Method for treating drawing defect of high-speed steel wire
Through alternating cycling of high-temperature heating and phase change temperature, the problem of low primary carbide cracks and secondary carbide quantity density of high-speed steel wire during the drawing process is solved, and the plasticity of high-speed steel wire is improved.
Patent Information
- Application Number
- CN202510424288.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2025-07-04
AI Technical Summary
During the drawing process, high-speed steel wires are prone to primary carbide cracking defects and low secondary carbide quantity density, resulting in insufficient plasticity.
Through high-temperature heating, alternating cycle treatment of phase change temperature and isothermal treatment, primary carbide crack breach and secondary carbide quantity density are increased. Specific steps include high-temperature heating to 1000℃~1150℃ insulation, cycle treatment above and below phase change temperatures, and rapid cooling to 730℃~780℃ after insulation at 850℃~950℃.
It effectively eliminates the drawing defects of high-speed steel wire, improves the plasticity of the steel wire, and increases the quantity density of secondary carbides.
Smart Images
Figure CN120249641A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a processing method for steel wires, and specifically to a method for treating drawing defects of high-speed steel wires. Background Art
[0002] Due to advantages such as high hardness, high wear resistance, and good red hardness, high-speed steel wires are widely used in manufacturing high-efficiency precision machining tools and are important basic materials for modern high-end equipment manufacturing. The traditional preparation process of high-speed steel wires is: smelting → refining → casting → electroslag remelting → forging → rolling → cold drawing → wire rods. However, due to the composition and microstructure characteristics of high-speed steel, the microstructure of high-speed steel is prone to organizational defects such as coarse, adhered, and coarsened carbide precipitation particles, resulting in insufficient plasticity of high-speed steel wires and easy wire breakage during drawing. Two types of defects mainly occur during the drawing process of high-speed steel wires. One is the primary carbide cracking defect, and this defect is not easily healed during conventional heat treatment. The other is the low number density of secondary carbides. Both will lead to a decrease in the plasticity of the steel wires. Summary of the Invention
[0003] Object of the Invention: The object of the present invention is to provide a method for treating drawing defects of high-speed steel wires that can eliminate drawing defects and improve plasticity.
[0004] Technical Solution: A method for treating drawing defects of high-speed steel wires according to the present invention includes the following steps:
[0005] (1) Heat the high-speed steel wire to 1000°C to 1150°C, hold for a certain time, and then cool to room temperature; eliminate the primary carbide defects during the drawing process of the high-speed steel wire and heal the primary carbide cracks.
[0006] (2) Heat the high-speed steel wire obtained in step (1) to 10°C to 50°C above Ac1 and then cool to 10°C to 80°C below Ar1, and perform cyclic treatment; the thermal cycle pretreatment generates a large number of micro-regions with element segregation in the matrix, laying a foundation for subsequent elimination of the defect of low number density of secondary carbides.
[0007] (3) Heat the high-speed steel wire obtained in step (2) to 850°C to 950°C, hold for a certain time, cool down to 730°C to 780°C for isothermal treatment, and then cool. A large number of secondary carbides precipitate in the micro-regions with element segregation formed by the pretreatment, eliminating the defect of low number density of secondary carbides caused by the high-temperature treatment in step (1).
[0008] Further, the heating rate in step (1) is 3°C to 5°C / min.
[0009] Further, the holding time in step (1) is 2 min to 20 min to prevent grain coarsening caused by too long heating time.
[0010] Further, the cooling rate in steps (1) to (3) is 2°C to 5°C / min. Rapid cooling can prevent the precipitation of proeutectoid carbides during slow cooling, so as to increase the precipitation amount of secondary carbides during the isothermal process at 730°C to 780°C.
[0011] Further, the holding time above Ac1 in step (2) is 10 min to 60 min, and the holding time below Ar1 is 30 min to 120 min.
[0012] Further, the number of cycle treatments in step (2) is not less than 3 times. By multiple cycles, the inhomogeneity of elements in the matrix is increased, and a large number of element segregation micro-regions are formed, preparing for the massive precipitation of secondary carbides in step (3).
[0013] Further, the holding time at 850°C to 950°C in step (3) is 30 min to 90 min, and the isothermal time at 730°C to 780°C is 120 min to 240 min.
[0014] Further, the cooling method in step (3) is to cool in the furnace to 490°C to 510°C and then take out of the furnace and air-cool.
[0015] Further, the high-speed steel wire is M42 high-speed steel wire.
[0016] Further, the diameter of the high-speed steel wire is 2 mm to 5 mm.
