Ultralow-temperature high-toughness copper alloy material and preparation method thereof

Abstract

The invention discloses an ultralow-temperature high-toughness copper alloy material and a preparation method thereof, and belongs to the technical field of ultralow-temperature high-toughness non-ferrous metal materials. The material comprises the following components in percentage by mass: 15-25% of nickel (Ni); manganese (Mn): 2-6%; 2.5%-6.5% of aluminum (Al); 0.2-1.0% of phosphorus (P), and the balance of copper and inevitable impurities. The preparation method comprises the following steps: preparing materials (pure Cu, pure nickel and pure manganese), melting, preserving heat, cooling, melting Cu-P intermediate alloy and pure aluminum, preserving heat, casting and molding, forging, and carrying out solid solution aging heat treatment. Compared with the prior art, the invention has the following advantages: by adding strengthening elements such as aluminum, phosphorus, nickel and the like, the obtained material can still maintain high toughness at ultralow temperature, and is applicable to the fields of mechanical equipment, spaceflight, traffic and the like applied in extremely cold and ultralow temperature environments.

Description

Technical Field

[0001] The present invention relates to the technical field of nonferrous metal materials, and in particular to an ultra-low temperature high-toughness copper alloy material and a preparation method thereof. Background Art

[0002] When the temperature drops, the strength, elastic modulus and fatigue resistance of most metals or alloys are improved, but the toughness is reduced. In addition to the lattice type, the influencing factors are also affected by chemical composition, microstructure (such as inclusions, bubbles, grain size, etc.), structural defects and micro stress, and the traditional method of studying metal micro stress and structural defects is not easy to achieve in-situ measurement of materials during temperature changes. This type of material also has a wider application prospect in major fields such as aviation, space satellites, and deep-sea exploration. The copper and copper processing industry in our province has a solid foundation and strong industrialization strength, which points out a new direction for the expanded application of materials and is more favorable.

[0003] Based on the requirements of components for ultra-low temperature application conditions in extremely cold regions, outer space, and liquid oxygen and liquid nitrogen environments, our team has successfully developed ultra-low temperature and high-toughness copper alloy materials with high impact toughness and safety adaptability, which has effectively solved the special performance requirements of components for materials in ultra-low temperature environments.

[0004] A large number of experimental results show that copper-nickel alloys with infinite solubility have similar crystal structures and close lattice constants, and will not undergo ductile-brittle transition at room temperature and low temperature, and have relatively excellent low-temperature high toughness properties. The room temperature impact energy of a certain annealed cupronickel alloy disclosed by the National Bureau of Standards of the United States can reach 150J; and when the temperature is reduced from room temperature, the impact energy of the alloy remains almost unchanged, indicating that cupronickel alloy is an excellent low-temperature alloy. At the same time, due to the spark insensitivity of nickel and copper themselves in oxygen-rich environments, they have been widely used in ultra-low temperature oxygen-rich environments. The US spacecraft material standard NASA-STD-8719.15 has clearly defined copper-nickel alloys as the development direction of ultra-low temperature copper alloy materials. Foreign research on copper alloy materials in ultra-low temperature environments has gradually formed an alloy series used in oxygen-rich environments, mainly copper-nickel alloys, such as MONEL400, K500, etc. Therefore, in response to the engine components' demands for high strength, wear resistance and high toughness, we have developed an ultra-low temperature, high-toughness copper alloy material. While meeting the strength and wear resistance requirements, its good toughness also ensures the stable use of components at ultra-low temperatures.

[0005] In response to market demand, the technology of the present invention introduces strengthening elements into the copper matrix and obtains in-situ precipitation strengthening phase through solid solution aging heat treatment, thereby improving the strength of the material while maintaining high toughness of the material. Summary of the invention

[0006] The purpose of the present invention is to solve the problems mentioned in the background technology and to provide an ultra-low temperature high-toughness copper alloy material and a preparation method thereof, so that it can be used in mechanical equipment, aerospace, transportation and other fields used in extremely cold and ultra-low temperature environments.

[0007] In order to solve the above technical problems, the technical solution provided by the present invention is: an ultra-low temperature and high-toughness copper alloy material, characterized in that the material composition includes, by mass percentage: nickel (Ni): 15-25%; manganese (Mn): 2-6%; aluminum (Al): 2.5-6.5%; phosphorus (P): 0.2-1.0%, and the remainder is copper and unavoidable impurities.

[0008] Furthermore, the mass percentage of the unavoidable impurities is ≤0.5% in total.

[0009] Furthermore, the effect of the strengthening element phosphorus (P) has to be considered, and its content is controlled at 0.2-1.0%.

[0010] The damping alloy of the present invention belongs to a solid solution aging alloy. Based on the infinite solid solution of copper and nickel, the alloy precipitates the strengthening phase NiAl3 and part of NiMn in situ through the implementation of the solid solution aging heat treatment process, so that no third phase will be precipitated when the material is subjected to deep cryogenic treatment, and the structure is stable. Therefore, the role of the element P must be considered, and the element is an effective deoxidizer for copper alloys.

