JP5916464B2 - Copper alloy wrought material, method for producing copper alloy wrought material, and method for producing copper alloy parts - Google Patents

Description

The present invention relates to a method for manufacturing a metal part used in electronic equipment, precision machines, automobiles, etc., in particular, a copper alloy part manufactured by cutting, and a copper alloy wrought material suitable for this copper alloy part and a method for manufacturing the same. and, more particularly, to a method of manufacturing a lead-free free-cutting does bronze wrought material.

  Cutting methods such as turning and drilling are methods for producing metal parts. Cutting is an effective processing method particularly for manufacturing parts having complicated shapes and parts requiring high dimensional accuracy. When cutting, machinability is often a problem. The machinability includes items such as scrap disposal, tool life, cutting resistance, and cutting surface roughness, and materials that improve these characteristics are being improved.

  Copper alloys are used in many metal parts for reasons such as high strength, excellent electrical conductivity and thermal conductivity, excellent corrosion resistance, and excellent color tone. Many processes by cutting a copper alloy are carried out. For example, water faucets, valves, gears, ornaments and the like are formed. These metal parts have improved machinability such as brass (Cu—Zn), bronze (Cu—Sn), aluminum bronze (Cu—Al), and white (Cu—Zn—Ni). Therefore, an alloy with lead added is used.

  Among them, phosphor bronze (Cu—Sn—P system) is used from the viewpoint of strength, toughness, and corrosion resistance. As a general-purpose free-cutting phosphor bronze, there is a free-cutting phosphor bronze to which lead is added like JIS H 3270 C5341. This alloy is cut by a precision machine tool such as an NC lathe and is also used for parts such as small screws, bearings, bolts and nuts.

Thus, conventionally, lead is generally added to improve the machinability of the copper alloy. This is because lead does not dissolve in the copper alloy, so it is finely dispersed in the material, and the cutting waste is easily divided at that portion during cutting. However, the use of lead is being restricted because it is believed to affect the human body and the environment, and there is an increasing demand for materials that have improved machinability without containing lead. As an alternative material for a copper alloy containing lead, a copper alloy in which Bi (bismuth) is added to brass or bronze is known (see Patent Documents 1 and 2). Further, there is a bronze in which S (sulfur) and MoS ₂ are added to form a sulfide (Patent Documents 3, 4, and 5). Moreover, what added S to Cu-Ni-Si alloy, ie, a precipitation-type Corson alloy, is known (patent document 6).

JP 2000-336442 A JP 2001-059123 A JP 2007-297675 A JP 2007-314871 A International Publication No. 2007/126006 Pamphlet JP 2011-231394 A

In the techniques described in Patent Documents 1 and 2, machinability is improved when Bi is added, but cracking is likely to occur during processing, and particularly hot processing becomes difficult. In addition, it is necessary to improve the hot workability again, and Bi is a rare metal, so that the production cost is also increased.
Patent Documents 3 and 4 are techniques related to castings, and are suitable for direct cutting of castings, but are disclosed as techniques for obtaining stretched materials (plastically processed materials) such as bars and plates. Absent. Further, Patent Document 5 is a sliding member in which S is added to a copper alloy containing bronze and the wear resistance and seizure resistance are examined, and the machinability is not examined. Moreover, there is no description which examined the obtained copper alloy by extending | stretching, and it is judged that patent document 5 is the technique regarding casting similarly to patent documents 3 and 4. FIG.
The technique described in Patent Document 6 relates to a precipitation strengthened Corson alloy, and has an alloy composition for obtaining high strength or high conductivity. It is an alloy that requires a complicated and appropriate manufacturing process such as solution treatment, cold working, age hardening, etc., and its manufacturing cost is high. Solid solution strengthened phosphor bronze, which is easy to process and can be manufactured at low cost, has not been studied.

Accordingly, the present invention provides a copper alloy wrought material, in particular, a lead-free free-cutting phosphor bronze wrought material, and a method for producing the same, which can reduce the environmental load without containing Pb and have excellent machinability and extensibility. Objective.

  As a result of intensive studies, the present inventors have dispersed sulfides of a specific size (average diameter) in a general-purpose Cu—Sn—P-based inexpensive solid solution strengthened phosphor bronze, and the area ratio of the sulfides It has been found that a lead-free free-cutting phosphor bronze wrought material having excellent malleability (hot and cold workability) and machinability can be obtained by controlling. Moreover, the specific component composition for obtaining said sulfide was discovered. The present invention has been made based on these findings.

