CN108699631B

CN108699631B - Tin-containing copper alloy, method for producing same and use thereof

Info

Publication number: CN108699631B
Application number: CN201780014996.3A
Authority: CN
Inventors: 凯·韦伯
Original assignee: Wieland Walker Open Co ltd
Current assignee: Wieland Walker Open Co ltd
Priority date: 2016-03-03
Filing date: 2017-02-10
Publication date: 2020-08-04
Anticipated expiration: 2037-02-10
Also published as: MX2018010583A; JP2019511632A; EP3423604B1; WO2017148568A1; DE102016002604A1; JP6679742B2; CN108699631A; EP3423604A1; KR20180121889A; US20190062876A1

Abstract

The present invention relates to a high strength as-cast tin-containing copper alloy having excellent hot and cold workability, high resistance to abrasive wear, adhesive wear and fretting wear, and improved corrosion resistance and stress relaxation resistance, comprising (% by weight): 4 to 23.0% Sn, 0.05 to 2% Si, 0.01 to 1.0% Al, 0.005 to 0.6% B, 0.001 to 0.08% P, optionally up to a maximum of 2.0% Zn, optionally up to a maximum of 0.6% Fe, optionally up to a maximum of 0.5% Mg, optionally up to a maximum of 0.25% Pb, the remainder being copper and unavoidable impurities, characterized in that the Si/B element content ratio of the elements silicon and boron is between 0.3 and 10. The invention also relates to a casting variant and a further processing variant of a tin-containing copper alloy, a method for producing the same, and the use of the alloy.

Description

Tin-containing copper alloy, method for producing same and use thereof

The present invention relates to a tin-containing copper alloy having excellent hot formability and cold formability, high resistance to abrasive wear, adhesive wear and fretting wear, and improved corrosion resistance and stress relaxation resistance according to the preamble of claims 1 to 3, to a process for its manufacture according to the preamble of claims 10 to 11, and to its use according to the preamble of claims 17 to 19.

Copper-tin alloys are characterized by high strength and hardness due to the tin alloy composition. In addition, copper-tin alloys are considered to be corrosion and seawater resistant.

This group of materials has a high resistance to abrasive wear. Furthermore, copper-tin alloys ensure good sliding properties and high fatigue endurance limits, which lead to excellent suitability for sliding elements and sliding surfaces in general engine and vehicle construction and mechanical engineering. Increased amounts of lead are often added to copper-tin alloys for sliding bearing applications for improved runability and machinability.

Copper-tin alloys have wide applications in the electronics and communications industries. They have often sufficient electrical conductivity, and good to very good spring properties. Adjustment of the spring properties requires excellent cold formability of the material.

In the music industry, percussion instruments are preferably made of copper-tin alloys due to their unusual acoustic properties. The manufacture of these cymbals requires very good material thermoformability. In particular two types of copper-tin alloys with 8% and 20% by weight of tin have a wide range of uses.

In the first manufacturing step, casting, the copper-tin material has a particularly high tendency to absorb gases (with consequent formation of porosity) and to show segregation phenomena, due to its wide solidification interval. Tin-rich segregation can be eliminated to a limited extent only by the homogenizing annealing operation after the casting process. As the tin content increases, the tendency of the copper-tin alloy to form voids and segregate increases.

Elemental phosphorus is added to the copper-tin alloy to sufficiently reduce the melt. However, phosphorus additionally extends the solidification interval of the copper-tin alloy, which leads to an increased tendency for porosity and segregation in the material group.

For this reason, for the initial forming of copper-tin alloys and for the process of spray compaction, documents DE 4126079C 2 and DE 19756815C 2 facilitate thin strip casting. In this way, by precisely adjusting the solidification rate of the melt, a low segregation preform can be produced with a finely and homogenously distributed tin-rich phase for subsequent hot forming operations.

Document DE 581507 a gives an indication of how to thermoform in principle pure copper-tin alloys with 14 to 32% by weight of tin and alloys with 10 to 32% by weight of tin in the presence of tin and copper. It is proposed to heat the alloy to 820 ℃ to 970 ℃, followed by very slow cooling to 520 ℃. The duration of this cooling should be at least 5 hours. After cooling to room temperature at normal cooling rates, the material can be thermoformed at 720 ℃ to 920 ℃.

Document DE 704398A describes a process for manufacturing shaped parts from a copper-tin alloy containing 6 to 14% by weight of tin, more than 0.1% by weight of phosphorus, preferably 0.2 to 0.4% by weight of phosphorus, which may be replaced by silicon, boron or beryllium. Preferably, the copper-tin alloy comprises about 91.2% by weight copper, about 8.5% by weight tin, and about 0.3% phosphorus. Prior to the final treatment by cold forming or hot forming, the casting is accordingly homogenized at temperatures below 700 ℃ until the tin and phosphorus rich eutectics dissolve.

The importance of crystalline seeds for forming fine-grained microstructures with a low proportion of tin-rich segregation for the hot formability of tin-containing copper alloys is highlighted in documents US 2, 128, 955A and DE 2536166 a 1. The phosphorus compound constitutes a crystalline seed which effects tempering of the cast structure and minimizes the formation of low melting copper phosphorus or copper phosphorus tin phases. This is said to give a significant improvement in thermoformability.

Due to the elevated operating temperatures and pressures in modern engines, machines, facilities and aggregates, a wide variety of different mechanisms of damage to individual system components arise. Therefore, from a material and structural point of view, there is a greater necessity, in particular for the design of the sliding element and of the plug connector, to take into account the type of sliding wear, and also the damage mechanism by oscillatory frictional wear.

Oscillatory frictional wear, also known in the term fretting wear, is a type of frictional wear that occurs between the oscillating contact surfaces. In addition to the geometric and/or volumetric wear of the components, the reaction with the surrounding medium also leads to fretting corrosion. Damage to the material can significantly reduce the local strength, particularly the fatigue strength, of the worn area. Fatigue cracks may travel from the damaged component surface, and these lead to fatigue fracture/fatigue failure. Under fretting corrosion, the fatigue strength of the component can be greatly reduced below the fatigue index of the material.

In a sense, the oscillating frictional wear is clearly different in its mechanism from the type of moving sliding wear. More specifically, the effect of corrosion is particularly pronounced with respect to oscillating frictional wear.

Document DE 102012105089 a1 describes the consequences of damage caused by oscillating frictional wear of the plain bearing. The operation of pressing the plain bearing into the bearing seat generates high stresses on the plain bearing which are further increased by thermal expansion and by dynamic shaft loads in modern engines. The change in the geometry of the sliding bearing due to the excessive increase in stress enables a slight movement of the sliding bearing relative to the bearing seat. The periodic relative movement of low oscillation width of the contact surface between the bearing and the bearing seat results in oscillatory fretting/fretting wear of the lining of the sliding bearing. The result is the initiation of cracks and ultimately the frictional fatigue failure of the sliding bearing.

In many engines and machines, electrical plug connectors are often provided in environments where they are subject to mechanical vibration oscillations. If elements of a connecting device are present in different assemblies which are moved relative to one another as a result of mechanical stress, the result can be a corresponding relative movement of the connecting elements. These relative movements lead to oscillating frictional wear and to fretting corrosion of the contact area of the plug connector. Microcracks form in this contact area, which greatly reduces the fatigue resistance of the plug connector material. Plug connector failure through fatigue failure may be the result. Furthermore, there is an increase in contact resistance due to fretting corrosion.

In order to reduce these forms of damage, document DE 102007010266B 3 proposes that each wire connected to the plug connector be equipped with a strain relief device by means of a construction device, whereby the movement of the wire can no longer affect the plug connector.

Document DE 3932536C 1 contains a method by which the tribological corrosion properties of the plug connector can be improved from a material point of view. For example, a contact material comprising silver, palladium or a palladium/silver alloy with a content of tin, indium and/or antimony of 20 to 50% by weight has been applied to a support, for example made of bronze. The silver and/or palladium content ensures corrosion resistance. Oxides of tin, indium and/or antimony increase the wear resistance. Thus, the consequences of fretting corrosion can be counteracted.

Thus, one key factor for adequate resistance to oscillating fretting/fretting is the combination of material properties of wear resistance, ductility and corrosion resistance.

Document DE 3627282 a1 describes the crystallization mechanism of metal melts. If only small amounts of crystalline seeds are present or if only small amounts of seeds are formed in the melt, the result is coarse grains, high segregation and often a dendritic solidification microstructure. A copper alloy having 0.1 to 25% by weight of calcium and 0.1 to 15% by weight of boron is named, which can be added to a melt of a copper material for grain refinement. In this way, the addition of a crystallizer can produce homogenization and a solidification microstructure of fine grains in the copper alloy.

