JPS6242978B1 - - Google Patents

Description

[Detailed description of the invention]

Copper-based alloys represent a class of practical metals with a wide range of uses. There is an extremely strong need to provide a wrought copper-based alloy material that has high strength and excellent toughness in the as-rolled state. Therefore, it is natural that it would be desirable to provide a wrought alloy material that is economical in terms of both material cost and manufacturing cost. Typical practical metal materials that have excellent strength in the as-rolled state are known to have low toughness, for example, elongation of less than 2% at area reduction of 50% or more. On the contrary, the wrought material produced by the method of the invention has high strength and improved toughness in the as-rolled state, e.g.
It usually has an elongation exceeding 3% at the area reduction rate above.
Such properties can be obtained through conventional copper alloy processing, namely casting and hot and cold rolling. The method for producing the wrought alloy material of the present invention includes heat treatments designed to improve toughness, such as precipitation hardening copper-beryllium alloys and martensitic copper alloys.
No special treatment required for aluminum alloys is required. Therefore, it is a first object of the present invention to provide a method for manufacturing a series of wrought copper-based alloy materials that satisfy the above-mentioned requirements. Another object of the invention is to
The object of the present invention is to provide a method for producing a novel wrought copper-based alloy material that has high toughness, high yield strength, high tensile strength, and excellent work hardening properties. Still another object of the present invention is to provide a method for manufacturing the above-mentioned wrought copper-based alloy material, which is relatively low cost and easy to manufacture. Other objects and effects of the present invention will become more apparent upon consideration of the following specification. According to the present invention, there is provided a method for obtaining a series of novel copper-based alloy wrought materials that easily achieve the above-mentioned objects and effects and have excellent work hardening properties. The alloy used in the present invention has the following characteristics. Contains at least one additional element selected from Group 1 of the Periodic Table of Elements that reduces the stacking fault energy of copper to 3 ergs per square centimeter or less, and the alloying element is substantially saturated in the copper matrix. It exists as a solid solution. The wrought materials produced according to the invention have a number of highly desirable advantages. It exhibits excellent work hardening behavior with high yield strength and tensile strength combined with a high degree of toughness, and also exhibits high strength for a given elongation in the highly rolled state. This wrought material can be easily hot rolled and cold rolled and is relatively inexpensive to manufacture.
In addition, when this alloy wrought material is subjected to low-temperature heat treatment, its strength in the cold rolled state increases. The wrought alloys produced in accordance with the present invention have a higher strength for a given elongation and therefore have wide use in current applications specifying high strength rolled copper alloys. For example, 70Kg/mm ² with 3% elongation
It is easy to obtain a tensile strength of (100000psi). In addition, the wrought alloys produced in accordance with the present invention also have other desirable properties such as excellent electrical conductivity. Due to the combination of high strength and excellent toughness in the as-rolled state, that is, in the work-hardened state due to rolling, the wrought alloy produced by the present invention has excellent formability that exceeds standard commercially available materials. have. Furthermore, the alloy wrought material produced by the present invention has excellent formability even in the annealed state after cold rolling, and at the same time, its production and material costs are comparable to or even lower than that of the most easily produced copper-based alloy. lower than. Other advantageous features of the wrought alloy material produced according to the present invention will be easily understood from the description. As described above, the copper-based alloy used in the present invention contains at least one alloying element that reduces the stacking fault energy of copper to 3 ergs per square centimeter or less. The stacking fault energy of copper is approximately 30 ergs per square centimeter. The most preferred alloying element is an element that reduces the stacking fault energy of copper to the maximum extent and facilitates the formation of defects. Copper and an alpha solid solution of copper crystallize into a face-centered cubic crystal lattice.
This crystal structure can be deformed by sliding on a dense layer of atoms corresponding to the {111} plane. This sliding deformation is caused by the movement of dislocations on the dense {111} plane. The magnitude of slip caused by dislocation motion is the Burgers vector.
is determined by 1/2a<110 in face-centered cubic structure
> is said to be. This unit of dislocation 1/2a<110> decomposes into a so-called half-dislocation that forms a lower energy state, but stacking faults occur between these half-dislocations. This stacking fault can be best explained or illustrated by considering the arrangement of dense {111} planes in a face-centered cubic crystal structure. These planes are stacked on top of each other in the order of ……ABCABCABC………. The atomic arrangement on one of these dense planes is determined by AHCottrell's Dislocation And Plastic Flow In.
