JP2008240002A - Steel wire for fastening component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drastically save man-powers by unifying a lubricant film treatment to a wire before cold plastic working and a lubrication treatment applied to the surface of a fastening component after a heat treatment for stabilizing fastening property into one process, and to provide a steel wire which can obtain a fastening component exhibiting a stable black appearance regardless of its production process. <P>SOLUTION: The steel wire for fastening components has a lubricant film containing, as essential components, (a) an alkali metal silicate in which the molar ratio of SiO<SB>2</SB>to M<SB>2</SB>O (M represents alkali metal) is 2-5, (b) crystalline graphite having an average diameter of <10 μm, and (c) a polyolefin wax, wherein the mass ratios of (b) and (c) to the total solid content are 1-30 mass% and 30-50 mass%, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wire rod or a steel wire that is excellent in surface lubricity for obtaining a stable tightening property when used and used for manufacturing a fastening part that exhibits a stable black appearance regardless of a manufacturing process. In recent years, a wire or steel wire having a lubricant film on the surface obtained by using a specific coating-type lubrication treatment liquid in a one-liquid tank, which is being used as a substitute for a conventional lubricant film that has a heavy impact on work and the environment The present invention relates to a wire or a steel wire that imparts a stable black color tone and lubricity to the surface of the fastening part after heat treatment such as cold plastic working or tempering treatment in the manufacturing process of the fastening part.

  Recently, the weight reduction of automobiles and the downsizing of engines, gear parts, and the like have progressed, and the fastening parts such as bolts used for these parts are also required to be reduced in size and diameter. In order to satisfy this requirement, a high-strength bolt manufactured using a high-strength material is required. These fastening parts are generally formed by cold plastic working by cutting a wire having a lubricating film that imparts surface lubricity or a steel wire obtained by further drawing the wire into a predetermined length, If necessary, it has been commercialized through heat treatment such as quenching and tempering, that is, tempering treatment. In particular, when a wire having a lubricating film formed thereon is drawn with a cross-section reduction rate of about 30% or less, the adhesion of the formed lubricating film is further increased. For this reason, steel wire that has been subjected to wire drawing is often used for cold plastic working of fastening parts rather than wire having a lubricating film formed thereon. Thus, as the material for cold plastic working, either “wire” with a lubricating film or “steel wire” with further wire drawing is used. "And" steel wire ", when referring to both, they are collectively referred to as" steel wire ". As a lubricating film used for a steel wire for fastening parts, a phosphate + soap-treated film, a lime soap-treated film, and the like have been used for a long time. In the former, an insoluble zinc phosphate crystal film is formed by increasing the pH of the surface by bringing an acidic zinc phosphate aqueous solution into contact with the surface of the wire to dissolve iron. A lubricant film is completed by applying a soap film layer to the upper layer. The cold plastic workability of the phosphate + soap treatment film is excellent and widely used, but sludge mainly composed of reaction by-products of iron and phosphoric acid dissolved during film treatment is industrial waste. And a large amount of heavy metal-containing wastewater is also generated. In addition, bolts molded from steel wire materials that have been subjected to phosphate coating treatment are then subjected to tempering treatment. In the tempering treatment process, phosphorus in the coating diffuses into the steel. In order to accelerate the embrittlement failure (delayed failure phenomenon) at the stress concentration part of the bolt after tightening work, it is necessary to remove the film before heat treatment, especially for high strength bolts that are sensitive to delayed failure, Considering the industrial control of the process increase and removal state, it cannot be used practically. On the other hand, the latter lime soap film is a lubricating film composed of slaked lime and metal soap, and can be formed on the surface of the wire by a simple process by coating and drying, but its cold plastic workability is insufficient. In addition, products with a high degree of processing cannot be molded due to seizure, etc., and the service life of the processing mold is shortened. Furthermore, it is a film that has problems such as severe dust caused by dropping off the surface of the steel wire during wire drawing and inferior working environment, and many coatings falling into the bolt forming machine, resulting in severe contamination of processing oil. is there.

