A high-temperature-resistant, fatigue-resistant, high-strength, high-conductivity copper alloy and its preparation method

Abstract

The present invention provides a high-temperature, fatigue-resistant, high-strength, and high-conductivity copper alloy and a preparation method thereof, relating to the technical field of alloy materials. The high-temperature, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention comprises the following elements, measured by mass percentage: Cr: 0.8-1.2%, Sn: 0.4-1.0%, Zr: 0.15-0.3%, Nb: 0.1-0.5%, and the remainder is Cu. The high-temperature, fatigue-resistant, high-strength, and high-conductivity copper alloy comprises a primary spherical Cr-rich phase and a primary Cr2Nb phase. The primary spherical Cr-rich phase has a size of 5-10 μm, and the primary Cr2Nb phase has a size of 10-20 μm. The average grain size of the high-temperature, fatigue-resistant, high-strength, and high-conductivity copper alloy in the longitudinal direction is 20-40 μm. The copper alloy provided by the present invention combines excellent high-temperature resistance and fatigue resistance with high strength and high conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and in particular to a high-temperature resistant, fatigue-resistant, high-strength, high-conductivity copper alloy and a preparation method thereof. Background Art

[0002] The development of high-strength and high-conductivity copper alloys has generally gone through three stages. The first stage, from the 1960s, was when copper was generally alloyed with elements that did not significantly reduce conductivity, such as Ag, Cd, As, Te, and Rb. The resulting materials had conductivity exceeding 90% IACS, but their strength and other properties were less than ideal. The second stage, from the 1970s onwards, began to select strengthening phase elements with low solid solution content and the ability to precipitate during aging. The use of thermomechanical treatment methods promoted the sufficient precipitation of the solid solution elements as nano-second phase particles, resulting in a synergistic improvement in conductivity and strengthening effects. However, their resistance to high-temperature softening was poor. The third stage, from the 1980s onwards, focused on the selection of alloying elements to conserve precious metals and avoid the addition of toxic elements (such as Ag, Cd, and As). The main focus was on developing copper alloys containing Cr, Zr, Ni, Si, Fe, Mg, Sn, Zn, P, RE, and Ti to improve their resistance to high-temperature softening. Attention was also paid to improvements and innovations in the preparation process.

[0003] With the development of many emerging science and technology industries in my country, key components of major equipment are becoming larger and thinner. Their service environments are also becoming increasingly harsh, requiring them to operate under the coupled effects of heat, force, and loading. This places increasingly stringent demands on the heat resistance and fatigue properties of copper alloys used in these components. Existing high-strength and high-conductivity copper alloys struggle to meet these requirements. Summary of the Invention

[0004] The object of the present invention is to provide a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy and a preparation method thereof. The copper alloy provided by the present invention has good high-temperature resistance and fatigue resistance, as well as high strength and high conductivity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, which comprises the following elements by mass percentage: Cr: 0.8-1.2%, Sn: 0.4-1.0%, Zr: 0.15-0.3%, Nb: 0.1-0.5%, and the remainder is Cu;

[0007] The high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy comprises a primary spherical Cr-rich phase and a primary Cr2Nb phase; the size of the primary spherical Cr-rich phase is 5 to 10 μm, and the size of the primary Cr2Nb phase is 10 to 20 μm;

[0008] The average grain size of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy in the longitudinal direction is 20 to 40 μm.

[0009] Preferably, it further comprises at least two of Mg, Si and Nd, wherein the content of Nd is 0.005-0.01%, the content of Si is 0.005-0.01%, and the content of Mg is 0.01-0.05%.

[0010] Preferably, at room temperature, the tensile strength is 500-600 MPa, the plastic elongation is 6-15%, the conductivity is 62-72% IACS, and the softening temperature is 550-660°C; the number of low-cycle fatigue cycles at a strain ratio of -1, a strain amplitude of 0.15%, a cyclic loading frequency of 5 Hz, and room temperature is 50,000-80,000.

