TWI554355B - Brazed jointed structure - Google Patents

Description

Hard welded structure

The present invention relates to a hard-welded structure in which a brazed portion is formed on a substrate made of a Cu-Zn alloy.

The present application claims priority based on Japanese Patent Application No. 2013-200149, filed on Sep

In general, guardrails, headboards, footboards, handrails, door handles, door handles, lever door handles, etc. used in medical institutions, public facilities, and sanitary research facilities (such as food, cosmetics, pharmaceuticals, etc.) In view of the discoloration resistance, a ferrous steel material, a copper alloy, a Zn die-cast material, an Al alloy, or the like in which a plating film such as Ni or Cr or a coating film such as a resin or a paint is formed is often used. Further, these products are often formed by connecting pipes, rods, members produced by forging, die casting, casting, and the like in combination. For example, the bed guard is constructed by joining a pipe that is subjected to bending processing and a pipe or a pipe of a different size (a pipe that is bent by 90 degrees). Since these constituent members are contacted by a large number of unspecified persons, it is preferable to have antibacterial properties from the viewpoint of preventing infection and preventing the spread of the virus.

As a steel material for a billet used as a component of a guardrail, a door handle, a door handle, a lever door handle, etc., an inexpensive general structural steel material is generally used (for example) There are many cases such as SS400 and SS330 defined in JIS G 3101. However, these materials generally perform antibacterial plating or antibacterial coating due to lack of discoloration resistance and antibacterial properties. Further, since the steel for general structural use is relatively low in strength, it may be impossible to cope with the weight reduction, miniaturization, and thinning of products in recent years.

Further, as the material for the above-described constituent member, stainless steel typified by SUS304 may be used. Stainless steel is excellent in discoloration resistance and does not require surface treatment, but lacks antibacterial properties. Austenitic stainless steel containing Ni is expensive and difficult to weld. According to the welding method, a phase transition occurs during the cooling process, so that the strength of the joint is generated. The problem, or the post-treatment after welding, takes a lot of time (the joint becomes black and therefore has to be polished), so it is not a material that is generally used.

Although copper and copper alloys exhibit excellent antibacterial properties or bactericidal properties, for example, discoloration occurs in only one month in an indoor environment, and there is a problem in terms of discoloration resistance. Further, if the hue or the color changes uniformly, there is no particular problem, but depending on the use environment, uneven discoloration may occur. For example, in a guardrail or the like, a portion in which a person frequently touches and a portion that is infrequently contacted are likely to have a difference in hue and color, which becomes a problem. In particular, since the joint portion is often formed in a portion where there is little contact with the human hand, the discoloration resistance is further required. As a result, when copper and a copper alloy are used as a constituent member such as a guardrail, a door handle, a door handle, or a lever door handle, plating or a colorless coating is required, and there is a problem that the excellent antibacterial property (bactericidal property) cannot be exhibited. . Further, in the case of copper alloy, pure copper and 65/35 brass generally have a problem that the temperature of the material rises to 700 ° C or higher during brazing, so that the strength of the brazed portion and its periphery is lowered. On the other hand, when the discoloration resistance is particularly excellent, the antibacterial property (bactericidal property) cannot be exhibited by the action of copper. That is, antibacterial (bactericidal) by means of copper alloy Hydrogen peroxide is generated on the surface to generate active oxygen. In other words, an oxidation-reduction reaction occurs on the surface of copper, and it reacts with water vapor or the like, thereby exhibiting antibacterial property (bactericidal property). This reaction corresponds to so-called corrosion, that is, discoloration, and if there is no reaction on the copper surface, the antibacterial property (bactericidal property) cannot be exhibited. In the present invention, it is one of the biggest problems to limit the corrosion reaction (discoloration) to a minimum and to maintain the antibacterial property (bactericidal property).

Further, the above-described constituent members are formed by joining pipes, plates, wires, rods, castings, and members of various shapes produced by forging.

For example, a bed guardrail (a safety fence for drop prevention) used in a medical or welfare institution or a guard rail for a stretcher joins a pipe and a pipe. In particular, in order to prevent falling or pinching, the bed rails used in medical institutions are joined to the large diameter of the large diameter pipe at appropriate intervals.

Regarding the joining method of the tubes, gas welding, TIG (Tungsten Inert Gas) welding, MIG (Metal Inert Gas) welding, and the like are mainly performed in the iron steel material. On the other hand, when a copper alloy containing Zn is welded, Zn is easily evaporated in the welding, and thus a technique is required for welding. Moreover, since the weld bead remains on the surface due to welding, the process of polishing the bead trace for solving the aesthetic problem is increased, and it is difficult to completely remove it depending on the shape, and the appearance is problematic and laborious. Not suitable for welding. Moreover, it is also possible to impair the antibacterial property (bactericidal property).

Other bonding methods include methods such as brazing, soldering, and friction bonding. However, since the bonding strength is low, the friction bonding is not preferable in terms of workability. Brazing is advantageous in terms of joint strength and reliability compared to other joining methods, but in brazing, the material temperature reaches 700 ° C, or sometimes even Since it is 800 ° C, it is one of the subjects that the discoloration resistance and the antibacterial property (bactericidal property) are not impaired and the brazed portion has high strength.

Therefore, in order to obtain sufficient antibacterial property (bactericidal property), it is attempted to attach a thin copper foil to a constituent member such as a handrail, a door handle, a door handle, a lever door handle, or the like, or a copper foil and a resin or paper. A method of bonding a composite material (for example, refer to Patent Documents 1 and 2).

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Patent Publication No. 2011-020264

Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 11-239603

However, as shown in Patent Documents 1 and 2, when the copper foil is attached to the surface of the constituent member, peeling of the constituent member and the copper foil may occur due to deterioration of the adhesive over the years. Further, the copper foil has a problem in discoloration resistance, and it is not always possible to maintain the antibacterial property (bactericidal property) and the discoloration resistance. Further, in these methods, the problem of the strength reduction of the joint portion constituting the member cannot be solved.

The present invention has been completed in the light of the above circumstances, and an object thereof is to provide a discoloration resistance and an antibacterial property (bactericidal property) independent of surface treatment such as plating, coating, and the like, and the tube and the rod are brazed by brazing. / Wire-shaped member, a member of various shapes produced by forging, die-casting, casting, etc., and combined, and a hard-welded structure having a high-strength brazed portion.

The hard-welded structure of the present invention has a brazed portion formed on a base material composed of a discolor-resistant copper alloy, and the discoloration-resistant copper alloy has a composition containing Zn: 17 to 37 mass% and Pb: 0.0005. -0.30 mass%, and at least one of Ni: 0.01 to 12.5 mass%, Al: 0.01 to 1.6 mass%, and Sn: 0.01 to 2.5 mass%, and the remainder is Cu and inevitable impurities, wherein The content of Zn [Zn] mass%, the content of Pb [Pb] mass%, the content of Ni [Ni] mass%, the content of Al [Al] mass%, and the content of Sn [Sn] mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al] 32 and 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] In the relational expression of 3.8, the metal structure including the heat-affected zone of the brazed portion is an α-phase matrix, and the total ratio of the ratio of the β phase to the ratio of the γ phase is set to 0% or more and 1.4% by area ratio. Hereinafter, the conductivity of the above-described discoloration-resistant copper alloy is 7 to 25% IACS.

According to the hard-welded structure of the present invention, since the brazed portion is formed on the substrate composed of the discolor-resistant copper alloy provided in the above composition range, the antibacterial property (bactericidal property) and the discoloration resistance are excellent. In addition, since the metal structure including the heat-affected zone of the brazed portion is an α-phase matrix, the total ratio of the ratio of the β phase to the ratio of the γ phase is set to 0% or more and 1.4% or less. It can ensure the corrosion resistance of the brazed part. Further, since the electric conductivity of the discoloration-resistant copper alloy is 7 to 25% IACS, the heat-affected portion formed by heating during brazing becomes small, and deterioration in strength and deterioration in antibacterial property (sterilization property) can be suppressed.

Here, in the hard-welded structure of the present invention, the discoloration-resistant copper alloy may have a configuration of: As: 0.01 to 0.09 mass%, P: 0.005 to 0.09 mass%, and Sb: 0.01 to 0.09 mass. Any one or more of %, Zn content [Zn] mass%, Pb content [Pb] mass%, Ni content [Ni] mass%, Al content [Al] mass%, and Sn content [Sn] Mass%, P content [P] mass%, Sb content [Sb] mass%, and As content [As] mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As] 32 relationship.

At this time, by adding As, Sb, and P, the corrosion resistance of the α-phase substrate is improved, and the discoloration resistance of the hard-welded structure can be further improved.

Further, in the hard-welded structure of the present invention, the discoloration-resistant copper alloy may have a composition of Mn: 0.01 to 2.0 mass%, Fe: 0.001 to 0.09 mass%, and Zr: 0.0005 to 0.03 mass. %, Co: 0.001 to 0.09 mass%, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C: 0.0001 to 0.01 mass%, and Zn content [Zn] mass%, Pb Content [Pb]mass%, Ni content [Ni]mass%, Al content [Al]mass%, Sn content [Sn]mass%, P content [P]mass%, Sb content [Sb] Mass%, As content [As] mass%, Mn content [Mn] mass%, Fe content [Fe] mass%, Zr content [Zr] mass%, Co content [Co] mass%, Si The content [Si]mass%, the content of Mg [Mg]mass%, and the content of C [C]mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] 32 relationship.

At this time, Mn, Fe, and the like are appropriately added within the above range depending on the intended use. An element such as Zr, Co, Si, Mg, or C can thereby obtain a hard-welded structure having desired color tone and characteristics.

Further, in the hard-welded structure of the present invention, the discoloration-resistant copper alloy is also composed of Zn: 17 to 37 mass%, Pb: 0.0005 to 0.30 mass%, and Ni: 1.5 to 12.5 mass%. Also, it contains Al: 0.01 to 1.6 mass%, Sn: 0.01 to 2.5 mass%, Mn: 0.01 to 2.0 mass%, Fe: 0.001 to 0.09 mass%, Zr: 0.0005 to 0.03 mass%, and Co: 0.001 to 0.09 mass. %, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C: 0.0001 to 0.01 mass%, and the remainder is set to the composition of Cu and unavoidable impurities, and the content of Zn [Zn 】 mass%, Pb content [Pb] mass%, Ni content [Ni] mass%, Al content [Al] mass%, Sn content [Sn] mass%, Mn content [Mn] mass%, Fe Content [Fe]mass%, Zr content [Zr]mass%, Co content [Co]mass%, Si content [Si]mass%, Mg content [Mg]mass%, and C content [C] Between mass% has 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]-0.5×[Mn]-0.5×[Fe]+0.5×[Zr]+0.5×[Co 〕 +1 × [Si] + 1 × [Mg] + 1 × [C] 32 and, with 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] In the relational expression of 3.8, the conductivity of the above-mentioned discoloration-resistant copper alloy is set to 7 to 22% IACS.

