CN108929999B - Bismuth-containing lead-free stainless steel wire for super free-cutting ball-point pen point and production method thereof - Google Patents
Bismuth-containing lead-free stainless steel wire for super free-cutting ball-point pen point and production method thereof Download PDFInfo
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Abstract
The invention discloses a stainless steel wire for a bismuth-containing lead-free type super free-cutting ball-point pen head and a production method thereof, wherein the stainless steel wire comprises the following raw materials in percentage by mass: c is less than or equal to 0.02%, Si is less than or equal to 0.3%, Cr: 19 to 21 percent of Ni, less than or equal to 0.15 percent of Ni, less than or equal to 0.01 percent of Al, less than or equal to 0.01 percent of Ti, 1.5 to 2.5 percent of Mo, 1 to 2 percent of Mn, 0.02 to 0.04 percent of P, 0.15 to 0.5 percent of S, 0.08 to 0.2 percent of Bi, 0.02 to 0.06 percent of Te, 0.05 to 0.25 percent of V, 0.01 to 0.1 percent of Nb, 0.01 to 0.03 percent of N, less than or equal to 0.0005 percent of H, 0.003 to 0.03 percent of O, 0.01 to 0.05 percent of Ce and less than or equal to 0.005; others are Fe and unavoidable impurities. The stainless steel wire for the ball-point pen point produced by the invention has the advantages that the free-cutting performance of the stainless steel wire is better improved, and meanwhile, the processability of the pen point is excellent.
Description
Technical Field
The invention relates to a bismuth-containing lead-free stainless steel wire for a super free-cutting ball-point pen point and a production method thereof, belonging to the technical field of metal alloys.
Background
In the pen point manufacturing industry, strict requirements are provided for the cutting performance, the wear resistance, the corrosion resistance and the like of materials used for manufacturing the pen point. For many years, the stainless steel for manufacturing the ballpoint pen point mainly comprises a free-cutting stainless steel material containing lead (Pb), and the Pb is uniformly distributed in a stainless steel matrix by using tiny elementary particles so as to achieve the purposes of free cutting and reducing the abrasion of a cutter.
However, Pb is a toxic element, which was classified as a class 2B carcinogen by the world health organization in 2017, and is prohibited from being sold and used when the Pb content in the nib is more than 0.05% in the european union REACH regulation.
In addition to limiting the Pb content, in the manufacturing process of pen tips, ferritic stainless steel wires are generally used for processing, and burrs during cutting and blade sticking or cracking during turning are easily caused. In addition, the problems that the rear excircle and the conical surface of the pen point are rough, the processing precision of the pen point is poor and the like due to the fact that a machine tool fixture is not firmly clamped are easy to occur in the production process, and the pen point is unqualified.
Disclosure of Invention
The invention aims to provide a bismuth-containing lead-free stainless steel wire for a super free-cutting ball-point pen head and a production method thereof, and solves the problems of Pb pollution, burr during cutting, cutter sticking or cracking during turning, rough rear excircle and conical surface of the pen head, poor processing precision of the pen head and the like in the prior art. The stainless steel wire for the ball-point pen head provided by the invention replaces lead element with bismuth element, so that the free-cutting performance of the stainless steel wire is better improved, and the ball-point pen head has excellent machinability.
The invention relates to a bismuth-containing lead-free stainless steel wire for a super free-cutting ball-point pen head, which comprises the following chemical components in percentage by mass: c is less than or equal to 0.02%, Si is less than or equal to 0.3%, Cr: 19 to 21 percent of Ni, less than or equal to 0.15 percent of Ni, less than or equal to 0.01 percent of Al, less than or equal to 0.01 percent of Ti, 1.5 to 2.5 percent of Mo, 1 to 2 percent of Mn, 0.02 to 0.04 percent of P, 0.15 to 0.5 percent of S, 0.08 to 0.2 percent of Bi, 0.02 to 0.06 percent of Te0.02, 0.05 to 0.25 percent of V, 0.01 to 0.1 percent of Nb, 0.01 to 0.03 percent of N, less than or equal to 0.0005 percent of H, 0.003 to 0.03 percent of O, 0.01 to 0.05 percent of Ce and less than or equal to; others are Fe and unavoidable impurities.
