A short process continuous production method of copper-nickel composite strip

Abstract

The present application belongs to the technical field of nonferrous metallurgy, and discloses a short-process continuous preparation method of copper-nickel composite strip. The method uses a concave pinch roll to transport a copper plate mother strip, and a crystal roll with the same concave degree to roll and composite high-purity nickel water obtained by vacuum smelting and the copper plate mother strip. After cooling to a hot rolling temperature, the composite is hot rolled, and after cooling to room temperature, the hot rolled composite is cold rolled. Finally, the copper-nickel composite strip product is obtained by coiling. The concave pinch roll makes the copper plate mother strip have a certain arc, increases the contact area between the molten nickel water and the mother strip, and improves the composite effect and the cooling speed. The copper-nickel composite cast strip produced by the concave crystal roll also has a certain arc, which provides a deformation space for subsequent rolling, avoids cracking of the different metal interfaces in the composite process, makes the thickness of the composite thin strip more uniform, and improves the surface quality of the thin strip. The method shortens the length of the production line and reduces the production cost of the copper-nickel composite strip.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nonferrous metallurgy, and particularly relates to a short-process continuous preparation method of copper-nickel composite strip. BACKGROUND

[0002] The core idea of thin strip casting technology is to directly roll molten metal into metal strip by means of high cooling speed. Since this technology concept was proposed in the 1950s, after a century of development, various forms of thin strip casting technology have been developed, mainly divided into belt type thin strip casting technology and roller type thin strip casting technology, and among them, the double-roller thin strip casting technology has attracted the attention of metallurgical field personnel due to its fast cooling speed, short production line and high efficiency, and is now hailed as the most revolutionary front technology in the field of steel metallurgy in the 21st century. The double-roller thin strip casting technology directly produces 1-5mm metal cast strip by directly pouring molten metal liquid on a water-cooled copper crystallization roller, during which the cooling speed of the metal melt is extremely fast, reaching the sub-rapid solidification range; at the same time, the technology successfully realizes the combination of casting and rolling by adjusting the crystallization roller gap width and casting rolling force, which can complete the direct forming of cast strip with a small amount of hot rolling or even omit hot rolling, greatly shortening the production line length, saving energy and reducing cost. With many advantages, the double-roller thin strip casting technology has become an advanced casting technology that steel companies around the world are competing to develop. China started late in the double-roller thin strip casting technology, but after decades of development, China Baosteel successfully built the country's first self-developed double-roller thin strip casting industrial production line in 2014, and made important progress in industrialization research. However, up to now, the existing double-roller thin strip casting production line is mostly used for the production and processing of steel materials, and the steel grades that can achieve commercial production are very limited, mainly low-carbon steel and low-carbon micro-alloy steel.

[0003] With the development of industrial level and the rise of various new technologies and new industries, the requirements for various properties of engineering materials have gradually increased. Due to the limitations of their own properties, natural resource reserves, or production and processing costs, single metal materials cannot fully meet the use requirements of more industrial fields. Under this background, the development of composite metal materials using two or more metals has become an important way to break through the limitations of existing single metal materials. So far, a variety of metal composite materials have been successfully developed and widely applied in different fields, such as copper-aluminum composite strip, magnesium-aluminum composite strip, and copper-nickel composite strip. Among them, copper-nickel composite strip has excellent electrical conductivity, thermal conductivity, and corrosion resistance due to the inheritance of the characteristics of copper and nickel, and is widely used in electronic devices, batteries, and other fields. Today, there are two main production methods for metal composite strips: explosive compounding and rolling compounding. Although these two production methods can achieve metallurgical bonding of different metals, the production process is very complicated and often requires repeated heating and rolling of the material, which not only causes a lot of resource waste but also significantly reduces the production efficiency of composite strips (Zhou J, Shi H, Yang W. Research status and development trend of metal composite plate processing technology [J]. Metal World, 2022(05):24-30.). Therefore, developing an economical and green metal plate compounding method is an important direction to expand the production of metal composite plates and broaden their application scope.