This is shown in Figure 1, taken from page 73 of 1953 (Crystal). Referring to Figure 1, B and C
The atomic positions on the plane are indicated by symbols B and C, respectively. In FIG. 1, vector arrows indicate the unit dislocation b ₁ and the respective half dislocations b ₂ and b ₃ . If we consider the atom to be a sphere, we can see that it is easier for slippage to occur along b ₂ and b ₃ than along b ₁ path.
If the slip occurs along one vector b ₂ between two dense planes, i.e. by the motion of half-dislocations, the stacking order will be...
A defect like ABCABCABC... will occur. When such stacking faults exist, the crystal structure becomes a thin layer structure equivalent to a close-packed hexagonal structure. When such stacking faults occur, the energy of the crystal increases slightly; this change is caused by a change in the arrangement of the nearest atoms within the face-centered cubic structure.
Heidenreich and Schötzklee (Heidenreich and
S′hockley) is a “report on the strength of solids”
(Report On Strength, Of Solids), 57 (1948
(2011) suggested that a unit dislocation in a face-centered cubic structure would be decomposed into two half-dislocations. For example, in the case of a unit dislocation on the {111} plane, 1/2a
The reaction [101] → 1/6a [211] + 1/6a [112] will occur. This reaction produces a lower dislocation than two half-dislocations in terms of rearrangement of the original unit. These half-dislocations repel each other due to their elastic self-energy, creating a stacking fault plate between them. The extent of this half-dislocation separation is determined by the increase in lattice energy associated with stacking faults. In an equilibrium state, the two half-dislocations are separated by a distance γ expressed by the following equation. γ=μa ² /24πε where μ is the shear modulus, a is the lattice constant, and ε is the defect energy. Each metal element exhibits a specific stacking fault energy. For example, the stacking fault energy of aluminum is approximately 270 ergs per square centimeter, and that of copper is 30 ergs per square centimeter. Addition of a solute element, primarily an element with a significant solubility and a higher electron valence than the solvent material, reduces the stacking fault energy of said solute element and allows greater separation of half-dislocations. The effects of several alloying element additions to copper were investigated by A. Howie and P.R. Swan.
RS'Wann)'s “Plil.Mag.” [8] 6, 1215
(1961). Second
In the figure, the electron-atomic ratio is plotted on the X axis (horizontal axis) and the stacking fault energy is plotted on the Y axis (vertical axis). A more in-depth examination of these considerations is in ``The Direct Observation of Dislocations,'' published by Academic Press Inc. in 1964.
Of Dislocations). When adding one or more alloying elements, two or more alloying elements are used in the examples, but the combination of alloying elements must reduce the stacking fault energy of copper to a predetermined level. It is further desirable that the stacking fault energy be reduced as close to zero as possible. The alloying elements must be present in substantially saturated solid solution with the copper matrix. That is, the amount of alloying elements is such that copper is saturated with respect to the alloying elements. This ensures that stacking fault energy is minimized and strength is maximized. In order to ensure such a saturated state, a solute element may be added in excess, but this excess may exist as a precipitated second equilibrium phase. According to the invention, the amount of excess second equilibrium phase must be less than 20% by volume. In other words, the first phase represents a solid solution in which the alloying elements are saturated in copper, and the second phase is a precipitate of a second equilibrium phase suitable for a particular alloy system. The reason why the amount of the second equilibrium phase must be 20% or less by volume as described above is as follows. That is, as mentioned above, the alloying element must exist as a substantially saturated solid solution in the copper matrix, but once this saturation point is exceeded, a second equilibrium phase occurs, and this phase can be removed by the method of the present invention. This is usually detrimental to the desired strength-toughness combination characteristic of the resulting copper-base alloy wrought material. However, slightly exceeding the saturation point can be tolerated; in practice, a small excess will ensure a saturated solid solution of the alloying elements in the copper matrix without deleterious effects. It makes it possible. However, excessive amounts significantly above the saturation point significantly impair the beneficial effects of the wrought alloy produced by the process of the invention. Practical results have shown that in order to avoid this deleterious effect, the excess second equilibrium phase must be limited to less than 20% by volume. The alloying elements are selected from the groups and groups of the periodic table of elements. The preferred elements of the group are zinc, the preferred elements of the group are aluminum, gallium, and indium, and the preferred elements of the group are silicon and germanium. The preferred elements mentioned above are those that most rapidly reduce the stacking fault energy to a value of 3 ergs per square centimeter or less. The stacking fault energy is reduced depending on the electron-to-atomic ratio of the solid solution, so high valence solute elements are generally preferred. Another selection criterion is to seek elements with high solubility in copper. The amount of element used is determined by its relative solubility in copper and its ability to reduce the stacking fault energy of copper to the required level. As mentioned earlier, the alloying elements are provided in copper in a saturated solid solution state. A preferred embodiment alloy system for use in the present invention utilizes aluminum and silicon as alloying elements, with aluminum present in an amount of 2.0 to 6.0%, preferably 2.5 to 4.0%, and silicon in an amount of 1.0 to 4.0%. % preferably from 1.5
