; the elongation delta 5 is more than or equal to 29 percent; the reduction of area psi is more than or equal to 41 percent. The alloy steel has very good mechanical property, high strength and good plasticity, and the crystal grains of the steel are refined by adding V, so that the strength is improved, the plasticity and the toughness are improved, and the yield ratio is high.
The steel has the design concept that: by properly increasing elements such as Si and Mn, solid solution strengthening is achieved, and by adding a small amount of V element, VN (vanadium nitride) particles are precipitated at grain boundaries to strengthen the grain boundaries, refine the grains, and the like, thereby improving the mechanical properties of the steel.
However, it should be noted that, in the prior art, 07Mn2SiV alloy steel needs to be applied by thermal refining, so the production cost is relatively high; in addition, with the development of technology, the mechanical properties of the steel cannot fully meet the requirements of current practical application and manufacturing. Therefore, the development of non-quenched and tempered alloy cold heading steel with higher strength, better ductility and toughness and more reasonable cost is needed to meet the requirement of practical application.
Disclosure of Invention
The invention aims to provide novel alloy cold forging steel which has excellent mechanical properties, wherein the yield strength is not less than 415MPa, the tensile strength is not less than 655MPa, the yield ratio is not less than 0.6, the elongation is not less than 31 percent, and the reduction of area is not less than 43 percent.
In order to achieve the purpose, the invention provides alloy cold forging steel, which contains Fe and inevitable impurity elements, and further contains the following chemical elements in percentage by mass:
C:0.05-0.12%、Si:1.0-1.5%、Mn:1.5-2.0%、V:0.01-0.04%、Al:0.018-0.05%、Sm:0.02-0.05%、Ca:0.001-0.005%、0<N≤0.005%、0<O≤0.001%、P≤0.025%、0<S≤0.015%。
further, in the alloy cold forging steel of the invention, the mass percentages of the chemical elements are as follows:
c:0.05-0.12%, si:1.0-1.5%, mn:1.5-2.0%, V:0.01-0.04%, al:0.018 to 0.05%, sm:0.02-0.05%, ca:0.001-0.005%, more than 0 and less than or equal to 0.005% of N, more than 0 and less than or equal to 0.001% of O, less than or equal to 0.025% of P, and more than 0 and less than or equal to 0.015% of S; the balance being Fe and other unavoidable impurities.
In the technical scheme of the invention, the alloy cold forging steel mainly adopts a trace alloy element adding design, and can further strengthen and toughen the steel by utilizing the characteristics of the added trace alloy element, thereby improving the mechanical property of the steel.
The alloy cold forging steel adopts a brand-new microalloy addition design, and in the case of adding V element originally, a proper amount of Sm (samarium) and Ca Wei alloy elements is added to control the O content in the steel to be lower, and the mechanical property of the steel is improved while the lower production cost is maintained, so that the yield strength of the steel is more than or equal to 415MPa, the tensile strength is more than or equal to 655MPa, the yield ratio is more than or equal to 0.6, the elongation is more than or equal to 31%, and the reduction of area is more than or equal to 43%.
In the alloy cold heading steel, the design principle of each chemical element is as follows:
c: in the alloy cold forging steel, C mainly influences the precipitation amount and the precipitation temperature range of carbide, and the mechanical property of steel can be improved by controlling the lower C content. C has a certain strengthening effect, but too high C content can reduce the corrosion resistance of the material, so that the C element needs to be strictly controlled within a required range in the smelting process, and the mechanical property and the impact toughness of the material are favorably considered.
It should be noted that the carbon content in steel has a great influence on the cold plastic deformation performance of steel, and the higher the carbon content in steel, the higher the strength of steel and the lower the plasticity. Based on this, in the alloy cold heading steel of the present invention, the content of C element by mass is controlled to be between 0.05-0.12% in consideration of the influence of the content of C element in steel on the properties of steel.
Si: in the alloy cold forging steel, the content of Si element in the steel is properly increased, so that the alloy cold forging steel is very favorable for the comprehensive mechanical property, particularly the elastic limit, of the steel, and simultaneously can increase the corrosion resistance of the steel. However, si is a residue of a deoxidizer in steel smelting, and when the content of silicon and carbon in steel is high, the plasticity of the steel is greatly affected. Therefore, the technical scheme needs to strictly control the upper limit of the content of the Si element in the steel. Based on the above, in the alloy cold forging steel, the mass percentage of Si element is controlled to be 1.0-1.5%.