[0004] Due to the dual functions of casting and rolling, as well as the rapid cooling of molten metal, the double-roller thin strip casting technology can directly produce composite billets by pouring one molten metal onto another solid metal mother strip, and then directly produce composite plate strips of a certain thickness through rolling. This production and processing method not only has high efficiency but also realizes solid-liquid compounding of metals, effectively utilizes the heat of molten metal, and reduces production costs, thus attracting widespread attention. Through continuous research and development, copper-aluminum composite plates and steel-aluminum composite plate strips have been successfully produced through thin strip casting, as shown in patents 202110966227.1 and 200810200706.7. Therefore, the double-roller thin strip production process has high feasibility in the production of metal composite plates. However, although the application of double-roller thin strip casting technology in metal composite plate production has been increasingly researched in recent years, there is no report on the use of double-roller thin strip casting technology for copper-nickel composite strip processing.

[0005] Through the previous laboratory research, it is found that it is difficult to realize the smooth preparation of copper-nickel composite plate by directly feeding the copper plate master tape into the crystallization roller molten pool through the pinch roll, and the proportion of copper-nickel layer of the obtained composite plate is uneven, the overall thickness fluctuation of the plate strip is large, and the copper-nickel composite effect in some areas is poor and easy to crack. Therefore, although the double-roller thin strip continuous casting technology has many advantages, it still needs to be further improved to adapt to the preparation of copper-nickel composite plate, so as to meet the continuous production of high-quality copper-nickel composite plate. Through the previous research, it is found that there is little record of using a concave pinch roll to prepare copper-nickel composite plate. SUMMARY

[0006] In order to solve the problems in the prior art, the present application provides a short process continuous preparation method of copper-nickel composite strip, which uses a pinch roll with a unique structure (i.e. a concave pinch roll) to cooperate with a crystallization roller with the same concave degree to feed the copper plate master tape along the crystallization roller into the crystallization roller molten pool. The function of the concave pinch roll is to transport the master tape, and its special structure can extrude the master tape into a plate strip with a certain arc under the cooperation with the crystallization roller. The existence of the arc can provide more sufficient composite space for the molten metal, ensure the composite effect, and make the master tape adhere more closely to the crystallization roller, thereby improving the heat transfer conditions and the uniformity of the composite plate strip grains. In addition, the existence of the arc can provide deformation space for the rolling process of the composite plate strip, relieve stress concentration on the surface of the composite strip, and reduce quality defects such as cracking.

[0007] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0008] The short process continuous preparation method of copper-nickel composite strip according to the present application comprises the following steps:

[0009] 1) Nickel water smelting

[0010] The high-purity nickel water is smelted by using an induction furnace in a vacuum environment, and the mass percentage of the chemical composition of the smelted molten nickel water is: C: ≤20.0ppm, Si: ≤10ppm, Mn: ≤12ppm, S: ≤2.0ppm, Mg: ≤3.0ppm, Al: ≤7ppm, Ti: ≤25ppm, and the balance is Ni and unavoidable impurities;

[0011] 2) Copper plate conveying

[0012] The copper plate master tape is fed into the crystallization roller molten pool along the crystallization roller through the concave pinch roll, and the conveying speed is consistent with the casting speed of the double-roller thin strip continuous casting machine. The copper plate adopts single master tape or double master tape.

[0013] The concave pinch roll used for transmitting the copper plate master tape has a spindle structure with large ends and a small middle part, which is defined as follows: after the concave pinch roll is erected, the top surface and the bottom surface are composed of two circles with equal radii and R, the height from the bottom surface to the top surface is H, the radius of the circle on the plane of 1 / 2H of the concave pinch roll is R1, the concavity is R-R1=0.2-0.3mm, and preferably 0.2mm, the diameter of the circle constituting the concave pinch roll decreases from the bottom surface to 1 / 2H, and the diameter of the circle constituting the concave pinch roll increases from the bottom surface to the top surface after passing 1 / 2H; the existence of the concavity is more conducive to the contact between the molten nickel water and the master tape, increases the contact area between them, and makes the cast tape form a certain arc, which is beneficial to the subsequent rolling; meanwhile, the ratio of the thickness of the solidified layer of the molten nickel water to the thickness of the copper plate master tape is 0.8-2.0, and preferably 1.2-1.6; the increasing or decreasing mode is preferably a circular arc shape.

[0014] 3) Composite plate casting

[0015] The molten nickel water is poured into the buffer bag through the long nozzle at the bottom of the vacuum induction furnace, and then enters the crystallization roll pool through the shunt nozzle at the bottom of the buffer bag, contacts the copper plate master tape sent by the concave pinch roll, and then is cast into a copper-nickel composite cast thin strip through the double-roll thin strip continuous casting machine; the crystallization roll used is a concave crystallization roll, and the concavity thereof is consistent with that of the concave pinch roll.

