A method for producing a high-elongation high-strength high-carbon steel wire

Abstract

The application discloses a production method of high-elongation high-strength high-carbon steel wire, and specifically comprises the following steps: (1) carrying out cold drawing on the treated coil rod to draw the coil rod into cold-drawn steel wire, and carrying out short-time electric pulse treatment on the cold-drawn steel wire in an oil bath environment; and (2) carrying out cold drawing on the steel wire after the short-time electric pulse treatment. The production method can carry out electric pulse treatment at room temperature, can inhibit the thermal effect of the electric pulse, can prevent spheroidization of cementite caused by high temperature, can prevent the destruction of the ferrite / cementite interface and thus can reduce the strength of the steel wire, and can significantly inhibit the thermal effect and prevent the reduction of the strength of the steel wire. The cold-drawn steel wire is subjected to electric pulse treatment by using the production method, and then is subjected to one-time cold drawing, so that the strength of the steel wire is significantly improved, and the plasticity of the steel wire does not change.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal products, and particularly relates to a production method of high-elongation high-strength high-carbon steel wire. BACKGROUND

[0002] High-carbon cold-drawing steel wire is the highest-strength engineering structural material among existing metal materials, has the advantages of high strength and good plasticity, and is widely used in many high-stress working environments. The traditional production method of high-strength steel wire is to deform high-carbon hot-rolled wire rod through multiple continuous cold-drawing deformations, which can reduce the interlamellar spacing, increase the dislocation density, and produce strong work hardening, so that the strength of the steel wire continuously increases with the increase of the strain.

[0003] The cold-drawing strain determines the work hardening rate of the steel wire. In the case of the same cold-drawing strain, the rising space of the strength of the steel wire produced by the traditional cold-drawing method is limited, which causes certain difficulties for further improving the strength of the steel wire. The production method of high-carbon steel wire disclosed in Chinese patent document CN108380678A can make the strength of the finished steel wire higher than that of the traditional process, but the process flow of the method is relatively long, and the traditional heat treatment and cold-drawing process need to be repeatedly performed for tens of hours, so the production process is complex, the efficiency is low, the production cost is high, and the method is difficult to be widely applied in industry. The production method of high-strength and high-toughness high-carbon steel wire disclosed in Chinese patent CN111763813A can significantly improve the plasticity of the cold-drawing steel wire, but the strength of the steel wire is reduced, and the strength of the steel wire cannot be improved under the fixed strain. Therefore, how to use a simple and efficient process to meet the requirement of improving the strength of high-carbon steel wire is a problem that attracts attention in the engineering field. SUMMARY

[0004] The present application provides a production method of high-elongation high-strength high-carbon steel wire, which can improve the strength of the steel wire under the fixed cold-drawing strain through the preparation process of electric pulse combined with cold-drawing, and has the advantages of simple and efficient production process, energy saving, and the like.

[0005] Technical scheme: In order to achieve the above-mentioned purpose, the production method of high-elongation high-strength high-carbon steel wire provided by the present application comprises the following steps:

[0006] (1) cold-drawing the treated wire rod into a cold-drawing steel wire, and performing short-time electric pulse treatment on the cold-drawing steel wire in an oil bath environment;

[0007] (2) cold-drawing the steel wire after the short-time electric pulse treatment.

[0008] Further, the wire rod in the step (1) is a high-carbon hot-rolled wire rod with a carbon content of 0.72-1.0wt.%.

[0009] Further, the cold drawing pass in step (1) is multiple passes.

[0010] Further, the total compression rate of the cold drawing pass in step (1) is greater than 80%, and the compression rate of each pass is 15-25%.

[0011] Further, the temperature of the oil bath environment in step (1) is room temperature.

[0012] Further, the electric pulse treatment in step (1) adopts a single pulse discharge mode, the current density is 50-500 A / mm2, the pulse width is 1-100 ms, the pulse frequency is controlled at 500-5000 Hz, and the total treatment time is 1-10 s.

[0013] Further, the cold drawing pass in step (2) is one pass.

[0014] Further, the compression rate of the cold drawing pass in step (2) is 15-25%.

[0015] The high-elongation high-strength high-carbon steel wire produced by the production method.

[0016] Invention principle: During the cold drawing process of the high-carbon steel wire, large strain deformation reduces the pearlite lamellar spacing, increases the ferrite / cementite interface, rapidly proliferates and entangles dislocations, produces strong work hardening effect, and improves the strength of the steel wire. Although the work hardening rate will increase with the increase of the drawing strain, if the strain of the steel wire is fixed, the work hardening rate of the steel wire has its limit, which will limit the further improvement of the strength of the steel wire.