In this case, since a relatively large amount of Ni is contained in the range of 1.5 to 12.5 mass%, sufficient discoloration resistance and antibacterial property (bactericidal property) can be maintained in a state of silver white or a white color even with a brass color.

Further, in the hard-welded structure of the present invention, the base material may be formed from the brazed portion to a distance of 10 mm. In the heat affected zone, the average crystal grain size of the α phase matrix is set to 80 μm or less.

In this case, the average crystal grain size of the α-phase substrate grown by heating during brazing is suppressed to 80 μm or less, so that the difference in characteristics between the heat-affected zone and the portion other than the non-heat-affected zone is reduced, and the hard soldering can be improved. The antibacterial property (bactericidal property) and discoloration resistance of the entire structure are combined. Further, it is possible to suppress a decrease in the strength of the heat-affected zone.

Further, in the hard-welded structure of the present invention, the brazed portion may include Cu: 10 to 96 mass% and the remainder includes Ag: 0.01 to 70 mass%, and Zn: 0.01 to 80 mass%. And one or more solders of Cd: 0.01 to 40 mass%, Sn: 0.01 to 20 mass%, P: 0.01 to 15 mass%, and Ni: 0.01 to 10 mass% are brazed.

At this time, since the melting point of the solder is relatively low, the brazing temperature can be kept low, the thermal influence at the time of brazing can be suppressed, and the joint strength of the brazed portion can be improved. Further, the antibacterial property (bactericidal property) and the discoloration resistance of the entire hard-welded structure can be improved.

Further, in the hard-welded structure of the present invention, the tensile strength of the portion including the brazed portion may be 200 MPa or more, or the endurance may be 60 MPa or more.

In this case, the strength of the portion including the brazed portion can be secured, and the strength of the entire hard-welded structure can be improved.

Further, in the hard-welded structure of the present invention, in the antibacterial property test, 10 minutes of the heat-affected zone from the brazed portion to the region of 10 mm in distance from the base material may be used. viable after the elapse of C _H, C _O ratio of viable cells with respect to the portion other than the heat-affected portion after 10 minutes as a C _H 1.25 × C _O .

In this case, in the antibacterial test, the difference between the viable cell rate C _H in the heat-affected zone and the viable cell rate C _O in the portion other than the heat-affected zone can be suppressed to be small, and the hard-welded structure can be secured. Antibacterial (bactericidal) of the whole body.

Further, in the hard-welded structure of the present invention, the hard-welded structure may be used as a bed guard rail, a headboard, a footboard, a stretcher guardrail, a door handle, an armrest, and a lever door handle. The components of the door handle, the struts, the table, the chair, the shelf, and the care trolley are used for antibacterial purposes.

Since the hard-welded structure of the present invention is excellent in antibacterial property (bactericidal property), discoloration resistance, and strength, it is particularly suitable as a material for a constituent member of the above-described antibacterial use.

According to the present invention, it is possible to provide a discoloration resistance and an antibacterial property (bactericidal property) without depending on surface treatment such as plating or coating, and to weld a tube, a rod/wire, a plate-shaped member, by forging, A hard-welded structure having a high-strength brazed portion in which various shapes of members produced by die casting and casting are joined and combined.

10‧‧‧Hard welded joint structure

11‧‧‧Substrate

12‧‧‧ Hard soldering department

13‧‧‧The Ministry of Thermal Impact

14‧‧‧ Non-thermal impact department

18‧‧‧ pipes

Fig. 1 is a schematic explanatory view showing a hard welded structure according to an embodiment of the present invention.

Hereinafter, the hard-welded structure of the embodiment of the present invention will be described. Further, in the present specification, the element mark with parentheses as in [Zn] indicates the content (mass%) of the element.

As shown in Fig. 1, the hard-welded structure 10 of the present embodiment is formed by forming a brazed portion 12 on a base material 11 made of a discolor-resistant copper alloy having a specific composition to be described later. In the present embodiment, a structure in which the pipe member 18 as another member is brazed to the tubular base material 11 is used.

Further, the brazed portion 12 may be formed by brazing another metal member on the substrate 11 made of a discolor-resistant copper alloy, or may be a substrate 11 or 11 formed by bonding a discolor-resistant copper alloy. Becoming each other. Further, in the hard-welded structure 10 of the present embodiment, of course, the brazed portion 12 is provided. However, other portions may be joined by other joining methods such as soldering, welding (welding), riveting, and screwing. Jointer.

(First embodiment)

In the hard-welded structure 10 of the first embodiment of the present invention, the discoloration-resistant copper alloy constituting the substrate 11 has a composition containing Zn: 17 to 37 mass% and Pb: 0.0005 to 0.30 mass%, and contains Ni. : 0.01 to 12.5 mass%, Al: 0.01 to 1.6 mass%, and Sn: 0.01 to 2.5 mass%, at least one or more, and the remainder is Cu and unavoidable impurities, and the Zn content [Zn] mass%, The content of Pb [Pb] mass%, the content of Ni [Ni] mass%, the content of Al [Al] mass%, and the content of Sn [Sn] mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al] 32 and 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] The relationship of 3.8. In addition, the discoloration-resistant copper alloy in the first embodiment having the above-described composition is referred to as a first invention alloy.

Further, in the hard-welded structure 10 of the present embodiment, the metal structure including the heat-affected zone 13 of the brazed portion 12 is an α-phase matrix, and the ratio of the ratio of the β phase to the ratio of the γ phase is the total area. The rate is set to 0% or more and 1.4% or less. Further, the conductivity of the discoloration-resistant copper alloy constituting the substrate 11 is set to 7 to 25% IACS.

Here, the reason for the composition of the components described above, the metal structure including the heat-affected zone 13 of the brazed portion 12, and the electrical conductivity will be described below.

(Zn: 17 mass% or more and 37 mass% or less)

In the above-mentioned discoloration-resistant copper alloy, Zn is added to Sn, Al, and Ni, which will be described later, to improve discoloration resistance and antibacterial property (bactericidal property), and to improve mechanical strength such as tensile strength and endurance. In the case of hard soldering, the bonding property (brazing property) and the like are important and important elements are important in securing the characteristics of the hard welded structure 10 . The above effects can be obtained by containing 17 mass% or more of Zn. On the other hand, even if it contains more than 37 mass%, the effect corresponding thereto is not obtained. Moreover, although a hard and brittle β phase tends to remain during brazing and the strength is improved, cold workability, bending workability, impact resistance, discoloration resistance, corrosion resistance, stress corrosion cracking resistance, and antibacterial property (sterilization) Sex) decline. Therefore, the amount of addition of Zn is set to be in the range of 17 mass% or more and 37 mass% or less. In addition, in order to maintain the strength, the bondability, and the discoloration resistance of the hard-welded joint portion, the content of Zn is preferably 18 mass% or more, and more preferably 20 mass% or more. Further, in order to maintain the antibacterial property (bactericidal property), it is preferred to set the content of Zn to 36 mass% or less.

(Pb: 0.0005 mass% or more and 0.30 mass% or less)

Pb has improved shearing and grinding in the above-mentioned discoloration-resistant copper alloy The element of the effect of processing. Here, the above effects can be obtained by containing 0.0005% or more of Pb. On the other hand, when the amount is more than 0.30 mass%, the effect corresponding to the content is not obtained, and the ductility, heat/cold workability, and bondability are lowered. Further, since Pb is a harmful substance, it is preferable to limit the content to a minimum. Therefore, the content of Pb is set to be in the range of 0.0005 mass% or more and 0.30 mass% or less. In addition, in order to reliably exhibit the above-described effects, it is preferred to set the content of Pb in the range of 0.001 mass% or more and 0.015 mass% or less.

(Ni: 0.01 mass% or more and 12.5 mass% or less)

Ni is an element which is important for ensuring discoloration resistance, strength, ductility of joints, and whiteness in the above-described discoloration-resistant copper alloy. Here, the above effects can be obtained by containing 0.01 mass% or more of Ni. On the other hand, even if it contains more than 12.5 mass%, the effect corresponding to it is not acquired, and cold ductility and press formability fall. Further, if Ni is too large, there is a possibility that it may cause allergy (Ni allergy). Therefore, when Ni is added, the content of Ni is set to be in the range of 0.01 mass% or more and 12.5 mass% or less.

In addition, when Ni is contained as a main component, when the content of Ni is 1.5 mass% or more, and particularly 2.0 mass% or more, the effect of improving discoloration resistance and the effect of improving wettability with solder are improved. The effect of the ductility at the joint interface is further enhanced by the effect of suppressing the grain growth of the heat-affected zone 13 in the vicinity of the brazed portion 12. When the content of Ni is 8.0 mass% or more, these effects are further remarkable, and the whiteness is also increased.

(Sn: 0.01 mass% or more and 2.5 mass% or less)

Sn is improved in discoloration resistance and strength in the above-described discoloration resistant copper alloy The effect of suppressing the effect of grain growth in the vicinity of the brazed portion 12 and the heat-affected portion 13 and the effect of improving the wettability with the solder. Here, the above effects can be obtained by containing 0.01 mass% or more of Sn. On the other hand, if it is contained in an amount exceeding 2.5 mass%, the effect corresponding to the added amount cannot be obtained. Further, the solidus temperature and the liquidus temperature increase during casting, which tends to cause concentration segregation, and the hot workability, cold workability, and bending workability of the welded pipe and the plate material are lowered. In addition, since the material temperature is heated to 700 ° C or higher during brazing, it is also related to other elements such as Zn. However, if a large amount of Sn is contained, the ratio of the β phase and the γ phase is increased, and corrosion resistance and discoloration resistance are increased. Reduced sex. Further, at the time of brazing, the Sn concentration becomes higher at the joint interface, whereby the joint strength of the brazing is lowered, and as a result, the impact strength is lowered. Therefore, when Sn is added, the content of Sn is set to be in the range of 0.01 mass% or more and 2.5 mass% or less. In addition, when Sn is added in combination with 0.3 mass% or more of Al, it is possible to obtain good discoloration resistance without increasing or decreasing the antibacterial property (bactericidal property). Here, in order to reliably exhibit the above-described effects, the content of Sn is set to 0.3 mass% or more, particularly preferably 0.5 mass% or more, and is preferably 2.2 mass% or less, and further preferably 1.8 mass% or less.

