阅读说明：本技术 一种易切削铬锆铜及其制备方法 (Free-cutting chromium zirconium copper and preparation method thereof ) 是由 欧阳好 于 2021-07-29 设计创作，主要内容包括：本发明公开了一种易切削铬锆铜,其特征在于：该铬锆铜的质量百分比组成为Cr：0.7wt％～1.2wt％,Zr：0.08wt％～0.12wt％,Te：0.2wt％～0.4wt％,Ca：0.02wt％～0.04wt％,Sc：0.01wt％～0.02wt％,余量为Cu和不可避免的杂质。本发明选择Ca、Te、Sc作为改善铬锆铜的切削性元素,并控制添加量,Ca、Te、Sc以单质的形式存在于铜基体内,在实现铬锆铜综合性能优异的同时实现易切削。该铬锆铜的导电率≥80％IACS,硬度≥80HRB,软化温度≥600℃,切削性为HPb59-1的50％以上。(The invention discloses free-cutting chromium zirconium copper, which is characterized in that: the chromium-zirconium-copper alloy comprises the following components in percentage by mass: 0.7 wt% -1.2 wt%, Zr: 0.08-0.12 wt%, Te: 0.2 wt% -0.4 wt%, Ca: 0.02 wt% -0.04 wt%, Sc: 0.01 wt% to 0.02 wt%, and the balance of Cu and unavoidable impurities. According to the invention, Ca, Te and Sc are selected as elements for improving the machinability of the chromium-zirconium-copper, the addition amount is controlled, Ca, Te and Sc exist in the copper matrix in the form of simple substances, and the chromium-zirconium-copper is excellent in comprehensive performance and easy to cut. The chromium-zirconium-copper alloy has the conductivity of more than or equal to 80% IACS, the hardness of more than or equal to 80HRB, the softening temperature of more than or equal to 600 ℃ and the machinability of more than 50% of HPb 59-1.)

1. An easy-cutting chromium zirconium copper is characterized in that: the chromium-zirconium-copper alloy comprises the following components in percentage by mass: 0.7 wt% -1.2 wt%, Zr: 0.08-0.12 wt%, Te: 0.2 wt% -0.4 wt%, Ca: 0.02 wt% -0.04 wt%, Sc: 0.01 wt% to 0.02 wt%, and the balance of Cu and unavoidable impurities.

2. The free-cutting chromium zirconium copper as claimed in claim 1, wherein: the chromium-zirconium-copper alloy has the conductivity of more than or equal to 80% IACS, the hardness of more than or equal to 80HRB, the softening temperature resistance of more than or equal to 600 ℃, and the machinability of more than 50% of that of HPb 59-1.

3. A method of making free-cutting chromium zirconium copper as claimed in claims 1 to 2, characterized in that: the preparation method comprises the following preparation steps:

1) smelting: adding an electrolytic plate into a furnace, after the electrolytic plate is melted, increasing the voltage to 550-650V, covering the liquid surface with baked glass and villiaumite, wherein the covering height is more than 5mm, the temperature reaches 1300-1350 ℃, adding the copper-chromium alloy, the copper-calcium alloy, the metal scandium and the metal tellurium into the copper liquid together by using a pressing spoon, keeping for 1-10 min, driving the voltage to 350-450V, reducing the temperature to 1260-1320 ℃, preserving the heat, testing the components of the alloy elements, and blending until the components are qualified;

2) semi-continuous casting: adding copper-zirconium alloy into a chute of a crystallizer at the casting temperature of 1300-1350 ℃, the casting speed of 250-550 r/min and the cooling water pressure of 0.2-0.4 MPa to obtain a casting blank;

3) water seal extrusion: extruding a bar blank into a water seal tank for solid solution;

4) peeling: planing the bar blank into a skin;

5) drawing: drawing the bar blank after peeling to obtain a wire;

6) and (5) aging annealing of the finished product.

4. The method for preparing free-cutting chromium zirconium copper according to claim 3, characterized in that: in the step 1), the mass content of chromium in the copper-chromium alloy is 5-10%, and the mass content of calcium in the copper-calcium alloy is 5-15%.

5. The method for preparing free-cutting chromium zirconium copper according to claim 3, characterized in that: in the step 2), the mass content of zirconium in the copper-zirconium alloy is 3-10%.

6. The method for preparing free-cutting chromium zirconium copper according to claim 3, characterized in that: in the step 3), the extrusion temperature is 850-890 ℃, and the solid solution temperature of the bar blank entering the water seal tank is 830-860 ℃.