[0011] The present invention provides a method for preparing the high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy described in the above scheme, comprising the following steps:

[0012] Corresponding to the element composition of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, the prepared raw materials are melted and then cast to obtain a casting billet;

[0013] Performing multi-directional hot forging on the ingot to obtain a forging;

[0014] The forging is subjected to solution treatment and aging treatment in sequence to obtain the high-temperature-resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0015] Preferably, the multi-directional hot forging is three upsetting and three drawing; the deformation of each upsetting and drawing is 60-80%, the initial forging temperature is 850-900°C, the final forging temperature is ≥700°C, and the forging speed is 6-10 mm / s.

[0016] Preferably, the temperature of the solution treatment is 950-1000° C., the holding time is 4-6 hours, and the cooling method is water cooling.

[0017] Preferably, the temperature of the aging treatment is 450-550° C., and the holding time is 1-8 hours.

[0018] Preferably, the raw materials include electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy and copper-niobium master alloy.

[0019] Preferably, when the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy further includes at least two of Mg, Si, and Nd, the preparation raw materials further include at least two of three intermediate alloys of copper-silicon, copper-neodymium, and copper-magnesium.

[0020] Preferably, the smelting temperature is 1350-1400°C, and the casting temperature is 1240-1280°C.

[0021] The present invention provides a high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, which includes the following elements, calculated by mass percentage: Cr: 0.8-1.2%, Sn: 0.4-1.0%, Zr: 0.15-0.3%, Nb: 0.1-0.5%, and the remainder is Cu; the high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy includes a primary spherical Cr-rich phase and a primary Cr2Nb phase; the size of the primary spherical Cr-rich phase is 5-10 μm, and the size of the primary Cr2Nb phase is 10-20 μm; the average grain size of the high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy in the longitudinal direction is 20-40 μm.

[0022] The copper alloy of the present invention has a primary Cr2Nb phase, which has high-temperature resistance. At the same time, the alloy also has a nanoscale Cr phase, which makes the alloy have high strength and high electrical conductivity. The grain size and primary phase refinement of the copper alloy of the present invention are uniform, which can significantly improve the uniformity of the material. The coordinated action of various elements produces a copper alloy with good high-temperature resistance and fatigue resistance, as well as high strength and high electrical conductivity.

[0023] The present invention provides a preparation method for the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy described in the above scheme. By performing multi-directional hot forging on the ingot, the grain size and primary phase of the alloy are significantly refined and uniform, significantly improving the material properties and uniformity; through subsequent solution treatment and aging treatment, the strength, conductivity, high-temperature resistance, and fatigue resistance of the alloy are significantly improved. Its tensile strength is 500-600 MPa, plastic elongation is 6-15%, conductivity is 62-72% IACS, high-temperature softening temperature is 550-600°C, and the number of low-cycle fatigue cycles is 50,000-80,000 (strain ratio -1, strain amplitude 0.15%, cyclic loading frequency 5Hz, room temperature). The comprehensive performance is significantly better than the QCr0.8 alloy used for the lining of the current rocket engine, and can meet the use requirements of the new generation of high-thrust rocket engine linings, high-speed railway contact network systems with a speed greater than 350 km / h, and new etched lead frames for high-strength and high-conductivity copper alloy materials. The QCr0.8 alloy has a cycle of 10 7 The fatigue strength under certain conditions is ≥60MPa (stress ratio is -1, room temperature). It is a disposable consumable and cannot be recycled. The copper alloy material of the present invention can be recycled, so the assessment is low-cycle fatigue. The tensile strength of QCr0.8 alloy is ≥230MPa, the elongation is ≥25%, the conductivity is ≥80%IACS, and the softening temperature is ≥500℃. DETAILED DESCRIPTION

[0024] The present invention provides a high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, which comprises the following elements by mass percentage: Cr: 0.8-1.2%, Sn: 0.4-1.0%, Zr: 0.15-0.3%, Nb: 0.1-0.5%, and the remainder is Cu;

[0025] The high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy comprises a primary spherical Cr-rich phase and a primary Cr2Nb phase; the size of the primary spherical Cr-rich phase is 5 to 10 μm, and the size of the primary Cr2Nb phase is 10 to 20 μm;

[0026] The average grain size of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy in the longitudinal direction is 20 to 40 μm.