That is, the present invention provides the following solutions.
(1) Component composition containing 0.5 to 11.0 mass% of Sn, 0.03 to 0.35 mass% of P, 0.02 to 1.0 mass% of S, and the balance being Cu and inevitable impurities A copper alloy wrought material having
In a cross section (cross section) perpendicular to the longitudinal direction of the wrought material, a copper alloy that contains sulfide having an average diameter of 0.1 to 10 μm in a dispersed manner and the area ratio of the sulfide is 0.1 to 10%. Stretched material.
(2) 0.5 to 11.0 mass% of Sn, 0.03 to 0.35 mass% of P, 0.02 to 1.0 mass% of S ,
At least one selected from the group consisting of Fe, Zn, Ni, Si, Al, Cr, Mn, Co, Zr, Ti and Ag is contained in a total amount of 0.05 to 2.40 mass%, of which Fe is 0.10 mass% or less, Zn is 2.30 mass% or less, Ni is 0.30 mass% or less, Si is 0.50 mass% or less, Al is 1.00 mass% or less, Cr is 0.15 mass% or less, and Mn is 0.00. 15 mass% or less, Co is 0.50 mass% or less, Zr is 0.10 mass% or less, Ti is 0.25 mass% or less, and Ag is 0.03 mass% or less,
Balance Ri copper alloy wrought der having a component composition consisting of Cu and unavoidable impurities,
In a cross section (cross section) perpendicular to the longitudinal direction of the wrought material, a copper alloy that contains sulfide having an average diameter of 0.1 to 10 μm in a dispersed manner and the area ratio of the sulfide is 0.1 to 10%. Stretched material.
(3) The sulfide is a group consisting of Cu-S, Al-S, Ti-S, Mn-S, Co-S, Ni-S, Fe-S, Zr-S, Zn-S, and Cr-S. copper alloy wrought according to Ru at least one der (2) selected from.
(4) the (1) to (3) any method of manufacturing a copper alloy parts formed by cutting a copper alloy wrought according to one of.
(5) the (1) to (3) a method for producing a copper alloy wrought according to any one of
A method for producing a copper alloy wrought material in which a copper alloy obtained by melt casting is subjected to a homogenization heat treatment and then subjected to cold working with a working rate of 30% or more.
( 6 ) The method for producing a copper alloy wrought material according to ( 5 ), wherein the intermediate annealing and the cold working with a processing rate of 30% or more are repeated one more time.

  The lead-free free-cutting phosphor bronze wrought material of the present invention has the same strength, springiness, fatigue properties, corrosion resistance, wear resistance, and conductivity as general-purpose phosphor bronze, and environmental load substances such as Pb, Bi, etc. Excellent machinability and extensibility without using rare metals. In particular, the lead-free free-cutting phosphor bronze wrought material of the present invention is suitable as a material for parts such as machine screws, bolts, nuts, and electronic equipment manufactured by cutting. The copper alloy part of the present invention can be manufactured with high precision by cutting, and has characteristics necessary for parts such as electrical equipment.

  Since Sn and P in the preferred embodiment of the copper alloy wrought material of the present invention are dissolved in the metal cloth (matrix) and have the effect of solid solution strengthening, the addition thereof increases the strength and conductivity of the copper alloy wrought material. Determine characteristics such as sex.

  In a preferred embodiment of the copper alloy wrought material of the present invention, a sulfide that contributes to improvement of machinability is formed in the matrix by the addition of S. The sulfide acts as a starting point for cutting waste when cutting is performed, so that the cutting waste is easily finely divided and machinability is improved.

  In the present embodiment, the sulfide formed in the copper alloy deteriorates the stretch workability, and therefore the sulfide must have a size (average diameter) and an area ratio that do not impair the workability. From this, the size (average diameter) and area ratio of the sulfide are defined. By obtaining the prescribed sulfide dispersion state, it becomes possible to simultaneously improve the stretch workability and the machinability.

  The higher the Sn content, the better the tensile strength and springiness is the same as general-purpose phosphor bronze. Therefore, it is desirable to select a desired Sn amount according to the intended use. Further, the amount of S contributes only to the machinability, and the amount of S relative to the amount of Sn is a prescribed amount of S regardless of the tensile strength and the spring property.

In the copper alloy wrought material of this embodiment, the size (average diameter) of sulfide is 0.1 to 10 μm, preferably 1.0 to 10 μm, and the area ratio of sulfide is 0.1 to 10%, preferably Must be present at 1.0-10%. For this purpose, the S content is 0.02 to 1.0 mass%, preferably 0.03 to 0.8 mass%. If the amount is too small, the area ratio of the sulfide is small, and sufficient cutting waste separation property cannot be obtained. When there is too much content of S, cold workability (namely, extensibility) will deteriorate.
These sulfide size (average diameter) and sulfide area ratio are achieved by adjusting the S content and cold working of 30% or more, and can be uniformly dispersed in the wrought material. .

