A production process for copper-chromium-zirconium alloy contact wire

Abstract

The present invention relates to a copper-chromium-zirconium alloy contact wire production process, comprising the following steps: upward continuous casting → primary cold working → solution treatment → rod blank cleaning → continuous extrusion → primary aging treatment → secondary cold working → secondary aging treatment → tertiary cold working. The present invention couples the upward continuous casting rod blank with a single solution treatment, a single continuous extrusion, three cold deformations, and two aging treatments to maximize the copper-chromium-zirconium alloy rod blank's fine grain strengthening, high-density dislocation network substructure strengthening, and precipitation dispersion strengthening effects. This results in a copper-chromium-zirconium alloy contact wire with a strength exceeding 630 MPa, a conductivity of ≥80% IACS, and high softening resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of copper and copper alloy wire materials, and in particular to a production process of a copper-chromium-zirconium alloy contact wire. Background Art

[0002] As a key component of the contact network, the contact wire plays a decisive role in the high-speed and safe operation of electric locomotives. Among the many high-strength and high-conductivity copper alloys, copper-chromium-zirconium alloy has become the preferred material for high-speed railway contact wires with speeds of 400 km / h and above due to its excellent performance.

[0003] The commonly used preparation process of copper-chromium-zirconium alloy contact wire is to first continuously extrude the copper-chromium-zirconium alloy rod billet produced by continuous casting, and then carry out solid solution treatment, cold working, aging treatment and other processes to prepare the copper-chromium-zirconium alloy contact wire. For example, a copper-chromium-zirconium alloy contact wire and its production process with application number 201710906689.8 can produce high-strength and high-conductivity contact wire products with a single weight of more than 2 tons, a conductivity of 75-90% IACS, and a tensile strength of 550-700 MPa. However, due to the serious composition segregation, loose core, deep crystal lines, and low-temperature melt adhesion of the copper-chromium-zirconium alloy rod billet produced by continuous casting, the copper-chromium-zirconium alloy contact wire is difficult to be produced. Problems near the surface of the rod blank lead to peeling, inclusions, and substandard performance of the copper-chromium-zirconium alloy contact wire during the preparation process; the grains refined by the solution treatment of the copper-chromium-zirconium alloy after the continuous extrusion process will grow rapidly at high temperatures, weakening the fine grain strengthening effect. At the same time, the presence of coarse-grained structure is not conducive to subsequent cold processing, and is even more detrimental to the improvement of the overall performance of the copper-chromium-zirconium alloy contact wire; the primary aging has the phenomenon of incomplete precipitation of the second phase, large differences in the size of the precipitated phase, and uneven distribution, which causes the copper-chromium-zirconium alloy contact wire to have large performance differences in the long length direction during the production process, and is prone to defects such as cracks and peeling. Summary of the Invention

[0004] The present invention aims to overcome the above-mentioned shortcomings and provides a copper-chromium-zirconium alloy contact wire production process. The process couples the upper continuous casting rod blank with one solution treatment, one continuous extrusion, three cold deformations and two aging treatments. This maximizes the solid solution strengthening, grain refinement strengthening, high-density dislocation network substructure strengthening and precipitation dispersion strengthening effects of the copper-chromium-zirconium alloy rod blank, thereby producing a copper-chromium-zirconium alloy contact wire with a strength of more than 630 MPa, a conductive property of ≥80% IACS, high softening resistance and stable performance along the long length.

[0005] The object of the present invention is achieved like this:

[0006] A copper-chromium-zirconium alloy contact wire production process comprises the following steps:

[0007] Step 1: Upward continuous casting: Electromagnetic oscillation upward continuous casting is used to produce copper-chromium-zirconium alloy rod blanks with a diameter of 26mm-32mm;

[0008] Step 2: Primary cold working: cold working the copper-chromium-zirconium rod blank with a deformation of 20%-50%;

[0009] Step 3: Solution treatment: Place the cold-worked rod blank into a furnace for solution treatment and then cool.

