Softening Resistant Copper Alloy, Preparation Method, and Application Thereof

Abstract

A softening resistant copper alloy, a preparation method, and an application thereof, the softening-resistant copper alloy, comprising 0.1%-1.0 wt % Cr, 0.01%-0.2 wt % Zr, 0.01%-0.10 wt % Si, and 0.10 wt % Fe, and with the remaining of copper and inevitable impurities, wherein the microstructure of the copper alloy contains comprises: an elemental Cr phase, a Cu.sub.5Zr phase, and a Cr.sub.3Si phase. In the copper alloy of the present invention, the high-temperature softening resistance effect of the material is improved by adding a proper amount of Si to form a compound Cr.sub.3Si, and the strength and the high-temperature softening resistance of the material are further improved by strengthening the copper alloy matrix by the elemental Cr phase and the Cu.sub.5Zr phase, using the synergistic effect of the Cr.sub.3Si phase and the elemental Cr phase and by controlling the content of the impurity Fe. The copper alloy can be applied to contact lines and welding materials to prolong the service life of the materials.

Claims

1. A softening-resistant copper alloy, comprising: 0.1%-1.0 wt % Cr, 0.01% -0.2 wt % Zr, 0.01%-0.10 wt % Si, and 0.10 wt % Fe, and with the remaining of copper and inevitable impurities, wherein the microstructure of the copper alloy comprises: an elemental Cr phase, a Cu.sub.5Zr phase, and a Cr.sub.3Si phase.

2. The copper alloy of claim 1, wherein the elemental Cr phase and the Cr.sub.3Si phase satisfy the following relationship: if the weight of the elemental Cr phase is X and the weight of the Cr.sub.3Si phase is Y, then 0<X/Y<20.

3. The copper alloy of claim 1, further comprising: 0.0001%-0.10 wt % Mg.

4. The copper alloy of claim 1, further comprising: 0.01% to 2.5 wt % of any one or more of Co, Zn, Mn, Sn and Nb, and their total amount does not exceed 3.5 wt % of the copper alloy.

5. The copper alloy of claim 1, wherein the softening temperature of the copper alloy is greater than or equal to 580 C.

6. A method for preparing the copper alloy of claim 1, the method comprising: alloying and refiningcasting into an ingotingot sawing, heating and extrudingsolid solution heat treatmentstretching and drawingaging heat treatmentstraightening and finalizing; wherein the casting temperature for the alloying treatment and the covered refining is 1150 C. to 1350 C.; the temperature for the hot extrusion is 850 C. to 950 C.; the temperature for the solid solution treatment is 850 C. to 1000 C.; the cooling medium is water, and the cooling rate is 10 C./min to 150 C./s; the machining rate of the cold stretching and drawing is 20% to 60%; the temperature for the aging heat treatment is 420 C. to 520 C.; and, the copper alloy is insulated for 2 h to 4 h.

7. The copper alloy of claim 1, the method comprising using the softening-resistant copper alloy in contact lines and welding materials.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030] To enable a further understanding of the present invention content of the invention herein, refer to the detailed description of the invention and the accompanying drawings below:

[0031] To avoid repetition, the technical parameters involved in the specific implementations will be uniformly described below, and will not be repeated in embodiments.

[0032] wt %: weight percentage.

[0033] % IACS: used for representing the electrical conductivity of a metal or alloy (reference to the standard annealed pure copper).The electrical conductivity of the standard annealed pure copper is generally defined as 100% IACS, i.e., 5.80E+7(1/.Math.m) or 58(m/.Math.mm.sup.2).The value is the ratio of the resistivity (in volume or mass) specified by the International Annealed Copper Standard to the resistivity of the sample in the same unit multiplied by 100.

[0034] HR: Rockwell hardness.

[0035] Rem.: remaining amount.

Embodiments 1-20

[0036]