  Furthermore, the copper alloy wrought material of this embodiment may contain one or more selected from Fe, Zn, Ni, Si, Al, Cr, Mn, Co, Zr, Ti, and Ag. . These elements improve the spring property, fatigue property, corrosion resistance, wear resistance, and strength of the Cu—Sn—P alloy by forming a solid solution or a precipitate. When contained, 0.05 to 3.0 mass% in total of one or more selected from Fe, Zn, Ni, Si, Al, Cr, Mn, Co, Zr, Ti and Ag It is preferable to make it. When the content is less than 0.05 mass%, the spring property, fatigue property, corrosion resistance, and wear resistance are the same as when these elements are not contained. On the other hand, when the content is more than 3.0 mass%, not only is the effect of improving spring property, fatigue property, corrosion resistance and wear resistance saturated, but also workability is deteriorated and conductivity is lowered, which is not a good idea.

Examples of the sulfide in the present embodiment include Cu-S, Al-S, Ti-S, Mn-S, Co-S, Ni-S, Fe-S, Zr-S, Zn-S, and Cr-S. Cu-S is particularly effective. There are also sulfides of unavoidable impurities and S. Here, “Cu—S” means a generic name of sulfides composed of Cu and S such as Cu ₂ S and CuS, and the same applies to “Al—S” and the like hereinafter.

  The specifications and characteristics of the size (average diameter) and area ratio of sulfide, which is a compound contributing to machinability improvement, will be described. Sulfide has the effect | action which cuts up the cutting waste generated at the time of cutting finely, and, thereby, machinability improves. However, if the sulfide size (average diameter) is smaller than 0.1 μm, a great effect cannot be obtained. Further, even if there is a sulfide having a size (average diameter) of 0.1 μm or more, the cutting waste is not finely divided if the total area ratio is small. Specifically, if the sulfide having a size (average diameter) of 0.1 μm or more is not distributed with a density of 0.1 to 10% in terms of area ratio, the cutting waste is not sufficiently divided. Since sulfides are soft, they may be elongated in the longitudinal direction depending on the degree of cold working, but the size (average diameter) and area ratio of sulfides are cross sections (transverse) perpendicular to the longitudinal direction of the wrought material. Surface), the above should be satisfied. The size of the sulfide (average diameter) is a value obtained by observing the cross section with an electron microscope, converting 100 or more sulfide particles into a circle, and averaging the diameters. The area ratio of sulfides is the number of sulfides seen in one field of view observed with an electron microscope. Each sulfide is converted into a circle to obtain its diameter, averaged, and the area is obtained from the average diameter. Multiply the number of sulfides to obtain the total area per field of sulfide and divide by the total area of one field (%).

  Sulfides degrade the cold workability of the material. The cause of worsening the cold workability is that the grain boundary strength decreases when a large amount of sulfide is formed at the grain boundaries. If the size (average diameter) of the sulfide is too large or the area ratio is too large, the sulfide is likely to form at the grain boundaries, causing cracks when cold-worked and can be used as a wrought material. Disappear. Therefore, the size (average diameter) of the sulfide needs to be 10 μm or less and the area ratio of the sulfide needs to be 10% or less.

  Copper alloy parts used for lead-containing phosphor bronze, used for gears, cams, bearings, machine screws, bolts, nuts, coaxial connectors male pins, female pins, IC sockets and battery terminal connectors Electrical components such as probe barrels and plunger materials, audio cable connector terminals, antenna hinges, fasteners, bearings, guide rails, resistance welders, mold eject pins, etc. Examples include parts that require conductivity, thermal conductivity, and wear resistance, and are manufactured in a complicated shape mainly by cutting. The “copper alloy part” in the present embodiment may include a copper alloy part manufactured by cutting.

Next, a method for producing the lead-free free-cutting phosphor bronze wrought material of the present invention will be described.
The copper alloy wrought material in the present embodiment is obtained by melting and casting an alloy of the components specified in the present invention, subjecting the obtained copper alloy to homogenization heat treatment, and then performing cold working with a processing rate of 30% or more. Manufactured by. More preferably, it is further manufactured by repeating cold working and intermediate annealing at least once. The homogenization heat treatment is preferably performed at 700 to 800 ° C. for 60 to 180 minutes. The intermediate annealing is performed to recrystallize the matrix structure, and is preferably performed at 600 to 700 ° C. for 60 to 120 minutes.