[0016] The temperature of the molten nickel water is 1500-1550℃; the temperature of the nickel water entering the crystallization roll pool is 1490-1530℃; the average roll gap of the concave crystallization roll is 3.0-6.0mm, which is too small to ensure the thickness ratio of the composite strip, and too large to cause excessive surface load of the crystallization roll, which is not conducive to continuous production; the temperature of the copper-nickel composite cast thin strip cast by the double-roll thin strip continuous casting machine is 900-1000℃.

[0017] Further, in order to ensure the service life of the crystallization roll and considering the heat transfer between the cast thin strip and the crystallization roll, the surface of the concave crystallization roll is plated with a nickel-chromium alloy plating layer, and the thickness of the plating layer is 20-60μm; as a further optimization, the content of nickel in the nickel-chromium alloy plating layer is 50-80%, and preferably 60-70%, and the balance is chromium.

[0018] After the copper-nickel composite cast thin strip is cast by the double-roll thin strip continuous casting machine, it needs to be further hot-rolled.

[0019] The copper-nickel composite cast thin strip is rapidly and uniformly cooled to 800-900℃ after leaving the crystallization roll, and is rolled to 1.5-2.0mm by 1-2 passes of hot rolling at 800-900℃, and the temperature of the hot-rolled copper-nickel composite rolled strip is 750-850℃.

[0020] The application discloses a short-process continuous preparation method of copper-nickel composite strip material, and after a hot-rolled copper-nickel composite rolling strip is manufactured by a hot rolling mill, the copper-nickel composite rolling strip needs to be further cold-rolled.

[0021] The copper-nickel composite rolling strip after hot rolling is cooled to room temperature, and then is continuously cold-rolled for 2-4 times to be rolled to a rolling strip with a thickness of 0.3-0.8 mm, so as to obtain a cold-rolled copper-nickel composite rolling strip.

[0022] The application discloses a short-process continuous preparation method of copper-nickel composite strip material, and after a cold-rolled copper-nickel composite thin strip is coiled by a coiling machine, a copper-nickel composite strip coil is finally obtained, and the coiling temperature is room temperature.

[0023] Further, in the step 1), the smelting mode is vacuum induction melting or double vacuum melting, that is, vacuum induction melting plus vacuum consumable, and further refining is used to control the nickel water composition, and the smelting process is carried out in a vacuum environment throughout the whole process until pouring, so that the oxidation of nickel water is effectively avoided.

[0024] Further, in the step 1), the superheat of the nickel water when the smelting is completed is 40-80 DEG C, and preferably 40-50 DEG C.

[0025] Further, in the step 2), the surface impurities of the copper plate mother strip need to be removed before the copper plate mother strip is conveyed, and the temperature of the copper plate mother strip before being sent into a crystallization roller pool is room temperature.

[0026] Further, before the nickel water is poured, the head of the copper plate mother strip is conveyed to a position flat with the bottom of the crystallization roller and is fixed; when the nickel water is poured, the conveying speed of the copper plate mother strip is consistent with the continuous casting speed, and is 60-100 m / min.

[0027] Further, in the step 3), after the nickel water smelting is completed, the vacuum needs to be broken, and inert gas is blown in to prevent the oxidation of the nickel water, and the inert gas is generally nitrogen.

[0028] Further, in the step 3), the thickness of the copper-nickel composite as-cast thin strip is 3.0-6.0 mm.

[0029] Further, after the copper-nickel composite as-cast thin strip is sent out of the crystallization roller, the inert gas is sprayed by a high-pressure gas cooling nozzle to cool the copper-nickel composite as-cast thin strip to 800-900 DEG C, and the cooling rate is 50-100 DEG C / s, and the nozzle gas is generally one of nitrogen, helium and argon; then, online hot rolling is carried out, and the hot rolling reduction is less than or equal to 70%.

[0030] Further, the copper-nickel composite rolling strip after hot rolling is cooled to room temperature by using a high-pressure water nozzle, and the cooling rate is 60-150 DEG C / s; then, cold rolling is carried out, and the total cold rolling reduction is less than or equal to 80%.

[0031] Further, the coiling temperature is room temperature.

[0032] The application relates to a short-process continuous preparation method of copper-nickel composite strip.

[0033] The technical concept of the application is as follows:

[0034] 1) The double-roller thin strip casting technology is effectively combined with casting and rolling, the copper plate mother strip is compounded with molten nickel water by virtue of the high cooling speed, and the copper-nickel composite cast strip is prepared through rolling of the crystallization roller.