[0027] Calculated by mass percentage, the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention includes 0.8-1.2% Cr, preferably 0.9-1.1%, and more preferably 1.0%.

[0028] Calculated by mass percentage, the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention includes 0.4-1.0% Sn, preferably 0.5-0.9%, and more preferably 0.6-0.8%.

[0029] Calculated by mass percentage, the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention includes 0.15-0.3% Zr, preferably 0.20-0.25%.

[0030] Calculated by mass percentage, the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention includes 0.1-0.5% Nb, preferably 0.2-0.4%, and more preferably 0.25-0.35%.

[0031] The high-temperature, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention preferably also includes at least two of Mg, Si, and Nd. The Nd content is preferably 0.005-0.01%, more preferably 0.006-0.009%, and even more preferably 0.007-0.008%. The Si content is preferably 0.005-0.01%, more preferably 0.006-0.009%, and even more preferably 0.007-0.008%. The Mg content is preferably 0.01-0.05%, more preferably 0.02-0.04%, and even more preferably 0.025-0.035%. In the present invention, the role of Mg is to control the size and morphology of the nanoscale Cr phase and the Zr-rich phase, thereby improving the strength of the alloy. The role of Si is mainly to form a Cr3Si phase with the Cr phase, further improving the strength and conductivity of the alloy. The role of Nd is the same as that of Mg.

[0032] The high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy provided by the present invention comprises a balance of copper.

[0033] In the present invention, the high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy includes a primary spherical Cr-rich phase and a primary Cr2Nb phase; the size of the primary spherical Cr-rich phase is 5 to 10 μm, preferably 6 to 9 μm; the size of the primary Cr2Nb phase is 10 to 20 μm, preferably 12 to 18 μm.

[0034] In the present invention, the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy preferably further includes a Zr-rich phase. In the present invention, the Zr-rich phase is beneficial for further improving the strength and conductivity of the copper alloy.

[0035] In the present invention, the average grain size of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy in the longitudinal direction is 20 to 40 μm, preferably 25 to 35 μm.

[0036] The invented copper alloy has a primary Cr2Nb phase, which has high-temperature resistance. At the same time, the alloy also has a nanoscale Cr phase, which gives the alloy high strength and high conductivity. The grain size and primary phase refinement of the copper alloy of the present invention are uniform, which can significantly improve the uniformity of the material. The coordinated effect of various elements produces a copper alloy with good high-temperature resistance and fatigue resistance, as well as high strength and high conductivity.

[0037] In the present invention, the high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy has a tensile strength of preferably 500-600 MPa, a plastic elongation of preferably 6-15%, a conductivity of preferably 62-72% IACS, and a softening temperature of preferably 550-660°C at room temperature; the number of low-cycle fatigue cycles at a strain ratio of -1, a strain amplitude of 0.15%, a cyclic loading frequency of 5 Hz and room temperature is preferably 50,000-80,000.

[0038] The present invention provides a method for preparing the high-temperature resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy described in the above scheme, comprising the following steps:

[0039] Corresponding to the element composition of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, the prepared raw materials are melted and then cast to obtain a casting billet;

[0040] Performing multi-directional hot forging on the ingot to obtain a forging;

[0041] The forging is subjected to solution treatment and aging treatment in sequence to obtain the high-temperature-resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0042] The present invention corresponds to the element composition of the high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy, and prepares raw materials by melting and then casting to obtain a casting blank.

[0043] In the present invention, the preparation raw materials preferably include electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy and copper-niobium master alloy; when the high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy also includes at least two of Mg, Si and Nd, the preparation raw materials preferably also include at least two of the three master alloys of copper-silicon, copper-neodymium and copper-magnesium.

[0044] In the present invention, the smelting is preferably performed in a vacuum induction furnace. In the present invention, the smelting temperature is preferably 1350-1400°C, more preferably 1360-1390°C, and even more preferably 1370-1380°C. In the present invention, the smelting preferably includes: adding the prepared raw materials to a vacuum induction furnace, raising the temperature to the smelting temperature, and after the melt is completely melted, introducing argon gas and stirring uniformly.