Mn: in the alloy cold forging steel, mn is a weaker austenitizing alloy element, and the Mn element can act with iron oxide (Mn + FeO → MnO + Fe) in the smelting of the steel to realize deoxidation, and is mainly added for deoxidizing the steel. In addition, the Mn element can also act with iron sulfide in the steel (Mn + FeS → MnS + Fe), which can reduce the harmful effect of sulfur on the steel, and the manganese sulfide formed by the action can improve the machinability of the steel. In the technical scheme, mn can improve the tensile strength and the yield strength of the steel, reduce the plasticity and is unfavorable for the cold plastic deformation of the steel, but the influence of Mn on the deformation force is only about 1/4 of C. Based on the above, in the alloy cold forging steel of the invention, the mass percentage of Mn element is controlled between 1.5-2.0% in consideration of the influence of Mn element content on the steel properties.
V: in the alloy cold forging steel, the V element has extremely strong affinity with carbon, oxygen and nitrogen, and can form corresponding stable compounds; in addition, the element V is mainly present in the form of carbides in the steel, and its main role is to refine the structure and grains of the steel; in addition, the addition of a proper amount of V element in the steel can also increase the tempering stability of the quenched steel and generate a secondary hardening effect; the V content in the steel is generally not more than 0.5% except for the high-speed tool steel. In the technical scheme, vanadium can effectively refine grains in the common low-carbon alloy steel, the strength, yield ratio and low-temperature characteristics after normalizing are improved, and the welding performance of steel is improved. Based on the above, in the alloy cold forging steel, the mass percentage of the V element is controlled to be 0.01-0.04%.
Of course, in some preferred embodiments, in order to obtain better implementation effect, the content of the V element by mass may be further preferably controlled to be between 0.01 and 0.03%.
Al: in the alloy cold forging steel, al element is mainly used for strengthening the alloy by controlling the oxygen content in the steel to influence dislocation behavior, and the solid solution temperature and the mechanical property of steel can be obviously improved by increasing the content of the Al element in the steel, but the plasticity of the material is damaged; the addition of a proper amount of Al in the steel is beneficial to the extension deformation performance of the steel and the improvement of the processing performance of the steel; the Al element content in the steel is not suitable to be too high, and when the Al element content in the steel is too high, the impact toughness of the steel is reduced. Based on the above, in the alloy cold forging steel, the mass percentage of the Al element is controlled to be 0.018-0.05%.
Sm: in the alloy cold forging steel of the invention, in molten steel at high temperature, sm element can react with S, 0 and P, C, N element to generate SmS and Sm 2 O 3 And SmN, which can improve the service performance of steel. In addition, sm may be added with Al as an inclusion 2 O 3 MnS to form Sm 2 O 3 SmS, to Al 2 O 3 And MnS is changed into Al and Mn, so that the comprehensive performance of the steel is improved. Based on the above, in the alloy cold forging steel, the mass percentage content of the element Sm is controlled to be 0.02-0.05%.
Of course, in some preferred embodiments, in order to obtain better implementation effect, the mass percentage content of the element Sm can be further preferably controlled to be between 0.025 and 0.045%.
Ca: in the alloy cold forging steel, ca is a very active metal element and has strong affinity with oxygen, nitrogen and sulfur. Ca is a good deoxidizing agent and a good desulfurizing agent in iron and steel smelting, and is also a good nodulizer of cast iron, and Ca is difficult to dissolve in a matrix of the cast iron and exists in the states of compounds CaS, caO and the like; in addition, ca may also form a series of compounds with C, such as CaC 2 、Ca 2 C 3 And the like. Based on the method, in the alloy cold forging steel, the content of Ca element by mass percent is controlled to be between 0.001 and 0.005 percent.
Of course, in some preferred embodiments, in order to obtain better implementation effect, the content of the Ca element by mass may be further preferably controlled to be between 0.001 and 0.0025%.
N: in the alloy cold forging steel of the present invention, N is a stable austenite element, and controlling a lower N content in the steel is advantageous for improving impact toughness of the steel, and when the N content in the steel is too high, it results in lowering toughness and ductility of the steel and reducing hot workability. Based on the method, in the alloy cold forging steel, the mass percentage content of N element is controlled to be more than 0 and less than or equal to 0.005 percent.
O: in the alloy cold forging steel, O is an impurity element in the steel and mainly exists in oxide inclusions, the higher the content of the O element in the steel is, the more the inclusions are, and the reduction of the total oxygen content is beneficial to improving the comprehensive performance of the material. Based on the above, in order to ensure that the steel has good mechanical properties and corrosion resistance, in the alloy cold forging steel provided by the invention, the mass percentage content of O element is controlled to be more than 0 and less than or equal to 0.001%.