[0010] Step 4: Clean the rod blank: clean the solution treated rod blank;

[0011] Step 5: Continuous extrusion: The cleaned rod blank is fed into a continuous extruder and extruded into a rod blank with a diameter of 28-32 mm;

[0012] Step 6: Primary aging treatment: After the extruded rod is ejected from the mold, it directly enters the heat preservation and oxygen isolation device for the first aging treatment and then cooling;

[0013] Step 7: Secondary cold working: The primary aging treated rod blank is subjected to secondary cold working with a deformation of 30%-50%;

[0014] Step 8: Secondary aging treatment: The secondary cold-processed rod blank is directly placed into the heat-insulating and oxygen-isolating device for secondary aging treatment and then cooled;

[0015] Step 9, three-time cold working: the rod blank subjected to the secondary aging treatment is subjected to 50%-70% cold working deformation to form a copper-chromium-zirconium alloy contact wire.

[0016] Preferably, the solution temperature in step three is 920° C.-980° C., and the holding time is 30 min-60 min.

[0017] Preferably, in step three, the furnace is preheated before the rod blank is placed in the furnace.

[0018] Preferably, the rod blank is preheated to 870-930°C in advance.

[0019] Preferably, in step 4, the diameter of the cleaned rod blank is reduced by 0.1-1 mm.

[0020] Preferably, in step five, the extrusion tooling cooling system is adjusted to maintain the extrusion rod outlet temperature at 460-480°C.

[0021] Preferably, the aging temperature in step six is ​​460-480° C., and the insulation time is 30 min-45 min.

[0022] Preferably, the aging temperature in step eight is 430-450° C., and the insulation time is 120 min-180 min.

[0023] The beneficial effects of the present invention are:

[0024] A cold working is performed before the solution treatment to effectively refine the upward casting structure, and at the same time, defects such as dislocations and vacancies are generated to enhance the instability of the copper-chromium-zirconium alloy matrix. This is conducive to the full dissolution of the undissolved Cr-rich and Zr-rich phases during casting into the copper-chromium-zirconium alloy matrix, forming a high-quality copper-chromium-zirconium alloy supersaturated solid solution. The formation of the high-quality copper-chromium-zirconium alloy supersaturated solid solution provides a strong guarantee for the subsequent two aging treatments. At the same time, the size of the rod blank is reduced after one processing, and it becomes soft after solution treatment. The requirements for equipment and tooling are low during continuous extrusion. Even conventional low-power extruders such as the TLJ500 extruder can meet the preparation requirements of the above-mentioned copper-chromium-zirconium alloy extruded rod blanks, and have little impact on the life of the tooling mold, and have a relatively wide applicability.

[0025] The continuous extrusion process is set after the solution treatment and rod blank cleaning. On the one hand, it effectively avoids the influence of oxides and impurities on the surface of the rod blank on the contact line quality of the copper-chromium-zirconium alloy; on the other hand, the continuous extrusion process makes the copper-chromium-zirconium alloy structure after solution treatment uniform and refined. At the same time, the undissolved phase is broken during the continuous extrusion process, and the distribution is improved, which significantly improves the mechanical properties of the copper-chromium-zirconium alloy rod blank. The uniform and fine structure is conducive to subsequent cold working.

[0026] After the continuous extrusion, the rod blank is directly subjected to a primary aging heat treatment after being ejected from the die. On the one hand, the heat generated during the continuous extrusion of the copper-chromium-zirconium alloy is fully utilized, not only completing the first aging precipitation under low energy consumption, but also eliminating the internal stress generated by the copper-chromium-zirconium alloy during the continuous extrusion process, thereby improving the subsequent cold deformation processing performance of the copper-chromium-zirconium alloy; on the other hand, the primary aging treatment precipitates the phases that are easy to precipitate and grow in advance, so that they are fully refined in advance during the subsequent cold deformation processing. At the same time, a large number of defects such as dislocations and vacancies are formed in the matrix during the cold deformation process, which puts the matrix in an unstable state. This not only enables the precipitation phase to precipitate in large quantities at a relatively low temperature, but also promotes the distribution of the precipitated phase to be more uniform and the size to be smaller during the secondary aging, effectively reducing the size difference of the precipitates in the copper-chromium-zirconium alloy matrix, and improving the comprehensive mechanical properties and performance stability of the copper-chromium-zirconium alloy.