[0017] Principle of the present invention: The method for treating the drawing defects of high-speed steel wire aims to eliminate the drawing defects of high-speed steel wire, including the primary carbide defects and secondary carbide defects generated during drawing, and obtain high-speed steel wire products with fewer defects and high plasticity. First, through high-temperature heat treatment at 1000°C to 1150°C, using the rapid diffusion and flow of atoms at high temperature, the matrix metal atoms rapidly migrate to the primary carbide cracks, promoting the healing of the primary carbide cracks generated during drawing and eliminating the primary carbide cracking defects generated during drawing. At the same time, a large amount of secondary carbides are dissolved during the high-temperature treatment, and the number density is low, resulting in more prone to crack generation during drawing. Then, an alternating cycle pretreatment above and below the phase transformation temperature is carried out. By using the difference in the element diffusion rate during the alternating cycle treatment above and below the phase transformation point temperature, the elements with fast diffusion rate and the elements with slow diffusion rate segregate respectively, promoting the generation of a large number of micro-regions with element segregation in the matrix, increasing the nucleation sites for the precipitation of secondary carbides during the subsequent annealing process, and laying a foundation for eliminating the defect of low number density of secondary carbides. Then, the pretreated wire is heated to 860°C to 1000°C for insulation and rapidly cooled to 730°C to 780°C for isothermal treatment, so that a large number of secondary carbides precipitate attached to the element segregation micro-regions formed by the cyclic pretreatment, thereby eliminating the defect of low number density of secondary carbides caused by high-temperature treatment. The treatment method of the present invention collaboratively solves the primary carbide defects and secondary carbide defects generated during drawing and improves the plasticity of high-speed steel wire.
[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant features: while reducing the primary carbide cracks of high-speed steel wire, increasing the number density of secondary carbides, eliminating the drawing defects of high-speed steel wire, and improving the plasticity of the wire. Description of the drawings
[0019] Figure 1 SEM image of the microstructure of the high-speed steel wire before treatment used in Example 1 of the present invention;
[0020] Figure 2 SEM image of the microstructure of the high-speed steel wire obtained after treatment in Example 1 of the present invention;
[0021] Figure 3 SEM image of the microstructure of the high-speed steel wire before treatment used in Example 2 of the present invention;
[0022] Figure 4 SEM image of the microstructure of the high-speed steel wire obtained after treatment in Example 2 of the present invention;
[0023] Figure 5 SEM image of the microstructure of the high-speed steel wire before treatment used in Example 3 of the present invention;
[0024] Figure 6 SEM image of the microstructure of the high-speed steel wire obtained after treatment in Example 3 of the present invention;
[0025] Figure 7 It is the SEM image of the high-speed steel wire structure obtained after the treatment of Comparative Example 1 of the present invention;
[0026] Figure 8 It is the SEM image of the high-speed steel wire structure obtained after the treatment of Comparative Example 2 of the present invention;
[0027] Figure 9 It is the SEM image of the high-speed steel wire structure obtained after the treatment of Comparative Example 3 of the present invention. Detailed implementation manners
[0028] In the following examples, the materials, reagents, etc. used can be obtained from commercial channels without special instructions. For the experimental methods without specific conditions noted in the examples, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.
[0029] Example 1
[0030] A method for treating drawing defects of high-speed steel wire includes the following steps:
[0031] (1) Primary carbide defect elimination treatment: Heat the M42 high-speed steel wire with a diameter of 2 mm to 1000 °C at a heating rate of 3 °C / min and hold for 20 min, then rapidly cool to room temperature at a cooling rate of 2 °C / min;
[0032] (2) Secondary carbide defect elimination pretreatment: Heat the high-speed steel wire obtained in step (1) cyclically to 850 °C and hold for 60 min, then cool to 750 °C at a cooling rate of 2 °C / min and hold for 30 min, and repeat the operation 3 times;
[0033] (3) Secondary carbide defect elimination treatment: Heat the high-speed steel wire obtained in step (2) to 850 °C and hold for 90 min, cool to 730 °C at a cooling rate of 2 °C / min and isothermally hold for 120 min, then cool in the furnace to 490 °C and take out of the furnace, and air-cool.
[0034] The original structure of the M42 high-speed steel wire with a diameter of 2 mm is as Figure 1 shown, with a large number of primary carbide defects, the initial secondary carbide number density of 0.3×10 6 pieces / cm 2 , and the elongation is 6%. As Figure 2 shown, after the treatment in Example 1, the primary carbide cracking defects of the obtained M42 high-speed steel wire are eliminated, the secondary carbide number density is as high as 8×10 6 pieces / cm 2 , and the elongation reaches 18%, with good plasticity.