  In recent years, a coating having excellent cold plastic workability is being marketed despite being a coating-type coating capable of forming a coating by a simple process. As such a coating film, Patent Document 1 contains (A) a synthetic resin, (B) a water-soluble inorganic salt, and water, and (B) / (A) (solid content weight ratio) is 0.25 / 1. A lubricant composition for plastic working of a metal material, which is ˜9 / 1 and has a synthetic resin dissolved or dispersed therein, is disclosed. In Patent Document 1, it is preferable to contain 1 to 20% by mass of at least one selected from the group consisting of metal soap, wax, polytetrafluoroethylene and oil as a lubricating component, and the water-soluble inorganic salt includes sulfuric acid. It is also described that at least one selected from the group consisting of a salt, borate, molybdate, vanadate and tungstate is preferable. This technology contains a lubricant component such as metal soap or wax dispersed in a coating component that can be a carrier, and by coating this on the surface of the work material, a lubricating coating having a high level of processing performance can be easily and easily obtained. It is an excellent technology that can be obtained in a labor-saving manner, and can be said to be a new generation lubricant film for plastic working.

Now, a fastening part such as a bolt formed by cold plastic working is commercialized through a heat treatment such as a tempering treatment to be heated to the AC ₃ point or higher. Since the tempering treatment is performed at 820 ° C. or higher, most of the lubricating components remaining on the surface of the fastening part lose the lubricity by being decomposed or sublimated, and the fastening part surface is covered with a black iron oxide film. In general, this black appearance is an important factor that determines the commercial value in terms of the design of the fastening part, but this color tone is greatly affected by the type of lubricant film remaining during cold plastic processing and the oil and film residue adhering during processing. For example, the appearance of a limestone soap film is mixed with white, and the appearance of a brown or red color is caused by adhesion of a new generation film or phosphate film residue of Patent Document 1. For this reason, efforts are made to stabilize the black appearance by introducing a cleaning process to the fastening parts before heat treatment, adjusting the heat treatment atmosphere, or using special quenching oil.

  In addition, it is important that a bolt representing a fastening part has a stable fastening property so that a specified axial force can be obtained at the time of fastening work. Therefore, it is necessary to keep the frictional state of the threaded portion and the bolt seating surface constant, and a normal bolt is subjected to lubrication again after heat treatment. As the lubricant, for example, a manganese phosphate-based film, a coating-type lubricating film, or oil is used. As mentioned above, the phosphate film treatment is complicated and the environmental burden such as industrial waste and wastewater is regarded as a problem. Therefore, it is better to provide surface lubricity by forming a coating type lubricant film. However, in addition to the film treatment process, a degreasing process, a drying process, and the like are also required, and much effort is required for the lubrication process for a large amount of bolt surfaces.

As a lubricant film for a bolt, Patent Document 2 discloses a lubricant characterized in that at least one surface of a bolt, a nut and a washer is coated with a lubricant containing a hydrous silicate rock powder in a lubricating oil. A bolt set to which is attached is disclosed. The concentration of the hydrous silicate rock is about 1% (wt) to 20% (wt) in the lubricant, the particle size is about 1 μm to 110 μm, and the adhesion amount per unit area is about 0.0091 g / cm ^{2 to} 0.00. 183 g / cm ² . The hydrous silicate rock refers to a series of rocks in the mineralogical classification, such as mica, talc, feldspar, kaolin or bentonite, and is one or more of any of these rocks. Further, the target bolt is a torcia type high strength bolt, and a stable friction coefficient value is obtained.
JP 2000-063880 A JP-A-7-224824

  As described above, in the manufacture of a fastening part, lubrication is performed twice, such as during cold plastic working from a steel wire and before shipment after heat treatment. As mentioned above, each type of coating treatment has come to employ a coating-type coating, which is a significant reduction in the process compared to conventional phosphate treatment, but still requires a lot of time and labor. Energy has been consumed, and further labor-saving technology has been demanded. In addition, the emergence of new technologies, including stabilization of the black appearance of the final product, has been awaited.

  The present invention solves the above-mentioned problems of the state of the art. In other words, drastic labor saving is achieved by combining the lubrication film treatment on the wire before cold plastic working and the lubrication treatment applied to the surface of the fastening part after heat treatment to stabilize the fastening performance into one process. An object of the present invention is to provide a steel wire that can be provided and that can provide a fastening part that exhibits a stable black appearance regardless of the manufacturing process.