[0045] In the present invention, the casting temperature is preferably 1240-1280° C., more preferably 1250-1270° C., and even more preferably 1255-1265° C. In the present invention, the casting is preferably semi-continuous casting. In the present invention, the cast strand is preferably a round cast strand.

[0046] After obtaining the ingot, the present invention performs multi-directional hot forging on the ingot to obtain a forging.

[0047] In the present invention, the multi-directional hot forging is preferably three-upsetting and three-drawing; the deformation of each upsetting and drawing is preferably 60-80%, more preferably 65-75%; the initial forging temperature is preferably 850-900°C, more preferably 860-880°C; the final forging temperature is preferably ≥700°C, and the forging speed is preferably 6-10 mm / s, more preferably 7-9 mm / s. In the present invention, the three-upsetting and three-drawing process is preferably: upsetting 1 → square 1 → chamfering 1 → upsetting 2 → square 2 → chamfering 2 → upsetting 3 → square 3 → chamfering 3 → rounding and eliminating corners.

[0048] The invention performs multi-directional hot forging on the ingot, so that the grain size and primary phase of the alloy are obviously refined and uniform, and the material performance and uniformity are significantly improved.

[0049] After obtaining the forging, the present invention performs a solid solution treatment on the forging.

[0050] In the present invention, the solution treatment temperature is preferably 950-1000°C, more preferably 960-990°C, and even more preferably 970-980°C; the holding time is preferably 4-6 hours, more preferably 4.5-5.5 hours; and the cooling method is preferably water cooling. The present invention utilizes solution treatment to allow the alloying elements to completely dissolve back into the matrix, allowing for the precipitation of dispersed nanoscale precipitates during the subsequent aging treatment.

[0051] After the solution treatment is completed, the present invention performs aging treatment on the forging after the solution treatment to obtain the high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0052] In the present invention, the aging treatment temperature is preferably 450-550°C, more preferably 460-540°C, and further preferably 480-520°C; the holding time is preferably 1-8h, more preferably 2-6h, and further preferably 3-5h.

[0053] The high-temperature-resistant, fatigue-resistant, high-strength, high-conductivity copper alloy and its preparation method provided by the present invention are described in detail below with reference to the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] This embodiment uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-silicon and copper-neodymium master alloy. The alloy composition is shown in Example 1 in Table 1.

[0056] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-silicon and copper-neodymium master alloy into a vacuum induction furnace, raise the temperature to 1350°C, introduce argon gas after the melt is completely melted, and then stir evenly. The casting temperature is controlled at 1240°C. After holding for 20 minutes, semi-continuous casting is performed to form a round billet with a diameter of 100 mm.

[0057] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 900℃, kept warm for 10 hours, and then forged by three stages and three draws, with each stage and draw deformation of 60%, the final forging temperature of 710℃, and the forging speed of 6mm / s.

[0058] 3. Solution treatment: The above forgings are solution treated at a temperature of 950°C, kept at this temperature for 6 hours, and then water-cooled.

[0059] 4. Aging treatment: The forgings after the above-mentioned solid solution treatment are subjected to aging treatment at an aging temperature of 450°C and a holding time of 8 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0060] Example 2

[0061] This embodiment uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-silicon and copper-neodymium master alloy. The alloy composition is shown in Example 2 of Table 1.

[0062] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-silicon and copper-neodymium master alloy into a vacuum induction furnace, raise the temperature to 1400°C, introduce argon gas after the melt is completely melted, and then stir evenly. The casting temperature is controlled at 1280°C. After holding for 20 minutes, semi-continuous casting is carried out to form a round ingot with a diameter of 350 mm.

[0063] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 950℃, kept warm for 6 hours, and then forged in three stages and three draws, with each stage and draw deformation of 80%. The final forging temperature is 720℃ and the forging speed is 10mm / s.

[0064] 3. Solution treatment: The above forgings are solution treated at a temperature of 1000°C, kept warm for 4 hours, and water-cooled.

