Non-vacuum up-drawing continuous casting production process of copper-chromium-zirconium alloy rod material

Abstract

The invention provides a non-vacuum up-drawing continuous casting production process of a copper-chromium-zirconium alloy rod material. The non-vacuum up-drawing continuous casting production process specifically comprises the following steps: adding electrolytic copper into a smelting furnace, adding a covering agent, intermittently filling nitrogen into the surface of the covering agent, heating until the covering agent is molten, adding a chromium raw material, and adding a copper-zirconium intermediate alloy; before up-drawing continuous casting, a graphite mold is installed at the bottom of a water-cooling copper sleeve, asbestos and a graphite protective sleeve are installed outside the mold, then the mold is installed on a traction rack, the head of a stainless steel traction rod is connected with a pure copper drawing head and placed into a crystallizer, and a water-cooling system is started after installation is completed; and upward continuous casting is conducted, specifically, a crystallizer is placed below the liquid level of the melt, a traction device is started, and the copper-chromium-zirconium alloy rod is cast according to preset traction parameters. And meanwhile, a servo motor is started, and the pure Cr wire and the pure Zr wire are automatically fed into the copper liquid. The method has the advantages that the graphite die can be prevented from becoming rough due to surface reaction in the pull casting process, the surface of a continuous casting rod material is bright, and the upward continuous casting process is continuously and stably carried out.

Description

Technical Field

[0001] The invention relates to a preparation technology of a high-performance copper alloy, belongs to the technical field of metal material preparation and processing, and in particular provides a non-vacuum upward continuous casting production process for a copper-chromium-zirconium alloy rod. Background Art

[0002] Copper-chromium-zirconium alloy is an ideal material for ultra-large-scale integrated circuit lead frames, high-speed rail transit contact lines, electromagnetic gun rails, resistance welding electrodes, etc. due to its high strength and high conductivity. However, the existing copper-chromium-zirconium alloy is obtained by vacuum melting to obtain ingots, and then the rod products are obtained by extrusion or rolling. The vacuum melting process has low efficiency and high energy consumption, and cannot be prepared on a large scale continuously. The prepared ingots are prone to defects such as component segregation and loose organization, resulting in uneven material organization. Therefore, how to achieve non-vacuum continuous casting of copper-chromium-zirconium is a common problem in the industry.

[0003] Patent CN113736970A invented a method for preparing a Cu-Cr-Zr rod by upward continuous casting, but it still uses vacuum induction melting to obtain the Cu-Cr-Zr alloy melt. Patent CN114438355A invented a method for controlling the composition of a copper-chromium-zirconium alloy during non-vacuum upward continuous casting, but there is no description of the surface quality of the rod. It can be seen that the process of non-vacuum upward continuous casting of copper-chromium-zirconium alloy is feasible, but the Cr and Zr elements are easily oxidized and react with the graphite crucible and mold, which will increase the viscosity of the melt, causing the surface of the rod to become black and small cracks to appear. Summary of the invention

[0004] In view of the problems pointed out in the above background technology, the present invention provides a non-vacuum upward continuous casting process for copper-chromium-zirconium alloy with higher production efficiency and more reasonable process structure design. By adding covering agents and filling inert gas to isolate oxygen, adjusting process parameters and improving ceramic tubes embedded in graphite molds, rods with good surface quality can be stably and continuously pulled out.

[0005] The present invention adopts the following technical scheme: a non-vacuum upward continuous casting production process of copper-chromium-zirconium alloy rod material, specifically comprising:

[0006] (1) According to the weight percentage content of Cu-Cr-Zr alloy, electrolytic copper is added into a smelting furnace, a covering agent is added, nitrogen is intermittently filled into the surface of the covering agent, and the mixture is heated to 1200-1300° C. to be completely melted, and then chromium raw material is added at 1300-1500° C., and the mixture is kept warm for 10-30 minutes. After the mixture is cooled to 1180-1270° C., a copper-zirconium master alloy is added;

[0007] (2) Before the upward continuous casting, the graphite mold is installed at the bottom of the water-cooled copper sleeve, and asbestos and graphite protective sleeves are installed on the outside of the mold, and then installed on the traction frame. The head of the stainless steel traction rod is connected to the pure copper lead and placed in the crystallizer. The crystallizer is a water-cooled copper sleeve plus a graphite mold, and the lead is exposed 10-20mm. After the installation is completed, the water cooling system is turned on;

[0008] (3) Upward continuous casting: The crystallizer is lowered to 20-70 mm below the melt surface, the traction device is turned on, and the copper-chromium-zirconium alloy rod is cast according to the preset traction parameters. At the same time, the servo motor is started to automatically feed the pure Cr wire and the pure Zr wire into the copper liquid.