[0035] 2) The matching of the concave pinch roller and the concave crystallization roller enables the copper plate mother strip to have a certain arc before entering the crystallization roller pool, the arc can make the mother strip better adhere to the surface of the crystallization roller, thereby improving the heat transfer condition and the cooling speed of the nickel water; meanwhile, the existence of the arc is more conducive to the filling of the nickel water on the surface of the mother strip, increases the contact area between the solid-liquid phases, and is beneficial to the compounding of different metals.

[0036] 3) The nickel water realizes sub-rapid solidification under the strong cooling of the crystallization roller, can form a metal liquid solidification layer on the surface of the copper plate mother strip, and through further rolling of the crystallization roller, the combination of the copper and nickel metals can be more closely, the internal porosity of the composite plate strip is effectively reduced, and the quality of the multi-composite plate strip is improved.

[0037] 4) The use of the concave crystallization roller can make the copper-nickel composite cast strip have a certain arc, the existence of the arc can provide a certain deformation space for the plate strip in the subsequent rolling process, and reduce the stress concentration on the surface of the cast strip, thereby improving the surface quality of the composite strip.

[0038] The component functions and the limitation of the copper-nickel composite strip are as follows:

[0039] C: The solubility of C in pure nickel at room temperature is extremely low, the rest of C will be deposited in the form of graphite or form segregation at the grain boundary position, and is extremely easy to be oxidized to deteriorate the quality of the nickel plate. Therefore, the C content of the application is not higher than 20ppm.

[0040] Si: Si is more active and is oxidized before Ni, thereby forming island-shaped SiO2 under the NiO layer. Due to the difference in expansion coefficient, the material after being heated is prone to the problem of NiO layer falling off in the cooling process, so the Si content must be strictly limited, and the application limits the Si content to be below 10ppm.

[0041] Mn: Mn element is more active than Ni, and is oxidized before Ni, thereby forming an oxide between Ni and the NiO layer, so the Mn content is controlled to be below 12ppm in the application.

[0042] Mg: The chemical properties of Mg element are also relatively active, and due to the small molar volume, it is easy to increase the porosity of the nickel plate, so the content of Mg is controlled to be less than 3ppm in the application.

[0043] S: S element has adverse effects on the toughness and tensile properties of the nickel plate, and too high S element in the nickel water will precipitate NiS at the grain boundary, thereby reducing the mechanical properties of the product, so the lower the sulfur content in the nickel, the better, considering the existing smelting level and economic factors, the S content is controlled to be less than 2ppm in the application.

[0044] Al: Al has strong oxygen affinity, so it is easy to form Al2O3 in the Ni matrix, and Al2O3 has high hardness and is difficult to deform during stress, so it is easy to form holes during material processing. Therefore, the Al content is controlled to be less than 7ppm in the application.

[0045] Ti: Ti in the nickel water is easy to diffuse to the surface of the nickel plate during processing to form TiO2, and conventional heat treatment cannot reduce it, therefore, the Ti content is controlled to be less than 25ppm in the application.

[0046] In the preferred embodiment of the application, the distance between the roll gaps of the crystallization rollers is defined as D, and the thickness of the copper plate mother tape is d, so the ratio of the thickness of the copper plate mother tape to the solidification layer thickness of the molten nickel water is (D-d) / d; the distance between the roll gaps of the crystallization rollers is controlled to be between 3.0-6.0mm, and the ratio of the solidification layer thickness of the molten nickel water to the thickness of the copper plate mother tape (D-d) / d is between 0.8-2.0, preferably 1.2-1.6.

[0047] In the preferred embodiment of the application, the diameters of the bottom surface and the top surface of the concave pinch rollers are 100mm, the diameter at 1 / 2H is 99.6mm, and the concavity is 0.2. When (D-d) / d=1.2, 1.6, the surface of the copper-nickel composite thin strip obtained has no cracks, and the surface quality is high, but the uniformity of the composite rolling strip manufactured by the (D-d) / d=1.6 scheme is better than that of the (D-d) / d=1.2 scheme.