[0065] 4. Aging treatment: The forgings after the above solution treatment are subjected to aging treatment at an aging temperature of 550°C and a holding time of 1 hour to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0066] Example 3

[0067] This embodiment uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-magnesium master alloy, and copper-neodymium master alloy. The alloy composition is shown in Example 3 of Table 1.

[0068] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-magnesium and copper-neodymium master alloy into a vacuum induction furnace, raise the temperature to 1370°C, introduce argon gas after the melt is completely melted, and then stir evenly. The casting temperature is controlled at 1250°C. After holding for 20 minutes, semi-continuous casting is performed to form a round ingot with a diameter of 250 mm.

[0069] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 920℃, kept at this temperature for 6 hours, and then subjected to three-stage and three-draw forging, with each stage and drawing deformation of 70%, the final forging temperature of 720℃, and the forging speed of 8mm / s.

[0070] 3. Solution treatment: The above forgings are solution treated at a temperature of 975°C, kept at this temperature for 4 hours, and then water-cooled.

[0071] 4. Aging treatment: The forgings after the above solution treatment are subjected to aging treatment at an aging temperature of 500°C and a holding time of 4 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0072] Example 4

[0073] This embodiment uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-magnesium master alloy, and copper-silicon master alloy. The alloy composition is shown in Example 4 in Table 1.

[0074] 1. Melting: Before melting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-magnesium and copper-silicon master alloy into a vacuum induction furnace, raise the temperature to 1370°C, introduce argon gas after the melt is completely melted, and then stir evenly. The casting temperature is controlled at 1260°C. After holding for 20 minutes, semi-continuous casting is performed to form a round billet with a diameter of 150 mm.

[0075] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 930℃, kept at this temperature for 8 hours, and then subjected to three-stage and three-draw forging, with each stage and drawing deformation of 70%, the final forging temperature of 710℃, and the forging speed of 7mm / s.

[0076] 3. Solution treatment: The above forgings are solution treated at a temperature of 950°C, kept at this temperature for 5 hours, and then water-cooled.

[0077] 4. Aging treatment: The forgings after the above-mentioned solid solution treatment are subjected to aging treatment at an aging temperature of 500°C and a holding time of 8 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0078] Example 5

[0079] This example uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-magnesium master alloy, and copper-neodymium master alloy. The alloy composition is shown in Example 5 in Table 1.

[0080] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-magnesium and copper-neodymium master alloy into a vacuum induction furnace, raise the temperature to 1350°C, introduce argon gas after the melt is completely melted, and then stir evenly. The casting temperature is controlled at 1260°C, and after holding for 20 minutes, semi-continuous casting is performed into a round ingot with a diameter of 300 mm.

[0081] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 930℃, kept warm for 10 hours, and then forged by three stages and three draws, with each stage and draw deformation of 70%, the final forging temperature of 710℃, and the forging speed of 10mm / s.

[0082] 3. Solution treatment: The above forgings are solution treated at a temperature of 975°C, kept at this temperature for 5 hours, and then water-cooled.

[0083] 4. Aging treatment: The forgings after the above-mentioned solid solution treatment are subjected to aging treatment at an aging temperature of 525°C and a holding time of 6 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0084] Example 6

[0085] This example uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-magnesium master alloy, and copper-silicon master alloy. The alloy composition is shown in Example 6 in Table 1.

[0086] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-magnesium and copper-silicon master alloy into a vacuum induction furnace, raise the temperature to 1400°C, and after the melt is completely melted, introduce argon gas and stir evenly. The casting temperature is controlled at 1250°C. After holding for 20 minutes, semi-continuous casting is performed to form a round billet with a diameter of 240 mm.

[0087] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 930℃, kept warm for 10 hours, and then forged in three stages and three draws, with each stage and draw deformation of 80%. The final forging temperature is 705℃ and the forging speed is 6mm / s.

[0088] 3. Solution treatment: The above forgings are solution treated at a temperature of 975°C, kept at this temperature for 6 hours, and then water-cooled.