P, S: in the alloy cold forging steel, P and S both belong to impurity elements in the steel, and the content of the impurity elements in the steel is reduced as much as possible in order to obtain a steel with better performance and better quality under the permission of technical conditions. The impurity elements P and S can seriously affect the mechanical property and the processing property of the steel for low temperature and must be strictly controlled, so in the alloy cold heading steel, the mass percentage of the P, S element is controlled to be P less than or equal to 0.025 percent and S more than 0 is less than or equal to 0.015 percent.
In the present invention, S is a harmful impurity, and S in steel separates crystal grains of metal from each other at the time of cold heading to cause cracks, and the presence of S also promotes hot embrittlement and rusting of steel. Therefore, in the alloy cold forging steel, the mass percentage content of the S element is controlled to be more than 0 and less than or equal to 0.015 percent.
Correspondingly, the impurity element P has extremely strong solid solution strengthening and work hardening effects, and is seriously segregated in steel, so that the cold brittleness of steel is increased, and the steel is easily corroded by acid; in addition, P element in steel deteriorates cold plastic deformability of steel, and causes breakage of wire rods at the time of drawing and cracking of products at the time of cold heading. Therefore, in the alloy cold forging steel, the mass percentage content of the P element is controlled to be less than or equal to 0.025 percent.
In addition to the above elements, some other alloying elements such as chromium (Cr), molybdenum (Mo), nickel (Ni), etc. may be present in the alloy cold heading steel according to the present invention, and these alloying elements are present (in an extremely small amount) as impurity elements, and the influence on the steel is far less than that of the C element.
Further, in the alloy cold forging steel, the mass percentage of each chemical element also meets the following requirements: sm/N = 4-20; sm/O =20 to 65. In the formula, sm, N and O are substituted into the mass percentage of the corresponding elements.
In the above technical solution of the present invention, while controlling the mass percentage content of the single chemical element, the mass percentage content of the element Sm, N, O may be further preferably controlled to satisfy: sm/N = 4-20; sm/O =20-65.
In the invention, while adding Sm element, the Sm element can be further controlled to meet the following requirements: sm/N = 4-20; sm/O =20-65.Sm is dissolved in steel, and part of Sm can be combined with O, N to form Sm 2 O 3 SmN particles, under which Sm in the alloy of the present invention can be controlled 2 O 3 The quantity of SmN particles is 5-15/mm 2 The particles can further refine grains and improve mechanical property and punching property; meanwhile, part of N in the steel is solidified, and the content of solid solution N is reduced.
Further, in the alloy cold forging steel, the mass percentage of each chemical element also meets the following requirements: ca/O =1 to 8; ca/S =0.2 to 0.8. In the formula, ca, S and O are substituted into the mass percentage of the corresponding elements.
In the above technical solution of the present invention, while controlling the mass percentage of a single chemical element, the mass percentage of the elements Ca, S, and O can be further preferably controlled to satisfy: ca/O =1 to 8; ca/S =0.2 to 0.8.
In the present invention, the present invention is addingCa element and Ca/O = 1-8; ca/S = 0.2-0.8, thus 3-10/mm can be formed in the process of molten steel condensation 2 The fine particles of CaO and CaS can not only refine and stabilize austenite grains, but also reduce the harm of oxygen and sulfur to grain boundaries, thereby improving the plasticity of the material.
Further, the alloy cold heading steel also contains at least one of the following elements with the total mass percent of less than or equal to 1 percent: ce. Hf, la, re and Sc.
In the technical scheme of the invention, in some preferred embodiments, in order to obtain better performance of the alloy cold heading steel, rare earth and reactive elements such as Ce, hf, la, re and Sc with the mass percent of less than or equal to 1% can be further added.
Further, in the alloy cold heading steel of the invention, each chemical element thereof satisfies at least one of the following:
V:0.01-0.03%;
Sm:0.025-0.045%;
Ca:0.001-0.0025%。
further, in the alloy cold heading steel of the present invention, the microstructure thereof is ferrite + pearlite.
Further, in the alloy cold heading steel of the invention, sm is contained 2 O 3 And SmN particles.
Further, in the alloy cold forging steel of the invention, sm is 2 0 3 The diameter of SmN particles is 0.1-5 μm.
Further, in the alloy cold forging steel of the present invention, sm is present in a thickness section of the steel plate 2 0 3 The quantity of SmN particles is 5-15/mm 2
Further, the alloy cold heading steel of the present invention contains CaO and CaS particles.
Furthermore, in the alloy cold heading steel, the diameter of CaO and CaS particles is 0.1-5 μm.
Further, the air conditioner is characterized in that,in the alloy cold heading steel, the number of CaO and CaS particles is 3-10/mm on the thickness section of the steel plate 2
Further, in the alloy cold forging steel of the invention, the performance can meet the following requirements: the yield strength is not less than 415MPa, the tensile strength is not less than 655MPa, the yield ratio is not less than 0.6, the elongation is not less than 31 percent, and the reduction of area is not less than 43 percent.
