JPH02179839A - High strength copper alloy having excellent impact resistance - Google Patents

Abstract

PURPOSE:To obtain the alloy having high strength and excellent impact resistance by specifying the contents of Ni, Si, Al and Cr in a copper alloy and regulating the amt. of Si by the relationship of Ni+Cr. CONSTITUTION:The alloy is formed with the compsn. constituted of, by weight, 3 to 10% Ni, 0.7 to 2.5% Si, 2 to 6% Al and 0.1 to 1.0% Cr as well as satisfying 1.2Cr+0.24Ni>=0.9Si and the balance Cu. If required, 0.05 to 0.5% of one or more kinds among Zr, Ti and Nb are furthermore incorporated thereto. Since the Cu-base alloy has excellent hot workability, its application to large-sized parts can be expanded.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a high-strength steel alloy with excellent impact resistance, particularly for mechanical parts that require impact resistance and wear resistance (eg, rifle nuts for rock drilling). It is suitable for mechanical parts that require low electrical resistance, non-magnetism, and impact resistance (eg, room-temperature rotor for superconducting generators). (Conventional technology and problems to be solved) In recent years, continuous
As the operating conditions of industrial machinery are becoming harsher, such as high-load use, the characteristics required of power transmission parts and sliding parts of various industrial machines are becoming stricter. Therefore, there are cases where conventional materials cannot fully satisfy the requirements. Specifically, the details are as follows. Traditionally, various phosphor bronze materials specified by JIS have been the most commonly used materials, but their wear resistance and impact resistance are not sufficient, and they have not been improved in strength through cold working. Because of this, there are size restrictions and there are economical problems. In addition, various aluminum bronze materials specified by JIS do not have sufficient wear resistance, while wear-resistant steel alloys (Japanese Patent Application No. 61-044872) and copper alloys for plastics (Japanese Patent Application No. 16491-1987) Although the former has sufficient wear resistance, it has poor impact resistance, and the latter has poor impact resistance. In addition, the so-called CA gold alloy Cor, which was developed as a material for long-span type wires,
son alloy) is known. A Cu-Ni2Si pseudo-binary alloy (3-6% Al
, some containing up to 10% Zn), and are subjected to solution treatment, quenching, tempering and age hardening treatment after hot working and cold working, and are materials with relatively good electrical conductivity, but There is a problem with machinability. The object of the present invention is to eliminate the drawbacks of the above-mentioned prior art, and to provide a material that has high strength and excellent impact resistance, and is applicable to large mechanical parts. (Means for Solving the Problems) As a material that can satisfy the above-mentioned characteristics, the present inventors first of all: (1) improve impact resistance and abrasion resistance compared to conventional materials, and increase durability. (2) Improving strength and impact resistance without cold working. (3) By improving hot workability, it can be applied to large mechanical parts. As a result of examining various materials from the viewpoint of
In base alloys, high strength and WI resistance can be achieved without cold working.
We conducted extensive research to find ways to improve the impact properties and hot workability. As a result, the following findings (1) to (4) were obtained, and the present invention was made. (2) Nx and Si, which are precipitation hardening elements, are added to Cu to disperse and precipitate intermetallic compounds such as Ni2Si to improve strength. (2) However, since sufficient toughness cannot be obtained by the method (2), Al, which is an α-phase solid solution strengthening element, is added to improve the toughness. (2) This Cu-Ni-S i -A Q system has poor hot workability due to low drawing and elongation at high temperatures, so Cr is added to improve hot workability. (2) Since impact resistance is affected by grain size, grain size refining elements such as Ti, Zr, and Nb are appropriately added to improve toughness and strength. ■ Si is an embrittlement element, and when Si is dissolved in the α phase, the toughness decreases. To prevent this, Ni
, Si, CrSi, etc. to fix Si as a precipitate, and the amount of Si is regulated in relation to the amount of Cr and Ni in order to prevent excessive free Si. That is, in the present invention, Ni: 3 to 10%, 5ilo. 7 to 2.5%, Al: 2 to 6%, and Cr: 0.1 to 1. The gist of the invention is a high-strength copper alloy with excellent impact resistance, characterized by containing 0.05 to 0.5% of one or more of these, with the remainder being Cu. The present invention will be explained in further detail below. First, the reasons for limiting the chemical components in the present invention are as follows. Ni: 3 to 10% Ni forms a precipitate (Ni2Si) with Si and is dispersed and precipitated in the α phase that is the parent structure, so it is an important element for improving strength. However, if it is less than 3%, sufficient strength cannot be obtained even if a theoretical amount of Si is present. Also, N
Since i improves toughness by solid solution in α phase,