[0027] Electromagnetic oscillation technology is used to make the copper-chromium-zirconium alloy solution form convection under the action of a magnetic field, thereby refining its casting structure and improving segregation and looseness.

[0028] Preheating before solution treatment can not only shorten the heating time and save energy, but also make the temperature in the furnace uniform, improve the solid solution uniformity of the copper-chromium-zirconium alloy rod billet, and effectively prevent microstructure coarsening and save copper resources.

[0029] In summary, the present invention couples the processes of subjecting the upward continuous casting rod blank to one solution treatment, one continuous extrusion, three cold deformations, and two aging treatments, so as to maximize the effects of solid solution strengthening, grain refinement strengthening, high-density dislocation network substructure strengthening, and precipitation dispersion strengthening of the copper-chromium-zirconium alloy rod blank, thereby producing a copper-chromium-zirconium alloy contact wire with a strength of more than 630 MPa, a conductive performance of ≥80% IACS, and high softening resistance. DETAILED DESCRIPTION

[0030] The present invention relates to a copper-chromium-zirconium alloy contact wire production process, comprising the following steps:

[0031] Step 1: Upward continuous casting: Electromagnetic oscillation upward continuous casting is used to produce copper-chromium-zirconium alloy rod blanks with a diameter of 26mm-32mm;

[0032] The composition of the copper-chromium-zirconium alloy is: 0.2-1.0wt% Cr, 0.02-0.2wt% Zr, the sum of other elements ≤ 0.1wt%, and the balance is Cu;

[0033] Electromagnetic oscillation causes the copper-chromium-zirconium alloy solution to form convection under the action of the magnetic field, thereby refining its casting structure and improving segregation and loosening.

[0034] Step 2, primary cold working: cold working the copper-chromium-zirconium rod blank with a deformation of 20%-50%; the primary cold working is performed before the solution treatment. The deformation energy storage generated by the primary cold working will promote the full dissolution of elements such as Cr and Zr into the matrix during the solution treatment to form a supersaturated solid solution of the copper-chromium-zirconium alloy. At the same time, the size of the rod blank is reduced after the primary processing, and it becomes soft after heat treatment. The continuous extrusion equipment and tooling requirements are low during continuous extrusion. Even conventional low-power extruders such as the TLJ500 extruder can meet the preparation requirements of the above-mentioned copper-chromium-zirconium alloy extruded rod blanks, and have little impact on the life of the tooling mold.

[0035] Step 3: Solution treatment: Place the cold-worked rod blank into a furnace for solution treatment at a temperature of 920-980°C, hold for 30-60 minutes, and then cool rapidly to form a supersaturated solid solution of copper-chromium-zirconium alloy.

[0036] Before the rod blank is placed in the furnace, the furnace is preheated to 870-930℃ in advance. Preheating in the furnace can not only shorten the heating time, prevent the growth of casting structure, save energy, and reduce the loss of copper-chromium-zirconium alloy rod blank, but also make the temperature in the furnace uniform, which is conducive to the uniform solid solution of copper-chromium-zirconium alloy rod blank.

[0037] Step 4: Clean the rod blank: Clean the heat-treated rod blank to remove impurities and defects on the surface and near the surface of the rod blank. The diameter of the cleaned rod blank is reduced by 0.1-1mm.

[0038] Step 5: Continuous extrusion: The cleaned rod blank is fed into a continuous extruder to be extruded into a rod blank with a diameter of 28-32 mm, and the extrusion tooling cooling system is adjusted to keep the temperature of the extruded rod at 460-480°C.

[0039] Step 6: Primary aging treatment: After the extruded rod is ejected from the mold, it is directly placed in a heat-insulating and oxygen-isolating device for the first aging treatment. The aging temperature is 460-480°C, and it is kept warm for 30-45 minutes before cooling.