The above-mentioned problems include an alkali metal silicate (a) having a molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) of 2 to 5, crystalline graphite (b) having an average particle diameter of less than 10 μm, polyolefin Treated with an aqueous treatment liquid of a composition having a wax (c) as an essential component and a mass ratio of (b) and (c) in the total solid content of 1 to 30% by mass and 30 to 50% by mass, respectively. Solved by steel wire for fastening parts. The surface of the steel wire for fastening parts treated with the aqueous treatment liquid of the composition has a lubricating film made of the composition.

  According to the steel wire for fastening parts of the present invention, the lubricating film treatment on the wire before cold plastic working, and the lubricating film treatment applied to the surface of the fastening part after heat treatment for stabilizing the fastening performance, It is possible to provide a fastening part manufactured by drastic labor saving by a specific lubricating film that can be integrated into one process. Furthermore, the fastening component by the steel wire rod of this invention can exhibit a stable black appearance irrespective of a manufacturing process. The lubricating film treatment in the manufacturing process of the fastening part is only a treatment on the wire before the cold plastic working, and it is not necessary to perform the lubricating film treatment again after the heat treatment such as tempering. Furthermore, since there is no need for a cleaning process before the tempering treatment for adjusting to a good black appearance, adjustment of the tempering treatment atmosphere, and the use of special quenching oil, the overall labor saving can be realized. Furthermore, since the phosphate film treatment is not performed, the fastening part molded from the steel wire of the present invention does not need to be concerned about the immersion phosphorus phenomenon in the subsequent tempering treatment. Therefore, the industrial utility value of the present invention is extremely large.

Hereinafter, the present invention will be described in detail.
The alkali metal silicate (a) having a SiO ₂ / M ₂ O (M represents alkali metal) molar ratio of 2 to 5 used in the present invention has an average particle size of less than 10 μm during cold plastic working. The surface of the molding die and the material are maintained by fixing the lubricating components such as the crystalline graphite (b) and the polyolefin wax (c) to the surface of the material and withstanding the high-temperature and high-pressure conditions on the surface during cold plastic working. Provides good cold plastic workability to prevent direct contact with the surface and suppress seizure phenomenon. Furthermore, it is an essential component that plays a role of keeping the crystalline graphite (b) stably on the surface of the material even after heat treatment such as tempering treatment.
The alkali metal silicate (a) having a molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) of the present invention of ₂ to 5 is present in a state of being dissolved or colloidally dispersed in water, and moisture is volatilized. By doing so, a solid film is formed at room temperature. M is preferably Na or K from the viewpoint of the stability of the aqueous solution and the film-forming property. When the SiO ₂ / M ₂ O molar ratio is less than 2, the continuous film property is lowered, the cold plastic workability is remarkably lowered, and the retention property of the graphite (b) is also extremely lowered. On the other hand, when the SiO ₂ / M ₂ O molar ratio exceeds 5, the aqueous treatment liquid becomes extremely unstable and the cold plastic workability decreases.

The crystalline graphite (b) having an average particle size of less than 10 μm used in the present invention does not undergo changes such as melting, decomposition, and sublimation even when exposed to a temperature of 1000 ° C. or higher, and is lubricated by cleavage of the layered crystal structure. Depending on the properties, it plays a role of reducing the friction coefficient of the processed surface during cold plastic working and the friction coefficient of the surface of the fastening part after tempering. In addition, the black color of graphite is stable to heat and has high hiding power for visible light, so that a stable black appearance is efficiently given to the surface of the fastening part of the present invention.
The crystalline graphite (b) of the present invention is measured with a laser diffraction particle size distribution measuring device from the viewpoint of the degree of manifestation of effects such as lubricity and blackening on the blending amount and dispersion stability in an aqueous treatment liquid. It is essential that the average particle diameter on the volume basis is less than 10 μm, preferably less than 6 μm, and more preferably less than 3 μm. In addition, although a lower limit is not specifically limited, 0.1 micrometer or more is preferable from economical efficiency. The crystalline graphite (b) is usually present in a dispersed state in the lubricating film treatment liquid in the process of producing the fastening part of the present invention, and an alkali metal silicate salt formed by volatilization of moisture ( In the film of a), it exists uniformly or in a concentrated state near the surface.
The graphite that can be used in the present invention needs to be crystalline graphite having a stable crystal structure. For example, non-crystalline carbon materials such as activated carbon and carbon black not only exhibit lubricity when used, but also cause a carburization phenomenon that carbon diffuses into the steel during heat treatment after cold plastic working, and fastening parts It can not be used because it tends to affect the strength characteristics.
Examples of the crystalline graphite (b) that can be used in the present invention include pulverized products such as artificial graphite, flaky graphite, spheroidized graphite, and expanded graphite, graphitized carbon black crystallized by heat treatment, and their Examples thereof include surface-treated graphite with improved water dispersibility.