(Al: 0.01 mass% or more and 1.6 mass% or less)

In the above-described discoloration-resistant copper alloy, Al has an effect of improving the fluidity (castability), discoloration resistance, and strength of molten metal during casting. Here, the above-described effects can be obtained by containing 0.01 mass% or more of Al. On the other hand, when the amount is more than 1.6 mass%, the effect corresponding to the content is not obtained, and a strong oxide film is formed, thereby suppressing the antibacterial property (bactericidal property). Further, the wettability at the time of brazing is lowered and the ductility of the brazed portion 12 is lowered, so The impact strength drops. Further, since the ductility of the base material 11 is lowered, the bending workability of the welded pipe and the plate material is lowered, and cracking may occur during processing. Therefore, when Al is added, the content of Al is set to be in the range of 0.01 mass% or more and 1.6 mass% or less. In addition, by adding Al together with 0.3 mass% or more of Sn, it is possible to obtain good discoloration resistance without increasing or decreasing the antibacterial property (bactericidal property). Here, in order to reliably exhibit the above-described effects, the content of Al is preferably 0.3 mass% or more, particularly preferably 0.5 mass% or more, and preferably 1.3 mass% or less.

(Relationship between the contents of Zn, Pb, Ni, Sn, and Al)

Here, in the above-described discoloration-resistant copper alloy, in order to simultaneously satisfy the opposite characteristics of the discoloration resistance and the antibacterial property (bactericidal property) and to obtain the sufficient strength of the brazed portion, 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al] The relationship of 32 is very important. Further, in the above formula, when the content of each of Ni, Sn, and Al is less than 0.01 mass%, the influence on the characteristics is small, so that [Ni], [Sn], and [Al] are each set to 0. Calculation. Further, when the content of Pb is less than 0.0005 mass%, the influence on the characteristics is small. Therefore, [Pb] is set to 0 to calculate. Further, when the total amount of impurities is less than 0.5 mass%, the impurities which are inevitably contained have little effect on the above formula. When the total unavoidable impurity amount exceeds 0.5 mass%, the value of [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al] satisfies the preferred range described below. Just fine.

In the relational expression, when the value of [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al] is less than 15, the discoloration resistance, strength, brazing property, The antibacterial property (bactericidal property) is deteriorated. On the other hand, if the value exceeds 32, the β phase, The γ phase is increased, and the discoloration resistance, the corrosion resistance, the stress corrosion cracking resistance, the brazing property, and the bending workability of the welded pipe and the plate material are deteriorated. Further, since the ductility is also lowered, the strength and impact strength of the brazed portion 12 are lowered. Moreover, the antibacterial property (bactericidal property) is not only unsaturated, but is rather deteriorated. In the above formula, Sn particularly affects the formation of the β phase and the γ phase, and contributes to the improvement of the strength and the antibacterial property (bactericidal property), and thus gives a positive coefficient. Al has an effect similar to that of Sn, but the degree of influence is less than that of Sn, and the coefficient is comprehensively imparted including the influence of discoloration resistance. Contrary to Sn, Ni is mainly evaluated to inhibit the formation of the β phase and the γ phase, and gives a negative coefficient in consideration of corrosion resistance and discoloration resistance.

Further, in the above formula, the value of [Zn]-0.5 × [Pb] - 1.2 × [Ni] + 2.4 × [Sn] + 1 × [Al] is preferably 17 or more, and most preferably 20 or more. On the other hand, 31 or less, more preferably 30 or less is preferable, and 29 or less is more preferable. In a preferable range, the characteristics of the strength, the discoloration resistance, and the antibacterial property (bactericidal property) of the brazed portion 12 are further excellent.

(Relationship between the contents of Ni, Sn, and Al)

Further, in the above-described discoloration-resistant copper alloy, in order to have both discoloration resistance and antibacterial property (bactericidal property), the balance of the contents of Ni, Sn, and Al is very important, and it is necessary to satisfy 0.7. 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] 3.8. Further, in the above formula, when the content of each of Ni, Sn, and Al is less than 0.01 mass%, the influence on the characteristics is small, so that [Ni], [Sn], and [Al] are each set to 0. Calculation. When the content of Ni, Sn, and Al is 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al], the value is less than 0.7, which causes problems in discoloration resistance and strength. On the other hand, when the value exceeds 3.8, the brazing property also decreases, and the joint interface between the billet and the copper material becomes brittle, and the strength such as impact strength is lowered. Moreover, the discoloration resistance is improved, and the antibacterial property (bactericidal property) is impaired.

In the above formula, Al exerts a large effect on the discoloration resistance. In particular, when it is added together with Sn, the discoloration resistance is particularly remarkable, and a large coefficient is given in consideration of characteristics other than the strength. On the other hand, the above formula shows that if the Al content is too large, the antibacterial property (bactericidal property) is impaired. Sn also shows a tendency similar to Al, but the effect of discoloration resistance and the like is smaller than that of Al, so the coefficient is small. Further, by the addition of Al and Sn, discoloration resistance and antibacterial property (bactericidal property) are remarkable, and these effects can also be expressed as a product of the contents of Al and Sn, 0.15. [Sn]×[Al] 1.2 is preferable, and [Sn] × [Al] is further preferably 0.18 or more, more preferably 0.20 or more. On the other hand, [Sn] × [Al] is preferably 1.0 or less, more preferably 0.85 or less.

On the other hand, in order to mainly exhibit the effect of discoloration resistance, a certain amount of Ni is required. At 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] In the relational expression of 3.8, a value of 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] is preferably 0.8 or more, more preferably 1.1 or more, and further preferably 1.6 or more, and on the other hand, 3.6. The following is preferred, and 3.5 or less is preferred. In a preferable range, the characteristics of the strength, the discoloration resistance, and the antibacterial property (bactericidal property) of the brazed portion 12 are further excellent.

(Metal structure of heat-affected portion 13)

Further, in the metal structure of the heat-affected portion 13, if there are more than a predetermined amount of hard and brittle β-phase and γ-phase in the α-phase matrix, ductility and stress corrosion cracking resistance in the brazed portion 12 are present. The discoloration resistance and corrosion resistance have an adverse effect, and the antibacterial property (bactericidal property) is rather deteriorated. Therefore, the metal structure of the heat-affected portion 13 including the brazed portion 12 is an α-phase matrix, and the proportion of the β phase and γ The total ratio of the phases is preferably 0% or more and 1.4% or less in terms of area ratio. Further, it is more preferable that the total area ratio of the β phase and the γ phase is 0.9% or less. On the other hand, the β phase and the γ phase have an effect of suppressing grain growth in the vicinity of the brazed portion 12 and the heat-affected portion 13, and the α phase before the precipitation of the β phase and the γ phase is the highest, and the antibacterial property (bactericidal property) is also good. . Therefore, the total ratio of the ratio of the β phase to the ratio of the γ phase is preferably 0% or 0.03% to 0.3% in terms of the area ratio.

(Electrical conductivity of discoloration-resistant copper alloy)

Further, the bonding by brazing is performed by melt diffusion of the molten base material and solder, and therefore, in order to perform strong bonding, the temperature of the base material of the brazed portion 12 must be at least higher than the melting point of the solder. However, when the thermal conductivity of the base material is good, heat is transferred to the entire base material, and it is difficult to locally increase the temperature of the portion to be brazed in the base material. In order to increase the temperature of the portion to be brazed, the temperature of the entire base material must be made. rise. If the base material is exposed to a high temperature for a long period of time, the surface oxidation is of course caused, and there is a problem in appearance, so that after the brazing, a long-time grinding operation is required. If the polishing is insufficient, the antibacterial property (bactericidal property) of the brazed portion 12 is impaired. The proportional relationship described by the Wiedeman-Franz law is confirmed in the relationship between the thermal conductivity of the metal material and the electrical conductivity. That is, a metal material having a low electrical conductivity has a low thermal conductivity, and the temperature of the portion to be brazed can be locally increased in a short time, and it is advantageous from the viewpoint of a decrease in strength due to heat influence during brazing. . When the above composition and relationship are satisfied and the conductivity of the substrate 11 is 25% or less (International Annealed Copper Standard) or less, the temperature of the entire substrate 11 is hard to rise during brazing, and only the temperature around the joined portion rises ( Local heating), so that heating can be performed in a short time, Not only the brazed portion 12 but also the strength reduction of the entire hard welded structure 10 can be suppressed. If the conductivity exceeds 25% IACS, for example, when pure copper (electrical conductivity 100% IACS) and 65Cu/35Zn brass (conductivity 27 to 28% IACS) are used as the substrate, it is confirmed that not only the brazed portion 12 is used. The strength of the periphery is lowered, and there is a possibility that the strength of the hard welded structure 10 as a whole is lowered. Therefore, the conductivity of the substrate 11 is preferably 23% IACS or less, more preferably 21% IACS or less, and most preferably 20% IACS or less. Further, when the electrical conductivity is less than 7% IACS, the thermal conductivity is inferior, so that an appropriate amount of heat cannot be released, and heat is accumulated in the heating portion, causing the temperature of the heat-affected portion to rise. From the above, the lower limit of the electrical conductivity of the substrate is set to 7% IACS.

(Second embodiment)

In the hard-welded structure 10 according to the first embodiment of the present invention, the discolor-resistant copper alloy constituting the base material 11 further contains As: Any one or more of 0.01 to 0.09 mass%, P: 0.005 to 0.09 mass%, and Sb: 0.01 to 0.09 mass%, Zn content [Zn] mass%, Pb content [Pb] mass%, and Ni content [ Ni]mass%, Al content [Al]mass%, Sn content [Sn]mass%, P content [P]mass%, Sb content [Sb]mass%, and As content [As]mass% Between 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As] 32 relationship. In addition, the discoloration-resistant copper alloy in the second embodiment is referred to as a second invention alloy.

Hereinafter, the reason why the component composition is further specified as described above will be described.

(P: 0.005 mass% or more and 0.09 mass% or less)

P system has improved corrosion resistance of the α phase matrix in the above-mentioned discoloration resistant copper alloy It has an action of etching and has an effect of improving the fluidity of the molten metal at the time of casting. Here, the above effects can be obtained by containing 0.005 mass% or more of P. On the other hand, when the content of P exceeds 0.09 mass%, the effect corresponding to the content is not obtained, and the hot ductility, cold ductility, and bending workability at the time of producing a billet are adversely affected. Therefore, when P is added, the content of P is set to be in the range of 0.005 mass% or more and 0.09 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of P is preferably 0.02 mass% or more and 0.06 mass% or less, but is not limited thereto.

(As: 0.01 mass% or more and 0.09 mass% or less)

As in the case of P, As is also an element which has an effect of improving the corrosion resistance of the α phase matrix in the above-mentioned discoloration-resistant copper alloy. Here, the above effects can be obtained by containing 0.01 mass% or more of As. On the other hand, when the content of As exceeds 0.09 mass%, the effect corresponding to the content is not obtained, and the ductility of the brazed portion 12 is adversely affected. Therefore, when As is added, the content of As is set to be in the range of 0.01 mass% or more and 0.09 mass% or less. Further, since As is highly toxic, it is preferably 0.05 mass% or less.