Correspondingly, the invention also aims to provide the manufacturing method of the alloy cold forging steel, the production efficiency is higher, the production cost is low, the alloy cold forging steel manufactured by the manufacturing method has excellent mechanical properties, the yield strength is larger than or equal to 415MPa, the tensile strength is larger than or equal to 655MPa, the yield ratio is larger than or equal to 0.6, the elongation is larger than or equal to 31%, and the reduction of area is larger than or equal to 43%.
In order to achieve the above object, the present invention provides a method for manufacturing the alloy cold heading steel, comprising the steps of:
(1) Smelting and refining;
(2) Continuously casting a bloom;
(3) Primary hot rolling and cogging;
(4) Performing secondary hot rolling to obtain a finished product;
(5) Quenching and tempering: wherein the quenching heating temperature is 855-890 ℃, and the quenching cooling speed is 50-90 ℃/s; the tempering heating temperature is 645-670 ℃, and the tempering cooling speed is 50-90 ℃/min.
In the technical scheme of the invention, in the step (5), after the steel is formed by secondary hot rolling, the hot rolled steel can obtain good mechanical property by controlling quenching and tempering, so that the room-temperature mechanical property and impact toughness can be improved, and a hot rolled product with comprehensive performance meeting requirements can be obtained.
In the invention, mineral oil can be used as the coolant in the quenching and cooling process; during tempering cooling, mineral oil or water can be used as the coolant.
In the step (1) of the present invention, an electric furnace or a converter may be used for smelting steel, and then LF and RH (or VD) may be used for refining. Wherein, can add a small amount of samarium iron alloy and calcium silicon alloy in RH (or VD) refining terminal stage to add Sm + Ca, after the chemical composition of control is qualified, can blow the soft stirring of argon gas, and control and blow the argon gas flow and be 5-8 liters/minute.
Accordingly, in the step (2) of the present invention, continuous casting of the bloom is required, and the bloom after continuous casting may be subjected to surface finishing and polishing to remove visible surface defects and ensure good surface quality.
Further, in the manufacturing method of the invention, in the step (2), the drawing speed is controlled to be 0.45-0.85m/min, a crystallizer is adopted for electromagnetic stirring in the continuous casting process, the current is controlled to be 500-700A, and the frequency is 2.5-3.5Hz; the equiaxed grain ratio of the continuously cast bloom is more than or equal to 25 percent.
Further, in the manufacturing method of the present invention, the heating temperature in the step (3) is 1150-1250 ℃; and/or the heating temperature in the step (4) is 1150-1250 ℃.
Compared with the prior art, the alloy cold forging steel and the manufacturing method thereof have the advantages and beneficial effects as follows:
(1) In the invention, a small amount of Sm (samarium) is added in the chemical composition design, part of Sm is solid-dissolved in a steel grade, and part of Sm can be combined with O, N to form Sm 2 O 3 SmN particles, which can further refine grains and improve mechanical property and punching property; meanwhile, part of N in the steel is solidified, and the content of solid solution N is reduced.
Of course, in some preferred embodiments, it may be controlled to satisfy: sm/N = 4-20; sm/O =20-65. Under such conditions, sm in the alloy of the present invention can be controlled 2 O 3 The quantity of SmN particles is 5-15/mm 2 To further improve the properties of the steel.
(2) Reduction of Al in steel 2 O 3 MnS type inclusions, sm (samarium) energy reduced part of Al in steel 2 O 3 MnS inclusions to form small amount of Sm 2 O 3 SmS fine particles (Bi Al) 2 O 3 The size of MnS inclusions is smaller), thereby improving the mechanical properties of the steel.
(3) The invention adds a trace amount of Ca element in the chemical composition design, thus forming CaO and CaS fine particles in the process of molten steel condensation, and the fine particles can play the roles of refining and stabilizing austenite grains, and can reduce the harm of oxygen and sulfur to grain boundaries, thereby improving the plasticity of the material.
Of course, in some preferred embodiments, it may be controlled to satisfy: ca/O =1 to 8; ca/S =0.2 to 0.8. Under the condition, the mass points of CaO and CaS in the alloy can be controlled to be 3-10/mm 2 To further improve the properties of the steel.