In another aspect, the invention also relates to a method for producing the stainless steel wire for the bismuth-containing lead-free type super free-cutting ball-point pen head, which comprises the following steps:
(1) smelting the molten steel into a steel ingot, and adding a material containing bismuth into a steel ladle after tapping of an electroslag furnace;
(2) forging the steel ingot into a square billet at 1180-1220 ℃, rolling the square billet at 1180-1220 ℃, controlling the finish rolling temperature at 800-830 ℃, and rolling the square billet into a wire rod at the temperature;
(3) the wire rod is subjected to heat preservation for 3-8 hours at 780-820 ℃, and then is quenched and cooled;
(4) peeling the heat-treated wire rod;
(5) then drawing the semi-finished product with the total deformation amount not less than 75 percent;
(6) carrying out heat treatment on the semi-finished product;
(7) and drawing the semi-finished product after the heat treatment by two dies to obtain a finished product, wherein the single-pass deformation is controlled to be below 25 percent, and the total deformation is controlled to be 40-50 percent.
Description
The invention provides a bismuth-containing lead-free stainless steel wire for a super free-cutting ball-point pen head, which comprises the following chemical components in percentage by mass: c is less than or equal to 0.02%, Si is less than or equal to 0.3%, Cr: 19 to 21 percent of Ni, less than or equal to 0.15 percent of Ni, less than or equal to 0.01 percent of Al, less than or equal to 0.01 percent of Ti, 1.5 to 2.5 percent of Mo, 1 to 2 percent of Mn, 0.02 to 0.04 percent of P, 0.15 to 0.5 percent of S, 0.08 to 0.2 percent of Bi, 0.02 to 0.06 percent of Te0.02, 0.05 to 0.25 percent of V, 0.01 to 0.1 percent of Nb, 0.01 to 0.03 percent of N, less than or equal to 0.0005 percent of H, 0.003 to 0.03 percent of O, 0.01 to 0.05 percent of Ce and less than or equal to; others are Fe and unavoidable impurities.
According to the stainless steel wire for the ball-point pen point, the A-type inclusion in the finished wire is a plastic inclusion, the content and the grade are high, the lathed scraps can be more easily broken and fall off in the turning process, the phenomenon that the turning quality is influenced by knife sticking is avoided, and therefore lower limit control is implemented. The A-type coarse inclusion in the finished steel wire is more than or equal to 1.5 grade.
According to the micro-cutting theory, when the feed amount is smaller than the arc radius of the tool nose, the phenomena of rough turning surface and accelerated tool abrasion are easy to occur along with the reduction of the cutting amount, which is called as the size effect. The wire diameter is controlled according to the range, so that the turning feed amount of the turning of the conical surface and the rear excircle of the pen point can be ensured, the influence of tool abrasion and turning surface roughness caused by size effect is avoided, and the smoothness of the turning surface is improved. In the stainless steel wire for the ball-point pen point, the diameter phi of the stainless steel wire is 2.285-2.295mm, the fluctuation range of the filament diameter of a single filament is less than or equal to +/-0.003 mm, and the out-of-roundness is less than or equal to 0.005 mm.
The stainless steel wire for the ball-point pen head has the hardness HV250-280 and the grain size more than or equal to 11.0 grade. According to the hardness and the grain size range designed by the invention, fracture burrs during segmenting and tool sticking during turning in the pen point manufacturing process can be avoided, the problem of cracking during punching of the five-star groove is prevented, and the ball leap range can be controlled within 0.03-0.04 mm.
The following are descriptions of the role of the main components involved in the invention and their limitations:
carbon: the carbon element can form a solid solution structure in the steel and improve the strength of the steel, but the excessively high carbon element can reduce the corrosion resistance and uniformity of the steel, and the C element is easy to form a compound with the Cr element to cause alloy brittleness, so the C element is controlled to be not more than 0.02 percent.
Silicon: since the silicon element has a certain strengthening effect but deteriorates corrosion resistance and tends to deteriorate cold workability of the alloy, the present invention limits the Si content to not more than 0.3% for promoting the purity in the ferrite matrix.
Chromium: the chromium element can improve the strength and the hardness of the steel, and mainly plays a role in improving the corrosion resistance of the alloy in the invention, so the Cr content is 19-21 percent in the invention.
Nickel: the nickel and the iron can be dissolved in the solid solution infinitely, and the austenite area of the iron is enlarged, and the stainless steel wire for the ball-point pen point is ferrite alloy, so that the Ni element is controlled to be not higher than 0.15% to strengthen the ferrite.