It is necessary to use a stoichiometric amount or more, but if the amount is 10% or more, the improvement effect becomes saturated. Therefore, the amount of Ni is in the range of 3 to 10%. Si: 0.7-2.5% Si is a mixture of Ni and Cr and precipitates (Ni, Si, CrSi,
etc.) and is an important element for improving strength. but,
If it is less than 0.7%, precipitation strengthening will not be sufficient, and 2.
If it exceeds 5%, the strength improving effect is saturated, the amount of precipitates increases, and the toughness decreases. therefore,
The amount of Si is in the range of 0.7 to 2.5%. Cr: 0.1 to 1.0% Cr is added to improve drawing and elongation at high temperatures, and is a necessary element to facilitate hot working. The effect is recognized from 0.1%, but the improvement effect is saturated at more than 1.0%. Therefore, the amount of Cr is 061~1
．． The range is 0%. However, Si needs to be regulated in relation to the above-mentioned Ni and Cr contents. That is, unless Si is fixed as a silicide, it causes a decrease in toughness. Therefore, Ni, Si, CrS
It must not be contained in much excess than the amount calculated from the stoichiometry of i2, and it is necessary to satisfy the following formula 1, %. Al: 2.0 to 6.0% Al is an element necessary to strengthen the α phase and is also essential for improving toughness. It also has the effect of improving high-temperature oxidation resistance when exposed to high temperatures.6 However, 2.
At less than 0%, no toughness improvement effect is observed, and at 6.0%
In the case of a larger amount, the toughness decreases because the hard and brittle third phase is formed along the grain boundaries without being completely dissolved in the α phase. Therefore, A
The amount of l is in the range of 2°0 to 6.0%. One or more of Zr, Ti and Nb: 0.05
~0.5% Zr, Ti, and Nb are elements for refining crystal grains. It has the effect of improving toughness and strength, and is particularly effective in improving impact resistance properties, which are affected by grain size. In addition, these elements, together with Cr, are recognized to have the effect of improving hot workability.
One or more of these elements can be added in appropriate amounts. When added, one or more of these elements should be in the range of 0.05 to 0.5%. 0.05
Such an effect is not significant below 0.5%.
Even if it is added in excess of this amount, the refinement effect will be saturated. The above-mentioned Cu-based alloy is produced by subjecting it to solution treatment and aging treatment after hot working, and it has excellent impact resistance, high strength, and excellent hot workability. It can also be applied to large parts. (Example) Next, an example of the present invention will be shown. An ingot produced by a conventional method from a copper alloy having the chemical components shown in Table 1 was hot worked at a reduction rate of approximately 75% at 750 to 850°C, and then subjected to solution treatment and aging treatment. did. However, since the comparative material Nα10 could not be sufficiently hot worked, it was subjected to cold working and aging treatment after solution treatment. Further, the comparison material Nα8 was tested after hot working at a rolling reduction rate of about 75%, and the comparison materials Nα7 and h9 were commercially available materials. The tensile strength, elongation, hardness, impact value, and wear amount of the obtained test materials are also listed in Table 1. The amount of wear was measured by the Odate wear test method under the following test conditions. In the wear test, as shown in Fig. 1, a rotating disk (counterpart material) 2 with a radius r and a diameter of 30 mmφ x 3 mm was pressed against a test piece 1 with dimensions of 10 mm x 20 mm x 30 mm with a constant load.
The amount of wear was measured using the following formula. ab' where, W: Amount of wear on the test piece (, m3) a: Thickness of the mating material (-m) b: Width of wear scar (mIn) (see Figure 2) r: Radius of the mating material (mm) ) Wear test conditions〉 Compatible material: SCM440 (carburized and quenched material), RC60 Load: 19.8kg (constant) Friction speed: 0.94m/see Friction distance: 600m Lubrication conditions: Number of non-lubricated tests: n = 3rd From Table 1, the following considerations can be made. Na 1 to Na 10 are comparative materials, and N(111-N
[116 is the material of the present invention. Comparative materials Nα1 to &2 have lower impact values than inventive materials &12 and Nα14 because the amount of Al is not appropriate. Comparative material Nα3 does not have sufficient strength due to insufficient Si content, and has a lower value than inventive material Nα13. Comparison material 4 is a case where excessive Ni and Si are included,
Although the hardness has improved, the impact value has decreased significantly. Comparison material 5 has an imbalance of Sl, Ni, and Cr, and S
The impact value is reduced because i is excessive. Comparative material No. 6 has Ni content below the appropriate range, and cannot be said to be sufficient in terms of strength and impact value. Comparative materials 1llQ7 and Nα9, commercially available materials, are improved in strength by cold working, but cannot be said to be sufficient in terms of Wf impact value and wear resistance. Comparative materials Nα8 and Na10 do not have sufficient impact values. On the other hand, all of the materials of the present invention have high impact values, sufficient strength, and exceed commercially available materials (Nα7, Nα9) in terms of wear resistance.