  The polyolefin wax (c) used in the present invention is an essential component for imparting excellent lubricity to the machined surface during cold plastic working from a steel wire. The polyolefin wax (c) is held in a dispersed state in the lubricating film during cold plastic working in the process of producing a fastening part produced by the steel wire of the present invention, and is in a solid or molten state during cold plastic working. To significantly reduce the coefficient of friction of the machined surface. Since the polyolefin wax (c) decomposes at about 500 ° C. during the heat treatment after molding, it hardly remains on the surface of the fastening part made of the steel wire of the present invention. The polyolefin wax (c) that can be used in the present invention is not limited in terms of molecular weight, acid value, particle size, etc., but polyethylene wax and polypropylene wax are preferable in order to efficiently exhibit excellent lubricity.

  The mass ratio of the crystalline graphite (b) and the polyolefin wax (c) in the lubricating film formed on the surface of the steel wire of the present invention needs to be 1 to 30% by mass and 30 to 50% by mass, respectively. In particular, from the viewpoint of more efficiently stabilizing the stable black appearance and the lubricity of the final fastening part surface, the mass ratio of the crystalline graphite (b) is preferably 5 to 15% by mass. If the content of the crystalline graphite (b) is less than 1% by mass, the black appearance and surface lubricity of the surface of the fastening part will be insufficient, and if it exceeds 30% by mass, the effects of the black appearance and surface lubricity will be saturated and economical. In addition to the waste, it leads to a decrease in film strength due to exceeding the amount retained by the alkali metal silicate (a), cold plastic workability by the lubricating film, and crystalline graphite ( The retainability of b) decreases. Further, if the content of the polyolefin wax (c) is less than 30% by mass, the molding processability by the lubricating film is insufficient, and if it exceeds 50% by mass, the film is caused to exceed the amount retained by the film as in the case of graphite. Due to the decrease in strength, cold plastic workability at the lubricating film, retention of crystalline graphite (b) on the surface of the fastening part, and the like are decreased.

  As a lubrication state of the surface of the fastening part manufactured from the steel wire rod according to the present invention, from the viewpoint of further stabilizing the bolt tightening operation, the vertical load is set to 1 kg using a Bowden friction wear tester. The surface friction coefficient is preferably less than 0.2, and more preferably less than 0.15.

The lubricating film which the steel wire rod of the present invention has on the surface is an alkali metal silicate (a) having a SiO ₂ / M ₂ O (M represents alkali metal) molar ratio of 2 to 5, and an average particle diameter of less than 10 μm The crystalline graphite (b) and polyolefin wax (c) can be formed by applying an aqueous treatment liquid in which water is dissolved or dispersed in water and then drying. The aqueous treatment liquid is applied to the surface of the wire by a conventional method such as dipping, spraying, pouring or brushing. Application is not limited as long as the surface of the wire is sufficiently covered with the aqueous treatment liquid, and the application time is not particularly limited. The treatment liquid film after coating needs to be dried. Drying may be performed at room temperature, but it is usually preferable to carry out at 60 ° C. to 150 ° C. for 2 seconds to 60 minutes. Although the film mass of the lubricating film after drying varies depending on the application, it is preferably 1 g / m ² or more as the dry film from the viewpoint of preventing seizure during processing in a bolt having a severe cold plastic working degree. more preferably from 3 to 30 g / ^{m 2,} and even more preferably from 5 to 20 g / ^{m 2.} As a steel wire for fastening parts, there is no problem even with such a dried wire, but in order to further improve the adhesion of the lubricating film, the wire after drying is further drawn with a cross-section reduction rate of about 30% or less. More preferably, a steel wire is applied.

  Furthermore, the lubricating film in the present invention may contain an optional lubricating component as necessary for the purpose of improving plastic workability. Examples of the lubricating component that can be contained include oil, soap, metal soap, fatty acid wax, polytetrafluoroethylene, organic molybdenum compound (molybdenum DTC), and melamine cyanurate.