[0048] The beneficial effects of the application are:

[0049] 1) The pinch rollers of the pinch mother tape are optimized in the application, and the cooperation of the concave pinch rollers and the concave crystallization rollers makes the copper plate mother tape have a certain arc, so that it can better fit the surface of the crystallization roller after inserting into the crystallization roller melt pool, improve the heat transfer conditions of the molten nickel water, and increase the cooling speed; at the same time, the existence of the concave of the mother tape increases the contact area of the molten nickel water and the mother tape, so that a more dense solidification layer of the molten nickel water is formed on the surface of the mother tape, and the composite effect is improved.

[0050] 2) The use of the concave crystallization roller provides a certain deformation space for the rolling composite process of the composite strip, reduces the stress concentration on the surface of the cast strip, thereby avoiding the cracking of the interface between different metals in the composite process; in addition, the cast strip also has a certain arc, and the existence of the arc can guide the cast strip to produce a certain deformation in the subsequent rolling process, on the one hand, the thickness of the final composite thin strip is more uniform, on the other hand, the stress on the surface of the thin strip in the rolling process is also uniform, and the surface quality of the composite thin strip is improved.

[0051] 3) Compared with the existing metal composite plate production process, the double-roller thin strip continuous casting technology involved in the present application completes the production and processing of copper-nickel composite plates, realizes the direct composite between the molten nickel water and the solid copper plate, simultaneously utilizes the heat of the molten nickel water, matches the online hot rolling, and is compactly matched with the continuous cold rolling, thereby avoiding repeated heating, shortening the production line length, and reducing the production cost of the copper-nickel composite plate. BRIEF DESCRIPTION OF DRAWINGS

[0052] Fig. 1 Fig. 1 is a schematic diagram of the process flow of the double-roller thin strip continuous casting machine set of the present application; wherein (a) is a process flow diagram of the part before hot rolling, and (b) is a process flow diagram of the part after hot rolling.

[0053] Fig. 2 Fig. 2 is a schematic diagram of the thickness of the copper plate mother strip and the solidification layer thickness of the molten nickel water.

[0054] Fig. 3 Fig. 3 is a schematic diagram of the concave degree of the concave crystallization roller.

[0055] In the figure, the vacuum cover 1, the contact type thermocouple 2, the induction furnace 3, the long nozzle 4, the buffer package 5, the flow distribution type nozzle 6, the molten pool 7, the side sealing plate 8a, 8b, the crystallization roller 9a, 9b, the metal wire roller brush 10a, 10b, the concave pinch roller 11, the copper plate mother strip 12, the high-pressure gas cooling nozzle 13, the as-cast thin strip 14, the fan-shaped guide plate 15, the gas protection box 16, the ordinary pinch roller 17, the conveying roller 18, the hot rolling machine 19, the 1# high-pressure water nozzle 20, the cold rolling machine 21, the flying shear 22, the coiling machine 23; D represents the crystallization roller gap distance, d represents the copper plate mother strip thickness, and D-d represents the solidification layer thickness of the molten nickel water. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0057] Embodiments 1-6, see Figs. 1-3 ;

[0058] The nickel water smelting work completed by the induction furnace 3 in the vacuum cover 1, the temperature of the nickel water is collected by the contact thermocouple 2 during the smelting process, and the PID temperature control system is used to realize the detection and regulation of the temperature of the nickel water. After the nickel water smelting is completed, it enters the buffer bag 5 through the long nozzle 4, the superheat degree of the nickel water in the buffer bag is 75℃, and then the nickel water enters the molten pool 7 composed of the crystallization rollers 9a, 9b and the side sealing plates 8a, 8b through the flow distribution nozzle 6; before the nickel water is poured, the head of the copper plate mother tape 12 after removing surface impurities is conveyed to a position level with the bottom of the crystallization rollers 9a, 9b and kept fixed, so as to ensure the continuous casting effect of the cast strip; during the pouring of the nickel water, the copper plate mother tape 12 after removing surface impurities continuously passes through the concave pinch roller 11 at room temperature and is sent into the molten pool 7 along the crystallization rollers 9a, 9b, the molten nickel water is cooled to form a solidified layer in a very short time after contacting the crystallization rollers and the copper plate mother tape 12 during the pouring process, and the composite of the copper plate mother tape 12 is further completed through the rolling action of the crystallization rollers, and finally the copper-nickel composite as-cast thin strip 14 with a thickness of 2.8mm (2.8mm in example 1, 3.6mm in example 2, 4.4mm in example 3, 5.2mm in example 4, 6.0mm in example 5, and 6.8mm in example 6) is cast by the double-roller thin strip continuous casting machine. Among them, the width of the concave crystallization roller 9a, 9b is 250mm (i.e. the height H is 250mm), the diameter of the bottom and top surface of the concave crystallization roller 9a, 9b is 300mm, the diameter at 1 / 2H is 299.6mm, and the concavity is R-R1=150-149.8=0.2mm; the diameter of the bottom and top surface of the concave pinch roller is 100mm, the diameter at 1 / 2H is 99.6mm, and the concavity is R-R1=50-49.8=0.2mm; the thickness d of the copper plate mother tape during processing is 2.0mm, the ratio of the solidified layer thickness of the molten nickel water to the copper plate mother tape thickness (D-d) / d is controlled between 0.8-2.0 (0.4 in example 1, 0.8 in example 2, 1.2 in example 3, 1.6 in example 4, 2.4 in example 4, and 2.4 in example 6); the casting speed of the casting machine is 90m / min. The outer sides of the two crystallization rollers 9a, 9b are arranged with metal wire roller brushes 10a, 10b with the same width as the crystallization rollers 9a, 9b, and the material of the metal wire roller brushes 10a, 10b is copper alloy, which is used to brush off the excess oxide deposition film generated on the surface of the crystallization roller 9a, 9b during continuous casting. From the flow distribution nozzle 6 to the area where gas cooling is completed is the gas protection box 16, which is filled with inert gas, generally nitrogen, which can prevent high-temperature oxidation of the thin strip.