[Left below]

In this example, the influence of Cr addition on hot workability was investigated. In the experiment, 5.1%Al-5.3%Ni-1.3%Si
- Using the composition of the remaining Cu as a base material, ingots were prepared by adding various amounts of Cr to this, and the elongation of these ingots at various temperatures (high temperatures) was investigated. The results are shown in FIG. As is clear from Fig. 3, compared to the Cr-free material, 0.
By adding 1% Cr, the elongation at high temperatures is significantly improved. Even with the addition of 60.9% Cr, the degree of improvement is not much different. Note that when hot working, solution treatment, and aging treatment were performed on the copper alloy to which Cr was added in these amounts under the same conditions as the inventive material of Example 1, the same results as the inventive material of Example 1 were obtained. Good results were obtained. (Effects of the Invention) As detailed above, according to the present invention, it is possible to have excellent impact properties and increase strength without cold working. Furthermore, since hot workability is improved, the application to large parts is expanded. Specific properties include impact value of 5 kg-m and tensile strength of 7.
0 kgf/mm" or more, and its industrial value is great.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams explaining the outline of the Odate wear test method. Figure 1 shows the test outline, Figure 2 shows the wear scar width, and Figure 3 shows the amount of Cr added. It is a figure showing the relationship between and high temperature elongation. Patent applicant Takashi Nakamura, Patent attorney representing Kobe Steel, Ltd. 1st shipment! ↓ Figure 3 Figure 2 I Rokujima broiled hair/! (゛gon

Claims (1)

[Claims] (1) In weight% (the same applies hereinafter), Ni: 3 to 10%, S
i: 0.7-2.5%, Al: 2-6% and Cr: 0.
1 to 1.0%, and satisfies the following formula: 1.2Cr+0.24Ni≧0.9Si, with the remainder being Cu. A high-strength copper alloy with excellent impact resistance. (2) Ni: 3-10%, Si: 0.7-2.5%, A
1 to 6% and Cr: 0.1 to 1.0%, and further contains 0.1 to 0.1% of one or more of Zr, Ti, and Nb.
A high-strength copper alloy with excellent impact resistance, characterized by containing 05 to 0.5% and satisfying the following formula: 1.2Cr+0.24Ni≧0.9Si, with the remainder being Cu.