The cold plastic processing, that is, the molding process in the manufacturing process of the fastening part manufactured from the steel wire rod of the present invention indicates general cold plastic processing such as forging, forging, and rolling. Next, the heat treatment to be performed is quenching and tempering, that is, a tempering treatment, and the quenching treatment is generally performed by heating the steel to an austenite region temperature of, for example, an _AC3 point or higher in order to harden or increase the strength of the steel, The operation of quenching with oil or other coolant is shown. Next, the structure formed by quenching is brought close to a stable structure by tempering that is heated to a temperature of A ₁ or less, and is tempered to the desired properties and state by precipitation strengthening and the like.

The steel wire in the present invention refers to a wire or steel wire typically used in the manufacture of a fastening member, typically in the form of a coil, such as JIS G4051 carbon steel for mechanical structure such as S45C, SCM415. These are various standard steel wires or steel wires used for cold plastic working such as JISG4105 chrome molybdenum steel material such as SCM435. Moreover, the fastening parts manufactured by the steel wire rod of the present invention refer to fastening parts that are subjected to heat treatment such as tempering after cold plastic working. For example, bolts and nuts used for automobiles, building materials, etc. Indicate fastening parts such as washers, especially high strength bolts of strength class 10T and 10.9 class and higher, represented by engine bolts and fastening bolts for undercarriage members of automobiles, where stability of fastening force is important Is targeted. On the surface of the fastening part, a lubricating film in the form in which the crystalline graphite (b) is held on the alkali metal silicate (a) film remains. The film amount of the lubricating film is preferably 0.1 g / m ² or more in order to exhibit a sufficient lubricating effect. Also, since the traces of the decomposition and volatilization of the polyolefin wax (c) during heat treatment remain on the surface of the lubricating film in the form of fine holes, a physical such as rust preventive oil generally applied to the surface of the fastening part Also exhibits a holding effect.

  The present invention will be described more specifically with its effects by giving examples of the present invention together with comparative examples. In addition, this invention is not restrict | limited by these Examples.

Example 1
(1) Preparation of Aqueous Treatment Liquid for Lubricating Film Formation Using the components shown below in the combinations and proportions shown in Table 1, aqueous treatment liquids of Examples 1-8 and Comparative Examples 1-18 shown in Table 1 Was prepared. In all these aqueous treatment liquids, the mass ratio of total solids: water in the aqueous treatment liquid was 1: 9.

<Lubricant component>
In the present Example and Comparative Example, each component blended in the aqueous treatment liquid is shown below.
(Component a)
a-1 Sodium silicate (Na ₂ O · 4SiO ₂ )
a-2 Potassium silicate (K ₂ O.2SiO ₂ )
a-3 Sodium silicate (Na ₂ O.3SiO ₂ ) + potassium sulfate
* Mass ratio is sodium silicate / potassium sulfate = 3.0
a-4 Sodium silicate (2Na ₂ O · SiO ₂ )
a-5 Potassium carbonate a-6 Polyurethane resin emulsion a-7 Sodium silicate (Na ₂ O · 6SiO ₂ )

(Component b)
b-1 flake graphite: particle size 5 μm
b-2 Scale-like graphite: particle diameter 1 μm
b-3 Scale-like graphite: particle diameter 20 μm
b-4 Lime b-5 Molybdenum disulfide b-6 Carbon black (registered trademark MA100, manufactured by Mitsubishi Chemical Corporation)

(Component c)
c-1 polyethylene wax c-2 polypropylene wax c-3 carbanau wax c-4 calcium stearate

(2) Lubricant film treatment (2-1) Pretreatment and lubricant film treatment For this example and comparative examples 1 to 19, lubrication was performed by the following treatment procedure using a carbon steel material S45C for mechanical structure of JIS G4051. Film treatment was performed.
(A) Test material for evaluation: Front extrusion test piece (S45C) 30 mm × φ25 mm
(B) Pickling: 17.5% aqueous solution of hydrochloric acid, temperature 40 ° C., immersion 10 minutes (c) Washing: tap water, room temperature, spray treatment 30 seconds (d) Lubricating film treatment: Each aqueous treatment solution prepared above , 40 ° C., immersion 1 minute treatment (e) Drying: 80 ° C. Hot air drying 3 minutes (f) Dry coating mass: 10 g / m ²
In addition, a commercially available lime soap treatment agent (registered trademark PALUB CAO2, manufactured by Nippon Parkerizing Co., Ltd.) was used for the lubricating film treatment of Comparative Example 19.