[0089] 4. Aging treatment: The forgings after the above-mentioned solid solution treatment are subjected to aging treatment at an aging temperature of 525°C and a holding time of 4 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0090] Example 7

[0091] This embodiment uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-magnesium master alloy, and copper-neodymium master alloy. The alloy composition is shown in Example 7 in Table 1.

[0092] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-magnesium and copper-neodymium master alloy into a vacuum induction furnace, raise the temperature to 1400°C, and after the melt is completely melted, introduce argon gas and stir evenly. The casting temperature is controlled at 1260°C. After holding for 20 minutes, semi-continuous casting is performed to form a round billet with a diameter of 270 mm.

[0093] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 950℃, kept warm for 10 hours, and then forged in three stages and three draws, with each stage and draw deformation of 75%, the final forging temperature of 705℃, and the forging speed of 8mm / s.

[0094] 3. Solution treatment: The above forgings are solution treated at a temperature of 975°C, kept at this temperature for 6 hours, and then water-cooled.

[0095] 4. Aging treatment: The forgings after the above solution treatment are subjected to aging treatment at an aging temperature of 550°C and a holding time of 4 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0096] Example 8

[0097] This embodiment uses the following raw materials for smelting: electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, copper-silicon and copper-neodymium master alloy. The alloy composition is shown in Example 8 in Table 1.

[0098] 1. Smelting: Before smelting, add electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy, copper-niobium master alloy, as well as copper-magnesium and copper-neodymium master alloy into a vacuum induction furnace, raise the temperature to 1350°C, introduce argon gas after the melt is completely melted, and then stir evenly. The casting temperature is controlled at 1260°C. After holding for 20 minutes, semi-continuous casting is performed to form a round ingot with a diameter of 240 mm.

[0099] 2. Multi-directional hot forging: The above alloy round billet is placed in a walking beam furnace and heated to 920℃, kept at this temperature for 8 hours, and then subjected to three-stage and three-draw forging, with each stage and drawing deformation of 70%, the final forging temperature of 705℃, and the forging speed of 7mm / s.

[0100] 3. Solution treatment: The above forgings are solution treated at a temperature of 975°C, kept at this temperature for 5 hours, and then water-cooled.

[0101] 4. Aging treatment: The forgings after the above-mentioned solid solution treatment are subjected to aging treatment at an aging temperature of 550°C and a holding time of 6 hours to obtain a high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

[0102] Comparative Example 1

[0103] The only difference from Example 1 is that one-time upsetting is adopted.

[0104] Table 1 Alloy composition formula of Examples 1 to 8 (wt%)

[0105]

[0106] The copper alloys prepared in Examples 1-8 and Comparative Example 1 were tested for microstructure and physical properties. The tensile strength, yield strength, and elongation were tested according to GB / T 228.1-2010, Metallic Materials - Tensile Tests - Part 1; the room temperature electrical conductivity was tested according to GB / T 32791-2016, Copper and Copper Alloys - Electrical Conductivity - Eddy Current Test Method; the softening temperature was tested according to GB / T 33370-2016, Copper and Copper Alloys - Determination of Softening Temperature; and the number of low-cycle fatigue cycles was tested according to GB / T 15248-2008, Metallic Materials - Axial Constant Amplitude Low-Cycle Fatigue Test Method. The test conditions were strain ratio -1, strain amplitude 0.15%, cyclic loading frequency 5 Hz, and room temperature. The results are shown in Tables 2 and 3.

[0107] Table 2 Microstructure characteristics of alloys of Examples 1 to 8 and Comparative Example 1

[0108] alloy Average longitudinal grain size / μm Size of primary spherical Cr-rich phase / μm <![CDATA[Size of primary Cr2Nb phase / μm]]> Comparative Example 1 30 15 25 Example 1 20 10 15 Example 2 24 8 10 Example 3 29 9 14 Example 4 34 7 12 Example 5 36 5 18 Example 6 40 7 20 Example 7 36 6 17 Example 8 30 8 15

[0109] Table 3 Physical properties of alloys of Examples 1 to 8 and Comparative Example 1

[0110]