[0035] Example 2
[0036] A method for treating drawing defects of high-speed steel wire, comprising the following steps:
[0037] (1) Treatment for eliminating primary carbide defects: Heat the M42 high-speed steel wire with a diameter of 5 mm to 1150 °C at a heating rate of 5 °C / min, hold for 2 min, and then rapidly cool to room temperature at a cooling rate of 5 °C / min;
[0038] (2) Pretreatment for eliminating secondary carbide defects: Heat the high-speed steel wire obtained in step (1) to 850 °C, hold for 10 min, cool to 750 °C at a cooling rate of 5 °C / min, hold for 120 min, and perform the cyclic operation 6 times;
[0039] (3) Treatment for eliminating secondary carbide defects: Heat the high-speed steel wire obtained in step (2) to 950 °C, hold for 30 min, cool to 780 °C at a cooling rate of 5 °C / min, isothermally hold for 240 min, then cool in the furnace to 510 °C, take out of the furnace, and air-cool.
[0040] The original structure of the M42 high-speed steel wire with a diameter of 5 mm is as Figure 3 shown, with a large number of primary carbide defects. The initial number density of secondary carbides is 0.9×10 6 pcs / cm 2 , and the elongation is 8%. As Figure 4 shown, after treatment in Example 2, the primary carbide cracking defects of the obtained M42 high-speed steel wire are eliminated, and the number density of secondary carbides is as high as 7×10 6 pcs / cm 2 , and the elongation reaches 20%, having good plasticity.
[0041] Example 3
[0042] A method for treating drawing defects of high-speed steel wire, comprising the following steps:
[0043] (1) Treatment for eliminating primary carbide defects: Heat the M42 high-speed steel wire with a diameter of 4 mm to 1100 °C at a heating rate of 3 °C / min, hold for 10 min, and then rapidly cool to room temperature at a cooling rate of 5 °C / min;
[0044] (2) Pretreatment for eliminating secondary carbide defects: Heat the high-speed steel wire obtained in step (1) to 850 °C, hold for 40 min, cool to 750 °C at a cooling rate of 5 °C / min, hold for 60 min, and perform the cyclic operation 8 times;
[0045] (3) Treatment for eliminating secondary carbide defects: Heat the high-speed steel wire obtained in step (2) to 850 °C, hold for 60 min, rapidly cool to 750 °C at a cooling rate of 5 °C / min, isothermally hold for 180 min, then cool in the furnace to 500 °C, take out of the furnace, and air-cool.
[0046] The original structure of M42 high-speed steel wire with a diameter of 4 mm is as Figure 5 shown, with a large number of primary carbide defects. The initial number density of secondary carbides is 0.5×10 6 pieces / cm 2 , and the elongation is 7%. As Figure 6 shown, Example 3 is the best example. After treatment, the primary carbide tearing defects of the obtained M42 high-speed steel wire are eliminated, and the number density of secondary carbides is as high as 9×10 6 pieces / cm 2 , and the elongation reaches 21%, with good plasticity.
[0047] Comparative Example 1
[0048] A method for treating drawing defects of high-speed steel wire includes the following steps:
[0049] (1) Elimination treatment of primary carbide defects: Heat the M42 high-speed steel wire with a diameter of 2 mm to 1100 °C at a heating rate of 5 °C / min and hold for 10 min, and then quickly cool to room temperature at a cooling rate of 5 °C / min;
[0050] (2) Elimination treatment of secondary carbide defects: Heat the high-speed steel wire obtained in step (1) to 850 °C and hold for 60 min, quickly cool to 750 °C at a cooling rate of 5 °C / min and isothermally hold for 180 min, then cool in the furnace to 500 °C and take out of the furnace, and air-cool.
[0051] The original structure of the original M42 high-speed steel wire with a diameter of 2 mm is as Figure 1 shown, with a large number of primary carbide defects. The initial number density of secondary carbides is 0.3×10 6 pieces / cm 2 , and the elongation is 6%. As Figure 7 shown, although the primary carbide tearing defects of the M42 high-speed steel wire obtained in Comparative Example 1 are eliminated, the number density of secondary carbides is only 0.7×10 6 pieces / cm 2 , and the elongation is only 11%.