Aluminum and titanium: the Al and Ti elements affect the type of the A-type inclusions, and the increase of the content thereof easily causes the particle size of the A-type inclusions to become smaller, which is disadvantageous for improving the free-cutting property, so that the Al and Ti elements are controlled to be not more than 0.01% in the present invention.
Molybdenum: molybdenum has a solid solution strengthening effect on ferrite, and the ball-point pen ink contains organic acid, so that the corrosion resistance of the material to the organic acid can be improved. In the invention, molybdenum is mainly used for improving the corrosion resistance of the alloy, so that the content of Mo is 1.5-2.5%.
Manganese, phosphorus and sulfur: mn and S are combined to form MnS which can be used as a crack source for cutting chips and is beneficial to improving the free-cutting property of the stainless steel wire for the ball-point pen point, and P can also improve the cutting property, so that the Mn content is 1-2%, the P content is 0.02-0.04%, and the S content is 0.15-0.5%.
Bismuth: the melting point of the bismuth element is lower than that of the lead element, the bismuth element exists in the steel in an independent simple substance like the lead element, the bismuth has better effect of improving the free-cutting performance of the stainless steel wire than the lead element, and when the content of the bismuth in the steel is equal to the level of half of the content of the lead, the same free-cutting effect can be achieved. In the alloy formula, the Bi content is designed to be 0.08-0.2%, so that the harm to the production and use processes caused by the existence of Pb element is eliminated.
Tellurium: the tellurium element can improve the length-width ratio of MnS, is beneficial to keeping the nearly spherical shape of the MnS in an as-cast state and improving the deformation resistance of the MnS in hot processing, and the Te element is 0.02 to 0.06 percent in the invention.
Vanadium, niobium and nitrogen: vanadium and niobium have the function of refining crystal grains, and the vanadium can improve the high-temperature strength of MnS and the deformation resistance of MnS when dissolved in the MnS; nitrogen and C, Nb form compound, which can strengthen the alloy, form solid solution in the alloy and improve the corrosion resistance, so the content of V is 0.05-0.25%, the content of Nb is 0.01-0.1% and the content of N is 0.01-0.03%.
Hydrogen: hydrogen is an element harmful to cold working, and the present invention controls the content of H to not more than 0.0005% to keep the content low enough to prevent hydrogen embrittlement or hydrogen induced cracking.
Oxygen: the oxygen element plays a role in adjusting the solubility of S in the alloy liquid, and the O content is 0.003-0.03 percent in the invention.
Cerium: the cerium element can improve the turning performance of the stainless steel wire for the ball-point pen point, and the Ce content in the invention is 0.01-0.05%.
Calcium: the content of calcium element is high, which easily generates built-up edge during cutting process, and the built-up edge is adhered on the tool face to roughen the turning surface of the pen point, so that the Ca element is controlled to be not more than 0.005 percent.
The stainless steel wire for the ballpoint pen head has class A coarse inclusions of more than or equal to 1.5 level, hardness HV250-280 and grain size of more than or equal to 11.0 level, the free-cutting performance of the stainless steel wire for the ballpoint pen head is further improved, and the stainless steel wire has excellent pen head machinability.
The invention also provides a production method of the stainless steel wire for the bismuth-containing lead-free type super free-cutting ball-point pen head, which comprises the following steps:
(1) smelting the molten steel into a steel ingot, and adding a material containing bismuth into a steel ladle after tapping of an electroslag furnace;
(2) forging the steel ingot into a square billet at 1180-1220 ℃, rolling the square billet at 1180-1220 ℃, controlling the finish rolling temperature at 800-830 ℃, and rolling the square billet into a wire rod at the temperature;
(3) the wire rod is subjected to heat preservation for 3-8 hours at 780-820 ℃, and then is quenched and cooled;
(4) peeling the heat-treated wire rod;
(5) then drawing the semi-finished product with the total deformation amount not less than 75 percent;
(6) carrying out heat treatment on the semi-finished product;
(7) and drawing the semi-finished product after the heat treatment by two dies to obtain a finished product, wherein the single-pass deformation is controlled to be below 25 percent, and the total deformation is controlled to be 40-50 percent.
According to the production method of the stainless steel wire for the ball-point pen head, disclosed by the invention, smelting can be carried out by adopting a three-phase lined electroslag furnace, the material containing the bismuth element is a bismuth ingot which is crushed into fragments or bismuth-manganese alloy with the diameter of less than 50mm, and the fragments or the bismuth-manganese alloy is added into a steel ladle after the electroslag furnace taps steel.