[0011] The present invention also provides an ultra-low temperature high-toughness copper alloy material and a preparation method thereof, which is mainly a preparation process of adding alloy elements by non-vacuum melting and casting, comprising: first weighing pure Cu, electrolytic nickel, Cu-P master alloy, pure zinc, pure aluminum, and pure manganese according to a proportion, and melting them in a non-vacuum induction furnace.

[0012] The specific steps include: (1) material preparation: taking pure Cu, Cu-P master alloy, pure nickel, pure aluminum and pure manganese as raw materials according to the mass ratio, and drying the non-vacuum induction furnace and the raw materials; (2) smelting: placing pure Cu, pure nickel and pure manganese in a graphite crucible and smelting them in a non-vacuum induction furnace, wherein firstly adding a composite salt covering agent (charcoal fragments with a thickness of more than 100 mm for oxidation isolation) and heating to 1230°C to 1250°C, keeping the temperature for 1 to 1.5 hours, then cooling to 1200°C to 1230°C, adding Cu-P master alloy and pure aluminum and keeping the temperature for 20 to 45 minutes, and when the alloy is completely melted, lowering the temperature to 1150°C to 1200°C, and then casting and molding. (3) Forging process: the ingot is forged after surface machining and turning, with the forging heating temperature at 850°C and insulation for 3 hours, and the total forging processing volume is not less than 50%; (4) the forging is subjected to solution aging heat treatment, with the solution temperature at 650-700°C and insulation for 3 hours, and the aging temperature at 450°C and insulation for 3-8 hours.

[0013] In the present invention, the specifications of the main raw materials used are as follows: pure copper block, T1 or T2 grade, purity ≥99.9wt.%; pure nickel block, purity ≥99.9wt.%; pure aluminum block, purity ≥99.9wt.%; pure manganese block, purity ≥99.9wt.%. Cu-P master alloy (preferably Cu-3P master alloy) is used, and the auxiliary raw material is a composite salt covering agent. P, Al and other elements are very easy to burn in the air, and the metal burning rate during the smelting process is P: 7%, Al: 15%.

[0014] The addition of aluminum, manganese, phosphorus and elements with deoxidation and strengthening effects, on the one hand, forms intermetallic compounds that precipitate after aging treatment and improve the strength of the material by preventing the migration of dislocations. They can serve as external nucleation cores during the solidification process to increase the nucleation rate of the solidification structure, thereby refining the grains; on the other hand, in the subsequent heat treatment and aging process, they will precipitate in the form of strengthening phases and be distributed within the crystals or on grain boundaries, thereby improving the tensile strength of the material and improving the wear resistance of the material.

[0015] The advantages of the present invention over the prior art are that by adding strengthening elements and adopting a solid solution strengthening and aging process to obtain an ultra-low temperature high-toughness copper alloy material, a relatively ultra-low temperature toughness can be obtained, and a relatively high strength and a good elongation can be maintained. The ultra-low temperature high-toughness copper alloy material obtained by the present invention has a tensile strength of 700-1000MPa, an elongation of up to 40%, and a low temperature impact toughness of up to 30J (Akv). DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] An ultra-low temperature and high-toughness copper alloy material, the production process method of which is as follows:

[0018] (1) Ingredients: Take pure copper (such as T1 or T2 grade), pure Cu, Cu-P master alloy, pure nickel, pure manganese and pure aluminum as raw materials according to the mass ratio.

[0019] (2) Melting: Put pure copper block, Cu-Fe master alloy, pure nickel and pure manganese into a non-vacuum induction furnace, heat to 1230℃~1250℃, keep warm for 1~1.5h, then cool to 1200℃~1230℃, add Cu-P master alloy and pure aluminum and keep warm for 20~45min, and lower the temperature to 1150℃~1200℃ after all the alloys are melted, and then cast into shape.

[0020] (3) Forging: The ingot is forged after surface machining and turning. The forging heating temperature is 850℃ for 3h, and the total forging processing volume is not less than 50%;

[0021] (4) Solution aging heat treatment: solution temperature 650-700℃ for 3h, aging temperature 450℃ for 3-8h.

[0022] Example 1

[0023] The specific process is: prepare the materials according to the ingredients in Table 1, phosphorus (P): 0.2-1.0%.

[0024] Table 1 Composition of an ultra-low temperature high toughness copper alloy material (wt.%)

[0025]

[0026] Put pure copper block, Cu-Fe master alloy, pure nickel and pure manganese into a non-vacuum induction furnace, heat to 1250℃, keep warm for 1.5h, then cool to 1230℃, add Cu-P master alloy and pure aluminum and keep warm for 45min, and lower the temperature to 1200℃ after the alloy is completely melted, and then cast. The ingot is forged after surface machining and turning, with a forging heating temperature of 850℃ and a heat preservation of 3h, and a total forging processing of 70%; the solution temperature is 700℃ and a heat preservation of 3h, and the aging temperature is 450℃ and a heat preservation of 8h. The properties of the prepared finished product are shown in Table 2.