Alloying with non-metals such as boron, silicon and phosphorus achieves lowering the relatively high base melting temperature, which is important from a processing standpoint. In the coating and high-temperature materials of the Ni-Si-B and Ni-Cr-Si-B systems, in particular boron and silicon alloying elements are believed to be responsible for a significant reduction in the melting temperature of the nickel-based hard alloys, which can be used as a spontaneous flow nickel-based hard alloy.

The base melting temperature is lowered by adding boron to the alloy for copper-tin materials, which find use as build-up materials. For example, document US 3, 392, 017A discloses an alloy having up to 0.4% by weight of Si, 0.02 to 0.5% by weight of B, 0.1 to 1% by weight of P, 4 to 25% by weight of Sn, and the balance Cu. The addition of boron and a very high content of phosphorus of not less than 0.1% by weight is here said to improve the spontaneous flow of the surfacing alloy and the wettability of the substrate surface, and does not require the use of additional fluxes. An especially high phosphorus content of 0.2 to 0.6% by weight and a silicon content of the alloy of 0.05 to 0.15% by weight are specified here. This highlights the main requirement for the spontaneous flowability of the material. However, with this high phosphorus content, the possibility of hot formability of the alloy is greatly limited.

Document DE 10208635B 4 describes a process in a diffusion brazing site in which intermetallic phases are present. By diffusion brazing, the aim is to bond parts with different coefficients of thermal expansion to each other. For thermomechanical stresses at the point of the braze or in the brazing operation itself, large stresses are generated at the interface, which can lead to cracks, in particular in the environment of intermetallic phases. One remedy proposed is to mix the brazed assembly with particles that cause a balance of different coefficients of expansion of the joining partners. For example, particles of borosilicate or phosphosilicate may minimize thermomechanical stresses in solder bonds due to their favorable coefficient of thermal expansion. Furthermore, these particles hinder the propagation of already induced cracks.

The published specification DE 2440010B 2 highlights the effect of elemental boron on the electrical conductivity of in particular cast silicon alloys with 0.1 to 2% by weight boron and 4 to 14% by weight iron. In this silicon-based alloy, a highly molten Si — B phase is precipitated, which is called silicon boride.

Usually present in SiB as determined by the boron content₃、SiB₄、SiB₆And/or SiB_NThe silicon boride in the variant differs significantly from silicon in its properties. These silicon borides have metallic properties and are therefore electrically conductive. They have exceptionally high thermal and oxidative stability. SiB preferably used with sintered articles due to its very high hardness and its high resistance to abrasive wear₆Variants are for example in ceramic manufacture and ceramic processing.

The object of the present invention is to provide a copper-tin alloy having excellent hot formability over the entire tin content range.

For hot forming, a precursor material may be used which has been manufactured and does not absolutely require the implementation of spray compaction or thin strip casting by conventional casting methods.

The copper-tin alloy should be free of porosity and shrinkage porosity and stress cracks and should be characterized by a microstructure having a homogeneous distribution of tin-rich phases present according to the tin content of the alloy. The as-cast condition of the copper-tin alloy does not necessarily need to be first homogenized by a suitable annealing treatment in order to be able to establish sufficient hot formability. Even cast materials should be characterized by high strength, high hardness and high corrosion resistance. By further processing including an annealing operation or a hot and/or cold forming operation with at least one annealing operation, a fine-grained microstructure should be established with high strength, high hardness, high stress relaxation and corrosion resistance, high electrical conductivity, and with highly complex wear resistance.

The invention has been described with respect to a copper-tin alloy with the features according to any one of claims 1 to 3, with respect to a manufacturing process with the features according to claims 10 to 11, and with respect to a use with the features of claims 17 to 19. Further dependent claims relate to advantageous forms and developments of the invention.

The present invention comprises a high strength tin-containing copper alloy having excellent hot and cold formability, high resistance to abrasive wear, adhesive wear and fretting wear, and improved corrosion resistance and stress relaxation resistance, comprising (% by weight):

4.0% to 23.0% Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.005% to 0.6% B,

0.001% to 0.08% P,

with or without the presence of up to a maximum of 2.0% Zn,

with or without up to a maximum of 0.6% Fe,

with or without up to a maximum of 0.5% Mg,

with or without up to a maximum of 0.25% Pb,

the balance being copper and unavoidable impurities,

wherein the Si/B element content ratio of the elements Si and B is between 0.3 and 10.

Further, the present invention includes a high strength tin-containing copper alloy having excellent hot formability and cold formability, high resistance to abrasive wear, adhesive wear, and fretting wear, and improved corrosion resistance and stress relaxation resistance, comprising (% by weight):

4 to 23.0 percent of Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.005% to 0.6% B,

0.001% to 0.08% P,

with or without the presence of up to a maximum of 2.0% Zn,

with or without up to a maximum of 0.6% Fe,

with or without up to a maximum of 0.5% Mg,

with or without up to a maximum of 0.25% Pb,

the balance being copper and unavoidable impurities,

it is characterized in that the preparation method is characterized in that,

-the Si/B element content ratio of the elements Si and B is between 0.3 and 10;

-after casting, the following microstructure components are present in the alloy:

a) from 1% to at most 98% by volume of a tin-rich phase,

b) from 1% to at most 20% by volume of an aluminium-and boron-containing phase, a silicon-and boron-containing phase and/or an addition compound and/or a mixture compound comprising both phases;

c) the balance being a copper solid solution including a low tin α phase,

wherein the aluminium-and boron-containing phase, the silicon-and boron-containing phase and/or the addition compound and/or the mixture compound comprising both phases are sheathed by a tin and/or tin-rich phase;

in the casting, the aluminium-and boron-containing phases, the silicon-and boron-containing phases and/or the addition compounds and/or the mixture compounds comprising both phases in the form of aluminium boride and silicon boride and/or in the form of addition compounds and/or mixture compounds of aluminium boride and silicon boride form seeds for a homogeneous crystallization during solidification/cooling of the melt, so that the tin-rich phase is homogeneously distributed in the microstructure in the form of islands and/or a network;

the aluminium-and boron-containing phases, the silicon-and boron-containing phases and/or the addition compounds and/or mixed compounds comprising these two phases, in the form of borosilicates and/or borophosphosilicates and/or aluminoborosilicate and/or aluminoborophosphosilicates, act as wear protection and/or corrosion protection coatings on the semifinished products and components of the alloys together with phosphosilicates and aluminium oxide.

The microstructure is free of tin-rich segregation due to the homogenized distribution of the tin-rich phase in the form of islands and/or in the form of a network. Such tin-rich segregation is understood to mean an accumulation of phases in the cast microstructure, in the form of so-called inverse block segregation and/or grain boundary segregation, which, under thermal and/or mechanical stresses on the casting, causes damage to the microstructure in the form of cracks that can lead to fractures. The microstructure after casting is still free of porosity, shrinkage porosity and stress cracks.

In this variant, the alloy is in the as-cast condition.

4.0% to 23.0% Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.005% to 0.6% B,

0.001% to 0.08% P,

with or without the presence of up to a maximum of 2.0% Zn,

with or without up to a maximum of 0.6% Fe,

with or without up to a maximum of 0.5% Mg,

with or without up to a maximum of 0.25% Pb,

the balance being copper and unavoidable impurities,

it is characterized in that the preparation method is characterized in that,

-the Si/B element content ratio of the elements Si and B is between 0.3 and 10;

-after further processing the alloy by at least one annealing operation or by at least one hot forming operation and/or cold forming operation in addition to the at least one annealing operation, the following microstructure components are present in the alloy:

a) up to 75% by volume of a tin-rich phase,

b) at most 1 to 25% by volume of an aluminium-and boron-containing phase, a silicon-and boron-containing phase and/or an addition compound and/or a mixture compound comprising both phases;

c) the balance comprising a low tin α phase copper solid solution wherein the aluminum and boron containing phases, the silicon and boron containing phases and/or the addition compounds and/or mixture compounds comprising both phases are encapsulated by tin and/or a tin rich phase;

the aluminium-and boron-containing phases, the silicon-and boron-containing phases and/or the addition compounds and/or the mixture compounds comprising both phases, in the form of aluminium and silicon borides and/or in the form of addition compounds and/or mixture compounds of aluminium and silicon borides, constitute seeds for static and dynamic recrystallization of the microstructure during the further processing of the alloy, which enable the establishment of a homogenized and fine-grained microstructure;

Preferably, the tin-rich phase is at least 1% by volume.