[0017] The electric pulse treatment adopted in the application has non-thermal effect. On the one hand, the electron wind force of the electric pulse can provide additional driving force for dislocations, promote the movement of dislocations, change the dislocation configuration, untangle and unpin the tangled and pinned dislocations, restore the mobility of the dislocations, increase the number of discrete mobile dislocations in the steel wire, and improve the plasticity of the material. On the other hand, the electric migration phenomenon of non-thermal effect can improve the movement rate of carbon atoms, promote the transformation of amorphous in the cementite lamellar into nanocrystals, and distribute the nanocrystals at the cementite lamellar and the interface. The nanocrystals can increase the resistance of dislocation movement and play a role in pinning dislocations. When the next pass of cold drawing is completed after the electric pulse, the mobile dislocations further proliferate and interact with the nanocrystals in the cementite, a large number of dislocations are pinned and re-entangled, the dislocation movement is severely hindered, and the work hardening effect of the steel wire is enhanced.

[0018] By using the electric pulse treatment and combining with further cold drawing deformation, the application affects the dislocation configuration and cementite morphology in the steel wire, enhances the interaction between the dislocations and the cementite nanocrystals in the steel wire, can significantly improve the strength of the steel wire under a fixed strain, and the plasticity is not obviously reduced.

[0019] Advantages: Compared with the prior art, the following advantages are achieved:

[0020] (1) The production method has the advantages of simple process, extremely high efficiency and low energy consumption. In addition to cold drawing processing, only one electric pulse treatment is needed, and the electric pulse treatment is efficient and rapid, with a treatment time of 1-10s and low energy consumption.

[0021] (2) The electric pulse treatment is carried out at room temperature in an oil bath environment, which can inhibit the thermal effect of the electric pulse and prevent the spheroidization of cementite caused by high temperature, thereby reducing the strength of the steel wire and significantly inhibiting the thermal effect to prevent the reduction of the strength of the steel wire.

[0022] (3) The cold-drawn steel wire is first subjected to electric pulse treatment, and then subjected to one more cold drawing. Compared with the conventional continuous cold drawing method, the strength of the steel wire can be significantly improved under the same strain, and the plasticity is not significantly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the electric pulse treatment device of the present application;

[0024] Figure 2 is a TEM photo after the last pass of cold drawing of Example 1;

[0025] Figure 3 is a TEM photo after low-temperature tempering treatment of Comparative Example 3. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with the drawings and examples.

[0027] Example 1

[0028] (1) The high-carbon hot-rolled wire rod with a carbon content of 0.82wt.% and a diameter of 5.50mm was rusted to make the surface of the high-carbon hot-rolled wire rod smooth and free of oxidation.

[0029] (2) The treated high-carbon hot-rolled wire rod was drawn into a cold-drawn steel wire using a wire drawing process, with a drawing diameter of 1.90mm and a compression rate of 20% for each drawing pass. A total of 9 drawing passes were performed, with a total compression rate of 88%, and the obtained steel wire had a tensile strength of 2020MPa and an elongation of 4.8%.

[0030] (3) The cold-drawn steel wire was subjected to electric pulse treatment under oil bath conditions, as shown in Figure 1, the two ends of the cold-drawn steel wire are connected to the positive and negative poles of the pulse power by copper guide wheels, the middle part of the copper guide wheels can be subjected to electric pulse treatment, the steel wire in the electric pulse treatment is in an oil bath environment, the temperature of the oil bath environment is room temperature, the part of the steel wire not in the oil bath treatment environment is not subjected to electric pulse treatment, and the electric pulse parameters are as follows: current density 100 A / mm2, pulse frequency 3000 Hz, pulse width 10 ms, and total treatment duration 5 s.

[0031] (4) After the electric pulse treatment is completed, the steel wire is cold-drawn to a diameter of 1.70 mm, the compression rate of this drawing pass is 20%, and a total of 10 drawing passes are performed, and the total compression rate of the steel wire is 90%. The tensile strength of the obtained steel wire is 2250 MPa, and the elongation is 4.0%, and it can be seen that the steel wire produced by the method has high strength and good plasticity. The TEM microstructure of the steel wire is shown in Figure 2 (4) After the electric pulse treatment is completed, the steel wire is cold-drawn to a diameter of 1.70 mm, the compression rate of this drawing pass is 20%, and a total of 10 drawing passes are performed, and the total compression rate of the steel wire is 90%. The tensile strength of the obtained steel wire is 2250 MPa, and the elongation is 4.0%, and it can be seen that the steel wire produced by the method has high strength and good plasticity. The TEM microstructure of the steel wire is shown in (4) After the electric pulse treatment is completed, the steel wire is cold-drawn to a diameter of 1.70 mm, the compression rate of this drawing pass is 20%, and a total of 10 drawing passes are performed, and the total compression rate of the steel wire is 90%. The tensile strength of the obtained steel wire is 2250 MPa, and the elongation is 4.0%, and it can be seen that the steel wire produced by the method has high strength and good plasticity. The TEM microstructure of the steel wire is shown in

[0032] Example 2

[0033] (1) The high-carbon hot-rolled wire rod with a carbon content of 0.82wt.% and a diameter of 5.50 mm is rusted, and the surface of the high-carbon hot-rolled wire rod is smooth without oxidation skin.