[0052] Comparative Example 2
[0053] A method for treating drawing defects of high-speed steel wire includes the following steps:
[0054] (1) Pretreatment for eliminating secondary carbide defects: Heat the M42 high-speed steel wire with a diameter of 5 mm to 850 °C and hold for 40 min, cool to 750 °C at a cooling rate of 5 °C / min and hold for 60 min, and repeat the operation 3 times;
[0055] (2) Treatment for eliminating secondary carbide defects: Heat the high-speed steel wire obtained in step (1) to 850 °C and hold for 60 min, then rapidly cool it to 750 °C at a cooling rate of 5 °C / min and isothermally hold for 180 min. Subsequently, cool it in the furnace to 500 °C and take it out of the furnace, then air-cool.
[0056] The original microstructure of the as-received M42 high-speed steel wire with a diameter of 5 mm is as Figure 3 shown, with a large number of primary carbide defects. The initial number density of secondary carbides is 0.9×10 6 pcs / cm 2 , and the elongation is 8%. As Figure 8 shown, the number density of secondary carbides in the M42 high-speed steel wire obtained in Comparative Example 2 reaches 3×10 6 pcs / cm 2 , but a large number of primary carbide cracking defects still exist, and the elongation is only 9%.
[0057] Comparative Example 3
[0058] A method for treating drawing defects of high-speed steel wire, comprising the following steps:
[0059] (1) Treatment for eliminating primary carbide defects: Different from Example 3, the heating temperature of the M42 high-speed steel wire with a diameter of 4 mm is 900 °C;
[0060] (2) Pretreatment for eliminating secondary carbide defects: Different from Example 3, the cyclic operation is performed 2 times;
[0061] (3) Treatment for eliminating secondary carbide defects: Different from Example 3, heat the high-speed steel wire obtained in step (2) to 800 °C and hold for 20 min, then rapidly cool it to 700 °C at a cooling rate of 5 °C / min and isothermally hold for 100 min. Subsequently, cool it in the furnace to 600 °C and take it out of the furnace, then air-cool.
[0062] The original microstructure of the M42 high-speed steel wire with a diameter of 4 mm is as Figure 5 shown, with a large number of primary carbide defects. The initial number density of secondary carbides is 0.5×10 6 pcs / cm 2 , and the elongation is 7%. As Figure 9 shown, the primary carbide cracking defects in the M42 high-speed steel wire obtained in Comparative Example 3 are not eliminated, and the number density of secondary carbides is about 4×10 6 pcs / cm 2 , and the elongation is only 13%.
Claims
1. A method for treating defects in high-speed wire drawing, characterized in that, It includes the following steps: (1) Heat the high-speed steel wire to 1000°C to 1150°C, hold the temperature, and then cool it to room temperature; (2) Heat the high-speed steel wire obtained in step (1) to 10°C to 50°C above Ac1 and then cool it to 10°C to 80°C below Ar1, and perform cyclic treatment; (3) Heat the high-speed steel wire obtained in step (2) to 850°C to 950°C for heat preservation, cool down to 730°C to 780°C for isothermal treatment, and then cool it.
2. The method for treating the high-speed steel wire drawing defect according to claim 1, wherein: In step (1), the heating rate is 3°C to 5°C / min.
3. The method for treating the high-speed steel wire drawing defect according to claim 1, wherein: In step (1), the heat preservation time is 2 min to 20 min.
4. The method for treating the defects in high-speed steel wire drawing according to claim 1, characterized in that: In steps (1) to (3), the cooling rate is 2°C to 5°C / min.
5. The method for treating the defects in high-speed wire drawing according to claim 1, characterized in that: In step (2), the heat preservation time above Ac1 is 10 min to 60 min, and the heat preservation time below Ar1 is 30 min to 120 min.
6. The method for treating the defects in high-speed steel wire drawing according to claim 1, wherein: In step (2), the number of cyclic treatment times is not less than 3 times.
7. The method for treating the defects in high-speed wire drawing according to claim 1, characterized in that: In step (3), the heat preservation time at 850°C to 950°C is 30 min to 90 min, and the isothermal time at 730°C to 780°C is 120 min to 240 min.
8. The method for treating the high-speed wire drawing defect according to claim 1, characterized in that: In step (3), the cooling method is to cool it in the furnace to 490°C to 510°C and then take it out of the furnace and air-cool it.
9. The method for treating the defects in high-speed wire drawing according to claim 1, wherein: The high-speed steel wire is M42 high-speed steel wire.
10. The method for treating the high-speed wire drawing defect according to claim 1, characterized in that: The diameter of the high-speed steel wire is 2 mm to 5 mm.