7. The method for preparing free-cutting chromium zirconium copper according to claim 3, characterized in that: in the step 6), the aging annealing temperature is 450-500 ℃, and the heat preservation time is 150-240 min.

Technical Field

The invention belongs to the technical field of copper alloy, and particularly relates to free-cutting chromium-zirconium-copper and a preparation method thereof.

Background

The chromium-zirconium-copper C18150 is a copper alloy material with high strength and high conductivity, has the requirements of high strength and high conductivity in a high-temperature environment, and is mainly applied to the fields of contact wires, welding gun tips, electrode materials and the like in high-speed rails at present. When the chromium zirconium copper is applied to the welding and cutting industry and a contact tip, the exterior of a part needs to be subjected to complex machining, and holes need to be punched simultaneously, so that the chromium zirconium copper is required to meet certain machinability.

The existing chromium zirconium copper has high requirement on electric conductivity, and the minimum requirement is more than 80% IACS, so that the traditional cutting elements such as Pb and Bi can not be added generally, and therefore, the cutting performance of the existing chromium zirconium copper needs to be further improved.

Disclosure of Invention

The invention aims to solve the first technical problem of providing the free-cutting chromium-zirconium-copper alloy which simultaneously meets the comprehensive properties of high strength, high conductivity and the like.

The technical scheme adopted by the invention for solving the first technical problem is as follows: an easy-cutting chromium zirconium copper is characterized in that: the chromium-zirconium-copper alloy comprises the following components in percentage by mass: 0.7 wt% -1.2 wt%, Zr: 0.08-0.12 wt%, Te: 0.2 wt% -0.4 wt%, Ca: 0.02 wt% -0.04 wt%, Sc: 0.01 wt% -0.02 wt%, and the balance of Cu and unavoidable impurities.

Preferably, the chromium-zirconium-copper alloy has the conductivity of more than or equal to 80% IACS, the hardness of more than or equal to 80HRB, the softening temperature resistance of more than or equal to 600 ℃ and the machinability of more than 50% of that of HPb 59-1.

The invention aims to solve the second technical problem of providing a preparation method of free-cutting chromium-zirconium-copper.

The technical scheme adopted by the invention for solving the second technical problem is as follows: a preparation method of free-cutting chromium zirconium copper is characterized by comprising the following steps: the preparation method comprises the following preparation steps:

1) smelting: adding an electrolytic plate into a furnace, after the electrolytic plate is melted, increasing the voltage to 550-650V, covering the liquid surface with baked glass and villiaumite, wherein the covering height is more than 5mm, the temperature reaches 1300-1350 ℃, adding the copper-chromium alloy, the copper-calcium alloy, the metal scandium and the metal tellurium into the copper liquid together by using a pressing spoon, keeping for 1-10 min, driving the voltage to 350-450V, reducing the temperature to 1260-1320 ℃, preserving the heat, testing the components of the alloy elements, and blending until the components are qualified;

2) semi-continuous casting: adding copper-zirconium alloy into a chute of a crystallizer at the casting temperature of 1300-1350 ℃, the casting speed of 250-550 r/min and the cooling water pressure of 0.2-0.4 MPa to obtain a casting blank;

3) water seal extrusion: extruding a bar blank into a water seal tank for solid solution;

4) peeling: planing the bar blank into a skin;

5) drawing: drawing the bar blank after peeling to obtain a wire;

6) and (5) aging annealing of the finished product.

The reason that the existing chromium zirconium copper is difficult to improve the machinability by adding the machinability elements is that Ca, Te and Sc do not influence the conductivity of the copper alloy but are difficult to be melted in the copper alloy matrix because: ca is one of its active elements, added with CaO, Te is one of the easy-cutting elements, and burnt at high temperature to form TeO₂Sc and scandium belong to rare earth elements and are easy to oxidize and slag formation at the high temperature of 1300 ℃, so that how to add Ca, Te and Sc into the matrix and disperse the Ca, Te and Sc in the copper matrix in the form of simple substances is the key point for realizing the easy cutting of chromium, zirconium and copper. The invention realizes the distribution of Ca, Te and Sc in the form of simple substances in the copper alloy matrix by controlling the preparation process and controlling related process parameters.

Preferably, in the step 1), the mass content of chromium in the copper-chromium alloy is 5-10%, and the mass content of calcium in the copper-calcium alloy is 5-15%.