Furthermore, the tin-rich phase is homogenously distributed in the microstructure in the form of islands and/or networks and/or extended lines. In this variant, the alloy is in a further processed state.

With respect to alloy variants, the present invention continues to consider providing a tin-containing copper alloy having aluminum-and boron-containing phases, silicon-and boron-containing phases and/or addition compounds and/or mixture compounds comprising both phases in the as-cast state and in the as-further-processed state, which can be manufactured by sand casting, shell casting, precision casting, full-mold casting, pressure die casting and permanent mold casting processes or by means of continuous or semi-continuous strand casting processes. The use of an initial forming technique, which is expensive and inconvenient from a processing point of view, is possible, but not absolutely necessary for the manufacture of the tin-containing copper alloy of the invention. For example, the use of spray compaction may be eliminated. The cast form of the tin-containing copper alloy of the present invention can be directly hot formed over the entire tin content range without performing a homogenizing annealing operation, such as by hot rolling, extrusion or forging. The processing-related limitations which have hitherto been present in the production of semi-finished products and components from copper-tin alloys and which lead to a separation of the group of materials into copper-tin mixed alloys and copper-tin cast alloys are therefore largely eliminated.

As the tin content of the alloy increases, depending on the casting process, the microstructure of the tin-containing copper alloy in the as-cast condition includes an increased proportion of phases (tin-rich) in the additional α phases (tin-deficient).

As the tin content of the alloys of the present invention increases, not only does the proportion of phases in the microstructure increase, but there is also a change in the arrangement of the phases in the microstructure. Thus, it has been found that in the tin content range from 4.0 to 9.0% by weight, the phases are homogenously distributed in the microstructure, with at most 40% by volume being predominantly in the form of islands. If the tin content of the alloy is between 9.0% and 13.0% by weight, the island form of the phase present in the microstructure is converted into a network form by up to 60% by volume. The network is likewise very homogenously distributed in the microstructure of the alloy. In the tin content range from 13.0 to 17.0% by weight, the phase is present almost completely in the microstructure in the form of a homogenized network up to 80% by volume. For a tin content of the alloy of 17.0 to 23.0% by weight, the proportion of the microstructure of the phases arranged in the microstructure in the form of a dense network is at most 98% by volume.

By the combined content of boron, silicon, aluminum and phosphorus, various operations are initiated in the melt of the alloy of the invention, which critically alter its solidification characteristics compared to copper-tin and copper-tin-phosphorus alloys.

In particular, the elements boron, silicon and phosphorus have a reducing action in the melt according to the invention. Thus, the formation of tin oxide in the tin-containing copper alloy is counteracted. The addition of boron and silicon allows the phosphorus content to be reduced without reducing the reduction strength of the melt. With this measure, the adverse effect of sufficient reduction of the melt can be suppressed by adding phosphorus. The high phosphorus content will therefore additionally extend the solidification interval of the tin-containing copper alloy, which is already very large in any case, which will lead to an increased tendency of this material type to produce porosity and segregation. In addition, the result may be increased formation of copper phosphorus phases. Such phases are believed to be one cause of hot shortness of tin-containing copper alloys. By limiting the phosphorus content in the alloy of the present invention to the range of 0.001% to 0.08% by weight, the adverse effect of increasing phosphorus is reduced.

The elements boron, silicon and aluminum are particularly important in the tin-containing copper alloy of the present invention. Even in the melt, phases of Al-B and Si-B systems and/or addition compounds and/or mixed compounds of both precipitate out. These Si-B phases, designated as silicon borides, may be present in SiB₃、SiB₄、SiB₆And SiB_nIn a variant. The symbol "n" in the latter variant is based on the fact that boron has a high solubility in the silicon lattice. These Al-B phases, designated aluminum borides, may be present in at least AlB₂And/or AlB₁₂In the microstructure in the variation.

The addition compounds and/or mixture compounds of the aluminium-and boron-containing phases, the silicon-and boron-containing phases and/or both in the form of addition compounds and/or mixture compounds of aluminium boride and silicon boride and/or aluminium boride and silicon boride are referred to hereinafter as hard particles. In the melt of the alloys of the present invention, they act as crystallization seeds during solidification and cooling. It is therefore no longer necessary to supply the melt with so-called external seeds, whose homogeneous distribution in the melt can only be ensured to an insufficient extent.

Lowering the base melting temperature, in particular by the presence of elemental boron and hard particles acting as crystallization seeds, results in a significant reduction in the size of the solidification intervals of the alloy of the invention. Thus, the as-cast condition of the invention has a very homogeneous microstructure, depending on the tin content, with the phases being finely distributed in the form of homogenized and densely arranged islands and/or in the form of homogenized dense networks. The accumulation of tin-rich phases in the form of so-called inverse block segregation and/or grain boundary segregation is not observed in the cast microstructure of the present invention.

In the melt of the alloy of the present invention, the elements boron, silicon, aluminum and phosphorus cause the reduction of the metal oxide. These elements are oxidized and rise to the surface of the casting, wherein, together with the phosphosilicates and aluminum oxide, in the form of borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate, they form a protective layer which protects the casting against gas absorption. An exceptionally smooth surface of the alloy castings of the present invention has been found, which indicates the formation of such a protective layer. The as-cast microstructure of the present invention also has no porosity throughout the cross-section of the casting.

The basic concept of the invention is to apply the influence of borosilicate and phosphosilicate to the processes in the casting, hot forming and heat treatment of copper-tin materials with regard to the balance of different thermal expansion coefficients of the joining partners in diffusion brazing. The wide solidification interval of these alloys results in large mechanical stresses between the tin-deficient and tin-rich structural regions that crystallize in an offset manner, which can lead to cracks and so-called shrinkage porosity. In addition, these damage characteristics also occur during hot forming and high temperature annealing on copper-tin alloys due to the different hot forming characteristics and different coefficients of thermal expansion of the tin-deficient and tin-rich microstructure components.

The combined addition of boron, silicon, aluminum and phosphorus to the tin-containing copper alloy of the invention leads firstly to a homogenized microstructure with a fine distribution of microstructural components of different tin content by the influence of hard-particle seeds as crystallization seeds during solidification of the melt. In addition to the hard particles, more particularly, the borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate formed during solidification of the melt, together with the phosphosilicate, ensure the necessary balance of the coefficients of thermal expansion of the tin-deficient and tin-rich phases. In this way, the formation of pores and stress cracks between phases with different tin contents is prevented.

Alternatively, the alloy of the present invention may be subjected to further processing by annealing or by hot and/or cold forming operations and at least one annealing operation.

The effect of hard particles as crystallization seeds is also observed during the hot forming operation of the tin-containing copper alloy of the present invention, which together with borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate and together with phosphosilicate, causes a balance of the coefficients of thermal expansion of the tin-deficient and tin-rich phases. During thermoforming, the hard particles act as seeds for dynamic recrystallization. For this reason, hard particles are believed to be responsible for the fact that dynamic recrystallization occurs in an advantageous manner in the hot forming of the alloys of the present invention. This results in a further increase in the homogeneity of the microstructure and in the fine grain structure.

In the same way as after casting, an abnormally smooth surface of the part was also detected after the hot forming of the casting. This observation indicates the formation of borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate and phosphosilicate and alumina that occurs in the material during thermoforming. Also during the hot forming process, the silicate and the hard particles lead in particular to a balance of different coefficients of thermal expansion of the tin-deficient and tin-rich components. Thus, after the casting operation, the microstructure is also free of cracks and voids after the hot forming operation.

During the annealing treatment after the cold forming operation, the hard particles were found to act as seeds for static recrystallization. The primary function of the hard particles as static recrystallization seeds is to reduce the necessary recrystallization temperature that has become possible, which additionally facilitates the establishment of the fine-grained fibrous structure of the alloys of the present invention.

Thus, during the further processing of the alloy according to the invention, a higher degree of cold forming can be achieved, by means of which a particularly high tensile strength R can be established_mYield point R_P0.2And hardness values. Parameter R_P0.2The level of (d) is important in particular for sliding and guiding elements in internal combustion engines, valves, turbochargers, gears, exhaust gas aftertreatment systems, lever systems, brake and engagement systems, hydraulic aggregates or in machines and installations in general in mechanical engineering. In addition, very high R_P0.2The value is a prerequisite for the necessary spring properties of plug connectors in electrical and electronic engineering.