[0027] Table 2 Performance of Example (-193℃ Mechanical Properties)

[0028]

[0029] Example 2

[0030] The specific process is: prepare the materials according to the ingredients in Table 3, phosphorus (P): 0.2-1.0%.

[0031] Table 3 Composition of an ultra-low temperature high toughness copper alloy material (wt.%)

[0032]

[0033] Put the pure copper block, Cu-Fe master alloy, pure nickel and pure manganese into a non-vacuum induction furnace, heat to 1230℃, keep it warm for 1h, then cool it down to 1200℃, add Cu-P master alloy and pure aluminum and keep it warm for 20min, and lower the temperature to 1170℃ after the alloy is completely melted, and then cast it. The ingot is forged after surface machining and turning, with a forging heating temperature of 850℃ and a heat preservation of 3h, and a total forging processing amount of 60%; the solution temperature is 650℃ and a heat preservation of 3h, and the aging temperature is 450℃ and a heat preservation of 3h. The properties of the prepared finished product are shown in Table 4.

[0034] Table 4 Example performance (-193℃ mechanical properties)

[0035]

[0036] Example 3

[0037] The specific process is: prepare the materials according to the ingredients in Table 5, phosphorus (P): 0.2-1.0%.

[0038] Table 5 Composition of an ultra-low temperature high-toughness copper alloy material (wt.%)

[0039]

[0040] Put the pure copper block, Cu-Fe master alloy, pure nickel and pure manganese into a non-vacuum induction furnace, heat to 1240℃, keep it warm for 1.2h, then cool it down to 1210℃, add Cu-P master alloy and pure aluminum and keep it warm for 30min, and lower the temperature to 1150℃ after the alloy is completely melted, and then cast it. The ingot is forged after surface machining and turning, with a forging heating temperature of 850℃ and a heat preservation of 3h, and a total forging processing of 50%; the solution temperature is 650℃ and a heat preservation of 3h, and the aging temperature is 450℃ and a heat preservation of 5h. The properties of the prepared finished product are shown in Table 6.

[0041] Table 6 Performance of the embodiment

[0042]

[0043] The present invention finally obtains a copper alloy material with good ultra-low temperature and high toughness by adding alloy elements such as aluminum, nickel, manganese and phosphorus.

[0044] The above is only a preferred embodiment of the present invention and does not limit the invention. It should be pointed out that for ordinary technicians in this field, under the technical enlightenment provided by the present invention, other equivalent improvements can be made, all of which can achieve the purpose of the present invention and should be regarded as the protection scope of the present invention.

Claims

1. An ultra-low temperature and high toughness copper alloy material, characterized in that: The composition includes, by mass percentage, 15-25% nickel, 2-6% manganese, 2.5-6.5% aluminum, 0.2-1.0% phosphorus, and the remainder copper and unavoidable impurities.

2. The ultra-low temperature and high toughness copper alloy material according to claim 1, characterized in that: The mass percentage of the unavoidable impurities is ≤0.5% in total.

3. A method for preparing an ultra-low temperature high-toughness copper alloy material, characterized in that: The specific steps include: 1) Material preparation: pure Cu, Cu-P master alloy, pure nickel, pure aluminum and pure manganese are taken as raw materials according to the mass ratio, and the non-vacuum induction furnace and the raw materials are dried; 2) Melting: pure Cu, pure nickel and pure manganese are placed in a graphite crucible and melted in a non-vacuum induction furnace, wherein a composite salt covering agent is first added and heated to 1230°C to 1250°C, and then the temperature is lowered to 1200°C to 1230°C after being kept warm for 1 to 1.5 hours, and Cu-P master alloy and pure aluminum are added and kept warm for 20 to 45 minutes. After the alloy is completely melted, the temperature is lowered to 1150°C to 1200°C, and then casting is performed; 3) Forging: The ingot is forged after surface machining and turning. The forging heating temperature is 850℃ for 3h, and the total forging processing volume is not less than 50%; 4) Solution aging heat treatment: The forgings are subjected to solution aging heat treatment, with the solution temperature at 650-700℃ for 3h and the aging temperature at 450℃ for 3-8h.

4. The method for preparing an ultra-low temperature high-toughness copper alloy material according to claim 3, characterized in that: The specifications of the raw materials are as follows: Pure copper block, T1 or T2 grade, purity ≥ 99.9wt.%; Pure nickel block, purity ≥99.9wt.%; Pure aluminum block, purity ≥99.9wt.%; Pure manganese block, purity ≥99.9wt.%.

5. The method for preparing an ultra-low temperature high-toughness copper alloy material according to claim 4, characterized in that: The Cu-P master alloy is a Cu-3P master alloy, and the auxiliary raw material is a composite salt covering agent; The metal loss rate of P element during smelting is 7%; The metal burnout rate of Al element during the smelting process is 15%.

6. The method for preparing an ultra-low temperature high-toughness copper alloy material according to claim 3, characterized in that: In the step 2), the composite salt covering agent is charcoal fragments with a thickness of more than 100 mm for oxidation isolation.

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