Preferably, in the step 2), the mass content of zirconium in the copper-zirconium alloy is 3-10%.

Preferably, in the step 3), the extrusion temperature is 850-890 ℃, and the solid solution temperature of the billet entering the water seal tank is 830-860 ℃. The extrusion temperature is 850-890 ℃, and when the extrusion temperature is higher than 890 ℃, high burning and grain growth of cast ingots can be caused, the homogeneity of the metallographic structure of products is easy to be deteriorated, finally, the electric conductivity is reduced, the strength and hardness are reduced, and the inhomogeneity of local hardness, electric conductivity, tensile strength and elongation is increased, namely the comprehensive physical and chemical properties are deteriorated. Below 850 deg.c, high deformation resistance and low subsequent solid dissolving temperature, and this is unfavorable for the complete solid dissolving of the second phase. The solid solution temperature is 830-860 ℃, so that Ca, Te, Sc, Zr and Cr can be fully dissolved in the matrix at the temperature, the temperature higher than the temperature directly results in coarse and large structure grains, and the risk of cracking is caused because the extrusion temperature is too high and the internal stress of the material is increased due to the too high solid solution temperature.

Preferably, in the step 6), the aging annealing temperature is 450-500 ℃, and the heat preservation time is 150-240 min. The material facilitates the precipitation of the second phase at this temperature and time range.

Compared with the prior art, the invention has the advantages that:

1) according to the invention, Ca, Te and Sc are selected as elements for improving the machinability of the chromium-zirconium-copper, the addition amount is controlled, Ca, Te and Sc exist in the copper matrix in the form of simple substances, and the chromium-zirconium-copper is excellent in comprehensive performance and easy to cut. The chromium-zirconium-copper alloy has the conductivity of more than or equal to 80% IACS, the hardness of more than or equal to 80HRB, the softening temperature of more than or equal to 600 ℃ and the machinability of more than 50% of HPb 59-1.

2) According to the invention, water seal extrusion is adopted, and Ca, Te, Sc, Cr and Zr can be fully dissolved in the copper matrix in a solid manner and dispersed and precipitated in the subsequent aging by controlling the extrusion temperature and the solid solution temperature, and the grains of the copper matrix are refined by the existence of the second phase, so that the average grain size is below 30 um.

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

The chromium-zirconium-copper alloy comprises, by mass, 0.95% of Cr0.95%, 0.09% of Zr0, 0.03% of Ca0, 0.25% of Te0.01% of Sc, and the balance of Cu.

The preparation steps are as follows:

1) smelting: adding an electrolytic plate into a furnace, after the electrolytic plate is melted, increasing the voltage to 600V, covering the liquid level with baked glass and villiaumite, wherein the covering height is more than 5mm, the temperature reaches 1300-1350 ℃, adding a copper-chromium alloy (the mass content of chromium is 7%), a copper-calcium alloy (the mass content of calcium is 10%), a metal scandium and a metal tellurium I into the copper liquid by a pressing spoon, keeping for 3min, increasing the voltage to 400V, reducing the temperature to 1260-1320 ℃, preserving the heat, testing the elemental components of the alloy, and blending until the components are qualified;

2) semi-continuous casting: adding copper-zirconium alloy (the mass content of zirconium is 5%) into a chute of a crystallizer in which copper water enters, adding 45g of copper-zirconium alloy every 30s, wherein the casting temperature is 1300-1350 ℃, the casting speed is 300r/min, and the cooling water pressure is 0.3MPa, so as to obtain a phi 27mm casting blank;

3) water seal extrusion: adopting a 1250 extruder, extruding at the extrusion temperature of 880 ℃, and extruding a bar billet with the diameter of 25mm into a water seal groove for solid solution, wherein the solid solution temperature of the bar billet entering the water seal groove is 850 ℃;

4) peeling: the bar blank is processed into a plane skin,

5) drawing: drawing the bar blank after peeling to obtain a wire rod with the diameter of 24 mm-21 mm-19 mm-17 mm-15 mm;

6) and (3) aging annealing of a finished product: 450 deg.C +240 min.

Example 2

The chromium-zirconium-copper alloy comprises, by mass, 0.78% of Cr0.78%, 0.11% of Zr0, 0.04% of Ca0, 0.31% of Te0.015% of Sc, and the balance of Cu.