The tin content of the present invention varies within a limit between 4.0% and 23% by weight. Tin contents below 4% by weight lead to too low strength values and hardness values. Furthermore, the running characteristics under sliding stress will be insufficient. The resistance of the alloy to abrasive and adhesive wear is not satisfactory. For tin contents exceeding 23% by weight, there is a rapid deterioration in the ductility properties of the alloy of the invention, which will reduce the dynamic durability of components made of this material.

The alloy of the present invention has a hard phase component due to precipitation of hard particles, which contributes to improving the abrasive wear resistance of the material due to the high hardness of boron silicide. Furthermore, the proportion of hard particles leads to an improved resistance to adhesive wear, since these phases show a low tendency to wear together with the metal counterpart in the case of sliding stresses. Therefore, they are used as important wear substrates in the tin-containing copper alloys of the present invention. In addition, the hard particles increase the heat resistance and stress relaxation resistance of the inventive component. This constitutes an important prerequisite for the use of the alloys according to the invention, in particular for sliding elements and for components, wire elements, guide elements and connecting elements in electrical/electronic engineering.

The formation of borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate and phosphosilicate in the alloys of the present invention not only results in a significant reduction of porosity and cracks in the microstructure. These silicate phases, together with the alumina, also play a role in wear protection and/or corrosion protection coatings on the components.

Thus, the alloy of the present invention ensures a combination of properties of wear resistance and corrosion resistance. This combination of properties leads to a high resistance to the frictional wear mechanism and to a high material resistance to frictional corrosion, as required. In this way, the present invention has excellent applicability as a sliding member and a plug connector because it has high resistance to sliding wear and oscillatory frictional wear (referred to as fretting).

The effect of hard particles as crystallization and recrystallization seeds can only be achieved to a certain extent in the alloys according to the invention when the silicon content is at least 0.05% by weight, the aluminium content is at least 0.01% by weight and the boron content is at least 0.005% by weight, due to the effect of the wear substrate and the alumina and silicate phases for corrosion protection purposes. In contrast, if the silicon content exceeds 2.0% by weight and/or the aluminum content exceeds 1.0% by weight and/or the boron content exceeds 0.6% by weight, this results in deterioration of casting characteristics. Too high a content of hard particles makes the melt critically more viscous. Furthermore, the result will be a reduced ductility property of the alloys of the present invention.

A silicon content range within the limits of 0.05 to 1.5% by weight, in particular 0.5 to 1.5% by weight, is evaluated as advantageous.

Furthermore, the advantageous aluminum content of the alloy according to the invention is 0.1 to 0.8% by weight.

For elemental boron, a content of from 0.01 to 0.6% by weight is considered advantageous. A particularly advantageous boron content has been found to be from 0.1 to 0.6% by weight.

In order to ensure a sufficient content of hard particles and borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate and phosphosilicate, it has been found important to establish a specific elemental ratio of the elements silicon and boron. For this purpose, the Si/B element content (in% by weight) ratio of the elements silicon and boron of the alloy according to the invention is between 0.3 and 10. Si/B ratios of 1 to 10 and in addition 1 to 6 have been found to be particularly advantageous.

Precipitation of hard particles affects the viscosity of the alloy melt of the invention. This fact additionally highlights why the addition of phosphorus is indispensable. The effect of phosphorus is that the melt is sufficiently flowable, regardless of the content of hard particles, which is very important for the castability according to the invention. The phosphorus content of the alloy of the invention is from 0.001 to 0.08% by weight. An advantageous phosphorus content is in the range from 0.001 to 0.05% by weight.

The sum of the elemental contents of the elements silicon, boron and phosphorus is advantageously at least 0.5% by weight.

The machining of semifinished products and components made from conventional copper-tin and copper-tin-phosphorus compounded alloys, in particular with tin contents of up to about 9% by weight, is possible with great difficulties due to insufficient workability. The occurrence of particularly long chips (turning) therefore leads to long machine downtimes, since these chips first have to be removed manually from the machining area of the machine.

For the alloy according to the invention, in contrast, the hard particles, in the region of which the elemental tin and/or phases have crystallized or precipitated out depending on the tin content of the alloy, act as chip breakers (turning breakers). The short, brittle chips and/or tangled chips thus produced promote machinability and, for this reason, the semi-finished products and components made of the alloy according to the invention have better machinability.

In an advantageous embodiment of the invention, the tin-copper alloy may comprise (in% by weight):

4.0% to 9.0% Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.01% to 0.6% B,

0.001% to 0.08% P,

and the balance: copper and inevitable impurities.

In a further advantageous embodiment of the invention, the tin-containing copper alloy may comprise (in% by weight):

4.0% to 9.0% Sn,

0.05% to 0.3% Si,

0.01 to 0.15% of Al,

0.1% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

In a particularly advantageous embodiment of the invention, the tin-containing copper alloy may comprise (in% by weight):

4.0% to 9.0% Sn,

0.5 to 1.5% Si,

0.1 to 0.8% of Al,

0.01% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

In the cast microstructures of these embodiments of the invention, the tin-rich phase is homogenously arranged in the form of islands up to 40% by volume. The elemental tin and/or the phase here generally crystallizes in the region of the hard particles and/or coats them.

The castings of these examples have excellent thermoformability at operating temperatures ranging from 600 to 880 ℃.

The significant increase in strength and increase in hardness after the hot forming operation step can be used for components for which cold forming is not required for their manufacture. In this case, the cooling can be accelerated preferentially after the thermoforming operation, advantageously in water.

By comparison, if a cold forming operation is required, it has been found advantageous to subject the thermoformed semifinished product to an annealing operation at a temperature of from 200 to 880 ℃ for a duration of from 10 minutes to 6 hours. This results in very good cold formability, with a degree of cold forming of more than 60%.

The hard particles precipitated within the microstructure act as recrystallization seeds in a heat treatment of the cold-formed material state at a temperature of 200 to 880 ℃ for a duration of 10 minutes to 6 hours. By this further processing step, a microstructure having a particle size of at most 20 μm can be established. Supporting the recrystallization mechanism by hard particles allows lowering the recrystallization temperature, making it possible to produce a microstructure having a particle size reduced to 10 μm. The size of the crystallites in the microstructure of the material can even be set below 5 μm by a multistage manufacturing process comprising cold forming and annealing operations and/or by a purpose specific lowering of the recrystallization temperature.

The mechanical properties of some embodiments represent the entire range of alloy compositions and manufacturing parameters. The corresponding working examples and the research results outlined below show that tensile strengths R of more than 700 to 800MPa can be achieved_mValue of yield point R of more than 600 to 700MPa_P0.2The value is obtained. At the same time, the ductility properties of these examples are at a very high level. This fact is expressed by a high elongation value at break a 5.

9.0% to 13.0% Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.01% to 0.6% B,

0.001% to 0.08% P,

and the balance: copper and inevitable impurities.

9.0% to 13.0% Sn,

0.05% to 0.3% Si,

0.01 to 0.15% of Al,

0.1% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

9.0% to 13.0% Sn,

0.5 to 1.5% Si,

0.1 to 0.8% of Al,

0.01% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

The microstructure of these embodiments of the invention is characterized by a phase content of at most 60% by volume, the phase types being homogenously distributed in the microstructure in the form of islands and networks. Again, here the elemental tin and/or phase generally crystallizes in the region of the hard particles and/or encases them.

The microstructure of these examples had a very fine grain structure after the thermoforming operation due to the already occurring dynamic recrystallization promoted by the hard particles. The cold formability is limited due to the high strength values in the hot formed state. This can be significantly improved by an annealing treatment after the hot forming operation at a temperature of 200 to 880 c for a duration of 10 minutes to 6 hours.

The hard particles precipitated within the microstructure act as recrystallization seeds in a heat treatment of the cold-formed material state at a temperature of 200 to 880 ℃ for a duration of 10 minutes to 6 hours. By this further processing step, a finer particle size microstructure can be established. Supporting the recrystallization mechanism by hard particles allows lowering the recrystallization temperature, so that a microstructure having a further reduced particle size can be produced. The fine grain size structure of the microstructure may be further optimized by a multi-stage manufacturing process including cold forming and annealing operations.

13.0% to 17.0% Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.01% to 0.6% B,

0.001% to 0.08% P,

and the balance: copper and inevitable impurities.

13.0% to 17.0% Sn,

0.05% to 0.3% Si,

0.01 to 0.15% of Al,

0.1% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

In a particularly advantageous embodiment of the invention, the tin-copper alloy may comprise (in% by weight):

13.0% to 17.0% Sn,

0.5 to 1.5% Si,

0.1 to 0.8% of Al,

0.01% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

The phases in the cast microstructures of these embodiments of the invention are in the form of a network of up to 80% by volume of a homogenized arrangement. The microstructures here can have dendritic structural components, but these likewise show a network character, owing to the very small distances between the so-called dendrite arms. Furthermore, the elemental tin and/or phase often crystallizes in the region of the hard particles and/or encases them.