[0111] It can be seen from the results in Table 2 and Table 3 that the present invention significantly refines and uniformizes the grain size and primary phase of the alloy by performing multi-directional hot forging on the ingot, thereby significantly improving the material properties and its uniformity; through subsequent solution treatment and aging treatment, the strength, conductivity, high temperature resistance and fatigue resistance of the alloy are significantly improved, and its tensile strength is 500-600 MPa, the plastic elongation is 6-15%, the conductivity is 62-72% IACS, the high temperature softening temperature is 550-600°C, and the number of low cycle fatigue cycles is 50,000-80,000. The comprehensive performance is significantly better than that of the QCr0.8 alloy used for the lining of current rocket engines.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high-temperature-resistant, fatigue-resistant, high-strength, high-conductivity copper alloy, characterized in that: Calculated by mass percentage, it includes the following elements: Cr: 0.8-1.2%, Sn: 0.4-1.0%, Zr: 0.17-0.3%, Nb: 0.2-0.5%, and the rest is Cu; The high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy comprises a primary spherical Cr-rich phase and a primary Cr2Nb phase; the size of the primary spherical Cr-rich phase is 5 to 10 μm, and the size of the primary Cr2Nb phase is 10 to 20 μm; The average grain size of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy in the longitudinal direction is 20 to 40 μm; At room temperature, the tensile strength of the high-temperature-resistant, fatigue-resistant, high-strength, high-conductivity copper alloy is 500-600 MPa, the plastic elongation is 6-15%, the conductivity is 62-72% IACS, and the softening temperature is 550-660°C; the number of low-cycle fatigue cycles at room temperature is 50,000-80,000 at a strain ratio of -1, a strain amplitude of 0.15%, a cyclic loading frequency of 5 Hz, and strain resistance of 0.15%. The preparation method of the high-temperature resistant, fatigue-resistant, high-strength and high-conductivity copper alloy comprises the following steps: Corresponding to the element composition of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, the prepared raw materials are melted and then cast to obtain a casting billet; Performing multi-directional hot forging on the ingot to obtain a forging; The forging is subjected to solution treatment and aging treatment in sequence to obtain the high-temperature-resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

2. The high-temperature-resistant, fatigue-resistant, high-strength, high-conductivity copper alloy according to claim 1, characterized in that: It also includes at least two of Mg, Si and Nd, wherein the content of Nd is 0.005-0.01%, the content of Si is 0.005-0.01%, and the content of Mg is 0.01-0.05%.

3. The method for preparing the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy according to any one of claims 1 to 2, characterized in that: The following steps are involved: Corresponding to the element composition of the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy, the prepared raw materials are melted and then cast to obtain a casting billet; Performing multi-directional hot forging on the ingot to obtain a forging; The forging is subjected to solution treatment and aging treatment in sequence to obtain the high-temperature-resistant, fatigue-resistant, high-strength and high-conductivity copper alloy.

4. The preparation method according to claim 3, characterized in that The multi-directional hot forging is three-upsetting and three-drawing; the deformation of each upsetting and drawing is 60-80%, the initial forging temperature is 850-900°C, the final forging temperature is ≥700°C, and the forging speed is 6-10 mm / s.

5. The preparation method according to claim 3, characterized in that The temperature of the solution treatment is 950-1000° C., the holding time is 4-6 hours, and the cooling method is water cooling.

6. The preparation method according to claim 3, characterized in that The temperature of the aging treatment is 450-550° C., and the holding time is 1-8 hours.

7. The preparation method according to claim 3, characterized in that The preparation raw materials include electrolytic copper, pure tin, copper-chromium master alloy, copper-zirconium master alloy and copper-niobium master alloy.

8. The preparation method according to claim 3 or 7, characterized in that When the high-temperature-resistant, fatigue-resistant, high-strength, and high-conductivity copper alloy further includes at least two of Mg, Si, and Nd, the preparation raw materials further include at least two of three intermediate alloys of copper-silicon, copper-neodymium, and copper-magnesium.

9. The preparation method according to claim 3 or 7, characterized in that The smelting temperature is 1350-1400°C, and the casting temperature is 1240-1280°C.

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