[0009] The Cu-Cr-Zr alloy composition is: 0.2-1.2wt% Cr, 0.02-0.2wt% Zr, impurities ≤0.1wt%, and the rest is copper

[0010] Preferably, the covering agent is calcined charcoal and graphite phosphorus flakes, the thickness of the covering agent is 100-150 mm, the chromium raw material is pure Cr flakes, and the copper-zirconium alloy is Cu-40Zr.

[0011] Preferably, the graphite mold in step (2) can be an improved ceramic-lined graphite mold, the length of the ceramic tube is 50-80 mm, the wall thickness is 1-1.5 mm, and a graphite baffle is added to the bottom of the mold, the baffle has threads inside, and is inlaid with the threads on the outer surface of the graphite mold, the baffle is 20-30 mm high, and the baffle thickness is 5 mm. Figure 1 As shown, the ceramic tube material may be one of boron nitride, zirconium oxide, and silicon nitride.

[0012] Preferably, the cooling water pressure in the water cooling system described in step (2) is set to 2-3 MPa, and the cooling water temperature is 10-18°C.

[0013] Preferably, the diameter of the upward continuous casting rod blank described in step (3) is 8-30 mm.

[0014] Preferably, the pulling parameters in step (3) are: pulling temperature of 1200-1300° C., pitch of 4 mm-9 mm, stop ratio of 50-75%, and pulling speed of 100-300 mm / min.

[0015] Preferably, the wire feeding speed of the servo motor in step (3) is: Cr: 2.5-4 g / min, Zr: 2-3 g / min.

[0016] Preferably, the composition difference between the core and the edge of the cross section of the target rod material does not exceed 3%, and the composition difference at three random positions in the longitudinal section does not exceed 5%.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The graphite mold used in the upward continuous casting process of the present invention can select an embedded ceramic tube material according to different Cr contents to prevent Cr from reacting with C, thereby preventing the graphite mold from becoming rough due to surface reaction during the casting process. The composition is homogenized by continuous feeding. In addition, combined with optimized process parameters, the surface quality of the continuous casting rod is bright, and the upward continuous casting process is continuously and stably carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of a ceramic tube embedded in a graphite mold and an external baffle;

[0020] Markings in the figure: 1-graphite mold; 2-embedded ceramic tube; 3-graphite baffle;

[0021] Figure 2 This is a physical picture of the upward continuous casting rod material. DETAILED DESCRIPTION

[0022] Example 1

[0023] According to the weight percentage, weigh 0.4% Cr, 0.1% Zr and the balance electrolytic copper. Add the electrolytic copper into the smelting furnace, add calcined charcoal and graphite phosphorus flakes, fill the surface of the graphite phosphorus flakes with nitrogen as a protective gas, heat to 1200℃ to completely melt, then heat to 1300℃, add chromium flakes, keep warm for 20 minutes, cool to 1250℃ and add Cu-40Zr alloy;

[0024] (2) Before the upward continuous casting, the improved graphite mold with embedded ceramic tube is installed at the bottom of the water-cooled copper sleeve, and asbestos and graphite protective sleeves are installed on the outside of the mold. Then it is installed on the traction frame, and the head of the stainless steel traction rod is connected to the pure copper guide, which is placed in the crystallizer, and the guide is exposed 15mm outside the graphite mold. After installation, the water cooling system is turned on, the water temperature is set to 16℃, and the cooling water pressure is 2.5MPa.

[0025] (3) Upward continuous casting: The crystallizer is lowered to 50 mm below the melt surface, and the traction device is turned on. The traction parameters are set as follows: traction temperature is 1250°C, pitch is 6 mm, stop ratio is 55%, and traction speed is 240 mm / min. At the same time, the servo motor is turned on for automatic wire feeding, and the wire feeding speed is: Cr: 2.5 g / min, Zr: 2 g / min.

[0026] Example 2

[0027] According to the weight percentage, weigh Cr: 1.0%; Zr: 0.1% and the balance electrolytic copper. Add the electrolytic copper into the smelting furnace, add calcined charcoal and graphite phosphorus flakes, fill the surface of the graphite phosphorus flakes with nitrogen as a protective gas, heat to 1200℃ to completely melt, then heat to 1350℃, add chromium flakes, keep warm for 20 minutes, cool to 1250℃ and add Cu-40Zr alloy.