[0040] The die cavity outlet of the continuous extruder is directly connected to a heat-insulating and oxygen-isolating device, so that the heat generated during the continuous extrusion of the copper-chromium-zirconium alloy is fully utilized. This not only completes the first aging precipitation with low energy consumption, but also eliminates the internal stress generated by the copper-chromium-zirconium alloy during the continuous extrusion process, thereby improving the subsequent cold deformation processing performance of the copper-chromium-zirconium alloy. Since the size of the primary aging precipitates is relatively large and the distribution is relatively concentrated, and the precipitated phases grow relatively rapidly with the extension of the aging time, the present invention uses a primary aging treatment to precipitate phases that are easy to precipitate and grow in advance. The phases precipitated in advance are fully refined after multiple cold workings, thereby reducing the difference in the size of the precipitated phases in the copper-chromium-zirconium alloy contact wire product structure and making the distribution more uniform.

[0041] Step 7: Secondary cold working: The primary aging treated rod blank is subjected to secondary cold working with a deformation of 30%-50%. The secondary cold working fully refines the precipitated phase and forms a large number of dislocations and lattice distortions in the matrix.

[0042] Step 8: Secondary aging treatment: The secondary cold-worked rod blank is directly placed in a heat-insulating and oxygen-isolating device for secondary aging treatment at a temperature of 430-450°C for 120-180 minutes, followed by cooling. During the secondary aging process, a large amount of fine precipitates are uniformly precipitated.

[0043] Step 9, three-time cold working: the rod blank subjected to the secondary aging treatment is subjected to 50%-70% cold working deformation to form a copper-chromium-zirconium alloy contact wire. Example 1

[0044] The present invention relates to a copper-chromium-zirconium alloy contact wire production process, comprising the following steps:

[0045] Step 1: Upward continuous casting: Electromagnetic oscillation upward continuous casting is used to produce copper-chromium-zirconium alloy rod blanks with a diameter of 32 mm.

[0046] The composition of the copper-chromium-zirconium alloy is: 0.2-1.0wt% Cr, 0.02-0.2wt% Zr, the sum of other elements ≤ 0.1wt%, and the balance is Cu;

[0047] Step 2: Primary cold working: cold working the copper-chromium-zirconium rod blank with a deformation of 50%;

[0048] Step 3: Solution treatment: Place the cold-worked rod blank into a furnace for solution treatment at 980°C, hold for 60 minutes, and then cool rapidly.

[0049] Before the rod billet is placed in the furnace, the furnace is preheated to 930℃;

[0050] Step 4: Clean the rod blank: Clean the heat-treated rod blank to remove impurities and defects on the surface and near the surface of the rod blank. The diameter of the cleaned rod blank is reduced by 0.1mm.

[0051] Step 5: Continuous extrusion: The cleaned rod blank is fed into a continuous extruder to be extruded into a rod blank with a diameter of 32 mm. The extrusion tooling cooling system is adjusted to keep the temperature of the extruded rod at 480°C.

[0052] Step 6: Primary aging treatment: After the extruded rod is ejected from the mold, it is directly placed in a heat preservation and oxygen isolation device for the first aging treatment. The aging temperature is 480°C, and it is kept at this temperature for 45 minutes before cooling.

[0053] Step 7: Secondary cold working: The primary aging treated rod blank is subjected to secondary cold working with a deformation of 50%;

[0054] Step 8: Secondary aging treatment: Place the secondary cold-worked rod blank directly into the heat-insulating and oxygen-isolating device for secondary aging treatment at a temperature of 450°C for 180 minutes, followed by cooling.

[0055] Step 9, tertiary cold working: The rod blank subjected to secondary aging treatment is subjected to 62% cold working deformation to produce a copper-chromium-zirconium alloy contact wire (CTCZ150). Example 2

[0056] The present invention relates to a copper-chromium-zirconium alloy contact wire production process, comprising the following steps:

[0057] Step 1: Upward continuous casting: Electromagnetic oscillation upward continuous casting is used to produce copper-chromium-zirconium alloy rod blanks with a diameter of 32 mm.

[0058] The composition of the copper-chromium-zirconium alloy is: 0.2-1.0wt% Cr, 0.02-0.2wt% Zr, the sum of other elements ≤ 0.1wt%, and the balance is Cu;

[0059] Step 2: Primary cold working: cold working the copper-chromium-zirconium rod blank by 20% deformation;

[0060] Step 3: Solution treatment: Place the cold-worked rod blank into a furnace for solution treatment at 980°C, hold for 30 minutes, and then cool rapidly.