The castings of these examples also have excellent thermoformability at operating temperatures in the range of 600 to 880 c. Especially in this content range of the alloying element tin from 13.0 to 17.0% by weight, conventional copper-tin alloys are only hot formed with a very high difficulty without thermal cracking and thermal fracture.

The microstructure of these examples had a very fine grain structure after the thermoforming operation due to the already occurring dynamic recrystallization promoted by the hard particles. The cold formability is limited due to the high strength values in the hot formed state. The annealing treatment after the hot forming operation at a temperature of 200 to 880 c for a duration of 10 minutes to 6 hours may improve the cold formability of the semifinished product. After the operative step of thermoforming, the elemental tin and/or phases crystallize in the hard particle regions and/or the microstructural features of these hard particles are sheathed with elemental tin and/or phases more complete relative to the as-cast state.

The hard particles precipitated within the microstructure act as recrystallization seeds in a heat treatment of the cold-formed material state at a temperature of 200 to 880 ℃ for a duration of 10 minutes to 6 hours. By this further processing step, a microstructure having a particle size of at most 35 μm can be established. Supporting the recrystallization mechanism by hard particles allows the recrystallization temperature to be lowered, making it possible to produce a microstructure having a particle size of at most 25 μm. The network-like arrangement of the phases in the microstructure is preserved.

The size of the crystallites in the microstructure of the material can even be set below 10 μm by a multi-stage manufacturing process comprising cold forming and annealing operations and/or a purpose specific lowering of the recrystallization temperature.

17.0% to 23.0% Sn,

0.05% to 2.0% Si,

0.01 to 1.0% of Al,

0.01% to 0.6% B,

0.001% to 0.08% P,

and the balance: copper and inevitable impurities.

17.0% to 23.0% Sn,

0.05% to 0.3% Si,

0.01 to 0.15% of Al,

0.1% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

17.0% to 23.0% Sn,

0.5 to 1.5% Si,

0.1 to 0.8% of Al,

0.01% to 0.6% B,

0.001% to 0.05% P,

and the balance: copper and inevitable impurities.

A very dense network of phases in a homogenized arrangement of up to 98% by volume in the cast microstructure is a feature of embodiments of the invention. The microstructures may have an increased level of dendritic structural components, but these also have a network character due to the very small distance between the so-called dendrite arms. Furthermore, the elemental tin and/or phases here usually crystallize and/or envelop them in the region of the hard particles.

The castings of these examples also have excellent hot formability at operating temperatures ranging from 600 to 880 c due to the homogeneity of the dense phase.

The alloy element tin contributes in particular to the formation of so-called friction layers between the friction partners in the adhesive wear stress on components made of the tin-containing copper alloy according to the invention. This mechanism is important as the commissioning performance of the material becomes more and more prominent, particularly under mixed friction conditions. The friction layer results in a reduction in the size of the pure metal contact area between the friction partners, which prevents welding or seizure of the components.

As modern engines, machines and aggregates increase in efficiency, higher and higher operating pressures and operating temperatures are emerging. This is observed in particular in newly developed internal combustion engines, where the aim is a more complete combustion of the fuel. In addition to the elevated temperatures in the combustion chamber of the internal combustion engine, there is also heat release that occurs during operation of the plain bearing system. Due to the high temperatures in the operation of the bearings, in the parts made of the alloy according to the invention, there is the formation of borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate and phosphosilicate and alumina, similar to the case of casting operations and hot forming operations. These compounds reinforce the friction layer, which leads to an increased resistance to adhesive wear of the sliding elements made of the alloy according to the invention.

Even during the casting operation of the present invention, there is precipitation of hard particles in the microstructure. These phases protect the material from abrasive wear stresses, i.e. from removal of material by scratch wear. Furthermore, the hard particles have a low tendency to weld together with the metallic friction partners, and therefore, together with the friction layer of the composite structure, they ensure the high resistance to adhesive wear of the invention.

In addition to its function as a wear substrate, the hard particles have the higher thermal stability of the microstructure of the copper alloy of the invention. This results in an improvement in the stability of the material with high heat resistance and stress relaxation resistance.

In the casting variants and further processing variants of the alloy according to the invention, the following optional elements may be present:

elemental zinc may be added to the tin-containing copper alloy of the present invention in an amount of 0.1 to 2% by weight. It has been found that depending on the tin content of the alloy, the alloying element zinc increases the proportion of tin-rich phases in the present invention, which leads to an increase in strength and hardness. However, it is not possible to find any indicator that the addition of zinc has a positive effect on the homogeneity of the microstructure and on the further reduction of the pore and crack content in the microstructure. It is clear that the influence of the combined alloying element content of boron, silicon and phosphorus is significant in this respect. Below 0.1% by weight of zinc, no strength and hardness enhancing effect was observed. For zinc contents of more than 2% by weight, the toughness properties of the alloy are reduced to a lower level. In addition, the tin-containing copper alloy of the present invention has deteriorated corrosion resistance. Advantageously, a zinc content in the range from 0.5 to 1.5% by weight may be added to the present invention.

To further improve the mechanical material properties of strength and hardness and resistance to stress relaxation at elevated temperatures, the alloying elements iron and magnesium may be added, either individually or in combination.

The alloy of the present invention may comprise 0.01 to 0.6% by weight of iron. In this case, up to 10% by volume of iron boride, iron phosphide and iron silicide and/or iron-rich particles are present in the microstructure. Furthermore, in the microstructure, addition compounds and/or mixed compounds of iron-containing phases with aluminium-and boron-containing phases, silicon-and boron-containing phases and/or Si-Al-B phases are formed. These phases and compounds help to increase strength, hardness, heat resistance, stress relaxation resistance, electrical conductivity, and to improve abrasive and adhesive wear stresses on the alloy. This improvement in performance is not achieved for iron contents below 0.01% by weight. If the iron content exceeds 0.6% by weight, there is a risk of iron cluster formation in the microstructure. This is associated with a marked deterioration in the processability and in-use properties.

In addition, elemental magnesium may be added to the alloys of the present invention from 0.01% to 0.5% by weight. In this case, up to 15% by volume of magnesium boride, magnesium phosphide and copper-magnesium phases and copper-tin-magnesium phases are present in the microstructure. Furthermore, addition compounds and/or mixed compounds of magnesium-containing phases and aluminium-and boron-containing phases, silicon-and boron-containing phases and/or silicon aluminium boron phases are formed in the microstructure. These phases and compounds also contribute to increased strength, hardness, heat resistance, stress relaxation resistance, electrical conductivity, and to improved abrasive and adhesive wear stresses on the alloy. This improvement in performance is not achieved for magnesium contents below 0.01% by weight. If the magnesium content exceeds 0.5% by weight, there is a deterioration in castability of the alloy in particular. Furthermore, too high a content of magnesium-containing compounds may deteriorate the toughness properties of the alloy of the invention to a critical degree.

The tin-containing copper alloy may or may not include a small proportion of lead. The lead content, which is still acceptable and here above the contamination limit, is at most 0.25% by weight. In a particularly preferred embodiment of the invention, the tin-containing copper alloy is free of lead, apart from any unavoidable impurities. In this regard, lead contents of up to a maximum of 0.1% by weight of lead are contemplated.

One particular advantage of the present invention is believed to be that the microstructure is substantially free of porosity and shrinkage porosity, craters, segregation and cracks in the cast state. This results in the alloy according to the invention being particularly suitable for use as a wear resistant layer, which is for example melted onto a body made of steel. The alloy composition of the present invention can suppress the formation of open pores particularly during melting, which increases the compressive strength of the sliding layer.

A further particular advantage of the present invention is the elimination of the absolute necessity to implement specific initial forming techniques (e.g. spray compaction or thin strip casting) for providing a homogenized, substantially pore-free and segregation-free microstructure. To establish such a microstructure, conventional casting methods for the initial forming operation of the alloys of the present invention may be used. Accordingly, one aspect of the present invention includes a process for manufacturing a final product or component in a near-final product form from the tin-copper alloy of the present invention by means of a sand casting process, a shell casting process, a precision casting process, a solid casting process, a press molding process, or a lost foam process.

Furthermore, one aspect of the invention comprises a process for manufacturing strips, sheets, plates, bolts, round wires, profiled wires, round rods, profiled bars, hollow rods, tubes and profiles from the tin-containing copper alloy of the invention by means of a permanent mold casting process or a continuous or semi-continuous strand continuous casting process.