(Sb: 0.01 mass% or more and 0.09 mass% or less)

Similarly to P, Sb is also an element having an effect of improving the corrosion resistance of the α phase matrix in the above-described discoloration resistant copper alloy. Here, the above effects can be obtained by containing 0.01 mass% or more of Sb. On the other hand, when the content of Sb exceeds 0.09 mass%, the effect corresponding to the content is not obtained, and the ductility of the brazed portion 12 is adversely affected. Therefore, when Sb is added, the content of Sb is set to be in the range of 0.01 mass% or more and 0.09 mass% or less. Further, since Sb is highly toxic, it is preferably 0.05 mass% or less.

(Relationship between the contents of Zn, Pb, Ni, Sn, Al, As, P, and Sb)

Here, in the above-described discoloration-resistant copper alloy, in order to simultaneously satisfy the opposite characteristics of discoloration resistance and antibacterial property (bactericidal property) and to obtain sufficient strength of the brazed portion 12, 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+.5×[As] The relationship of 32 is often important.

Further, in the above formula, when the content of each of Ni, Sn, and Al is less than 0.01 mass%, the influence on the characteristics is small, so that [Ni], [Sn], and [Al] are each set to 0. Calculation. Further, when the content of Pb is less than 0.0005 mass%, the influence on the characteristics is small. Therefore, [Pb] is set to 0 to calculate. Further, when the content of As is less than 0.01 mass%, the influence on the characteristics is small, so the calculation is performed by setting [As] to 0. Regarding P, when the content is less than 0.005 mass%, the influence on the characteristics is small. Therefore, [P] is set to 0 to calculate. When the content of Sb is less than 0.01 mass%, the influence on the characteristics is small. Therefore, the calculation is performed by setting [Sb] to zero. Further, when the total amount of impurities is less than 0.5 mass%, the impurities which are inevitably contained have little effect on the above formula. When the total unavoidable impurity mass exceeds 0.5 mass%, [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5× The value of Sb]+0.5×[As] may satisfy the preferred range described below.

In the same manner as the hard-welded structure 10 of the first embodiment, the discoloration resistance and the antibacterial property (bactericidal property) can be obtained in the same manner as in the above-described relationship. Further, in the above formula, [Zn] - 0.5 × [Pb] - 1.2 × [Ni] + 2.4 × [Sn] + 1 × [Al] + 2 × [P] + 2.5 × [Sb] + 0.5 × The value of As] is preferably 17 or more, and most preferably 20 or more. On the other hand, 31 or less is preferable, and 30 or less is further. Good, 29 or better. In a preferable range, the characteristics of the strength, the discoloration resistance, and the antibacterial property (bactericidal property) of the brazed portion 12 are further excellent.

(Third embodiment)

The hard-welded structure 10 according to the third embodiment of the present invention is characterized in that, in the hard-welded structure 10 of the first and second embodiments, the discolor-resistant copper alloy constituting the substrate 11 is further Mn: 0.01 to 2.0 mass%, Fe: 0.001 to 0.09 mass%, Zr: 0.0005 to 0.03 mass%, Co: 0.001 to 0.09 mass%, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C Any one or more of 0.0001 to 0.01 mass%, Zn content [Zn] mass%, Pb content [Pb] mass%, Ni content [Ni] mass%, Al content [Al] mass%, Sn Content [Sn]mass%, P content [P]mass%, Sb content [Sb]mass%, As content [As]mass%, Mn content [Mn]mass%, Fe content [Fe] Mass%, Zr content [Zr]mass%, Co content [Co]mass%, Si content [Si]mass%, Mg content [Mg]mass%, and C content [C]mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] 32 relationship. Moreover, the discoloration-resistant copper alloy in the third embodiment is referred to as a third invention alloy.

Hereinafter, the reason why the component composition is further defined as described above in the present embodiment will be described.

(Mn: 0.01 mass% or more and 2.0 mass% or less)

Mn is based on the color tone of the above-described discoloration-resistant copper alloy by co-existing with Ni An element which exhibits an effect of acting as a substitute element for Ni, which is an element which exhibits an effect of being a substitute element of Ni, is an element which exhibits an effect of being added as an alternative element of Ni. Further, the addition of Mn also has an effect of improving strength, abrasion resistance, press formability, and bending workability. Here, the above effects can be obtained by containing 0.01 mass% or more of Mn. On the other hand, when the content of Mn exceeds 2.0 mass%, the effect corresponding to the content is not obtained, and hot workability such as hot rolling, hot pressing, hot forging, etc. is lowered, and the antibacterial property (bactericidal property) may be lowered. . Therefore, when Mn is added, the content of Mn is set to be in the range of 0.01 mass% or more and 2.0 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of Mn is preferably 0.2 mass% or more and 1.2 mass% or less.

(Fe: 0.001 mass% or more and 0.09 mass% or less)

Fe has an effect of suppressing grain growth even when exposed to high temperatures during brazing. In particular, precipitates of Fe-P-based precipitates are precipitated by adding a small amount together with P to the Cu-Zn alloy. Further, by adding P and Co together, the Fe-Co-P-based precipitates are precipitated to refine the crystal grains, and as a result, the strength and heat resistance are improved. Here, the above effects can be obtained by containing 0.001 mass% or more of Fe. On the other hand, when the content of Fe exceeds 0.09 mass%, not only the effect of suppressing the crystal grains is saturated, but also the effect corresponding to the amount of addition is not obtained, and the strength and heat resistance are not affected. Further, excessive Fe-P-based or Fe-Co-P-based precipitates are precipitated at the crystal grain boundary during cooling after brazing, and the cold-extensibility, bending workability, and impact resistance of the heat-affected zone 13 are lowered. Therefore, when Fe is added, the content of Fe is set to be in the range of 0.001 mass% or more and 0.09 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of Fe is preferably 0.02 mass% or more and 0.05 mass% or less, but is not limited thereto.

(Co: 0.001 mass% or more and 0.09 mass% or less)

Co has an effect of suppressing grain growth even when exposed to a high temperature during brazing. In particular, precipitates of Co-P-based precipitates are precipitated by adding a small amount together with P to the Cu-Zn alloy. Further, by adding P and Fe together, precipitates of Fe-Co-P-based precipitates are precipitated, and crystal grains are refined, and strength and heat resistance are improved. Here, the above effects can be obtained by containing 0.001 mass% or more of Co. On the other hand, when the content of Co exceeds 0.09 mass%, not only the effect of suppressing the crystal grains is saturated, but also the effect corresponding to the amount of addition is not obtained, and the strength and heat resistance are not affected. Further, excessive Co-P-based or Fe-Co-P-based precipitates are precipitated at the crystal grain boundaries during cooling after brazing, and the cold-extensibility, bending workability, and impact resistance of the heat-affected zone 13 are lowered. Therefore, when Co is added, the content of Co is set to be in the range of 0.001 mass% or more and 0.09 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of Co is preferably 0.02 mass% or more and 0.05 mass% or less, but is not limited thereto.

(Zr: 0.0005 mass% or more and 0.03 mass% or less)

The Zr system has an effect of making the crystal grains finer and improving the strength by the addition of an extremely small amount of the Cu-Zn alloy. Further, it has an effect of suppressing grain growth even during brazing. Here, the above effects can be obtained by containing 0.005 mass% or more of Zr. On the other hand, when the content of Zr exceeds 0.03 mass%, the effect corresponding to the content cannot be obtained, and the grain refinement is impaired. Therefore, when Zr is added, the content of Zr is set to be in the range of 0.0005 mass% or more and 0.03 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of Zr is preferably 0.00075 mass% or more and 0.015 mass% or less, but is not limited thereto.

(Si: 0.001 mass% or more and 0.09 mass% or less)

The Si-based element has an effect of improving the fluidity, strength, and corrosion resistance of the molten metal when the Cu-Zn alloy is cast. Here, the above effects can be obtained by containing 0.001 mass% or more of Si. On the other hand, when the content of Si exceeds 0.09 mass%, the effect corresponding to the content cannot be obtained, and the cold workability is impaired. Therefore, when Si is added, the content of Si is set to be in the range of 0.001 mass% or more and 0.09 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of Si is preferably 0.01 mass% or more and 0.03 mass% or less, but is not limited thereto.

(Mg: 0.001 mass% or more and 0.05 mass% or less)

The Mg system has an effect of improving the strength, corrosion resistance, and discoloration resistance of the Cu-Zn alloy, and particularly has an effect of preventing the effect of grain boundary corrosion from the viewpoint of corrosion resistance. Here, the above effects can be obtained by containing 0.001 mass% or more of Mg. On the other hand, Mg is easily oxidized, and if it is contained in excess, it is oxidized during casting, and casting defects such as entrapment of oxide may occur, so it is necessary to set it to 0.05 mass% or less. Therefore, when Mg is added, the content of Mg is set to be in the range of 0.001 mass% or more and 0.05 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of Mg is preferably 0.01 mass% or more and 0.02 mass% or less, but is not limited thereto.

(C: 0.0001 mass% or more and 0.01 mass% or less)

The C system can obtain the same effect as the addition of Pb and has an effect of improving the workability of the workability of the Cu-Zn alloy such as shear workability and polishing. Here, the above effects can be obtained by containing 0.0001 mass% or more of C. On the other hand, if the content of C exceeds 0.01 mass%, the corresponding The effect is that ductility, heat/cold workability, and jointability are lowered. Therefore, when C is added, the content of C is set to be in the range of 0.0001 mass% or more and 0.01 mass% or less. In addition, in order to reliably exhibit the above-described effects, the content of C is preferably 0.002 mass% or more and 0.005 mass% or less, but is not limited thereto.

(Relationship between the contents of Zn, Pb, Ni, Sn, Al, As, P, Sb, Mn, Fe, Zr, Co, Si, Mg, and C)

Here, in the above-described discoloration-resistant copper alloy, in order to simultaneously satisfy the opposite characteristics of discoloration resistance and antibacterial property (bactericidal property) and to obtain sufficient strength of the brazed portion 12, 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] The relationship of 32 is very important.