Therefore, in the design of chemical element components, on the premise of adding the V element to refine grains, the invention also controls and adds two microalloy elements of Sm and Ca, which can promote the formation of a small amount of 0.1-5 mu m in diameter and 8-25 pieces in total per mm in the alloy in the cooling solidification process 2 Sm (b) in 2 O 3 Particles of SmS, smN, caO and CaS. The particles can further refine and stabilize the grain size of austenite in the continuous casting, cooling and solidifying process and the hot rolling process, and simultaneously, al is reduced 2 O 3 And the MnS inclusion has harmful effects of avoiding forming defects on the surfaces of bloom and hot rolling products and improving the mechanical properties of the materials.
The similar steel grade in the prior art does not have the design, and for some applications, the mechanical property and the plasticity of the steel cannot meet higher requirements.
The alloy cold forging steel designed by the invention has a ferrite plus pearlite structure at room temperature, has finer grains than the existing steel grade, has good mechanical property, higher strength and better plasticity, is refined by adding V, improves the strength, improves the plasticity and the toughness and has higher yield ratio. The alloy cold heading steel can be used for producing standard parts such as screws, pins, nuts and the like, and can be widely applied to industries such as automobiles, shipbuilding, equipment manufacturing, electronics, household appliances, bicycles, tools, light steel structures, buildings and the like.
Detailed Description
The alloy cold heading steel and the manufacturing method thereof according to the present invention will be further explained and illustrated with reference to specific examples, which, however, should not be construed to unduly limit the technical scope of the present invention.
Examples 1 to 6 and comparative examples 1 to 3
The alloy cold forging steels of the embodiments 1 to 6 of the invention are all prepared by the following steps:
(1) Smelting and casting were carried out according to the chemical compositions shown in tables 1-1 and 1-2: an electric furnace or a converter is adopted for smelting and steelmaking, and then LF and RH (or VD) can be utilized for refining. Wherein, a small amount of samarium-iron alloy (Sm) and calcium-silicon alloy (Ca) can be added at the final stage of RH (or VD) refining, after the chemical components are controlled to be qualified, argon-blowing soft stirring is carried out, and the flow of argon-blowing is controlled to be 5-8 liters/minute.
(2) Continuous casting of a bloom: adopting a bloom continuous casting machine for casting, controlling the casting speed to be 0.45-0.85m/min, adopting a crystallizer for electromagnetic stirring in the continuous casting process, controlling the current to be 500-700A and the frequency to be 2.5-3.5Hz; the isometric crystal proportion of the bloom after continuous casting is more than or equal to 25 percent; and after continuous casting, finishing and coping the large square slab at room temperature.
(3) Primary hot rolling and cogging: the heating temperature is controlled to be 1150-1250 ℃, and a bloom with the diameter of 300mm multiplied by 400mm-500mm multiplied by 600mm is firstly hot rolled and cogging into a billet with the diameter of 200mm multiplied by 200mm-300mm multiplied by 300mm of middle section.
(4) Secondary hot rolling to form a material: the billet is heated to 1150-1250 ℃ and rolled into round steel or square steel with the thickness of 25-250mm again.
(5) Quenching and tempering: carrying out heat treatment of quenching and tempering on round steel or square steel, wherein the quenching heating temperature is controlled to be 855-890 ℃, and the quenching cooling speed is 50-90 ℃/s; controlling the tempering heating temperature to be 645-670 ℃ and the tempering cooling speed to be 50-90 ℃/min.
The chemical element components and the related process design of the alloy cold forging steel of the embodiments 1 to 6 meet the design specification requirements of the invention; the comparative steels of comparative examples 1 to 3 were designed with conventional compositions, and the specific chemical element compositions are shown in Table 1 below.
Tables 1 to 1 and tables 1 to 2 show the mass percentage ratios of each chemical element of the alloy cold heading steels of examples 1 to 6 and the comparative steel sheets of comparative examples 1 to 3.
TABLE 1-1. (wt%, balance Fe and unavoidable impurities other than P, S, O, N)
Figure BDA0003285793350000091
Figure BDA0003285793350000101
Tables 1-2.
Number of Sm/N Sm/O Ca/O Ca/S
Example 1 4 20 4 0.267
Example 2 16.67 62.5 2.50 0.25
Example 3 7.5 42.86 7.14 0.5
Example 4 20 44.44 3.33 0.25
Example 5 6.667 28.57 7.14 0.714
Example 6 10 44.44 1.11 0.2
Comparative example 1 - - - -
Comparative example 2 - - - -
Comparative example 3 - - - -
Note: in the table above, sm, ca, O, N and S in formulas Sm/N, sm/O, ca/O and Ca/S respectively represent the mass percent of each corresponding element.
Table 2 shows specific process parameters in the above process steps for the alloy cold heading steels of examples 1 to 6 and the comparative steels of comparative examples 1 to 3.
Table 2.