The second system is aluminum and germanium, where aluminum is the same as above and germanium is present at 3.0 to 5.0%. In addition to the alloying elements mentioned above, the alloys used in the present invention may contain cobalt as a transition element in a range of 0.01 to 5% by weight, preferably 0.1 to 1.5% by weight. This transition element suppresses grain growth at high temperatures, increases strength in the annealed state, and also stabilizes the roll-hardened state properties with a certain amount of cold work, resulting in higher tensile strength for a given elongation. give. The alloys used in the present invention may contain optional additional additive elements to achieve particular results. In addition to this, impurities present in normal alloy systems may be present. The method of the invention, the wrought alloy produced and the improvements resulting therefrom are clear from the illustrative examples below. Example 1 A copper base alloy was prepared by conventional DC casting, hot rolling, cold rolling and intermediate annealing. The composition of this alloy is 3.1% aluminum, 2.1% silicon, and the balance is mainly copper, with an electron atomic ratio of approximately 1.3 and α
It consisted of units. The stacking fault energy of this alloy was less than 3 ergs per square centimeter, and the added elements existed essentially as saturated solid solutions within the copper matrix. This alloy was processed as follows to provide the properties described below. 1 Annealed at 550℃ for 1 hour and then 30% cold rolled Tensile strength 71.4℃/mm ² (102000psi) 0.2% yield strength 54.6Kg/mm ² (78000psi) Elongation 12% 2 Sintered at 550℃ for 1 hour 30% cold rolled after annealing Tensile strength 84Kg/mm ² (120000psi) 0.2% yield strength 70Kg/mm ² (100000psi) Elongation 4% 3 70% cold rolled after annealing at 550℃ for 1 hour Tensile strength Strength 89.6Kg/mm ² (128000psi) 0.2% Yield Strength 78.4Kg/mm ² (112000psi) Elongation 3% Example 2 An alloy having the following components was prepared in the same manner as in Example 1. Aluminum 3.1%; Silicon 2.1%; Cobalt 0.4
%: The remainder is essentially copper. This alloy had an electron-to-atomic ratio of 1.3 and consisted of a single α phase. Furthermore, the stacking fault energy of this alloy was less than 3 ergs per square centimeter, and the aluminum and silicon were present in a saturated solid solution within the copper matrix. This alloy was processed by the method shown below to obtain the following properties. 1 After annealing at 550°C for 1 hour, 30% cold rolling was added. Tensile strength 79.8Kg/mm ² 0.2% yield strength 61.3Kg/mm ² Elongation 5% 2 After annealing at 550°C for 1 hour, 50% cold rolling was applied. Tensile strength 89.6Kg/mm ² 0.2% yield strength 72.8Kg/mm ² Elongation 3% 3 After annealing at 550°C for 1 hour, 70% cold rolling was applied. Tensile strength 93.8Kg/mm ² 0.2% yield strength 77.7Kg/mm ² Elongation 3% Example 3 A copper-based alloy consisting of 3.5% aluminum, 4.8% germanium, and the balance copper was prepared according to the method of Example 1. This alloy had an electron-to-atomic ratio of 1.3 and consisted of a single α phase. The stacking fault energy of the alloy was less than 3 ergs per square centimeter, and the added alloying elements were present as saturated solid solutions in the copper matrix. This alloy was processed as described below to give it the following properties. After annealing at 600°C for 1 hour, 50% cold rolling was applied. Tensile strength 77.7Kg/mm ² 0.2% Yield strength 63Kg/mm ² Elongation 5% In the present invention, intermediate annealing is performed by DC casting, hot rolling and cold rolling as described in the first row of Example 1. This is the next step and is carried out to harden the alloy that has been work hardened by cold rolling so that it can be subjected to final cold rolling. The reason why the intermediate annealing temperature was set at 550 to 600°C is as follows. That is, if the intermediate annealing temperature exceeds 600°C, irregular crystal grain growth occurs, making it impossible to maintain a desirable fine crystal grain structure.
If the intermediate annealing temperature is lower than 550° C., recrystallization and softening of the work-hardened alloy structure will be difficult to occur, and a long time will be required for recrystallization and softening, which is practically unacceptable. In Examples 1, 2, and 3, the intermediate annealing time is all shown as one hour, but the intermediate annealing time varies depending on the weight or thickness of the alloy material being treated. This is because the intermediate annealing merely softens the work-hardened material during cold working without causing grain coarsening, so that it can be subjected to subsequent final cold working. Hot rolling in the present invention is simply a necessary step to reduce the thickness of the material, and cold rolling is used to reduce the thickness of the alloy as well as to achieve high strength and good formability. The requirement that the stacking fault energy be less than 3 ergs/cm ² is necessary for the alloy to achieve high yield and tensile strengths upon work hardening while retaining a high degree of ductility. The present invention may be embodied in other forms or carried out in other ways without departing from its spirit or essential characteristics. Therefore, the embodiments described herein are in all respects illustrative and not restrictive, and all changes that fall within the scope of the claims and the concept of equivalents are included therein. It is something that should be done.