It is noteworthy that after the permanent die casting or strand continuous casting form of the alloy of the present invention, there is also no need to perform any complicated forging or indentation process at elevated temperature to weld, i.e. close, the pores and cracks in the material.

Further, in the present invention, in order to secure sufficient thermoformability, it is no longer absolutely necessary to more finely distribute the tin-rich phase present according to the tin content in the microstructure, or to dissolve it by homogenizing annealing or solution annealing, thereby eliminating it. The phases, which are in any case homogenized and finely distributed in the cast microstructure of the alloy according to the invention with a suitable tin content, assume the necessary function of the service properties of the alloy.

In a preferred construction of the invention, the further processing of the as-cast condition may include performing at least one hot forming operation at a temperature in the range of 600 to 880 ℃.

The thermoformed blanks and components may advantageously be cooled using calm or accelerated air or water.

The microstructure of these examples had a very homogeneous and fine grain structure after the hot forming operation due to the already occurring dynamic recrystallization promoted by the hard particles. It has additionally been found that the hot formed state of the present invention has extremely high strength and hardness values. It is evident that continued precipitation of smaller sized hard particles occurs during the thermoforming process. These are formed to a greater extent during thermoforming due to the slowness of the precipitation of aluminium-containing hard particles.

Advantageously, at least one annealing treatment of the cast and/or hot-formed state of the invention can be carried out at a temperature ranging from 200 to 880 ℃ for a duration of 10 minutes to 6 hours, or alternatively with calm or accelerated air or water cooling.

One aspect of the invention relates to an advantageous method for further processing the as-cast condition or the as-hot-formed condition or the as-annealed as-cast condition or the as-annealed as-hot-formed condition, which comprises carrying out at least one cold forming operation.

Preferably, the at least one annealing treatment of the cold-formed state of the invention can be carried out at a temperature ranging from 200 to 880 ℃ for a duration ranging from 10 minutes to 6 hours.

Advantageously, the stress relief annealing/age-aging annealing operation may be performed at a temperature in the range of 200 to 650 ℃ for a time duration of 0.5 to 6 hours.

The matrix of the homogenized microstructure of the invention comprises a proportion of phases and extended α phases depending on the tin content of the alloy, the phases leading to a high abrasive wear resistance of the alloy due to its high strength and hardness, furthermore, the phases increasing the adhesive wear resistance of the material due to its high tin content leading to its tendency to form a friction layer.

This heterogeneous structure comprising a metallic base material consisting of α and phases, to which precipitated precipitates of high hardness are added, confers an excellent combination of properties on the subject of the invention, it is noted in this respect that high strength and hardness values with simultaneously good toughness, excellent hot formability, sufficient cold formability, high thermal stability of the resulting microstructure with high heat resistance and high stress relaxation resistance, sufficient electrical conductivity for many applications, high corrosion resistance, and high resistance to wear, adhesion, surface cracking and to oscillating frictional wear, known as fretting.

Because the homogenized and fine grain microstructure is substantially free of porosity, cracks, and segregation and hard particle content, the alloys of the present invention have a high degree of strength, hardness, ductility, complex wear and corrosion resistance, even in the as-cast state. For this reason, the alloy of the present invention has a wide range of applications even in the cast state.

The result is that the alloy according to the invention is particularly suitable for use as a wear resistant layer, which is for example melted onto a body made of steel. In this connection, it should be noted that the treatment temperature of the quenched and tempered steel (820 to 860 ℃ C., 540 to 660 ℃ C.; DIN EN10083-1) is within the heat treatment range of the present invention. This means that the mechanical properties of the two composite counterparts can be optimized in only one processing step after melting the tin-copper containing alloy onto the body made of hardened and tempered steel. A further advantage is that during the melting operation the formation of open porosity is inhibited, which increases the compressive strength of the wear resistant layer.

In addition to melting, there are further useful joining methods. In this connection, composite production by forging, brazing or welding is also conceivable, wherein at least one annealing operation is optionally carried out in a temperature range of 200 to 880 ℃. For example, bearing composite shells or bearing composite bushings can likewise be produced by roll cladding, induction or conductive roll cladding or by laser roll cladding.

Even cast forms in the form of strips, sheets, plates, bolts, wires, rods, tubes and profiles can be used for the production of sliding and guiding elements in internal combustion engines, valves, turbochargers, gears, exhaust gas aftertreatment systems, lever systems, brake and joint systems, hydraulic aggregates or in machines and installations in general in mechanical engineering. By further processing of the cast state, semi-finished products and components can be manufactured with complex geometries for these end uses and with enhanced mechanical properties and optimized wear properties. This takes into account the elevated component requirements under dynamic stress.

A further aspect of the invention comprises the use of the tin-containing copper alloy of the invention in components, wire elements, guide elements and connection elements in electronic/electrical engineering.

Further possible uses exist due to the excellent strength properties and wear and corrosion resistance of the tin-containing copper alloy of the present invention. The invention is therefore applicable to metal products in structures for the cultivation of marine organisms (aquaculture). Another aspect of the invention includes the use of the tin-containing copper alloy of the invention for propellers, wings, marine propellers and hubs for shipbuilding, housings for water, oil and fuel pumps, guide, runner and paddle wheels for pumps and turbines, for gears, worm gears, bevel gears, and for forcing nuts and spindle nuts, and for pipes, seals and connecting bolts in the marine and chemical industries.

This material is of great significance for the use of the alloy of the present invention for the manufacture of percussion instruments. In particular, high quality cymbals are manufactured from tin-containing copper alloys by hot forming and at least one annealing operation before they are typically converted into their final shape by a bell or enclosure. Subsequently, the mark is annealed again before its final treatment for material removal. Cymbal variants such as spot cymbals, striking cymbals, chinese cymbals, side-striking cymbals, and sound cymbals (effect cymbals) are manufactured, and therefore require particularly advantageous thermo-formability of the materials guaranteed by the alloys of the present invention. Within the limits of the range of chemical compositions according to the invention, the different microstructural components of the phase and of the hard particles can be set in a very wide range. In this way, the sound characteristics of the cymbal may be affected even from the perspective of the alloy. Further important working examples of the invention are set forth in tables 1 to 11. The cast block of the tin-copper alloy of the present invention is made by permanent mold casting. The chemical composition of the castings is apparent from tables 1 and 3.

Table 1 shows the chemical composition of alloy modification 1. The material is characterized by a tin content of 7.35% by weight, a silicon content of 0.74% by weight, an aluminum content of 0.34% by weight, a boron content of 0.33% by weight and a phosphorus content of 0.015% by weight, with the balance copper.

Table 1: chemical composition of working example 1 (% by weight)

	Cu	Sn	Si	Al	B	P
							1	Balance of	7.35	0.074	0.34	0.33	0.015

After casting, the microstructure of this working example 1 was shaped by a rather small proportion of phase (about 15 to 20% by volume) and hard particles in a very homogenized island-like distribution of copper solid solution. The hardness of this alloy was 108HB (Table 2).

Table 2: hardness of permanent mold casting Block of working example 1

Table 3 shows the chemical composition of further alloy modification 2. The material contains, in addition to about 15.09% by weight of tin and 0.027% by weight of phosphorus, the further elements silicon (0.80% by weight), aluminum (0.54% by weight) and boron (0.24% by weight), and the balance copper.

Table 3: chemical composition of working example 2 (% by weight)

	Cu	Sn	Si	Al	B	P
								2	Balance of	15.09	0.80	0.54	0.24	0.027

It is a feature of the present invention that as the tin content of the alloy increases, the microstructure in the as-cast condition includes an increasing proportion of phases, depending on the casting/cooling operation. As the tin content of the alloy increases, the arrangement of the tin-rich phase transforms from a finely distributed island form to a dense network structure.

In the cast microstructure of alloy type 2, there is a phase with a significantly higher content (up to about 70% by volume). This microstructure is shown at 200 times magnification in fig. 3 and at 500 times magnification in fig. 4. The reference numeral 1 in each case denotes a tin-rich phase arranged in a network-shaped manner in the microstructure. Furthermore, it is evident from the hard particles 2 encapsulated by tin and/or a tin-rich phase. The microstructure component of the copper solid solution is marked with the reference numeral 3.

The increase in material hardness with increasing tin content is indicated by a significantly higher value of 210HB for alloy 2 (Table 4).

Table 4: hardness of permanent mold casting Block of working example 2

The homogeneous distribution of the phases in the form of islands and/or networks in the microstructure of the tin-containing copper alloy of the present invention highlights the effect of the hard particles as crystallization seeds for forming the phases.