Figure BDA0003285793350000102
It should be noted that, in the step (2), the billet after continuous casting can be observed, and the equiaxed grain ratio of the billet of each of the steel products of examples and comparative examples is observed to be not less than 25% by an area method.
The obtained alloy cold heading steels of examples 1 to 6 and comparative steel sheets of comparative examples 1 to 3, having finished thicknesses of 25mm, were sampled, respectively, and observed and examined to obtain Sm in slab thickness sections of the respective steel sheets of examples and comparative examples 2 0 3 The diameters and numbers of particles of SmN, caO and CaS, and the associated observations are set forth in Table 3.
Table 3.
Figure BDA0003285793350000111
Accordingly, after the above observation and examination, the alloy cold heading steels of examples 1 to 6 and the comparative steel sheets of comparative examples 1 to 3, each having a finished thickness of 25mm, were further sampled, and the mechanical property test thereof was performed, and the results of the mechanical property test were shown in Table 4.
The relevant mechanical property test method is as follows:
and (3) tensile test testing: test tests were conducted at room temperature in accordance with GB/T228-2002 to examine the yield strength, tensile strength, yield ratio, elongation and reduction of area of the alloy cold heading steels according to examples 1 to 6 and the comparative steels according to comparative examples 1 to 3. The final results were calculated from 30 averages in the experiment and the performance results are shown in table 4.
Table 4 shows the results of the mechanical property tests of the alloy cold heading steels of examples 1 to 6 and the comparative steels of comparative examples 1 to 3.
Table 4.
Figure BDA0003285793350000112
Figure BDA0003285793350000121
As can be seen from Table 4, compared with the comparative steel plates of comparative examples 1 to 3 which adopt chemical element components in the prior art, the alloy cold heading steels of examples 1 to 6 of the present invention have significantly better mechanical properties, the yield strengths of examples 1 to 6 are between 415 to 425MPa, the tensile strengths are between 655 to 672MPa, the yield ratios are between 0.62 to 0.64, the elongations are between 31 to 35%, and the reduction of area is between 43 to 46%, and the alloy cold heading steels can be used for producing standard parts such as screws, pins, nuts, etc., and can be widely used in the industries such as automobiles, shipbuilding, equipment manufacturing, electronics, household appliances, bicycles, tools, light steel structures, buildings, etc.
Unlike the alloy cold forging steels of examples 1 to 6, the comparative steels of comparative examples 1 to 3 do not contain Sm and Ca elements, and the chemical composition designs thereof do not satisfy the requirements of the present invention, and the final steels are significantly inferior to examples 1 to 6 in yield strength, tensile strength, qujiang ratio, elongation and section elongation.
It should be noted that the combination of the features in the present application is not limited to the combination described in the claims of the present application or the combination described in the embodiments, and all the features described in the present application may be freely combined or combined in any manner unless contradicted by each other.
It should also be noted that the above-mentioned embodiments are only specific embodiments of the present invention. It is apparent that the present invention is not limited to the above embodiments and similar changes or modifications can be easily made by those skilled in the art from the disclosure of the present invention and shall fall within the scope of the present invention.

Claims (17)

1. The alloy cold forging steel contains Fe and inevitable impurity elements, and is characterized by also containing the following chemical elements in percentage by mass:
C:0.05-0.12%、Si:1.0-1.5%、Mn:1.5-2.0%、V:0.01-0.04%、Al:0.018-0.05%、Sm:0.02-0.05%、Ca:0.001-0.005%、0<N≤0.005%、0<O≤0.001%、P≤0.025%、0<S≤0.015%。
2. the alloy cold heading steel as claimed in claim 1, wherein the alloy cold heading steel comprises the following chemical elements in percentage by mass:
c:0.05-0.12%, si:1.0-1.5%, mn:1.5-2.0%, V:0.01-0.04%, al:0.018 to 0.05%, sm:0.02-0.05%, ca:0.001-0.005%, more than 0 and less than or equal to 0.005% of N, more than 0 and less than or equal to 0.001% of O, less than or equal to 0.025% of P, and more than 0 and less than or equal to 0.015% of S; the balance being Fe and other unavoidable impurities.
3. The alloy cold heading steel as claimed in claim 1 or 2, wherein the contents of the chemical elements by mass further satisfy: sm/N = 4-20; sm/O =20 to 65.
4. The alloy cold heading steel as claimed in claim 1 or 2, wherein the mass percentage of each chemical element further satisfies: ca/O =1 to 8; ca/S =0.2 to 0.8.
5. The alloy cold heading steel as claimed in claim 1 or 2, further comprising at least one of the following elements in a total mass% of 1% or less: ce. Hf, la, re, sc.