Further, in the above formula, when the content of each of Ni, Sn, and Al is less than 0.01 mass%, the influence on the characteristics is small, so that [Ni], [Sn], and [Al] are each set to 0. Calculation. Further, when the content of Pb is less than 0.0005 mass%, the influence on the characteristics is small. Therefore, [Pb] is set to 0 to calculate. Further, when the content of As is less than 0.01 mass%, the influence on the characteristics is small, so the calculation is performed by setting [As] to zero. Regarding P, when the content is less than 0.005 mass%, the influence on the characteristics is small. Therefore, [P] is set to 0 to calculate. When the content of Sb is less than 0.01 mass%, the influence on the characteristics is small. Therefore, the calculation is performed by setting [Sb] to zero. Further, when the content of Mn is less than 0.01 mass%, the influence on the characteristics is small. Therefore, [Mn] is set to 0 to calculate. About Fe, its content is less than 0.001 mass% When the influence on the characteristics is small, the calculation is performed by setting [Fe] to 0. Regarding Zr, when the content is less than 0.0005 mass%, the influence on the characteristics is small, so the calculation is performed by setting [Zr] to zero. When the content of Co is less than 0.001 mass%, the influence on the characteristics is small. Therefore, [Co] is set to 0 to calculate. When the content of Si is less than 0.001 mass%, the influence on the characteristics is small. Therefore, [Si] is set to 0 to calculate. When the content of Mg is less than 0.001 mass%, the influence on the characteristics is small. Therefore, [Mg] is set to 0 to calculate. Regarding C, when the content is less than 0.0001 mass%, the influence on the characteristics is small, so the calculation is performed by setting [C] to zero. Further, when the total amount of impurities is less than 0.5 mass% with respect to impurities which are inevitably contained, there is almost no influence on the above formula. When the total unavoidable impurity mass exceeds 0.5 mass%, [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5× Sb]+0.5×[As]-0.5×[Mn]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] The value satisfies the preferred range described below.

By satisfying the relationship, the discoloration resistance and the antibacterial property (bactericidal property) can be obtained in the same manner as the hard-welded structure 10 of the first and second embodiments. Further, in the above formula, [Zn] - 0.5 × [Pb] - 1.2 × [Ni] + 2.4 × [Sn] + 1 × [Al] + 2 × [P] + 2.5 × [Sb] + 0.5 × As]-0.5×[Mn]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] has a value of 17 or more. Preferably, 20 or more is the most preferable. On the other hand, 31 or less is preferable, 30 or less is further more preferable, and 29 or less is more preferable. In a preferable range, the characteristics of the strength, the discoloration resistance, and the antibacterial property (bactericidal property) of the brazed portion 12 are further excellent.

(Fourth embodiment)

In the hard-welded structure 10 of the first embodiment of the present invention, the discolor-resistant copper alloy constituting the base material 11 has the following composition: Zn: 17~ 37mass%, Pb: 0.0005~0.30mass% and Ni: 1.5~12.5mass%, and also contains Al: 0.01~1.6mass%, Sn: 0.01~2.5mass%, Mn: 0.01~2.0mass%, Fe: 0.001~ 0.09 mass%, Zr: 0.0005 to 0.03 mass%, Co: 0.001 to 0.09 mass%, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C: 0.0001 to 0.01 mass%, any one or more of The remainder is Cu and inevitable impurities, Zn content [Zn] mass%, Pb content [Pb] mass%, Ni content [Ni] mass%, Al content [Al] mass%, and Sn content. [Sn]mass%, Mn content [Mn]mass%, Fe content [Fe]mass%, Zr content [Zr]mass%, Co content [Co]mass%, Si content [Si]mass% , the content of Mg [Mg] mass% and the content of C [C] mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]-0.5×[Mn]-0.5×[Fe]+0.5×[Zr]+0.5×[Co 〕 +1 × [Si] + 1 × [Mg] + 1 × [C] 32 and 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] In the relation of 3.8, further, the conductivity of the discoloration-resistant copper alloy is set to 7 to 22% IACS. Further, the discoloration-resistant copper alloy in the fourth embodiment is referred to as a fourth invention alloy.

Hereinafter, the reason why the component composition and the electrical conductivity are further defined as described above in the present embodiment will be described.

Further, in the hard-welded structure 10 of the fourth embodiment, Ni is added to the discoloration-resistant copper alloy of the hard-welded structure 10 of the first embodiment. The lower limit of the content is set to be 1.5 mass%. Hereinafter, the reason will be described. Further, other elements are described in the first, second, and third embodiments.

(Ni: 1.5 mass% or more and 12.5 mass% or less)

In the Cu-Zn alloy, strength, discoloration resistance, antibacterial property (bactericidal property), brazing property, and grain growth of the heat-affected zone 13 are suppressed in a state of silver white or even a brass color with a white hue. The effect is that the Ni content needs to be 1.5 mass% or more. On the other hand, when the content of Ni exceeds 12.5 mass%, Ni allergy may occur, and the antibacterial property (bactericidal property) may be saturated and may be deteriorated. Therefore, in the present embodiment, the content of Ni is set to be in the range of 1.5 mass% or more and 12.5 mass% or less. In addition, in order to reliably exhibit the above-described effects, it is more preferable that the content of Ni is 2.0 mass% or more, and it is more preferably 2.5 mass% or more. Further, it is preferably 12 mass% or less.

(The relationship between Zn, Pb, Ni, Sn, and Al)

In the Cu-Zn alloy, strength, discoloration resistance, and antibacterial properties are obtained in a state of silver white or even a brass color with a white hue. [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]-0.5×[Mn]-0.5×[Fe]+0.5×[Zr]+0.5×[Co 〕 +1 × [Si] + 1 × [Mg] + 1 × [C] The relationship of 32 is very important. In the relation, [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]-0.5×[Mn]-0.5×[Fe]+0.5×[ When the value of Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] is less than the lower limit, discoloration resistance, strength, bondability (hardness), and antibacterial property (Bactericidal property) is deteriorated, and if it exceeds the upper limit, it is embrittled, the antibacterial property (bactericidal property) is saturated, and the corrosion resistance is deteriorated.

(The relationship between Ni, Sn, and Al)

Further, in the Cu-Zn alloy, in order to obtain strength, discoloration resistance, and antibacterial property (bactericidal property) in a state of silver white or even a brass color with a white hue, the relationship between the contents of Ni, Sn, and Al is required. Meet 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] 3.8. In the relational expression, when the value of 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] is less than 0.7, there is a possibility that a problem occurs in hue (increased in yellow), discoloration resistance, and strength. When the value exceeds 3.8, there is a possibility that a problem occurs in saturation of color tone (silver white), cold workability, bending workability, and antibacterial property (bactericidal property).

(Electrical conductivity of discoloration-resistant copper alloy)

In the discoloration-resistant copper alloy (the fourth invention alloy) of the fourth embodiment, since a relatively large amount of Ni of 1.5 mass% or more is contained, the electrical conductivity can be set to a relatively low 22% IACS or less. As described above, by setting the conductivity to be low, only the temperature around the joined portion is raised (local heating) during brazing, and the temperature of the entire substrate 11 is hard to rise, so that it is not only the brazed portion 12 but also The strength reduction of the entire hard welded structure 10 can be suppressed.

In the discoloration-resistant copper alloy of the hard-welded structure 10 of the first to fourth embodiments, the remaining portion of each of the above elements may be substantially Cu and an unavoidable impurity. Here, examples of the unavoidable impurities include Cr, Ag, Ca, Sr, Ba, Sc, Y, Hf, V, Nb, Ta, Mo, W, Re, Ru, Os, Se, Te, and Rh. Ir, Pd, Pt, Au, Cd, Ga, In, Li, Ge, Ti, Tl, Bi, S, O, Be, N, H, Hg, B, and rare earths. It is preferable that the inevitable impurities are 0.5 mass% or less in the total amount.

(average crystal grain size of the α phase matrix)

Here, in the hard-welded structure 10 of the first to fourth embodiments, the average crystal of the α-phase matrix in the heat-affected zone 13 from the brazed portion 12 to the region of 10 mm in the base material 11 is used. The particle diameter is set to 80 μm or less.

Further, in the present embodiment, the crystal grain size is measured from the portion of the brazed portion 12 to the three portions of the distance of 10 mm, and the average crystal grain size of the α-phase matrix in the heat-affected portion is calculated.

When the average crystal grain size of the heat-affected zone 13 of the base material 11 formed by brazing exceeds 80 μm, when stress and impact are applied to the hard-welded structure 10, it is easy to form the heat-affected portion 13 and non-heat by the joint. Stress concentration occurs at the boundary portion of the influential portion 14 (portion other than the heat-affected portion 13), which may cause an increase in crack sensitivity. That is, the average crystal grain size of the heat-affected zone 13 around the brazed portion 12 is closer to the crystal grain size of the non-heat-affected portion 14 as possible. Further, when the crystal grains of the heat-affected zone 13 are coarse or the difference between the average crystal grain size of the heat-affected zone 13 and the non-heat-affected zone 14 is large, not only the crack sensitivity but also the sensitivity of the stress corrosion cracking is improved. Therefore, the above composition, relationship, and average crystal grain size become very important.

(solder)

Further, the solder used in the hard-welded structure 10 of the present embodiment includes silver solder, phosphor bronze solder, and brass solder, and is defined as a Cu content of at least 10 mass% or more and 96 mass% or less and the remaining portion includes Ag: at least one of 0.01 to 70 mass%, Zn: 0.01 to 80 mass%, Cd: 0.01 to 40 mass%, Sn: 0.01 to 20 mass%, P: 0.01 to 15 mass%, and Ni: 0.01 to 10 mass%. a content of Cu of at least 10 mass% or more and 96 mass% or less and containing 3 mass% or more and 10 mass% or less of P, Ag of 0.5 mass% or more and 65 mass% or less, Zn of 12 mass% or more and 70 mass% or less, Cd of 12 mass% or more and 30 mass% or less, Ni of 1 mass% or more and 5 mass% or less, and Sn of 2 mass% or more and 12 mass% or less. At least one or more of them are more preferable.

Solder used for brazing copper alloys generally uses silver solder, phosphor bronze solder, brass solder, and the melting point of phosphor bronze solder (BCuP) specified in JIS Z 3264 is 790-925 ° C, the melting point of brass solder. In the case of about 900 ° C, the melting point of the silver solder (BAg) prescribed in JIS Z 3261 is 620 to 800 ° C, and the melting point greatly differs depending on the solder. However, when the material is brazed, the solder needs to be raised to a temperature higher than the melting point, so that the strength of the brazed portion 12 is lowered by the influence of heat. Further, as an example of 65Cu/35Zn brass, when heated to 700 to 800 ° C, precipitation of the β phase occurs, and if the cooling rate is too fast, the β phase remains, causing a decrease in corrosion resistance.