  The sulfide of the copper alloy wrought material in this embodiment is formed at the time of casting by addition of sulfur, but when formed, Sn exists on the segregated dendrite and has workability (ie, extensibility). make worse. Therefore, after melt casting, homogenization heat treatment is performed for the purpose of homogenizing the segregation of Sn and dispersing the sulfide in the matrix. In the subsequent process, cold working is performed, and a large amount of sulfide is present at the grain boundaries, which deteriorates workability (ie, extensibility). Therefore, by performing homogenization heat treatment after melting and casting so as not to impair the workability, it becomes possible to perform a stretching process such as rolling or drawing. Therefore, there is no particular limitation other than performing homogenization heat treatment after melt casting and performing cold working in the subsequent steps. For example, the area of the cross section of the ingot (cake or billet) may be larger than the area of the cross section of the wrought material.

The copper alloy wrought material in this embodiment is subjected to cold working and intermediate annealing in a state where Sn and P are in a solid solution, but when the cold working rate is less than 30%, brittle fracture occurs during annealing. Therefore, cold work of 30% or more is performed. More preferably, cold working of 50% or more is performed. This cold working is performed after the homogenization heat treatment, and it is preferable to repeat the intermediate annealing and the cold working at a cold working rate of 30% or more, preferably 50% or more once or more. In these cold working steps, the sulfide also spreads in the same manner as the matrix, and is uniformly dispersed in the matrix with the degree of the drawing work, which is preferable as a form during cutting. That is, the sulfide is uniformly dispersed by the extension process, and the machinability is greatly improved. The upper limit of the processing rate is not particularly limited, but is practically 99% or less.
Note that the cold work rate is, for example, the cross-sectional area reduction rate when cold working is performed from an ingot bar (after homogenization heat treatment), and thereafter, until intermediate annealing is performed once and further intermediate annealing is performed. It is the cross-sectional area reduction rate at the time.

  The copper alloy wrought material of this embodiment can be manufactured by a manufacturing method such as hot forging of an ingot or continuous casting, for example. Further, the shape of the product is not particularly limited, but it is preferable to make the shape easy to obtain a copper alloy part as a final form by a cutting process which is a subsequent process. That is, it can be manufactured as a copper alloy wrought material having a predetermined shape such as a wire, a bar, a strip, a plate, or a tube depending on the use of the copper alloy component. For example, when the copper alloy part in the final form is a screw or a rivet, the shape of the copper alloy wrought material is preferably a round bar shape.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

Example 1
A round bar having a diameter of 15 mm was cast from a copper alloy having the composition shown in Table 1 using a horizontal continuous casting machine. The obtained round bar with a diameter of 15 mm was subjected to homogenization heat treatment at 700 ° C. for 2 hours, and then the round bar was subjected to 60% cold working to obtain a round bar with a diameter of 9.5 mm. Then, after performing intermediate annealing, 60% of cold work was given and the final form 6mm diameter round bar was manufactured.
Each copper alloy wrought material (round bar) sample thus obtained was examined for sulfide dispersion and machinability by the following methods. The measurement method for each evaluation item is as follows.

<Sulfide dispersion state>
As for the size (average diameter) and area ratio of sulfides, the structure should be observed for each of three fields using a scanning electron microscope (SEM) at any three cross-sections of a 6 mm diameter round bar sample. Determined by The size (average diameter) of the sulfide was obtained by converting 100 or more sulfides per field of view into a circle and averaging the diameters. The area ratio of sulfides is obtained by counting the number of sulfides seen in one field of view and calculating the total area per field of sulfide by multiplying the area obtained from the average diameter assuming that the sulfide is a circle. It was calculated by dividing by the area.
Moreover, the component of sulfide was investigated using the energy dispersive X-ray fluorescence spectrometer (EDX) attached to SEM.

<Machinability>
For machinability evaluation, a round bar having a diameter of 6 mm was directly machined, and then a stepped cutting of the outer diameter of the round bar was performed using a general-purpose lathe. The shape of the cutting waste generated by producing a rivet having a diameter of 6 mm for the large diameter portion and a diameter of 5 mm for the small diameter portion was observed. If the cutting waste is cut to a length of less than 5 mm, it is “good”, and the cutting waste is cut. The thing exceeding 10 mm and the thing in which the cutting scraps are connected in a spiral shape were regarded as “defective”. It is good and good that there is no practical problem. The cutting conditions were a rotation speed of 1010 rpm, a feed rate of 0.09 mm per rotation, and a cutting allowance of 0.25 mm. The cutting tool was a carbide tool (Mitsubishi Materials insert: GTAT0431200R-VT VP15KZ), and no cutting oil was used.