TABLE-US-00001 TABLE 1 Composition instances of components of the softening-resistant copper alloy of the present invention (wt %): Component Chemical component (wt %) Other Embodiment Cr Zr Si Mg Fe elements Cu Embodiment 1 0.10 0.010 0.015 Rem. Embodiment 2 0.187 0.016 0.010 0.018 0.027 Rem. Embodiment 3 0.192 0.189 0.027 0.014 0.017 Rem. Embodiment 4 0.24 0.027 0.022 0.035 0.009 Rem. Embodiment 5 0.297 0.029 0.026 0.043 0.028 Rem. Embodiment 6 0.367 0.046 0.026 0.016 0.009 Rem. Embodiment 7 0.43 0.048 0.035 0.006 0.042 Rem. Embodiment 8 0.46 0.059 0.038 0.068 0.021 Rem. Embodiment 9 0.51 0.06 0.065 0.072 0.057 Rem. Embodiment 0.59 0.072 0.046 0.088 0.068 Rem. 10 Embodiment 0.64 0.079 0.028 0.096 0.079 Rem. 11 Embodiment 0.68 0.085 0.067 0.005 0.100 Rem. 12 Embodiment 0.75 0.091 0.096 0.052 0.062 Rem. 13 Embodiment 0.81 0.115 0.062 0.002 0.004 Rem. 14 Embodiment 0.84 0.127 0.042 0.017 0.037 Rem. 15 Embodiment 0.89 0.149 0.019 0.002 0.023 Rem. 16 Embodiment 0.89 0.147 0.031 0.021 Nb: 0.031 Rem. 17 Embodiment 0.95 0.176 0.079 0.021 0.023 Nb: 0.097 Rem. 18 Embodiment 0.87 0.177 0.082 0.031 0.014 Co: 0.12 Rem. 19 Embodiment 1.00 0.200 0.100 0.012 0.067 Zn: 0.13 Rem. 20 Comparison 0.92 0.051 0.0021 0.013 0.032 Rem. embodiment

[0037] The finished softening-resistant copper alloy products in Embodiments 21-40 of the present invention were obtained by preparing materials according to the components and their mass percentages of the softening-resistant copper alloy in Embodiments 1-20 in Table 1, then smelting, casting into an ingot, processing and molding, heating to 450 C. to 520 C. at an average heating rate of 1 C./min to 30 C./min and holding this temperature for 2 h to 4 h (Embodiments 21-40 where the finished products were obtained, corresponding to the components and their mass percentages of the softening-resistant copper alloy in Embodiments 1-20, respectively).

[0038] The microstructures of the finished softening-resistant copper alloy products in Embodiments 21-40 were analyzed. The results of analysis are shown in Table 2.

[0039] In the softening-resistant copper alloys in Embodiments 21-40 of the present invention, microscopic intermediate phases and elementary substances with different properties are formed by various added alloy elements and a particular aging process, and the microscopic phases are dispersedly distributed in the copper matrix, so that various performances of the copper alloys are effectively improved. The related phases and their contents in the softening-resistant copper alloys in Embodiments 21-40 of the present invention are shown in Table 2.

TABLE-US-00002 TABLE 2 Intermediate phases and their contents in the softening-resistant copper alloys in Embodiments 21-40 of the present invention Embodiment Cr Cr.sub.3Si Cu.sub.5Zr Second phase (wt %) (wt %) (wt %) Embodiment 21 0.0525 0.0975 0.0495 Embodiment 22 0.1045 0.0975 0.072 Embodiment 23 0.0435 0.1755 0.8505 Embodiment 24 0.119 0.143 0.1215 Embodiment 25 0.154 0.169 0.1305 Embodiment 26 0.224 0.169 0.207 Embodiment 27 0.2375 0.2275 0.216 Embodiment 28 0.251 0.247 0.2655 Embodiment 29 0.1525 0.4225 0.27 Embodiment 30 0.337 0.299 0.324 Embodiment 31 0.486 0.182 0.3555 Embodiment 32 0.3115 0.4355 0.3825 Embodiment 33 0.0312 0.624 0.4095 Embodiment 34 0.469 0.403 0.5175 Embodiment 35 0.609 0.273 0.5715 Embodiment 36 0.7855 0.1235 0.6705 Embodiment 37 0.7195 0.2015 0.6615 Embodiment 38 0.5155 0.5135 0.792 Embodiment 39 0.419 0.533 0.7965 Embodiment 40 0.4365 0.6305 0.873 Comparison 0.92 0.2295 embodiment

[0040] The materials were prepared according to the components and their mass percentages of the softening-resistant copper alloy in Embodiments 1-20 in Table 1, and then treated under the following conditions: the casting temperature for the alloying treatment and the covered refining was 1150 C. to 1350 C., the temperature for hot extrusion was 850 C. to 950 C., the temperature for solid solution treatment was 850 C. to 1000 C., the cooling medium was water, the cooling rate was 10 C./min to 150 C./s, the machining rate of cold drawing was 20% to 60%, the temperature for aging heat treatment was 420 C. to 520 C., and the temperature holding time was 2 h to 4 h. Finally, the finished softening-resistant copper alloy bar products in 18 in Embodiments 41-60, corresponding to the components and their mass percentages of the softening-resistant copper alloy in Embodiments 1-20, were obtained by finishing.