From the viewpoint of the strength and corrosion resistance of the brazed portion 12, it is preferable to use a phosphor bronze solder not containing Ag, a silver solder having a lower melting point than brass solder, or a phosphor bronze solder containing Ag. In other words, the solder used in the hard-welded structure 10 of the present embodiment contains at least 10 mass% or more and 96 mass% or less of Cu and 0.5 mass% or more and 65 mass% or less of Ag. Although Ag is expensive, when the solder contains 0.5 mass% or more of Ag, the melting point of the solder is lowered, and the adhesion to the substrate 11 and the wettability are improved. A solder containing 12 mass% or more and 50 mass% or less of Cu and 2.0 mass% or more and 60 mass% or less of Ag is more preferable, and Cu containing 20 mass% or more and 40 mass% or less and Ag solder of 30 mass% or more and 60 mass% or less are more preferable. It is better. In addition, the remaining part may contain at least one of Zn, Cd, Sn, P, and Ni.

As an example, it contains Ag: 55.0 to 57.0 mass%, Cu: 21.0 to 23.0 mass%, Zn: 15.0 to 19.0 mass%, Sn: 4.5 to 5.5 mass%, and Ag: 24.0 to 26.0 mass%, Cu: 40.0~42.0mass% and Zn: 33.0~35.0mass% of the solder has a silver-white color tone, and the base material 11 of the hard-welded structure 10 of the fourth embodiment which is composed of a silver-white color-resistant copper alloy Close. Therefore, it is preferable from the viewpoint of the deterioration of the strength of the brazed portion 12 from the viewpoint of aesthetics.

Here, in the brazing joining structure 10 of the present embodiment, the brazing method is performed by melting the solder at a temperature within a melting point (liquidus) + 50 ° C to perform brazing. In order to suppress grain coarsening of the α phase matrix, the time required for brazing is preferably less than 1 minute, more preferably less than 30 seconds. In the metal structure after brazing, in order to suppress precipitation of a hard and brittle β phase in the α phase matrix at normal temperature and to set the ratio of the β + γ phase to 1.4% or less, it will be from after brazing to 100. It is preferred that the temperature region of °C be cooled at a cooling rate of 50 ° C /sec or less. When the cooling rate exceeds 50 ° C / sec, a large amount of β phase remains, and corrosion resistance and ductility are lowered.

Further, in the hard-welded structure 10 of the present embodiment, the bonding can be performed by using the phosphor bronze solder not including Ag as defined in JIS Z 3264. However, since the brazing temperature is 800 ° C or more, it is contained. Cu: 79 to 96 mass%, P: 4 to 8 mass%, and a small amount of Ag (specifically, 0.5 mass% or more, 2 mass% or more is preferable, 4 mass% or more is more preferable, and the upper limit is specifically set to 7 mass% or less) The melting point is drastically reduced, thereby ensuring a maximum balance of performance and cost. The disadvantage that the melting point of the solder is high is that the crystal grains of the α phase matrix are coarsened in the metal structure, which is not preferable. Regarding the grain coarsening of the metal material, the stress area is reduced and the stress capacity is processed. It is easy to concentrate on the crystal grain boundary, and not only the crack sensitivity is increased, but also the surface roughness is generated during the bending process, and the appearance may also cause problems. Further, in the present embodiment, since brazing is performed in the air, if the brazing is performed at a high temperature, a large amount of oxide is rapidly formed as the temperature rises, and the bonding may become insufficient. Further, the brass solder specified in JIS Z 3262 is suitable for a copper alloy having a hue of gold, but the melting point is higher than that of the phosphor bronze solder, so the strength of the joint portion may be lowered. Therefore, a copper alloy containing Ni, Fe or the like which has low thermal conductivity and can suppress grain growth is preferably used as the substrate 11. Further, although the proportion of the brazed portion 12 is small, it is preferable to use a solder containing Ag from the viewpoint of discoloration resistance.

(Strength of the brazed portion 12)

Further, in the hard-welded structure 10 of the present embodiment, the tensile strength of the portion including the brazed portion 12 is 200 MPa or more, or the endurance is 60 MPa or more.

The strength of the brazed portion 12 of the hard-welded structure 10 is lower than that of the non-heat-affected portion 14 due to the heat influence at the time of brazing. Further, at the time of brazing, when the molten diffusion of the solder and the base material is insufficient, or when an oxide is formed at the joint interface, the strength of the brazed portion is further lowered.

In the present embodiment, the brazed portion 12 has a tensile strength of 200 MPa or more or an endurance of 60 MPa. The mechanical properties such as the tensile strength of 200 MPa or the endurance of 60 MPa are equivalent to the tempered O-materials of pure copper which is subjected to hot working, cold working, and annealing, and are used as armrests, door handles, guardrails, and the like for use in medical institutions, public facilities, and the like. The hard-welded structure 10 of the constituent members is practically free from problems. Further, if the tensile strength is 250 MPa or more or When the endurance is 70 MPa or more, it corresponds to a tempered O material of a copper alloy containing 15 mass% of Zn in Cu. In view of the high-temperature brazing, the strength due to the coarsening of the crystal grains of the heat-affected portion 13 and the bonding caused by the molten diffusion of the solder and the base material can be said to have a tensile strength of 250 MPa or more or a withstand strength of 70 MPa or more. Full strength. For example, a copper-phosphorus solder: BCuP-2 (93 mass% Cu-7 mass% P) is used as the solder, and brazing conditions are set to a temperature of 800 ° C for 30 seconds or less to perform brazing, whereby the tensile strength can be set to 250 MPa. The above, or the endurance is set to 70 MPa or more. Here, when the time required for the brazing is 1 minute or more, the joint of the brazed portion is oxidized, and the joint strength may be lowered. Therefore, it is preferred to set the time required for brazing to less than 1 minute.

(antibacterial)

The above-described composition range and two relational expressions are very important for the antibacterial property (bactericidal property) of the hard-welded structure 10 of the present embodiment. When the material is oxidized, the antibacterial property (bactericidal property) is impaired. However, in the range of the above-mentioned components and the relationship between the two relational formulas, oxidation due to temperature rise during brazing can be suppressed, and in the brazed portion. Good antibacterial properties (bactericidal) can also be obtained in 12.

Specifically, in the hard-welded structure 10 of the present embodiment, in the antibacterial property test, after the passage of 10 minutes in the heat-affected zone 13 from the brazed portion 12 to the region of 10 mm in the substrate 11 the viable rate of C _H, C ₀ with respect to the ratio of viable cells in the non-heat affected portion 14 after 10 minutes, to C _H 1.25 × C ₀ . In other words, the difference between the non-heat-affected zone 14 and the heat-affected zone 13 is small, and a hard-welded structure 10 having more uniform antibacterial property (bactericidal property) can be obtained.

Here, the live bacteria rate is evaluated by referring to the test method of JIS Z 2801 (antibacterial processed product - antibacterial test method / antibacterial effect).

Further, the hard-welded structure 10 of the present embodiment is excellent in antibacterial property (bactericidal property) and discoloration resistance, and the strength of the brazed portion 12 is sufficiently ensured, so that it is not necessary to perform plating, colorless coating, coating, and the like. Surface treatment. Therefore, it is suitable as a bed guardrail, a stretcher guardrail, a headboard, a footboard, a door handle, an armrest, a stay, etc. used in a medical institution, a public facility, and a research institute (food, cosmetics, pharmaceuticals, etc.) with strict hygiene management. In particular, it is required to use an antibacterial component.

In addition, in general, the bending radius at the time of bending a pipe is set to R (bending radius) = the outer diameter of the pipe is 1.5 or more, but in the bed guardrail used in medical institutions and welfare facilities, from the viewpoint of preventing a pinch accident, Regarding the bent portion of the tube, there is a tendency to take a small R (bending radius), and it is necessary to eliminate the bending process (the limit bending of the pipe) of R = outer diameter × 1.5. In addition, from the viewpoint of decorativeness and design, a door having a small bending radius R is often used for door handles used in medical institutions, public facilities, and the like. Depending on the shape of the object, sometimes the bending process is performed after the joining, and sometimes the part affected by the heat is processed by the joining.

Depending on the structure of the final product, it is sometimes also necessary to join one welded pipe (including the welded pipe welded by bending) to other welded pipes, plates, elbows (castings, forged parts) in a 90-degree or 0-degree direction. A cross-shaped, T-shaped, L-shaped hard welded joint structure 10. In addition, the welded pipe includes a welded pipe which is subjected to a 90° bending process.

Although the embodiments of the present invention have been described above, the present invention does not The present invention is not limited thereto, and can be appropriately modified without departing from the scope of the technical idea of the invention.

For example, in the first embodiment, the pipe members are welded at 90° to each other. However, the present invention is not limited thereto, and the substrate is composed of the discoloration-resistant copper alloy having the above composition. It is sufficient to form a brazed part on it.

[Examples]

Hereinafter, the results of the confirmation experiment performed to confirm the effects of the present invention are shown. The following examples are intended to illustrate the effects of the present invention, and the configurations, procedures, and conditions described in the examples are not intended to limit the technical scope of the present invention.

Here, in the present embodiment, the discoloration-resistant copper alloy having the composition range described in Patent Application No. 1 of the present invention is referred to as the first invention alloy (indicated as "first" in the table), and will be set as The discoloration-resistant copper alloy having the composition range described in Patent Application No. 2 of the present invention is referred to as a second invention alloy (indicated as "second" in the table), and is set as the composition range described in Patent Application No. 3 of the present invention. The discoloration-resistant copper alloy is referred to as a third invention alloy (labeled as "3" in the table), and the discoloration-resistant copper alloy having the composition range described in Patent Application No. 4 of the present invention is referred to as a fourth invention alloy. (The table is labeled "4th"), and those who deviate from the composition range of the present invention are referred to as comparative alloys (labeled "Comparative" in the table). Further, C2680, C4621, C4430, C6870, C7511, C7511, and C7451 were used as conventional alloys.

Further, in Tables 1 to 12 to be described later, No. A-1 to 21, B-1 to 14, C-1 to 15, D1 to 5, and E1 to 8 are examples of the present invention, and No. A-101 to 108 , B-101~ 111, C-101~115, D-101~104, E-101~104 are comparative examples, and C2680, C4621, C4430, C6870, C7521, C7541, and C7451 are conventional examples.

Copper and copper alloy tubes are roughly classified into two types: welded tubes and seamless tubes. From the viewpoint of the difference in the respective manufacturing methods, the pipe diameter, wall thickness, strength, billet, surface properties, and the like are used in accordance with the use.

In the present embodiment, after the copper alloy strips of the compositions shown in Table 1, Table 2, Table 3, and Table 4 are gradually plastically processed in the width direction by a forming die to be formed into a substantially circular shape, a frequency-sensing heating coil that induces heat generation, a welded pipe manufactured by butting and joining (resistance welding) at both ends; and a TIG welding machine for butt-joining both ends thereof in an inert atmosphere of argon (TIG welding process) The welded tube is manufactured as a substrate. Further, a seamless pipe manufactured by annealing a pipe (extrusion process) in which a copper alloy billet is extruded by an extruder, and performing pickling (sectional reduction ratio Re=10%) is used as a substrate. . The manufacturing process of the substrate to be used is described in Tables 5, 6, 6, and 8.