[Claims]

1. A method for producing a non-aging copper-based alloy wrought material having good toughness, high tensile strength, and excellent work hardening properties, comprising: (a) 2.0 to 6.0% by weight of aluminum and 1.5 to 3.0% by weight of silicon as starting materials; %, cobalt 0.01~
5.0% by weight, with the remainder consisting essentially of copper and unavoidable impurities, the content of these alloying elements being selected to reduce the copper stacking fault energy to less than 3 ergs per square centimeter, followed by such that, when annealed, the alloying elements exist as substantially saturated equilibrium solid solutions within the copper matrix at room temperature;
Or, in order to ensure a saturated equilibrium state, the alloying elements are selected within the composition range to be present in excess of the saturation point, and if the total amount of the alloying elements exceeds the saturation point, the excess amount is (b) preparing by casting a copper alloy which is adapted to be present as a secondary equilibrium phase in an amount of not more than 20% by volume so as not to substantially impair work hardening properties and toughness; (c) cold rolling the alloy to a predetermined temper condition, the alloy being heated to a temperature of 550 to 600°C and having good formability. Cold rolling through intermediate annealing held for a sufficient time to show an area reduction of 50
Tensile strength 84Kg/mm ² in temper-rolled condition
and have the characteristics of elongation of 3% or more.

[Brief explanation of the drawing]

Figure 1 shows the atomic arrangement on the dense lattice plane, and the second
The figure shows the effects of several additive elements on copper, with the X-axis representing the electron-atomic ratio and the Y-axis representing the stacking fault energy.

Claims (1)

A method for producing a wrought copper-based alloy material, comprising the steps of: 2. A method for producing a non-aging copper-based alloy wrought material having good toughness, high tensile strength, and excellent work hardening properties, comprising: (a) 2.0 to 6.0% by weight of aluminum and 1.5 to 3.0% by weight of silicon as starting materials; %, with the remainder essentially consisting of copper and unavoidable impurities, and the content of these alloying elements is such that the stacking fault energy of copper is 1
Copper-based alloys selected to reduce the reduction to less than 3 ergs per square centimeter, such that when subsequently annealed the alloying elements exist as substantially saturated equilibrium solid solutions within the copper matrix at room temperature. (b) hot rolling the alloy to predetermined dimensions; and (c) cold rolling the alloy to a predetermined temper condition. Through an intermediate annealing held at a temperature of 550-600°C and for a sufficient time for the alloy to exhibit good formability, cold rolling reduces the area by 50.
Tensile strength 84Kg/mm ² in temper-rolled condition
A method for producing a wrought copper-based alloy material, comprising the steps of: achieving the above properties and having an elongation of 3% or more. 3. A method for producing a non-aging copper-based alloy wrought material having good toughness, high tensile strength, and excellent work hardening properties, comprising: (a) 2.0 to 6.0% by weight of aluminum and 3.0 to 5.0% by weight of germanium as starting materials; %, the remainder consisting essentially of copper and unavoidable impurities, the content of these alloying elements being selected to reduce the stacking fault energy of the copper to below 3 ergs per square centimeter, followed by annealing. (b) preparing by casting a copper-based alloy such that when the alloying elements are present at room temperature as solid solutions in substantially saturated equilibrium within a matrix of copper; (c) cold rolling the alloy to a predetermined temper condition at a temperature of 550 to 600°C and such that the alloy exhibits good formability; Through intermediate annealing that is held for a sufficient period of time, the area reduction rate in cold rolling can be reduced.
Tensile strength 84Kg/mm ² in 50% temper rolled state
A method for producing a wrought copper-based alloy material, comprising the steps of: making it have the above characteristics and an elongation of 3% or more.