6. The alloy cold heading steel according to claim 1 or 2, wherein each chemical element thereof satisfies at least one of the following:
V:0.01-0.03%;
Sm:0.025-0.045%;
Ca:0.001-0.0025%。
7. the alloy cold heading steel as claimed in claim 1 or 2, wherein the microstructure thereof is ferrite + pearlite.
8. The alloy cold heading steel as claimed in claim 1 or 2, wherein Sm is contained in 2 O 3 And SmN particles.
9. The alloy cold heading steel of claim 8, wherein Sm 2 0 3 The diameter of SmN particles is 0.1-5 μm.
10. The alloy cold heading steel as claimed in claim 8, wherein Sm is present in a cross section of the thickness of the steel plate 2 0 3 The number of SmN particles is 5-15/mm 2
11. The alloy cold heading steel as claimed in claim 1 or 2, which contains particles of CaO and CaS.
12. The alloy cold heading steel of claim 11, wherein the CaO and CaS particles have a diameter of 0.1 to 5 μm.
13. The alloy cold heading steel as claimed in claim 11, wherein the number of CaO and CaS particles is 3 to 10 particles/mm in a thickness section of the steel plate 2
14. The alloy cold heading steel as claimed in claim 1 or 2, wherein the properties satisfy: the yield strength is more than or equal to 415MPa, the tensile strength is more than or equal to 655MPa, the yield ratio is more than or equal to 0.6, the elongation is more than or equal to 31 percent, and the reduction of area is more than or equal to 43 percent.
15. The method for manufacturing alloy cold heading steel according to any one of claims 1 to 14, comprising the steps of:
(1) Smelting and refining;
(2) Continuously casting a bloom;
(3) Primary hot rolling and cogging;
(4) Secondary hot rolling to form a material;
(5) Quenching and tempering: wherein the quenching heating temperature is 855-890 ℃, and the quenching cooling speed is 50-90 ℃/s; the tempering heating temperature is 645-670 ℃, and the tempering cooling speed is 50-90 ℃/min.
16. The manufacturing method according to claim 15, wherein in the step (2), the drawing speed is controlled to be 0.45-0.85m/min, the crystallizer is adopted for electromagnetic stirring in the continuous casting process, the current is controlled to be 500-700A, and the frequency is 2.5-3.5Hz; the equiaxed grain ratio of the continuously cast bloom is more than or equal to 25 percent.
17. The manufacturing method according to claim 15, wherein the heating temperature in the step (3) is 1150-1250 ℃; and/or the heating temperature in the step (4) is 1150-1250 ℃.
CN202111146953.5A 2021-09-29 2021-09-29 Alloy cold heading steel and manufacturing method thereof Active CN115874109B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111146953.5A CN115874109B (en) 2021-09-29 2021-09-29 Alloy cold heading steel and manufacturing method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111146953.5A CN115874109B (en) 2021-09-29 2021-09-29 Alloy cold heading steel and manufacturing method thereof

Publications (2)

Publication Number Publication Date
CN115874109A true CN115874109A (en) 2023-03-31
CN115874109B CN115874109B (en) 2024-07-12

Family

ID=85755868

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111146953.5A Active CN115874109B (en) 2021-09-29 2021-09-29 Alloy cold heading steel and manufacturing method thereof

Country Status (1)

Country Link
CN (1) CN115874109B (en)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03193823A (en) * 1989-12-22 1991-08-23 Daido Steel Co Ltd Production of high strength stainless steel bolt for structural use
KR19980038066A (en) * 1996-11-23 1998-08-05 김종진 Manufacturing method of cold-rolled steel with excellent de-elasticity and softening heat treatment
JP2001303197A (en) * 2000-04-26 2001-10-31 Nippon Steel Corp Steel with fine solidification structure
CN1643176A (en) * 2002-03-25 2005-07-20 朴庸秀 High-grade duplex stainless steel with much suppressed formation of intermetallic phases and having an excellent corrosion resistance , embrittlement resistance, castability and hot workability
CN101194037A (en) * 2005-04-11 2008-06-04 住友金属工业株式会社 Austenitic stainless steel
CN101220439A (en) * 2007-01-08 2008-07-16 宝山钢铁股份有限公司 Non-quenching and tempering double-phase cold heading steel for high-strength fastener and method for manufacturing same
EP2199422A1 (en) * 2008-12-15 2010-06-23 Swiss Steel AG Low-carbon precipitation-strengthened steel for cold heading applications
CN102892910A (en) * 2010-05-10 2013-01-23 新日铁住金株式会社 High-strength steel sheet and method for producing same
CN104073731A (en) * 2013-03-27 2014-10-01 鞍钢股份有限公司 Ultrahigh-strength ship plate adopting direct quenching process and production method thereof