Further, the values of the following relational expressions were calculated from the compositions shown in Tables 1, 2, 3, and 4 described above, and are shown in Tables 5, 6, 6, and 8.

f(1)=[Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As] -0.5 × [Mn] - 0.5 × [Fe] + 0.5 × [Zr] + 0.5 × [Co] + 1 × [Si] + 1 × [Mg] + 1 × [C]

f(2)=0.3×[Ni]+1×[Sn]+1.8×[Al]

A welded pipe and a seamless pipe having a pipe outer diameter: φ25.4 mm × wall thickness: 1.2 mm × length: 1000 mm were cut into 100 mm, and brazed in a T shape to manufacture various hard welded structures. In the evaluation of bending workability, the pipelines are butted together to perform (straight line) brazing, thereby producing various hard solder joints. Construct. Hard brazing was carried out under the conditions shown in Tables 5, 6, 6, and 8. Further, the composition of the solder "BAg-7" was 56 mass% Ag-22 mass% Cu-17 mass% Zn-5 mass%. Further, the composition of the solder "BCuP-6" was 91 mass% Cu-7 mass% P-2 mass% Ag, and the composition of "BCuP-2" was 93 mass% Cu-7 mass% P.

With respect to these hard-welded structures, the tensile strength of the brazed portion and the substrate, the electrical conductivity of the substrate, the bending workability, the discoloration resistance, the antibacterial property (bactericidal property), and the corrosion resistance were measured. Then, the metal structure of the heat-affected zone was observed to determine the area ratio of the β phase and the γ phase, and the average crystal grain size of the α phase matrix in the heat affected zone and the non-heat affected zone was measured. In addition, the area ratio of the β phase and the γ phase in the heat affected zone and the average crystal grain size of the α phase matrix are performed on three sites on the substrate 11 at a distance of 3 mm, 5 mm, and 10 mm from the brazed portion. For the measurement, the average value is used as the data in Table 5, Table 6, Table 7, and Table 8. The average crystal grain size of the α phase matrix in the non-heat-affected zone is measured at one position on the cross section of the pipe 18 having a distance of 20 mm from the brazed portion 12 and two portions on the cross section of the substrate 11 . The average values are as shown in Tables 5, 6, 6, and 8. Further, in the measurement of the area ratio of the β phase and the γ phase and the average crystal grain size of the α phase substrate, the measurement magnification was 500 times, and the measurement area was 270 μm × 220 μm.

(area ratio of β phase and γ phase)

With respect to the area ratio of the β phase and the γ phase, a tissue photograph was taken at a magnification of 500 times using an inverted metal microscope (ECLIPSE MA200) manufactured by Nikon Corporation Instruments Company, and the α phase matrix and the β + γ phase were subjected to image analysis software WinRoof. Bipolarization, determination of β phase and γ phase Area ratio. The evaluation results are shown in Table 5, Table 6, Table 7, and Table 8.

(average crystal grain size)

In the measurement of the crystal grain size, the cross section of the heat-affected zone and the non-heat-affected zone was observed by an inverted metal microscope (ECLIPSE MA200) manufactured by Nikon Corporation Instruments Company, and was determined by the JIS H 0501 copper product crystal grain size determination method. The comparison method of the record is obtained. The evaluation results are shown in Table 5, Table 6, Table 7, and Table 8.

(Conductivity)

The electrical conductivity of the substrate (the discoloration-resistant copper alloy) was measured using a conductivity measuring device (SIGMATEST D2.069) manufactured by FOERSTER JAPAN Limited, and the three ends of the surface and the central portion of the substrate were measured and averaged. As information. Further, since the curvature surface of the pipeline shape may have a very large influence on the measured value, the measurement is performed using a dedicated pressing jig, and the conductivity is obtained using the curvature correction coefficient. The evaluation results are shown in Table 5, Table 6, Table 7, and Table 8.

(Tensile Strength)

For the tensile strength, the stress value at the time of breaking the hard welded structure was determined using a universal material testing machine (AUTOGRAPH AG-X100kN) manufactured by Shimadzu Corporation, and the value of the cross-sectional area of the welded pipe was used as the brazing. The tensile strength T _{B of the} brazed portion of the structure. Further, the tensile strength T ₀ of the substrate (non-heat-affected portion) was measured using a welded tube which was not subjected to brazing. Further, the rate of decrease in tensile strength of the brazed portion was calculated = (T _{0 -} T _B ) / T ₀ × 100. Tensile strength T _{B of the} brazed portion, tensile strength T ₀ of the base material (non-heat affected portion), rate of decrease in tensile strength of the brazed portion, and endurance and elongation of the substrate (non-heat affected portion) Table 9, Table 10, Table 11, and Table 12 are shown.

(bending workability)

For the bending workability, a hard-welded structure in which the pipelines were butt-joined to each other was subjected to a 90° bending process using a CNC bending machine manufactured by Chiyoda Industrial Co., Ltd., and the presence or absence of wrinkles, surface roughness, and cracking were visually evaluated. Further, the bending R at the time of bending processing was 38 which was an outer diameter × 1.5. In the evaluation of the bending workability, it was set as "A": no wrinkles, rough surface, crack, "B": wrinkles or surface roughness, and "C": cracking for evaluation. The evaluation results are shown in Table 9, Table 10, Table 11, and Table 12.

(resistance to discoloration)

With respect to the discoloration resistance, the material of the hard-welded structure exposed to the atmosphere (air-conditioned room) for 3 months is measured by a spectrophotometer according to L ^* a ^* b ^* described in JIS Z 8729. Surface (heat-affected zone), the color difference before and after exposure was calculated and evaluated. Further, chromatic aberrations are described in JIS Z 8730 as ΔE = {(ΔL*) ² + (Δa*) ² + (Δb*) ² } ¹ / ² : ΔL ^* , Δa ^* , Δb ^* The difference between the two objects (before and after exposure). Regarding the evaluation criteria, the value of the color difference was set to "A": 0 to 4.9, "B": 5 to 9.9, and "C": 10 or more for evaluation. In addition, the human hand was touched every day during the exposure period, and the most visible color change was observed. The evaluation results are shown in Table 9, Table 10, Table 11, and Table 12.

(antibacterial)

The antibacterial property (bactericidal property) was carried out by a test method based on JIS Z 2801 (antibacterial processed product - antibacterial test method / antibacterial effect), and the test area (film area) and contact time were changed to evaluate. The bacteria used for the test were set to Escherichia coli (strain storage number: NBRC3972), and pre-cultured at 35±1° C. using a 1/500 NB dilution (the method of pre-culture was the method of 5.6.a described in JIS Z 2801). In Escherichia coli, a liquid having a bacterial count adjusted to 1.0 × 10 ⁶ /mL was used as a test bacterial solution. The test method is as follows: a heat-affected portion and a non-heat-affected portion formed by brazing are respectively cut into a 10 mm square sample and placed in a sterilized culture vessel, and the aforementioned test bacterial solution (Escherichia coli: 1.0×10 ⁶ /mL) is dropped. 0.045 mL, covering a film of φ 5 mm, covered with a lid of the culture vessel. The culture vessel was cultured in an atmosphere of 35 ° C ± 1 ° C and a relative humidity of 95% for 10 minutes (inoculation time: 10 minutes). The cultured test bacterial solution was washed out by 10 mL of SCDLP (Soys-Casein Digest Broth with Lecithin & Polysorbate) medium to obtain a washed bacterial solution. The bacterial solution was washed with a phosphate buffered physiological saline solution every 10 times, and a standard agar medium was added to the bacterial solution, and cultured at 35 ± 1 ° C for 48 hours, and the number of colonies was measured when the number of colonies (number of colonies) was 30 or more. And find the number of viable bacteria (cfu / mL).

In the evaluation of the antibacterial property (bactericidal property), the viable cell rate C _H in the heat-affected zone of the hard-welded structure is C _H <1.10 × C ₀ with respect to the viable cell rate C ₀ in the non-heat-affected zone. Set to A rating, 1.10 × C ₀ C _H When 1.25 × C ₀ , B is evaluated, and when C _H > 1.25 × C ₀ , C is evaluated. The evaluation results are shown in Table 9, Table 10, Table 11, and Table 12.

(corrosion resistance)

For the corrosion resistance, the natural rupture test of the bar of JIS H 3250 copper and copper alloy was carried out to produce ammonia water having a volume concentration of 12%, and the liquid surface distance from the ammonia water placed in the dryer was 100 mm or more. Place the brazed structure. After maintaining this state for 4 hours (a multiple of a predetermined time), the sample was taken out from the dryer to confirm the presence or absence of cracking. The stress corrosion cracking test was evaluated visually, and it was set as "○": no crack, and "x": cracking was performed for evaluation. The evaluation results are shown in Table 9, Table 10, Table 11, and Table 12.

The results of the test are known as follows.

The alloy of the first invention (the discoloration-resistant copper alloy having the composition range described in Patent Application No. 1) is such that the total area ratio of the β phase and the γ phase in the matrix of the α phase is 0. ++γ 1.4 (%) metal structure and a hard-welded structure having a conductivity of 7 to 25% IACS, which is excellent in strength and bending workability of the brazed portion, and has corrosion resistance, discoloration resistance, and antibacterial property (bactericidal property) Excellent. In particular, if the area ratio of the β phase and the γ phase in the matrix of the α phase is 0% or 0.03 ++γ 0.30 (%) of metal structure and conductivity of 7 to 20% IACS, the rate of strength reduction during brazing is also low, and the strength of the brazed portion can be maintained high, and at the same time, discoloration resistance and antibacterial property ( Excellent in bactericidal properties.

The alloy of the second invention (the discoloration-resistant copper alloy having the composition range described in Patent Application No. 2) is such that the total area ratio of the β phase and the γ phase in the matrix of the α phase is 0. ++γ 1.4 (%) of the metal structure and the hard-welded structure having a conductivity of 7 to 25% IACS contained P, As, and Sb, and it was confirmed that the corrosion resistance was improved.

The alloy of the third invention (the discoloration-resistant copper alloy having the composition range described in Patent Application No. 3) is such that the total area ratio of the β phase and the γ phase in the matrix of the α phase is 0. ++γ 1.4 (%) of a metal-bonded structure having a conductivity of 7 to 25% IACS in a hard-welded structure, in which Fe, Co, and Zr are contained, by suppressing grain growth caused by heating during brazing, The strength of the brazed portion is improved. Further, in the case of containing Mn, Si, and Mg, corrosion resistance is improved.