One aspect of the invention relates to a process for producing strips, sheets, plates, bolts, wires, rods, profiles, hollow rods, tubes and profiles from the tin-containing copper alloy of the invention by means of a permanent mold casting process or a continuous or semicontinuous strand casting process.

The alloy of the present invention may additionally be subjected to further processing. This enables, firstly, the manufacture of specific and often complex geometries. Secondly, the need for improved complex operating properties of materials, in particular for wear-stressed components and connecting elements in electrical/electronic engineering, is met in this way, since the stresses on the system components in the respective machines, engines, gears, aggregates, structures and facilities are markedly increased. During this further processing, a significant improvement in the toughness properties and/or the tensile strength R is achieved_mYield point R_P0.2And a significant increase in hardness.

Due to the excellent hot formability of the alloys of the present invention, further processing of the as-cast condition may advantageously include performing at least one hot forming operation at a temperature in the range of from 600 to 880 ℃. By hot rolling, plates, sheets and strips can be manufactured. Extrusion enables the manufacture of wires, rods, tubes and profiles. Finally, the forging process is in some cases suitable for manufacturing near-net-shape components with complex geometries.

Another advantageous way of further processing the as-cast condition or the as-hot-formed condition or the as-annealed as-cast condition or the as-annealed as-hot-formed condition comprises carrying out at least one cold forming operation. In particular, this process step significantly increases the material index R_m、RP_0.2And hardness. This is important for applications where there are mechanical stresses and/or severe wear and/or adhesive wear stresses on the components. In addition, the combination of the invention is significantly improved due to the cold forming operationSpring properties of gold-made components.

In order to recrystallize the microstructure according to the invention accordingly after the cold forming operation, at least one annealing treatment may be carried out at a temperature in the range of 200 to 880 ℃ for a duration of 10 minutes to 6 hours. The very fine grain structure thus formed is an important prerequisite for establishing the combination of high strength and hardness properties and sufficient toughness of the material.

In order to reduce the residual stress of the component, it is advantageously additionally possible to carry out a stress relief annealing operation in a temperature range from 200 to 650 ℃ for a time duration of 0.5 to 6 hours.

For fields of use with particularly severe stresses of complex components, further processing operations may be selected, which comprise at least one cold forming operation or a combination of at least one hot forming operation and at least one cold forming operation cooperating with at least one annealing operation for a duration of 10 minutes to 6 hours in the temperature range of 200 to 800 ℃, and which lead to a recrystallized microstructure of the alloy of the invention. The fine grain structure of the alloy established in this way ensures a combination of high strength, high hardness and good toughness properties. In addition, in order to reduce the residual stress of the assembly, the stress relief annealing treatment may be performed at a temperature ranging from 200 to 650 ℃ for a duration of 0.5 to 6 hours.

In order to produce a semifinished product in strip form from working example 1 (table 1), three different production sequences were selected. They differ mainly in the number of cold forming/annealing cycles and in the degree of cold forming and annealing temperature levels used (table 5).

Table 5: manufacturing procedure of working example 1

After permanent mold casting and hot rolling, the respective block or semi-finished product is characterized by an abnormally smooth surface. The hot formed state of alloy modification 1 has excellent cold formability due to dynamic recrystallization of the microstructure that has occurred during the hot rolling operation. In order to further improve the cold formability of the thermoformed semifinished products, it was found to be advantageous to carry out the annealing treatment at a temperature in the range of 600 to 880 ℃ for a duration of 3 hours. Therefore, the hot-rolled sheet can be cold-rolled without cracks to about 85% in cold forming.

In the process of manufacture 1, the cold-rolled strip was annealed at a temperature of 280 ℃ for a duration of 2 h. The indices of the strip thus subjected to stress relief are apparent from table 6. Despite the high strength and hardness values, the strip of this alloy has sufficient toughness properties as measured by the high elongation value at break a 5.

Table 6: microstructural characteristics and mechanical index of the strip of working example 1 in the final state (manufacture 1)

In the process of manufacturing 2, the strip of alloy modification 1 was annealed at 680 ℃ for 3 hours after the first cold rolling operation. This was followed by cold rolling of the strip to about 60%. To complete the manufacture, the strip is subjected to thermal stress relief at different temperatures between 280 ℃ and 400 ℃ for a duration of 2 to 4 hours. The indices of the resulting material states are listed in table 7.

Table 7: microstructural characteristics and mechanical characteristics of the strip of working example 1 in the final state (manufacture 2)

From table 7 it can be concluded that the microstructure of the strip subjected to stress relief at 280 ℃ comprises deformation characteristics, and therefore no values are reported for the grain size. At about 340 ℃, recrystallization of the microstructure begins, which results in a significant decrease in strength and hardness. For this reason, in the process of manufacturing 3, the annealing temperature after the first cold forming operation is reduced to 450 ℃. An annealing operation at this temperature for three hours is followed by cold rolling of the strip, with a cold forming of about 30%. A two hour final stress relief anneal at a temperature between 240 c and 360 c resulted in the indices shown in table 8.

The microstructure at 500 times magnification of the final state of the strip with working example 1, which has been subjected to stress relief annealing at 240 ℃/2 hour, is shown in fig. 2. It can be seen that there is a microstructure of fine particles of the hard particles 2 added to the copper solid solution 3. The hard particles are encapsulated by a tin and/or tin-rich phase.

The results are directed to high strength and hardness values. However, a high elongation value at break a5 indicates a material state of good ductility.

Table 8: microstructural characteristics and mechanical characteristics of the strip of working example 1 in the final state (manufacture 3)

The strip of working example 2 of the present invention was produced by the manufacturing procedure shown in table 9, the chemical composition of which can be found in table 3. Hot rolling in the form of permanent mould casting is achieved at a temperature of 750 ℃ followed by water cooling. After permanent mold casting and hot rolling, the respective block or semi-finished product is characterized by an abnormally smooth surface.

After the hot forming operation, the strips were cold rolled with a cold forming level of about 3%. A portion of the strip labeled 2-a was then annealed at temperatures of 500, 550 and 600 ℃ for 3 hours and inspected.

A second portion of the strip, designated 2-B, cold rolled to 7.04mm was further produced by cyclically performing the annealing and cold forming operations.

Table 9: manufacturing procedure of working example 2

The grain size and hardness of the cold rolled state and the cold rolled and annealed state of the strip 2-a are shown in table 10. Due to the dynamic recrystallization of the microstructure already occurring during the hot rolling of the cast block, the structure is in homogenized form even after the first cold rolling operation, with a grain size of 20 to 25 μm. The toughness properties can also be improved by annealing treatment in the temperature range from 200 to 650 ℃. Thus, fig. 5 shows the microstructure of working example 2 after annealing at 500 ℃ for 3 hours. The phase (black color) is very homogenously distributed in the microstructure of the material. A further reduction of the phase fraction was achieved by an annealing operation at 600 ℃/3h (fig. 6).

For the as-cast condition, the hard particles are more completely present in the phase region. This highlights the function of the hard particles as recrystallization/precipitation seed crystals even during the thermomechanical further processing of the alloy.

Table 10: grain size and hardness of strip 2-A cold rolled from working example 2 (after manufacturing step 4 in Table 9) and subsequently annealed

The microstructure of the strip 2-a, which was finally heat treated with the parameters 500 ℃/3h + air and 600 ℃/3h + air, is shown in fig. 5 and 6, the microstructure of these two states, apart from the tin-rich phase 1, comprises very fine hard particles 2 sheathed by tin and/or tin-rich phases, it is also visible that the copper solid solution 3 comprises a tin-deficient α phase, the microstructure of the strip 2-a, after annealing at a higher temperature of 600 ℃, is in the form of coarse grains (fig. 6).

The second portion of the strip labeled 2-B is further processed with a plurality of cold rolling/annealing cycles. The indices of the final state that has undergone stress relaxation at different temperatures are listed in table 11.

The microstructure of working example 3 of the present invention was continuously stretched in a linear manner for each cycle including the cold rolling step and the annealing treatment. The linear arrangement of the very high components resulting from the high tin content of the alloy results in high hardness values close to 300HV 1. At the same time, there is an increase in the brittle characteristics of the alloy.

Table 11: grain size and hardness of the finally produced strip 2-B from working example 2 (after the production step 10 of Table 9)

Therefore, it can be concluded that the alloy of the present invention has excellent castability and hot formability over the entire tin content range from 4% to 23.0% tin. The cold formability is also at a very high level. However, ductility of the present invention naturally deteriorates with increasing tin content due to the increased composition of the microstructure.