[0059] After the as-cast thin strip 14 passes through the crystallization rollers 9a, 9b, high-pressure gas cooling nozzles 13 are arranged uniformly along the width and the casting direction of the as-cast thin strip 14 on both sides of the wide face of the as-cast thin strip 14. The length of the entire gas cooling cooling section is 0.3 mm. The gas of the nozzles is inert gas, which is generally helium, so that the oxidation of the surface of the thin strip during the cooling process can be avoided. The inert gas sprayed by the high-pressure gas cooling nozzles 13 causes the as-cast thin strip to cool rapidly and uniformly to 850°C, and the cooling rate of the thin strip is 50-100°C / s. The thin strip is transported to the ordinary pinch roller 17 through the fan-shaped guide plate 15, and then transported into the online hot rolling mill 19 through the transport roller 18. The hot rolling mill 19 rolls the thin strip to 1.6 mm (1.6 mm in Example 1, 1.7 mm in Example 2, 1.7 mm in Example 3, 2.0 mm in Example 4, 2.2 mm in Example 5, and 2.2 mm in Example 6), and the hot rolling reduction rate is 68%. After the hot rolling, the thin strip is subjected to laminar cooling using the 1# high-pressure water nozzle 20, and the cooling rate is 60-150°C / s. The thin strip is cooled directly to room temperature, and then is subjected to cold rolling in the subsequent 2-4 pass cold rolling mill 21. The thin strip is further rolled to 0.5 mm (0.5 mm in Examples 1, 4-6, and 0.6 mm in Examples 2-3) through continuous cold rolling, and the total cold rolling reduction rate is 71%. The thin strip is cut by the flying shear 22 and then is coiled by the power coiler 23 to obtain the copper-nickel composite strip coil. The coiling temperature of the thin strip is room temperature.

[0060] The copper-nickel composite thin strips in Examples 1-6 are obtained by using the double-roller thin strip continuous casting process to composite the high-purity nickel water with the copper plate substrate, and the comparative example is obtained by rolling the copper plate and the pure nickel plate. The concave degree of the crystallization roller, the concave degree of the pinch roller, the thickness of the copper plate mother strip, the ratio of the thickness of the nickel water solidification layer to the thickness of the mother strip, the superheat degree of the nickel water, the average austenite grain size, the rolling thickness, the rolling surface quality, and the bonding of the rolling strip corresponding to Examples 1-6 and Comparative Example 1 are shown in Table 1.