The alloy of the fourth invention (the discoloration-resistant copper alloy having the composition range described in Patent Application No. 4) is such that the total area ratio of the β phase and the γ phase in the matrix of the α phase is 0. ++γ 1.4 (%) of a metal structure and a hard-welded structure having a conductivity of 7 to 22% IACS, which has a silver-white color tone, is excellent in strength and bending workability of a brazed portion, and has corrosion resistance and discoloration resistance. Excellent antibacterial property (bactericidal). In particular, if the area ratio of the β phase and the γ phase in the matrix of the α phase is 0% or 0.03 ++γ 0.30 (%) of metal structure and conductivity of 7 to 12% IACS or less, it has a stronger white-white hue, and the strength of the brazed portion is also lower, and at the same time, discoloration resistance and antibacterial property (sterilization) Excellent).

Although the content of various elements is within the alloy composition range of the first to fourth invention alloys, at 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] In the relationship of 32, [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As ] - 0.5 × [Mn] - 0.5 × [Fe] + 0.5 × [Zr] + 0.5 × [Co] + 1 × [Si] + 1 × [Mg] + 1 × [C] The value is less than the lower limit ( 15), strength, bending workability, discoloration resistance, and antibacterial property (bactericidal property) are deteriorated. Further, when the upper limit is exceeded, the antibacterial property (bactericidal property) is saturated, and the corrosion resistance is deteriorated.

Further, at 0.7 0.3 × [Ni] + [Sn] + 1.8 × [Al] In the relational expression of 3.8, when the value of 0.3 × [Ni] + [Sn] + 1.8 × [Al] is less than the lower limit, the strength and discoloration resistance of the brazed portion are insufficient. In addition, when the upper limit is exceeded, the bending workability and the antibacterial property (bactericidal property) are deteriorated.

In the hard-welded structure having the base material composed of the alloy composition of the first to fourth invention alloys, when Sn and Al are added together, if 15 is satisfied [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] 32 and 0.7 0.3 × [Ni] + [Sn] + 1.8 × [Al] The relationship of 3.8, and is 0.75 [Sn]×[Al] 1.2 (where both elements need to contain more than 0.3 mass%) and 1.5 Ni 2.5, it has a gold color tone, and the strength, discoloration resistance, and antibacterial property (bactericidal property) of the brazed portion are improved.

In a hard-welded structure having a base material composed of an alloy composition of the first to fourth invention alloys, a hard-welded structure joined by a solder containing 10 to 96 mass% of Cu is used, which includes brazing. The tensile strength of the part is 200 MPa or more, and a hard-welded structure which is a structural member used for a handrail, a door handle, a guardrail, or the like used in a medical institution, a public facility, or the like is obtained, and the strength of the problem is not practically applied. . Further, the hard-welded structure joined by the solder containing 0.5 mass% or more of Ag and 10 mass% or more of Cu is suppressed in grain growth during brazing, and the strength of the brazed portion and its periphery is also lowered. The precipitation of the β phase and the γ phase is also suppressed, and the strength, the bending workability, the corrosion resistance, the discoloration resistance, and the antibacterial property (bactericidal property) are excellent. Moreover, compared with BCuP-6 (91 mass% Cu-7mass% P-2mass% Ag) having a small Ag content, BAg-7 (56 mass% Ag-22 mass% Cu-17 mass% Zn-) having a large Ag content is used. 5mass%Sn) As a solder, the average crystal grain size of the heat-affected zone is reduced, and a high strength is obtained.

As described above, the hard-welded structure according to the embodiment of the present invention is excellent in antibacterial property (bactericidal property) and discoloration resistance, and can secure the strength of the brazed portion.

[Industrial availability]

The hard-welded structure of the present invention has high strength and excellent discoloration resistance and antibacterial property (bactericidal property), and thus is most suitable as a bed guardrail used in medical institutions, public facilities, and sanitary management research facilities. , headboard, footboard, stretcher guardrail, door handle, handrail, lever door handle, door handle, struts, tables, chairs, shelves, components for care trolleys.

10‧‧‧Hard welded joint structure

11‧‧‧Substrate

12‧‧‧ Hard soldering department

13‧‧‧The Ministry of Thermal Impact

14‧‧‧ Non-thermal impact department

18‧‧‧ pipes

Claims (10)

A hard-welded structure in which a brazed portion is formed on a base material composed of a discolor-resistant copper alloy, and the discoloration-resistant copper alloy has a composition containing Zn: 17 to 37 mass%, and Sn: 0.01 to 2.5 mass % and Pb: 0.0005 to 0.30 mass%, and at least one of Ni: 0.01 to 12.5 mass% and Al: 0.3 to 1.6 mass%, and the remainder is Cu and unavoidable impurities, and the above-mentioned hard welded structure The body is characterized by the content of Zn [Zn] mass%, the content of Pb [Pb] mass%, the content of Ni [Ni] mass%, the content of Al [Al] mass%, and the content of Sn [Sn] mass%. Between 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al] 32 and 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] In the relational expression of 3.8, the metal structure including the heat-affected zone of the brazed portion is an α-phase matrix, and the total ratio of the ratio of the β phase to the ratio of the γ phase is set to 0% or more and 1.4. Further, the conductivity of the above-mentioned discoloration-resistant copper alloy is 7 to 25% IACS. The hard-welded structure according to the first aspect of the invention, wherein the discoloration-resistant copper alloy further contains As: 0.01 to 0.09 mass%, P: 0.005 to 0.09 mass%, and Sb: 0.01 to 0.09 mass%. Any one or more of Zn content [Zn] mass%, Pb content [Pb] mass%, Ni content [Ni] mass%, Al content [Al] mass%, and Sn content [Sn] mass% And the content of P [P] mass%, the content of Sb [Sb] mass%, and the content of As [As] mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni] +2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As] 32 relationship. The hard-welded structure according to claim 1, wherein the discoloration-resistant copper alloy further contains Mn: 0.01 to 2.0 mass%, Fe: 0.001 to 0.09 mass%, and Zr: 0.0005 to 0.03 mass%. Co: 0.001 to 0.09 mass%, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C: 0.0001 to 0.01 mass%, and Zn content [Zn] mass%, Pb content [Pb]mass%, Ni content [Ni]mass%, Al content [Al]mass%, Sn content [Sn]mass%, P content [P]mass%, Sb content [Sb]mass% As content [As] mass%, Mn content [Mn] mass%, Fe content [Fe] mass%, Zr content [Zr] mass%, Co content [Co] mass%, Si content [ Si]mass%, Mg content [Mg]mass%, and C content [C]mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] 32 relationship. The hard-welded structure according to claim 2, wherein the discoloration-resistant copper alloy further contains Mn: 0.01 to 2.0 mass%, Fe: 0.001 to 0.09 mass%, and Zr: 0.0005 to 0.03 mass%, Co: 0.001 to 0.09 mass%, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C: 0.0001 to 0.01 mass%, and Zn content [Zn] mass%, Pb content [Pb]mass%, Ni content [Ni]mass%, Al content [Al]mass%, Sn content [Sn] mass%, P content [P]mass%, Sb content [Sb]mass% As content [As] mass%, Mn content [Mn] mass%, Fe content [Fe] mass%, Zr content [Zr] mass%, Co content [Co] mass%, Si content [ Si]mass%, Mg content [Mg]mass%, and C content [C]mass% have 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]+2×[P]+2.5×[Sb]+0.5×[As]-0.5×[Mn ]-0.5×[Fe]+0.5×[Zr]+0.5×[Co]+1×[Si]+1×[Mg]+1×[C] 32 relationship. The hard-welded structure according to the first aspect of the invention, wherein the discoloration-resistant copper alloy has a composition of Zn: 17 to 37 mass%, Sn: 0.01 to 2.5 mass%, and Pb: 0.0005 to 0.30. Mass% and Ni: 1.5 to 12.5 mass%, and also contain Al: 0.3 to 1.6 mass%, Mn: 0.01 to 2.0 mass%, Fe: 0.001 to 0.09 mass%, Zr: 0.0005 to 0.03 mass%, Co: 0.001 0.09 mass%, Si: 0.001 to 0.09 mass%, Mg: 0.001 to 0.05 mass%, and C: 0.0001 to 0.01 mass%, and the remainder is Cu and inevitable impurities, and Zn content [Zn 】 mass%, Pb content [Pb] mass%, Ni content [Ni] mass%, Al content [Al] mass%, Sn content [Sn] mass%, Mn content [Mn] mass%, Fe Content [Fe]mass%, Zr content [Zr]mass%, Co content [Co]mass%, Si content [Si]mass%, Mg content [Mg]mass%, and C content [C] Between mass% has 15 [Zn]-0.5×[Pb]-1.2×[Ni]+2.4×[Sn]+1×[Al]-0.5×[Mn]-0.5×[Fe]+0.5×[Zr]+0.5×[Co 〕××[Si]+1×[Mg]+1×[C] 32 and, 0.7 0.3 × [Ni] + 1 × [Sn] + 1.8 × [Al] In the relational expression of 3.8, the conductivity of the above-mentioned discoloration-resistant copper alloy is set to 7 to 22% IACS. The hard-welded structure according to any one of the first to fifth aspects of the present invention, wherein the base material is a heat-affected portion from the brazed portion to a region of a distance of 10 mm, α phase The average crystal grain size of the matrix is set to 80 μm or less. The hard-welded structure according to any one of claims 1 to 5, wherein the brazed portion comprises Cu: 10 to 96 mass% and the remaining portion contains Ag: 0.01 to 70 mass%, Zn : Soldering is performed by using one or more kinds of solders of 0.01 to 80 mass%, Cd: 0.01 to 40 mass%, Sn: 0.01 to 20 mass%, P: 0.01 to 15 mass%, and Ni: 0.01 to 10 mass%. The hard-welded structure according to any one of claims 1 to 5, wherein the portion including the brazed portion has a tensile strength of 200 MPa or more, or a withstand strength of 60 MPa or more. The hard-welded structure according to any one of claims 1 to 5, wherein in the antibacterial test, heat is applied from the brazed portion to a region of 10 mm in the substrate. Effect portion of viable cells after 10 minutes of C _H, C ₀ with respect to the rate of viable cells after the portion other than the heat-affected part for 10 min after, set C _H 1.25 × C ₀ . The hard-welded structure according to any one of claims 1 to 5, wherein the hard-welded structure is used as a bed guardrail, a headboard, a footboard, a stretcher guardrail, a door handle, and a handrail The components of the lever door handle, the door handle, the struts, the table, the chair, the shelf, and the care trolley are used for antibacterial purposes.