[0028] (2) Before the upward continuous casting, the improved graphite mold with embedded ceramic tube is installed at the bottom of the water-cooled copper sleeve. The length of the ceramic tube is 70mm and the wall thickness is 1mm. A graphite baffle is added to the bottom of the mold. The baffle is threaded and embedded with the outer surface of the graphite mold. The baffle is 30mm high and 5mm thick. Asbestos and graphite protective sleeves are installed outside the mold. Then the whole is installed from top to bottom on the traction frame. The head of the stainless steel traction rod is connected to the pure copper guide and placed in the crystallizer. The guide is exposed 15mm outside the graphite mold. After installation, turn on the water cooling system, set the water temperature to 14℃, and the cooling water pressure to 2.5MPa.

[0029] (3) Upward continuous casting: The crystallizer is lowered to 50 mm below the melt surface, and the traction device is turned on. The traction parameters are set as follows: traction temperature is 1260°C, pitch is 6 mm, stop ratio is 75%, and traction speed is 105 mm / min. At the same time, the servo motor is turned on for automatic wire feeding, and the wire feeding speed is: Cr: 2.5 g / min, Zr: 2 g / min.

Claims

1. A non-vacuum upward continuous casting production process for copper-chromium-zirconium alloy rods, characterized in that: Specifically include: (1) According to the weight percentage content of Cu-Cr-Zr alloy, electrolytic copper is added into a smelting furnace, a covering agent is added, nitrogen is intermittently filled onto the covering agent, and the mixture is heated to 1200-1300° C. to be completely melted, and then chromium raw material is added at 1300-1500° C., and the temperature is kept at 10-30 minutes. After the temperature is lowered to 1200-1300° C., a copper-zirconium master alloy is added; (2) Before the upward continuous casting, the graphite mold is installed at the bottom of the water-cooled copper sleeve, and asbestos and graphite protective sleeves are installed on the outside of the mold. Then the whole is installed on the traction frame. The head of the stainless steel traction rod is connected to the pure copper guide and placed in the crystallizer. The guide is exposed 10-20mm. After the installation is completed, the water cooling system is turned on; (3) Upward continuous casting: The crystallizer is lowered to 20-70 mm below the melt surface, the traction device is turned on, and the copper-chromium-zirconium alloy rod is cast according to the preset traction parameters; at the same time, the servo motor is started to automatically feed the pure Cr wire and the pure Zr wire into the copper liquid.

2. The non-vacuum upward continuous casting production process of a copper-chromium-zirconium alloy rod according to claim 1 is characterized in that: The composition of the Cu-Cr-Zr alloy in step (1) is: 0.2-1.2wt% Cr, 0.02-0.2wt% Zr.

3. The non-vacuum upward continuous casting production process of a copper-chromium-zirconium alloy rod according to claim 1, characterized in that: The covering agent in step (1) is calcined charcoal and graphite phosphorus flakes, and the thickness of the covering agent is 100-200 mm.

4. The non-vacuum upward continuous casting production process of a copper-chromium-zirconium alloy rod according to claim 1, characterized in that: The chromium raw material in step (1) is pure Cr flakes, and the copper-zirconium master alloy is Cu-40Zr.

5. The non-vacuum upward continuous casting production process of a copper-chromium-zirconium alloy rod according to claim 1, characterized in that: The graphite mold described in step (2) can adopt an improved ceramic-lined graphite mold, the length of the ceramic tube is: 50-80mm, the wall thickness is 1-1.5mm, and a graphite baffle is added to the bottom of the mold, the baffle is threaded, and the baffle is embedded with the thread on the outer surface of the graphite mold. The baffle is 20-30mm high and 5mm thick. The ceramic tube material is one of boron nitride, zirconium oxide or silicon nitride.

6. The non-vacuum upward continuous casting production process of a copper-chromium-zirconium alloy rod according to claim 1, characterized in that: In the water cooling system in step (2), the cooling water pressure is 2-3 MPa and the cooling water temperature is 10-18°C.

7. The non-vacuum upward continuous casting production process of copper-chromium-zirconium alloy rod according to claim 1, characterized in that: The diameter of the upward continuous casting rod blank described in step (3) is 8-30 mm.

8. The non-vacuum upward continuous casting production process of copper-chromium-zirconium alloy rod according to claim 1, characterized in that: The pulling parameters described in step (3) are: pulling temperature is 1180-1270° C., pitch is 4 mm-9 mm, stop ratio is 50-75%, and pulling speed is 100-300 mm / min.

9. The non-vacuum upward continuous casting production process of copper-chromium-zirconium alloy rod according to claim 1, characterized in that: The wire feeding speed of the servo motor described in step (3) is: Cr: 2.5-4g / min, Zr: 2-3g / min.

10. A non-vacuum upward continuous casting production process for copper-chromium-zirconium alloy rods according to claims 1-9, characterized in that: The composition difference between the core and edge of the cross section of the target rod does not exceed 3%, and the composition difference at three random positions in the longitudinal section does not exceed 5%.

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