[0034] (2) The treated high-carbon hot-rolled wire rod is drawn into a cold-drawn steel wire by using a conventional steel wire drawing process, and is drawn to a diameter of 2.35 mm, the compression rate of each drawing pass is 18%, a total of 9 drawing passes are performed, and the total compression rate is 82%. The tensile strength of the obtained steel wire is 1720 MPa, and the elongation is 6.5%.

[0035] (3) The cold-drawn steel wire is subjected to electric pulse treatment in an oil bath environment by using the treatment method of Example 1, the temperature of the oil bath environment is room temperature, and the electric pulse parameters are as follows: current density 300 A / mm2, pulse frequency 5000 Hz, pulse width 50 ms, and total treatment duration 10 s.

[0036] (4) After the electric pulse treatment is completed, the steel wire is cold-drawn to a diameter of 1.70 mm, the compression rate of this drawing pass is 20%, and a total of 10 drawing passes are performed, and the total compression rate of the steel wire is 90%. The tensile strength of the obtained steel wire is 2250 MPa, and the elongation is 4.0%, and it can be seen that the steel wire produced by the method has high strength and good plasticity. The TEM microstructure of the steel wire is shown in

[0037] Example 3

[0038] (1) The high-carbon hot-rolled wire rod with a carbon content of 0.92wt.% and a diameter of 6.00 mm is rusted, and the surface of the high-carbon hot-rolled wire rod is smooth without oxidation skin.

[0039] (2) The treated high carbon hot-rolled wire rod was drawn into cold-drawn steel wire with a diameter of 1.50 mm by using a conventional steel wire drawing process, and the compression rate of each drawing pass was 24%, and the total compression rate was 96% after 12 drawing passes, and the tensile strength of the obtained steel wire was 2430 MPa, and the elongation was 2.8%.

[0040] (3) The cold-drawn steel wire was treated by electric pulse treatment in an oil bath environment by using the treatment method of Example 1, and the oil bath environment temperature was room temperature, and the electric pulse parameters were: current density 50 A / mm2, pulse frequency 1000 Hz, pulse width 20 ms, and total treatment time 3 s.

[0041] (4) After electric pulse treatment, the steel wire was cold-drawn to a diameter of 1.30 mm, and the compression rate of this drawing pass was 25%, and the total compression rate of the steel wire was 97% after 13 drawing passes. The tensile strength of the obtained steel wire was 2520 MPa, and the elongation was 2.6%.

[0042] Comparative Example 1

[0043] A high carbon hot-rolled wire rod with a carbon content of 0.82wt.% and a diameter of 5.50 mm was rusted, and the surface of the high carbon hot-rolled wire rod was smooth without oxidation skin. The treated high carbon hot-rolled wire rod was drawn into cold-drawn steel wire with a diameter of 1.70 mm by using a conventional steel wire drawing process, and the compression rate of each drawing pass was 20%, and the total compression rate was 90% after 10 drawing passes, and the tensile strength of the obtained steel wire was 2140 MPa, and the elongation was 4.3%.

[0044] Comparative Example 2

[0045] (1) A high carbon hot-rolled wire rod with a carbon content of 0.82wt.% and a diameter of 5.50 mm was rusted, and the surface of the high carbon hot-rolled wire rod was smooth without oxidation skin. The treated high carbon hot-rolled wire rod was drawn into cold-drawn steel wire with a diameter of 1.70 mm by using a conventional steel wire drawing process, and the compression rate of each drawing pass was 20%, and the total compression rate was 90% after 10 drawing passes, and the tensile strength of the obtained steel wire was 2140 MPa, and the elongation was 4.3%.

[0046] (2) The cold-drawn steel wire was treated by electric pulse treatment in an oil bath environment by using the method of Example 1, and the oil bath environment temperature was room temperature, and the electric pulse parameters were: current density 100 A / mm2, pulse frequency 3000 Hz, pulse width 10 ms, and total treatment time 5 s. Due to the disentanglement and denailing of the entangled pinned dislocations after electric pulse treatment, the number of movable dislocations increased, which led to the increase of plasticity and the decrease of strength of the steel wire, and the tensile strength of the steel wire was 2090 MPa, and the elongation was 4.9%.