About the comparative example 20, the protective film process was performed in the following process procedures using the wire material of carbon steel material S45C for machine structures of JISG4051 like a present Example and Comparative Examples 1-19.
(A) Test material for evaluation: Front extrusion test piece (S45C) 30 mm × φ25 mm
(B) Pickling: 17.5% aqueous solution of hydrochloric acid, temperature 40 ° C., immersion 10 minutes (c) Water washing: tap water, room temperature, spray treatment 30 seconds (d) Chemical conversion treatment: Commercial zinc phosphate chemical conversion treatment agent ( (Registered trademark Palbond 181X, manufactured by Nihon Parkerizing Co., Ltd.), concentration 90 g / L, temperature 80 ° C., immersion 10 minutes (e) water washing: tap water, room temperature, spray treatment 30 seconds (f) soap treatment: commercially available reaction soap lubrication Agent (registered trademark PALOVE 235, manufactured by Nippon Parkerizing Co., Ltd.), concentration 70 g / L, temperature 80 ° C., immersion 5 minutes (g) drying: 80 ° C. hot air drying 3 minutes (h) dry film mass: 12 g / m ²

(3) Cold plastic working test Using the test piece that has been subjected to the above-mentioned lubricating coating, forward extrusion is performed, and the degree of film following to the processing tip of the test piece after processing and the presence or absence of seizure are visually evaluated. did. Those having good followability have sufficient seizure resistance against surface area expansion during cold plastic working, and seizure is likely to occur if the coating does not follow.
Forward extrusion processing conditions: Tip diameter φ10mm, extrusion length 12mm
Evaluation criteria: ○: The film follows up to the tip and there is no seizure.
Δ: The film does not follow up to the tip, but there is no seizure
×: The film does not follow the tip, and there is a seizure part

(4) Appearance evaluation and lubricity evaluation after tempering treatment The test piece molded as described above was subjected to tempering treatment under the following conditions without performing a cleaning step. Thereafter, appearance evaluation and lubricity evaluation were performed according to the following evaluation criteria.
Quenching: held at 870 ° C. for 30 minutes in a nitrogen atmosphere, then cooled with quenching oil.
Tempering: Continuous to the quenching step, held at 470 ° C. for 1 hour in an air atmosphere, and then oil cooled.
<Appearance evaluation>
The color tone of the test piece after the tempering treatment was visually evaluated. The industrial acceptable level is “Δ” or more.
Evaluation criteria: ○: The whole test piece is black with no spots
Δ: Black shading is observed depending on the processed part
×: Lots of spots in the color tone, red part or white part can be seen <Evaluation of lubricity>
The surface of the test piece after the tempering treatment was subjected to a sliding test using a friction wear tester. As the frictional wear test, the most standard Bowden test was performed. As the lubrication performance evaluation, evaluation was made based on the coefficient of dynamic friction at the time of sliding 30 times. The industrial acceptable level is “Δ” or more.
Test conditions: 10 mmφ SUJ2 steel balls used as indenters Vertical load = 1 kg, sliding speed = 10 mm / s, temperature = room temperature Evaluation criteria: ○: Dynamic friction coefficient is less than 0.15
Δ: Dynamic friction coefficient is 0.15 or more and less than 0.2
×: Dynamic friction coefficient is 0.2 or more