The preparation steps are as follows:

1) smelting: adding an electrolytic plate into a furnace, after the electrolytic plate is melted, increasing the voltage to 580V, covering the liquid level with baked glass and villiaumite, wherein the covering height is more than 5mm, the temperature reaches 1300-1350 ℃, adding a copper-chromium alloy (the mass content of chromium is 7%), a copper-calcium alloy (the mass content of calcium is 10%), a metal scandium and a metal tellurium I into the copper liquid by a pressing spoon, keeping for 5min, driving the voltage to 405V, reducing the temperature to 1260-1320 ℃, preserving the heat, testing the elemental components of the alloy, and blending until the components are qualified;

2) semi-continuous casting: adding copper-zirconium alloy (the mass content of zirconium is 5%) into a chute of a crystallizer in which copper water enters, adding 40g of copper-zirconium alloy every 30s, wherein the casting temperature is 1300-1350 ℃, the casting speed is 250r/min, and the cooling water pressure is 0.2MPa, so as to obtain a phi 36mm casting blank;

3) water seal extrusion: extruding a bar billet with the diameter of 34mm into a water seal groove by adopting a 1250 extruder at the extrusion temperature of 860 ℃ for solid solution, wherein the solid solution temperature of the bar billet entering the water seal groove is 830 ℃;

4) peeling: the bar blank is processed into a plane skin,

5) drawing: drawing the bar blank after peeling to obtain a wire rod,

6) and (3) aging annealing of a finished product: 470 ℃ and 240 min.

Example 3

The chromium-zirconium-copper alloy comprises, by mass, 0.12% of Cr0.12%, 0.08% of Zr0, 0.03% of Ca0.35% of Te0.35%, 0.01% of Sc, and the balance of Cu.

The preparation steps are as follows:

1) smelting: adding an electrolytic plate into a furnace, after the electrolytic plate is melted, increasing the voltage to 600V, covering the liquid level with baked glass and villiaumite, covering the liquid level with the height of more than 5mm, and when the temperature reaches 1300-1350 ℃, adding a copper-chromium alloy (the mass content of chromium is 7%), a copper-calcium alloy (the mass content of calcium is 10%), a metal scandium and a metal tellurium I into the copper liquid by a pressing spoon, keeping for 5min, increasing the voltage to 400V, reducing the temperature to 1260-1320 ℃, preserving the heat, testing the elemental components of the alloy, and blending until the components are qualified;

2) semi-continuous casting: adding copper-zirconium alloy (the mass content of zirconium is 5%) into a chute of a crystallizer in which copper water enters, adding 40g of copper-zirconium alloy every 30s, wherein the casting temperature is 1300-1350 ℃, the casting speed is 500r/min, and the cooling water pressure is 0.2MPa, so as to obtain a phi 54mm casting blank;

3) water seal extrusion: adopting a 1250 extruder, wherein the extrusion temperature is 890 ℃, extruding a bar billet with the diameter of 52mm into a water seal groove for solid solution, and the solid solution temperature of the bar billet entering the water seal groove is 860 ℃;

4) peeling: the bar blank is processed into a plane skin,

5) drawing: drawing the bar blank after peeling to obtain a wire rod,

6) and (3) aging annealing of a finished product: 500 deg.C +180 min.

The comparative examples comprise the following components in percentage by mass: 0.11 percent of Cr0.09 percent of Zr0.09 percent of Cu, and the balance of Cu.

The examples and comparative examples were tested for performance.

Tensile test at room temperature according to GB/T228.1-2010 Metal Material tensile test part 1: room temperature test method was performed on an electronic universal mechanical property tester using a tape head specimen with a width of 12.5mm and a tensile speed of 5 mm/min.

Conductivity testing according to GB/T3048.2-2007 test method for electric properties of wires and cables part 2: resistivity test of metal material, the tester is ZFD microcomputer bridge DC resistance tester, sample width is 20mm, length is 500 mm.

The hardness is detected by GB/T231.3-2021.

The high temperature softening resistance is detected by GB/T33370-2016.

And (3) cutting performance detection: the machinability of HPb59-1 was defined as 100%, and the machinability of this example was compared with that of HPb 59-1.

As can be seen from Table 1, the mechanical properties of the alloy are slightly better than those of the comparative example, but the machinability of the alloy is far higher than that of the comparative example, so that the alloy meets the machinability requirements of chromium zirconium copper on welding and cutting industries and contact tips.

TABLE 1 Properties of examples of the invention and comparative examples