According to the production method of the stainless steel wire for the ball-point pen point, the temperature control rolling technology is adopted for the hot rolled wire rod, the finish rolling temperature is controlled at 800-.
According to the production method of the stainless steel wire for the ball-point pen point, the wire rod is subjected to long-time heat treatment in the pit furnace, and is kept at 780-820 ℃ for 5-8 hours, so that the work hardening and residual stress caused by deformation in the hot rolling process are fully eliminated, the length-width ratio of MnS inclusions deformed by processing in the hot processing process is reduced, and the A-type coarse inclusions on the finished steel wire can be kept to be more than 1.5 level. The surface of the hot-rolled wire rod subjected to heat treatment has a plurality of hot rolling defects and oxide skin, and the oxide skin and various surface defects on the surface of the hot-rolled wire rod are thoroughly eliminated by turning and peeling, so that the pen point reject ratio is ensured to be less than five per ten thousandth.
According to the production method of the stainless steel wire for the ball-point pen head, the wire rod after full heat treatment can bear deformation amount of more than 75%, because the deformation on the cross section of the wire rod is that the surface layer precedes the core part when the wire rod passes through a die hole in the drawing process, the deformation amount which is not large enough can not lead the core part to be fully deformed, and therefore, the grains with coarse core part can not be fully refined. The invention can adopt a polycrystalline die continuous drawing machine to draw the heat-treated wire rod by taking special wire drawing oil as a lubricant. The grain size is improved to more than 11.0 grade by the drawing, and the grain sizes of the upper surface layer and the core part of the cross section tend to be consistent.
Because the material is ultra-low carbon ferrite steel, the conditional yield strength is very low, and the steel wire still generates plastic deformation after being demoulded because the drawing force is greater than the conditional yield strength of the material, so that the diameter size is unstable. The method of the invention firstly draws the wire rod into a semi-finished product through more than 75% of deformation rate, and then carries out finished product drawing of two dies after heat treatment. Because the deformation of the semi-finished product is large, the total deformation of the finished product in drawing can be controlled to be 40-50%, and the finished product is uniformly drawn by two dies, so that the drawing resistance of the finished product in drawing is greatly reduced, the drawing force born by the steel wire passing through the dies is smaller than the conditional yield strength of the steel wire, and the plastic deformation after the steel wire is discharged from the dies is well controlled. Thus, the wire diameter of the finished steel wire produced by the method is stabilized within phi 2.285-2.295mm, the fluctuation of the wire diameter is less than or equal to +/-0.003 mm, and the out-of-roundness is less than or equal to 0.005 mm.
The production method makes the crystal grain refined, controls the total drawing deformation of the finished product within the range of 40-50%, and can make the hardness of the finished steel wire distributed within the range of HV250-280 under the action of work hardening.
According to the production method of the stainless steel wire for the ball-point pen point, the semi-finished product adopts a continuous heat treatment furnace, hydrogen is taken as protective gas, the heat treatment temperature is 800-850 ℃, and the heat treatment speed is 10-15 m/min.
According to the bismuth-containing lead-free stainless steel wire for the super free-cutting ballpoint pen point and the production method thereof, the A-type coarse inclusions of the produced stainless steel wire for the steel ballpoint pen point are more than or equal to 1.5 grade, the hardness is HV250-280 grade, and the grain size is more than or equal to 11.0 grade by controlling chemical components and controlling processes such as rolling, heat treatment, drawing and the like, so that the stainless steel wire for the ballpoint pen point further improves the free-cutting performance and has excellent pen point processability.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
The following is an example of the present invention for producing a stainless steel wire for a bismuth-containing lead-free type super free-cutting ballpoint pen head:
examples 1 to 5:
the molten steel is smelted into steel ingots, after the electroslag furnace discharges steel, the bismuth ingots are crushed into fragments with the diameter of less than 50mm or bismuth-manganese alloy is added into a steel ladle, and the chemical components of the molten steel are shown in table 1. Forging the steel ingot into a square blank, rolling the square blank into a wire rod by adopting a temperature-controlled rolling technology, carrying out heat treatment on the wire rod, then carrying out peeling treatment, and then drawing the wire rod into a semi-finished product with the total deformation amount of not less than 75%; after the semi-finished product is subjected to heat treatment, the semi-finished product is drawn into a finished product through two dies, and the specific process parameters are shown in table 2. The non-metallic inclusions of the finished steel wire are graded according to the GB/T10561 standard, the average grain size of the finished steel wire is graded according to the GB/T6394 standard, the HV hardness value is measured according to the GB/T4340.1, the wire diameter and the out-of-roundness are measured by a micrometer, and the related structural properties are shown in the table 3.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (7)
1. A method for producing a stainless steel wire for a bismuth-containing lead-free type super free-cutting ball-point pen head comprises the following steps:
(1) smelting the molten steel into a steel ingot, and adding a material containing bismuth into a steel ladle after tapping of an electroslag furnace; wherein the raw materials comprise the following chemical components in percentage by mass (%): c is less than or equal to 0.02%, Si is less than or equal to 0.3%, Cr: 19 to 21 percent of Ni, less than or equal to 0.15 percent of Ni, less than or equal to 0.01 percent of Al, less than or equal to 0.01 percent of Ti, 1.5 to 2.5 percent of Mo, 1 to 2 percent of Mn, 0.02 to 0.04 percent of P, 0.15 to 0.5 percent of S, 0.08 to 0.2 percent of Bi, 0.02 to 0.06 percent of Te, 0.05 to 0.25 percent of V, 0.01 to 0.1 percent of Nb, 0.01 to 0.03 percent of N, less than or equal to 0.0005 percent of H, 0.003 to 0.03 percent of O, 0.01 to 0.05 percent of Ce and less than or equal to 0.005; the others are Fe and unavoidable impurities;
(2) forging the steel ingot into a square billet at the temperature of 1180-1220 ℃, rolling the square billet at the temperature of 1180-1220 ℃, controlling the finish rolling temperature to be 800-830 ℃, rolling at the temperature of 1180-1220 ℃, and rolling the square billet into a wire rod under the condition that the finish rolling temperature is 800-830 ℃;
(3) the wire rod is subjected to heat preservation for 3-8 hours at 780-820 ℃, and then is quenched and cooled;
(4) peeling the heat-treated wire rod;
(5) then drawing the semi-finished product with the total deformation amount not less than 75 percent;
(6) carrying out heat treatment on the semi-finished product; wherein the semi-finished product is subjected to heat treatment by adopting a continuous heat treatment furnace, hydrogen is taken as protective gas, the heat treatment temperature is 800-850 ℃, and the heat treatment speed is 10-15 m/min;
(7) and drawing the semi-finished product after the heat treatment by two dies to obtain a finished product, wherein the single-pass deformation is controlled to be below 25 percent, and the total deformation is controlled to be 40-50 percent.
2. The method for producing a stainless steel wire for a ballpoint pen as described in claim 1, wherein said electroslag furnace is a three-phase lined electroslag furnace.
3. The method for producing a stainless steel wire for a ballpoint pen as described in claim 1, wherein the material containing bismuth is a bismuth ingot crushed into pieces having a diameter of less than 50mm or a bismuth-manganese alloy.
4. The method for producing a stainless steel wire for a ballpoint pen as described in claim 1, wherein the wire rod rolled in the step (2) has a diameter of 6.5 to 7.0 mm.
5. The stainless steel wire for ballpoint pen prepared by the production method as set forth in claim 1, wherein the class A coarse inclusions in the stainless steel wire for ballpoint pen are not less than 1.5 grade.
6. The stainless steel wire for ballpoint pen tips produced by the production method as set forth in claim 1, wherein the stainless steel wire for ballpoint pen tips has a diameter phi of 2.285 to 2.295mm, a variation range of the wire diameter of the monofilament of ± 0.003mm, and an out-of-roundness of not more than 0.005 mm.
7. The stainless steel wire for ballpoint pen tips produced by the production method as described in claim 1, wherein the stainless steel wire for ballpoint pen tips has a hardness of HV250 to 280 and a grain size of 11.0 or more.
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| CN109865804B (en) * | 2019-03-13 | 2021-08-03 | 北京首钢吉泰安新材料有限公司 | Bismuth-tellurium alloying method of free-cutting stainless steel for ball-point pen head |
| CN111334712B (en) * | 2020-03-27 | 2021-05-14 | 武汉科技大学 | Environment-friendly free-cutting ferritic stainless steel and manufacturing method thereof |
| CN111621710B (en) * | 2020-07-20 | 2021-02-19 | 启东市荣盛铜业有限公司 | Free-cutting stainless steel and application thereof |
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| CN106756503B (en) * | 2016-12-27 | 2018-05-22 | 北京首钢吉泰安新材料有限公司 | Free cutting alloy, B alloy wire, its preparation method, nib, pen core and pen |
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