The test results are shown in Table 2. As is apparent from Table 2, Examples 1 to 8, which are the scope of the present invention, were all excellent in cold plastic workability, black appearance after tempering treatment, and surface lubricity. On the other hand, Comparative Example 13, in which the alkali metal silicate (a) is not blended, Comparative Graph 1, 2, 14, in which the crystalline graphite (b) is not blended or the blending amount is outside the scope of the present invention. Comparative Examples 3, 4 and 15 in which the polyolefin wax (c) is not blended or the blending amount is out of the scope of the present invention, and the SiO ₂ / M ₂ O ratio of the alkali metal silicate (a) is that of the present invention. Comparative Examples 5 and 16 which are out of the range, Comparative Examples 6 and 7 which do not use the alkali metal silicate (a) as the film component, and components outside the range of the present invention are used instead of the graphite (b). In Comparative Examples 11, 12, and 18 in which the components outside the scope of the present invention are used without including the polyolefin wax (c) in the range of the present invention in Comparative Examples 8, 12, and 18, the aqueous treatment liquid is unstable. Could not form a lubricating film suitable for evaluation, or cold plastic workability Any of the black appearance and surface lubricity after the tempering treatment did not reach the industrial use level. In Comparative Example 19 which is a conventional film, the cold plastic workability and the black appearance after the tempering treatment did not satisfy the object of the present invention. In Comparative Example 20, the black appearance and surface lubricity after the tempering treatment did not satisfy the object of the present invention.

(Example 2)
(1) Preparation of Aqueous Treatment Solution for Lubricating Film Formation An aqueous treatment solution was prepared using the components shown below in the combinations and proportions shown in Table 3. The a-2, b-2, and c-2 of Example 1 were used as the a component, the b component, and the c component that form the lubricating film. In all these aqueous treatment liquids, the mass ratio of total solids: water in the aqueous treatment liquid was 1: 9.

(2) Lubricant film treatment Using a JIS G4105 chromium molybdenum steel steel material SCM415 φ12.3 mm wire, a lubricating film treatment was performed by the following treatment procedure to draw a steel wire.
(A) Pickling: 17.5% aqueous solution of sulfuric acid, temperature 70 ° C., immersion 10 minutes (b) Washing: Pulling up after immersion in a normal temperature washing bath (c) Lubricating film treatment: Each aqueous treatment solution prepared above, 60 ° C., immersion 5 minutes treatment (d) Drying: Natural drying (e) Dry film mass: 10 g / m ²
(F) Wire drawing: Wire drawing to φ12.0mm

(3) Lubricity evaluation of cold plastic working For the purpose of evaluating the deterioration of the lubricating film due to an increase in material surface temperature during cold plastic working, the steel wire subjected to the above lubricating film treatment is cut and In order to simulate the rise of the material surface temperature in the plastic working, a test piece that was heated to 100, 200, 300, 400, and 500 ° C. for 5 minutes and then cooled was prepared. The test piece was subjected to a sliding test using a friction wear tester. As the frictional wear test, the most standard Bowden test was performed. The lubrication performance was evaluated by the number of sliding times until the dynamic friction coefficient value reached 0.2.
Test conditions: SUJ2 steel ball of 2 mmφ used as indenter Vertical load = 3 kg, sliding speed = 3.6 mm / s, temperature = normal temperature Test results above, that is, the number of sliding times in the Bowden test are shown in Table 4 and FIG. . As can be seen from FIG. 1, the lubricating performance is excellent even when the heating temperature is up to 300 ° C. without containing graphite, but when the heating temperature exceeds 300 ° C., the lubricating performance is rapidly deteriorated.
From this, it can be inferred that when a lubricating film containing graphite within the scope of the present invention is formed, the lubricating performance during cold plastic working is excellent.

  As described above, it has been explained that the steel wire for fastening parts of the present invention can be obtained by treating the surface of the wire with a predetermined aqueous treatment liquid or, if necessary, further forming a steel wire by wire drawing. It goes without saying that a similar effect can be obtained by using a steel wire that has been previously drawn and reduced in diameter, and therefore the surface of the steel wire is obtained by treating it with a predetermined aqueous treatment liquid. Steel wires that have been drawn and further drawn are also “steel wires” according to the present invention.

FIG. 1 is a diagram showing the test results of Example 2.

Claims (2)

Silica alkali metal salt (a) having a molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) of 2 to 5, crystalline graphite (b) having an average particle diameter of less than 10 μm, polyolefin wax (c) For fastening parts treated with an aqueous treatment liquid of a composition in which the mass ratio of (b) and (c) in the total solid content is 1 to 30% by mass and 30 to 50% by mass, respectively, Steel wire rod. Silica alkali metal salt (a) having a molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) of 2 to 5, crystalline graphite (b) having an average particle diameter of less than 10 μm, polyolefin wax (c) Is a steel wire for fastening parts having a lubricating film in which the mass ratio of (b) and (c) in the total solid content is 1 to 30% by mass and 30 to 50% by mass, respectively.

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