[0041] The tensile strength, hardness, electrical conductivity and softening temperature of the softening-resistant copper alloy bars in Embodiments 41-60 of the present invention were tested by methods specified by the related national and industrial standards. The test results are shown in Table 3.The room-temperature tensile tests were carried out by an electronic universal mechanical property testing machine according to GB/T228.1-2010 Metal Material Tensile Test Section 1: Test at Room Temperature. The samples were circular cross-section proportional samples having a proportional coefficient of 5.65.The electrical conductivity tests were carried out according to GB/T228.1-2010 Test Methods for Electrical Performance of Electric Wires and Cables Section 2: Metal Material Resistivity Test. As the test instrument, a ZFD microcomputer bridge DC resistance tester was used, and the samples were 1000 mm in length. The electrical conductivity was represented by % IACS. The hardness tests were carried out by a hardometer according to GB/T 230.1-2009 Metal Material: Rockwell Hardness Test.

TABLE-US-00003 TABLE 3 Test results of performances of the softening-resistant copper alloy bars in Embodiments 41-60 of the present invention Performance Tensile Electrical strength Hardness conductivity Embodiment (MPa) (HR) (% IACS) Embodiment 41 472 75 90.1 Embodiment 42 491 77 88.6 Embodiment 43 482 75 91.1 Embodiment 44 487 78 86 Embodiment 45 496 78 85.7 Embodiment 46 499 80 86 Embodiment 47 489 81 84.2 Embodiment 48 492 80 85.1 Embodiment 49 498 82 83.8 Embodiment 50 506 81 84.1 Embodiment 51 517 84 81.2 Embodiment 52 528 86 79.1 Embodiment 53 509 82 76.4 Embodiment 54 558 87 75.2 Embodiment 55 537 85 76.3 Embodiment 56 568 85 77.7 Embodiment 57 566 87 77.5 Embodiment 58 571 86 76.8 Embodiment 59 573 86 75.7 Embodiment 60 578 88 75.2 Comparison 495 85 83.1 embodiment

[0042] In the present invention, the tensile strength is higher than or equal to 470 MPa, the Rockwell hardness is above 75, and the electrical conductivity is above 75% IACS.

[0043] Embodiments 61-80 The components and their mass percentages of the softening-resistant copper alloys in Embodiments 61-80 are the same as those in Embodiments 41-60. That is, the materials were prepared according to the components and their mass percentages of the softening-resistant copper alloy in Embodiments 1-20 in Table 1, and then treated under the following conditions: the casting temperature for the alloying treatment and the covered refining was 1150 C. to 1350 C., the temperature for hot extrusion was 850 C. to 950 C., the temperature for solid solution treatment was 850 C. to 1000 C., the cooling medium was water, the cooling rate was 10 C./min to 150 C./s, the machining rate of cold drawing was 20% to 60%, the temperature for aging heat treatment was 420 C. to 520 C., and the temperature holding time was 2 h to 4 h. Finally, the finished softening-resistant copper alloy bar products in 8 were obtained by finishing.

[0044] The softening temperature tests were carried out by methods specified by HB5420-89 Copper and Copper Alloys for Resistance Welding Electrodes and Auxiliary Devices. The test temperature was 580 C. The test results are shown in Table 4.

TABLE-US-00004 TABLE 4 Test results of the softening temperature of the softening-resistant copper alloy bars in Embodiments 61-80 of the present invention Original 580 C. hardness Hardness after Softening Embodiment (HRB) softening (HRB) rate (%) Embodiment 61 75 70 6.67 Embodiment 62 77 71 7.79 Embodiment 63 75 69 8 Embodiment 64 78 73 6.41 Embodiment 65 78 72 7.69 Embodiment 66 80 75 6.25 Embodiment 67 81 77 4.94 Embodiment 68 80 76 5 Embodiment 69 82 76 7.32 Embodiment 70 81 75 7.41 Embodiment 71 84 79 5.95 Embodiment 72 86 80 6.98 Embodiment 73 82 78 4.88 Embodiment 74 87 81.5 6.32 Embodiment 75 85 80 5.88 Embodiment 76 85 81 4.71 Embodiment 77 87 81 6.90 Embodiment 78 86 80 6.98 Embodiment 79 86 81 5.81 Embodiment 80 88 82 6.82 Comparison 85 69 18.8 embodiment

[0045] It can be deduced from the above embodiments that, in accordance with the standard test methods, the hardness loss of the copper alloy of the present invention at 580 C. is below 8%, while the hardness loss of the conventional copper chromium zirconium alloy in the comparison embodiment is greater than 18%. It is indicated that the high-temperature softening resistance of the copper alloy of the present invention is greatly improved.

Application Embodiment

[0046] The softening-resistant copper alloy bars in anyone of Embodiments 41-60 are machined into appliances for welding.

[0047] The softening-resistant copper alloy bars in anyone of Embodiments 41-60 are machined into contact lines for electrified railways.

[0048] In conclusion, the softening-resistant copper alloy of the present invention has high strength, good electrical performance and excellent high-temperature softening resistance, and is particularly applied in industrial fields such as welding appliances and contact lines for electrified railways.