CN111511936A (en) * 2017-12-26 2020-08-07 株式会社Posco Wire rod for cold heading, worked product using the same, and method for manufacturing the same
CN112575242A (en) * 2019-09-27 2021-03-30 宝山钢铁股份有限公司 Steel for alloy structure and manufacturing method thereof

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03193823A (en) * 1989-12-22 1991-08-23 Daido Steel Co Ltd Production of high strength stainless steel bolt for structural use
KR19980038066A (en) * 1996-11-23 1998-08-05 김종진 Manufacturing method of cold-rolled steel with excellent de-elasticity and softening heat treatment
JP2001303197A (en) * 2000-04-26 2001-10-31 Nippon Steel Corp Steel with fine solidification structure
CN1643176A (en) * 2002-03-25 2005-07-20 朴庸秀 High-grade duplex stainless steel with much suppressed formation of intermetallic phases and having an excellent corrosion resistance , embrittlement resistance, castability and hot workability
CN101194037A (en) * 2005-04-11 2008-06-04 住友金属工业株式会社 Austenitic stainless steel
CN101220439A (en) * 2007-01-08 2008-07-16 宝山钢铁股份有限公司 Non-quenching and tempering double-phase cold heading steel for high-strength fastener and method for manufacturing same
EP2199422A1 (en) * 2008-12-15 2010-06-23 Swiss Steel AG Low-carbon precipitation-strengthened steel for cold heading applications
CN102892910A (en) * 2010-05-10 2013-01-23 新日铁住金株式会社 High-strength steel sheet and method for producing same
CN104073731A (en) * 2013-03-27 2014-10-01 鞍钢股份有限公司 Ultrahigh-strength ship plate adopting direct quenching process and production method thereof
CN111511936A (en) * 2017-12-26 2020-08-07 株式会社Posco Wire rod for cold heading, worked product using the same, and method for manufacturing the same
CN112575242A (en) * 2019-09-27 2021-03-30 宝山钢铁股份有限公司 Steel for alloy structure and manufacturing method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
完卫国等: "非调质高强度紧固件用双相钢盘条的试用", 金属制品, vol. 31, no. 4, pages 288 - 291 *

Also Published As

Publication number Publication date
CN115874109B (en) 2024-07-12

Similar Documents

Publication Publication Date Title
CN106661705B (en) carburized alloy steel and preparation method and application thereof
CN107904492B (en) Low-silicon high-carbon chromium bearing steel and hot rolling production method thereof
CN114134411B (en) Spheroidized annealed steel for low-temperature-resistant high-strength ball screw and manufacturing method thereof
CN111074148B (en) 800 MPa-level hot stamping axle housing steel and manufacturing method thereof
CN109136779B (en) Preparation method of 1100 MPa-level rare earth Q & P steel with martensite matrix
CN113930681B (en) High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof
CN111926236B (en) Method for producing steel plate with excellent Z-direction performance for welding structure by adopting continuous casting billet under condition of small compression ratio
EP4310216A1 (en) Steel for high-temperature carburized gear shaft and manufacturing method for steel
CN114134409A (en) Steel for ball screw bearing and manufacturing method thereof
CN111485167A (en) Hot-rolled round steel for rare earth microalloyed 25MnCrNiMoA coupler yoke and production method thereof
CN114134397B (en) Steel suitable for cold extrusion of ball screw and production method thereof
CN113604745A (en) High-sulfur free-cutting tool steel bar and preparation method thereof
CN112442629B (en) Medium-carbon steel for mechanical structure and manufacturing method thereof
CN112981266A (en) Steel for rack of steering gear of passenger car and manufacturing method thereof
CN115679223B (en) High-yield-ratio cold-rolled DH980 steel and preparation method thereof
CN108315645B (en) Wear-resistant steel and production process thereof
CN115874109B (en) Alloy cold heading steel and manufacturing method thereof
CN109881123B (en) 1000 Mpa-grade high-strength metastable austenite-martensite stainless steel
CN113774282B (en) Cast steel large gear material of mining mill and preparation process thereof
CN116497290B (en) Stainless steel material with good machinability and cutting destructiveness
CN113832390A (en) Steel for non-quenched and tempered alloy structure and manufacturing method thereof
CN118256825A (en) Bainite non-quenched and tempered steel and preparation method thereof
CN118086769A (en) Economical steel for saw blade matrix and production method
CN117344232A (en) 490 MPa-level thick steel plate with high core fatigue strength and manufacturing method thereof
CN117535583A (en) 850 MPa-level high-elongation quenched and tempered steel plate 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