List of reference numerals

1 tin-rich phase

2 hard particles enveloped by tin and/or tin-rich phases

3 copper solid solution containing tin-deficient α phase

Claims

1. A high strength tin-containing copper alloy having excellent hot formability and cold formability, high resistance to abrasive wear, adhesive wear, and fretting wear, and improved corrosion resistance and stress relaxation resistance, comprising in weight%:

4.0% to 23.0% Sn,

0.05% to 1.5% Si,

0.01 to 1.0% of Al,

0.01% to 0.6% B,

0.001% to 0.08% P,

no Zn is present or a maximum of 2.0% Zn is present,

no Fe or maximum 0.6% Fe is present,

no Mg or a maximum of 0.5% Mg,

no Pb is present or a maximum of 0.25% Pb is present,

the balance being copper and unavoidable impurities,

it is characterized in that the preparation method is characterized in that,

-the Si/B element content ratio of the elements Si and B is between 0.3 and 10;

-the following microstructural components are present in the alloy after casting with boron, silicon, aluminium and phosphorus added in combination:

a) from 1% to at most 98% by volume of a tin-rich phase (1),

b) 1 to at most 20% by volume of an aluminium-and boron-containing phase, a silicon-and boron-containing phase and/or an addition compound and/or a mixture compound (2) comprising both phases;

c) the balance copper solid solution comprising a low tin α phase (3) wherein an aluminum-and boron-containing phase, a silicon-and boron-containing phase and/or an addition compound and/or a mixed compound comprising both phases (2) are encased by a tin and/or tin-rich phase (1);

-in the casting, the aluminium-and boron-containing phases, the silicon-and boron-containing phases and/or the addition compounds and/or the mixture compounds comprising both phases (2) in the form of aluminium boride and silicon boride and/or in the form of addition compounds and/or mixtures of aluminium boride and silicon boride constitute seeds for a homogeneous crystallization during solidification/cooling of the melt, so that the tin-rich phase (1) is homogenously distributed in the microstructure in the form of islands and/or a network;

an aluminium-and boron-containing phase, a silicon-and boron-containing phase and/or an addition compound and/or a mixture compound (2) comprising both phases in the form of a borosilicate and/or borophosphosilicate and/or aluminoborosilicate and/or aluminoborophosphosilicate act as a wear protection and/or corrosion protection coating on the semifinished products and components of the alloy together with the phosphosilicate and alumina.

2. A high strength tin-containing copper alloy having excellent hot formability and cold formability, high resistance to abrasive wear, adhesive wear, and fretting wear, and improved corrosion resistance and stress relaxation resistance, comprising in weight%:

4.0% to 23.0% Sn,

0.05% to 1.5% Si,

0.01 to 1.0% of Al,

0.01% to 0.6% B,

0.001% to 0.08% P,

no Zn is present or a maximum of 2.0% Zn is present,

no Fe or maximum 0.6% Fe is present,

no Mg or a maximum of 0.5% Mg,

no Pb is present or a maximum of 0.25% Pb is present,

the balance being copper and unavoidable impurities,

it is characterized in that the preparation method is characterized in that,

-the Si/B element content ratio of the elements Si and B is between 0.3 and 10;

-after further processing of the alloy with the combined additions of boron, silicon, aluminium and phosphorus by at least one annealing operation or by at least one hot forming operation and/or cold forming operation in addition to at least one annealing operation, the following microstructural components are present in the alloy:

a) up to 75% by volume of a tin-rich phase (1);

b) 1 to at most 25% by volume of an aluminium-and boron-containing phase, a silicon-and boron-containing phase and/or an addition compound and/or a mixture compound (2) comprising both phases;

c) the balance copper solid solution comprising a low tin α phase (3) comprising aluminium and boron containing phases, the silicon and boron containing phases and/or an addition compound and/or a mixed compound comprising both phases (2) being encapsulated by the tin and/or tin rich phase (1);

-the aluminium-and boron-containing phases, the silicon-and boron-containing phases and/or the addition compounds and/or the mixture compounds comprising both phases in the form of aluminium boride and silicon boride and/or in the form of addition compounds and/or mixture compounds of aluminium boride and silicon boride (2) constitute seeds for static and dynamic recrystallization of the microstructure during further processing of the alloy, which enable the establishment of a homogenized and fine-grained microstructure, wherein the tin-rich phase is homogenously distributed in the microstructure in the form of islands and/or networks and/or extended lines;

3. A tin-containing copper alloy as claimed in claim 1 or 2 characterised in that between 0.5% and 1.5% elemental silicon is present.

4. A tin-containing copper alloy as claimed in claim 1 or 2 characterised in that 0.1% to 0.8% elemental aluminium is present.

5. A tin-containing copper alloy as claimed in claim 1 or 2 characterised in that between 0.001% and 0.05% elemental phosphorus is present.

6. A tin-containing copper alloy as claimed in claim 1 or 2, characterized in that the alloy is free of lead, apart from any unavoidable impurities.

7. A method of manufacturing an end product or component having a near-end product form from a tin-containing copper alloy as claimed in any one of claims 1 to 6 by means of a sand casting process, a shell casting process, a precision casting process, a solid casting process, a pressure die casting process or a lost foam process.

8. A method for producing strips, sheets, plates, bolts, round wires, profiled wires, round bars, profiled bars and hollow bars from a tin-containing copper alloy as claimed in any of claims 1 to 6 by means of a permanent mould casting process or a continuous or semi-continuous strand continuous casting method.

9. A method of manufacturing a tube or a profile from a tin-containing copper alloy as claimed in any one of claims 1 to 6 by means of a permanent mould casting process or a continuous or semi-continuous strand continuous casting method.

10. A method as claimed in claim 8 or 9, wherein the further treatment of the as-cast condition comprises carrying out at least one hot forming operation at a temperature in the range of 600 to 880 ℃.

11. A method as claimed in claim 7, 8 or 9, characterized in that at least one annealing treatment is carried out at a temperature in the range of 200 to 880 ℃ for a duration of 10 minutes to 6 hours.

12. A method as claimed in claim 10, characterized in that the at least one annealing treatment is carried out at a temperature in the range of 200 to 880 ℃ for a duration of 10 minutes to 6 hours.

13. A method as claimed in claim 8 or 9, wherein the as-cast condition is further processed including performing at least one cold forming operation.

14. A method as claimed in claim 10, wherein the further processing of the hot formed state comprises performing at least one cold forming operation.

15. A method as claimed in claim 11, wherein the further treatment of the annealed cast condition comprises performing at least one cold forming operation.

16. A method as claimed in claim 12, characterized in that the further processing of the annealed hot formed state comprises carrying out at least one cold forming operation.

17. A method as claimed in claim 13, characterized in that the at least one annealing treatment is carried out at a temperature in the range of 200 to 880 ℃ for a duration of 10 minutes to 6 hours.

18. A method as claimed in claim 11, characterized in that the stress relief annealing/age-aging annealing operation is carried out at a temperature in the range of 200 to 650 ℃ for a time of 0.5 to 6 hours.

19. A method as claimed in claim 12 or 17, characterised in that the stress relief annealing/age ageing annealing operation is carried out at a temperature in the range of 200 to 650 ℃ for a duration of 0.5 to 6 hours.

20. Use of the tin-copper containing alloy as claimed in any of claims 1 to 6 for adjusting and sliding cantilevers, for friction rings and friction disks, for sliding bearing surfaces in composite material components, for sliding elements and guide elements in internal combustion engines, valves, turbochargers, gears, exhaust gas aftertreatment systems, lever systems, joint systems, hydraulic aggregates or in machinery and installations in general in mechanical engineering.

21. Use of a tin-containing copper alloy as claimed in any one of claims 1 to 6 for a brake system.

22. Use of a tin-containing copper alloy as claimed in any one of claims 1 to 6 for components in electronic/electrical engineering.

23. Use of a tin-containing copper alloy as claimed in any of claims 1 to 6 for wire elements, lead elements and connecting elements in electrical/electronic engineering.

24. Use of the tin-copper alloy as claimed in any one of claims 1 to 6 for the production of marine farmed organisms, for percussion instruments, propellers, wings, housings for water, oil and fuel pumps, guide, runner and paddle wheels for pumps and water turbines, for gears, worm gears, bevel gears, and for forcing and spindle nuts, and for pipes, seals and connecting bolts in the marine and chemical industries.

25. Use of a tin-containing copper alloy as claimed in any one of claims 1 to 6 for marine propellers and hubs for shipbuilding.