[0061] Before the rod billet is placed in the furnace, the furnace is preheated to 930℃;

[0062] Step 4: Clean the rod blank: Clean the heat-treated rod blank to remove impurities and defects on the surface and near the surface of the rod blank. The diameter of the cleaned rod blank is reduced by 0.1mm.

[0063] Step 5: Continuous extrusion: The cleaned rod blank is fed into a continuous extruder to be extruded into a rod blank with a diameter of 32 mm. The extrusion tooling cooling system is adjusted to keep the temperature of the extruded rod at 480°C.

[0064] Step 6: Primary aging treatment: After the extruded rod is ejected from the mold, it is directly placed in a heat preservation and oxygen isolation device for the first aging treatment. The aging temperature is 480°C, and it is kept warm for 30 minutes before cooling.

[0065] Step 7: Secondary cold working: The primary aging treated rod blank is subjected to secondary cold working with a deformation of 50%;

[0066] Step 8: Secondary aging treatment: Place the secondary cold-worked rod blank directly into the heat-insulating and oxygen-isolating device for secondary aging treatment at a temperature of 450°C for 180 minutes, followed by cooling.

[0067] Step 9, tertiary cold working: The rod blank subjected to secondary aging treatment is subjected to 62% cold working deformation to produce a copper-chromium-zirconium alloy contact wire (CTCZ150).

[0068] Comparative Example 1:

[0069] Step 6: The first aging treatment time is 60 minutes, and the remaining steps are the same as in Example 1.

[0070] Comparative Example 2:

[0071] The first aging treatment in step 6 was omitted, and the remaining steps were the same as those in Example 1.

[0072] Comparative Example 3:

[0073] The cold working in step 2 and the aging treatment in step 6 are omitted, and the remaining steps are the same as those in Example 1.

[0074] Comparative Example 4:

[0075] Step 5: continuous extrusion is performed before the first cold working in step 2; step 9: cold working is performed to produce a copper-chromium-zirconium alloy contact wire (CTCZ150) of the same specification as in Example 1; and the remaining steps are the same as in Example 1.

[0076] Comparative Example 5:

[0077] In step 5, the continuous extrusion process is performed before the first cold working in step 2, and the first aging treatment in step 6 is omitted. The copper-chromium-zirconium alloy contact wire (CTCZ150) with the same specifications as in Example 1 is cold worked. The remaining steps are the same as in Example 1.

[0078] Comparative Example 6:

[0079] Step 3: No preheating in the furnace is performed before solution treatment, and the remaining steps are the same as in Example 1.

[0080] Comparative Example 7:

[0081] In step 6 and step 8, no heat-insulating and oxygen-isolating device is provided, and the remaining steps are the same as those in embodiment 1.

[0082] According to the relevant requirements of TB / T2809-2017 "Copper and Copper Alloy Contact Wires for Electrified Railways", the copper-chromium-zirconium alloy contact wires (CTCZ150) prepared according to Examples 1-2 and Comparative Examples 1-7 were tested for performance. The main electromechanical performance test results are shown in the following table:

[0083]

[0084] As can be seen from the above table, the electromechanical properties of the copper-chromium-zirconium alloy contact wires prepared in Example 1 and Example 2 meet the relevant requirements of TB / T2809-2017 "Copper and copper alloy contact wires for electrified railways", and their tensile strength reaches above 630 MPa, while the electrical conductivity is ≥80% IACS and the softening rate is as high as above 98%.

[0085] In comparative example 1, the primary aging time is too long and more precipitated phases are formed, resulting in over-aging during the secondary aging, which greatly reduces the tensile strength of the copper-chromium-zirconium alloy contact wire and fails to meet the standard, while the electrical conductivity and plasticity are significantly improved.

[0086] In comparative example 2, the copper-chromium-zirconium alloy contact wire was bent repeatedly for 3 times until it broke, which did not meet the standard requirements.