[0047] Comparative Example 3

[0048] (1) The high carbon hot rolled rod wire with 0.82wt.% carbon content and 5.50mm diameter was derusted to make the surface of the high carbon hot rolled rod wire smooth without oxide skin. And the rod wire was drawn into cold drawn steel wire with 1.90mm diameter according to the conventional steel wire drawing process, the compression rate of each drawing pass was 20%, and the total compression rate was 88% after 9 drawing passes, the tensile strength of the obtained steel wire was 2020MPa, and the elongation was 4.8%.

[0049] (2) The cold drawn steel wire was tempered at low temperature in a muffle furnace, the tempering temperature was 350°C, and the tempering time was 60 minutes.

[0050] (3) After low temperature tempering, the steel wire was cold drawn to 1.70mm diameter, the compression rate of the drawing pass was 20%, the tensile strength of the obtained steel wire was 2070MPa, and the elongation was 5.6%. Due to the high tempering temperature, the spheroidization of cementite occurred, which led to a large decrease of the strength of the steel wire, and the TEM microstructure of the steel wire after low temperature tempering was shown in Figure 3 , it could be seen that the spheroidization of cementite was obvious, and the ferrite / cementite interface was destroyed.

[0051] Table 1 Tensile properties of the steel wire (1.70mm diameter) with 0.82% carbon content after treatment

[0052]

[0053] As shown in Table 1, the high carbon hot rolled rod wire after treatment was treated by cold drawing-electric pulse-cold drawing (Example 1), the total compression rate was 90%, the strength reached 2250MPa, and the elongation was 4.0%. The high carbon hot rolled rod wire after treatment was treated by cold drawing (Comparative Example 1), the total compression rate was 90%, and the elongation was 4.3%. But the strength was only 2140MPa. If the electric pulse treatment was performed after the last drawing pass (Comparative Example 2), it was found that due to the interaction of dislocations and cementite without subsequent cold drawing, the strength of the steel wire would decrease. If the cold drawing was performed first, then the heat treatment tempering was performed, and finally one pass of cold drawing was performed (Comparative Example 3), it was found that due to the influence of the high temperature during the heat treatment tempering, the dislocation configuration and the specific effect of the microstructure of the steel wire were difficult to form, which would decrease the strength of the steel wire, and the treatment time was long, and the treatment efficiency was low. If the strength of 2250MPa was to be reached, the drawing pass needed to be increased, which would increase the engineering quantity, and the diameter of the steel wire would decrease, the plasticity would decrease, and the application would be limited. The electric pulse treatment only needed to be performed once, and the treatment time only needed to be within 10s, which was much shorter than the heat treatment in terms of treatment time and efficiency; compared with the steel wire treated by the conventional cold drawing only, the method of the present application could reduce the strain amount under the same strength, reduce the drawing pass, and save time.

[0054] The production method of the application is that the treated high-carbon hot-rolled wire rod is cold-drawn, then subjected to electric pulse treatment, and finally subjected to one-time cold-drawing. The steel wire prepared through the production method has significantly improved strength on the basis of unchanged strain, and the plasticity is not obviously reduced. The electric pulse treatment cooperates with the deformation of the next pass of cold-drawing. The purpose of the electric pulse treatment is to change the dislocation configuration and cementite morphology, thereby enhancing the interaction of dislocations and cementite nanocrystals during further drawing deformation, and significantly improving the strength of the steel wire after the next pass of cold-drawing. If the electric pulse treatment is not added throughout the process and only cold-drawing treatment is used, the final strength is lower. If the electric pulse treatment is performed after cold-drawing to the final strain, on the one hand, the dislocation configuration changes and the dislocation density decreases; on the other hand, the cementite nanocrystals cannot produce strong interaction with the drawing proliferated dislocations during subsequent cold-drawing, the work hardening effect of the steel wire is low, and finally the strength of the steel wire is reduced (Chinese patent CN111763813A).

Claims

1. A method of producing a high-elongation high-strength high-carbon steel wire, characterized by, It comprises the following steps: (1) cold-drawing the treated wire rod into cold-drawn steel wire, and carrying out short-time electric pulse treatment on the cold-drawn steel wire in an oil bath environment; (2) cold-drawing the steel wire after the short-time electric pulse treatment again; In the step (1), the wire rod is high-carbon hot-rolled wire rod with a carbon content of 0.72-1.0 wt.%; In the step (1), the cold-drawing passes are multiple passes; In the step (1), the total compression rate of the cold-drawing passes is greater than 80%, and the compression rate of each pass is 15-25%; In the step (1), the temperature of the oil bath environment is room temperature; The electric pulse treatment in step (1) adopts single pulse discharge mode, the current density is 50-500 A / mm 2 , the pulse width is 1-100 ms, the pulse frequency is controlled at 500-5000 Hz, and the total treatment time length is 1-10 s. In the step (2), the cold-drawing pass is one pass; In the step (2), the compression rate of the cold-drawing pass is 15-25%.

2. A high-elongation high-strength high-carbon steel wire produced by the production method of claim 1.

Images