Table 1 shows the results.

In Examples 1 to 17 of the present invention, the components are within the scope of the present invention, and sulfides are dispersed in the copper alloy wrought material. The dispersed sulfides are within the specified ranges for both the average diameter and the area ratio. Therefore, it was possible to perform the extension processing, there was no crack during the material processing, and the machinability was also good.

In Comparative Examples 1 to 4, the alloy components of Sn and P were within the scope of the present invention and could be stretched. However, since there was no addition of S and the range of S was lower than specified, sulfide The area ratio of the object was smaller than specified and the machinability was inferior.
In Comparative Examples 5 to 6, the alloy components of Sn and P were within the scope of the present invention and could be stretched. However, S was more than the standard, and Comparative Example 5 had an average sulfide diameter and area ratio. Both were within the specified range, but the machinability was inferior. In Comparative Example 6, the average diameter of the sulfide was within the range of the standard, the area ratio was larger than the standard, and the machinability was inferior.

In Comparative Example 7, the alloy components of Sn and P were within the scope of the present invention, S was larger than the scope of the present invention, breakage occurred during cold working, and workability was inferior. Moreover, the average diameter and area ratio of the sulfide were larger than the standard and the machinability was inferior.
In Comparative Example 8, although the alloy components of Sn, P, and S are within the scope of the present invention, the total amount of Fe, Zn, Ni, Si, Al, Cr, Mn, Co, Zr, Ti, and Ag is larger than specified. The wire breakage occurred during cold working, resulting in poor workability.
In Comparative Example 9, the amount of Sn was larger than specified, breakage occurred during cold working, and a round bar having a final shape diameter of 6 mm could not be produced.

  Conventional Example 1 is the same test as a free-cutting phosphor bronze C5341 equivalent. From this result, it can be seen that the examples of the present invention showed machinability not inferior to conventional products using lead.

(Comparative Example 10) (Comparative Example of Manufacturing Method)
A round bar having a diameter of 15 mm was cast from a copper alloy having the same composition as that of Invention Example 10 in Table 1 using a horizontal continuous casting machine. Next, the round bar was subjected to 20% cold working to obtain a round bar having a diameter of 13.4 mm. Thereafter, intermediate annealing was performed.
The material subjected to the intermediate annealing was annealed and could not be cold worked.

Claims (6)

Copper having a component composition containing Sn of 0.5 to 11.0 mass%, P of 0.03 to 0.35 mass%, S of 0.02 to 1.0 mass%, the balance of Cu and inevitable impurities Alloy wrought material,
In a cross section (cross section) perpendicular to the longitudinal direction of the wrought material, a copper alloy that contains sulfide having an average diameter of 0.1 to 10 μm in a dispersed manner and the area ratio of the sulfide is 0.1 to 10%. Stretched material. 0.5 to 11.0 mass% of Sn, 0.03 to 0.35 mass% of P, 0.02 to 1.0 mass% of S ,
At least one selected from the group consisting of Fe, Zn, Ni, Si, Al, Cr, Mn, Co, Zr, Ti and Ag is contained in a total amount of 0.05 to 2.40 mass%, of which Fe is 0.10 mass% or less, Zn is 2.30 mass% or less, Ni is 0.30 mass% or less, Si is 0.50 mass% or less, Al is 1.00 mass% or less, Cr is 0.15 mass% or less, and Mn is 0.00. 15 mass% or less, Co is 0.50 mass% or less, Zr is 0.10 mass% or less, Ti is 0.25 mass% or less, and Ag is 0.03 mass% or less,
Balance Ri copper alloy wrought der having a component composition consisting of Cu and unavoidable impurities,
In a cross section (cross section) perpendicular to the longitudinal direction of the wrought material, a copper alloy that contains sulfide having an average diameter of 0.1 to 10 μm in a dispersed manner and the area ratio of the sulfide is 0.1 to 10%. Stretched material. The sulfide is selected from the group consisting of Cu-S, Al-S, Ti-S, Mn-S, Co-S, Ni-S, Fe-S, Zr-S, Zn-S and Cr-S. copper alloy wrought according to 請 Motomeko 2 Ru least one der. The manufacturing method of the copper alloy component formed by cutting the copper alloy wrought material of any one of Claims 1-3. A method for producing the copper alloy wrought material according to any one of claims 1 to 3,
A method for producing a copper alloy wrought material in which a copper alloy obtained by melt casting is subjected to a homogenization heat treatment and then subjected to cold working with a working rate of 30% or more. The method for producing a copper alloy wrought material according to claim 5 , wherein the intermediate annealing and the cold working at a working rate of 30% or more are repeated one more times.