[0087] In comparative example 3, no deformation was performed before solution treatment, and the solution treatment effect was poor, which significantly reduced the effects of solution strengthening and precipitation strengthening of the copper-chromium-zirconium alloy contact wire. As a result, the tensile strength and repeated bending performance of the copper-chromium-zirconium alloy contact wire did not meet the standards, and the conductivity, elongation and softening rate were relatively low.

[0088] In comparative example 4, the tensile strength of the copper-chromium-zirconium alloy contact wire is much lower than that of Examples 1 and 2, and its repeated bending performance does not meet the standards, with defects such as intermittent peeling and cracks appearing on the surface. In addition, the 32 mm copper-chromium-zirconium alloy upper cast rod is directly and continuously extruded, which requires the use of a high-power continuous extruder such as the TLJ630, and conventional low-power continuous extruders cannot be used.

[0089] Comparative Example 5 has basically the same problems as Comparative Example 4, but its various performances are lower than those of Comparative Example 4.

[0090] In Comparative Example 6, after the copper-chromium-zirconium alloy rod blank after solution treatment is cooled, there is a relatively obvious color difference between the center layer and the surface layer, and the corresponding performance difference is relatively large; the operation time of the solution process is extended by about 30 minutes, which increases energy consumption. At the same time, the loss rate of the copper-chromium-zirconium alloy rod blank is increased by 0.5%-1%, which is not conducive to the low-energy, low-cost, and stable performance mass production of copper-chromium-zirconium alloy contact wires.

[0091] In Comparative Example 7, the repeated bending performance and surface quality of the copper-chromium-zirconium alloy contact wire were unqualified. This was because the oxide layer formed on the surface of the copper-chromium-zirconium alloy rod blank during the aging treatment entered the interior of the copper-chromium-zirconium alloy contact wire during the subsequent cold working deformation process, resulting in surface defects and poor bending performance.

[0092] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A copper-chromium-zirconium alloy contact wire production process, characterized by: The following steps are involved: Step 1: Upward continuous casting: Electromagnetic oscillation upward continuous casting is used to produce copper-chromium-zirconium alloy rod blanks with a diameter of 26mm-32mm; Step 2: Primary cold working: cold working the copper-chromium-zirconium alloy rod blank with a deformation amount of 20%-50%; Step 3: Solution treatment: Place the cold-worked rod blank into a furnace for solution treatment and then cool. Step 4: Clean the rod blank: clean the heat-treated rod blank; Step 5: Continuous extrusion: The cleaned rod blank is fed into a continuous extruder and extruded into a rod blank with a diameter of 28-32 mm; Step 6: Primary aging treatment: After the extruded rod billet is ejected from the mold, it is directly placed in a heat preservation and oxygen isolation device for the first aging treatment and then cooled; Step 7: Secondary cold working: The primary aging treated rod blank is subjected to secondary cold working with a deformation of 30%-50%; Step 8: Secondary aging treatment: The secondary cold-processed rod blank is directly placed into the heat-insulating and oxygen-isolating device for secondary aging treatment and then cooled; Step 9, tertiary cold working: the rod blank subjected to secondary aging treatment is subjected to 50%-70% cold working deformation to produce a copper-chromium-zirconium alloy contact wire; The solution temperature in step 3 is 920-980°C, and the holding time is 30-60 minutes. Before the rod blank is placed in the furnace, the furnace is preheated in advance; The aging temperature in step 6 is 460-480°C and kept warm for 30-45 minutes; The aging temperature in step eight is 430-450° C., and the temperature is kept at this temperature for 120-180 minutes.

2. The copper-chromium-zirconium alloy contact wire production process according to claim 1, characterized in that: The rod blank is preheated to 870-930°C in advance.

3. The copper-chromium-zirconium alloy contact wire production process according to claim 1, characterized in that: In the step 4, the diameter of the cleaned rod blank is reduced by 0.1-1 mm.

4. The copper-chromium-zirconium alloy contact wire production process according to claim 1, characterized in that: In the step 5, the cooling system of the extrusion tooling is adjusted to keep the temperature of the extrusion rod at 460-480°C.

Images