[0061] As shown in Table 1, the quality of the copper-nickel composite strip manufactured by the double-roller thin strip casting process (concave crystallization rollers 9a, 9b + concave pinch rollers 11) of Examples 1-6 is obviously higher than that of the copper-nickel composite strip obtained by rolling compounding in Comparative Example 1, the pits are reduced, the surface cracks of the strip are reduced, and the average austenite grain size is reduced; the definition of the crystallization roller gap distance is D, and the copper plate mother strip thickness is d, so the ratio of the molten nickel water solidification layer thickness to the copper plate mother strip thickness is (D-d) / d, when (D-d) / d = 1.2 (Example 3) or 1.6 (Example 4), the surface of the obtained copper-nickel composite thin strip is free of cracks and pits, the copper-nickel composite strip is tightly combined, and the surface quality is better than that of the copper-nickel composite thin strip obtained when (D-d) / d = 0.8 (Example 2) or 2.0 (Example 5), and better than that of (D-d) / d = 0.4 (Example 1) or 2.4 (Example 6), especially when (D-d) / d = 1.6 (Example 4), the strip thickness tolerance is smaller than that when (D-d) / d = 1.2 (Example 3), that is, the uniformity of the strip thickness of the former is better than that of the latter;

[0062] In addition, the copper-nickel composite thin strips of the present application are all metallurgically bonded and have good surface quality, and the elongation reaches 45%, and the copper-nickel composite strip produced by thin strip casting meets the requirements in terms of surface quality, bonding effect and material elongation, indicating that this technology can fully meet the production needs of copper-nickel composite strips.

[0063] Table 1: Composite strip casting process parameters and properties of Examples 1-6 and Comparative Example 1

[0064]

Claims

1. A short-process continuous preparation method for copper-nickel composite strip, characterized in that, Includes the following steps: 1) Nickel smelting High-purity nickel was smelted in an induction furnace under vacuum conditions. The chemical composition of the molten nickel obtained was as follows (mass percentage): C: ≤20.0 ppm, Si: ≤10 ppm, Mn: ≤12 ppm, S: ≤2.0 ppm, Mg: ≤3.0 ppm, Al: ≤7 ppm, Ti: ≤25 ppm, with the balance being Ni and unavoidable impurities. 2) Copper Coin Conveying The copper plate master strip is fed into the crystallizing roll molten pool via concave pinch rollers. The conveying speed is consistent with the casting speed of the twin-roll thin strip continuous casting machine. The copper plate uses a single master strip or a double master strip. The surface of the copper plate master strip needs to be cleaned before conveying. The temperature of the copper plate master strip before being fed into the crystallizing roll molten pool is room temperature. The concave pinch roller has a spindle structure that is large at both ends and small in the middle. It is defined as follows: when the concave pinch roller is upright, the top and bottom surfaces are composed of two circles with equal radii R. The height from the bottom surface to the top surface is H. The radius of the circle on the plane where 1 / 2H of the concave pinch roller is located is R1. The concavity is R-R1=0.2-0.3mm. The diameter of the circle forming the concave pinch roller decreases from the bottom surface upwards to 1 / 2H. From the bottom surface upwards, after passing 1 / 2H, the diameter of the circle forming the concave pinch roller increases from the bottom surface upwards towards the top surface. The ratio of the thickness of the solidified molten nickel layer to the thickness of the copper plate master strip is 1.2-1.

6. 3) Composite plate casting Molten nickel is poured into a buffer ladle through a long nozzle at the bottom of a vacuum induction furnace, and then enters the crystallizing roll pool through a branch nozzle at the bottom of the buffer ladle. It comes into contact with the copper strip fed in by the concave pinch roll, and is cast into a copper-nickel composite as-cast strip by a twin-roll thin strip casting machine. The crystallizing roll used is a concave crystallizing roll, and its concavity is consistent with that of the concave pinch roll. The temperature of the molten nickel is 1500-1550℃; the temperature of the molten nickel entering the crystallizing roll pool is 1490-1530℃; the average spacing of the concave crystallizing rolls is 3.0-6.0mm; the temperature of the copper-nickel composite as-cast thin strip cast by the twin-roll thin strip casting machine is 900℃-1000℃; Before pouring the nickel molten metal, the head of the copper plate strip is conveyed to a position level with the bottom of the crystallizing roll and kept fixed; when pouring the nickel molten metal, the conveying speed of the copper plate strip is the same as the continuous casting speed, which is 60-100m / min. 4) Hot rolling After exiting the crystallization roll, the copper-nickel composite cast strip is rapidly and uniformly cooled to 800-900℃. The cast strip is then hot-rolled to 1.5-2.0mm in 1-2 passes at 800-900℃, resulting in a hot-rolled copper-nickel composite strip at a temperature of 750-850℃. 5) Cold rolling After hot rolling, the copper-nickel composite strip is continuously cooled to room temperature, and then subjected to 2 to 4 consecutive cold rolling passes to roll it into a strip with a thickness of 0.3-0.8 mm. 6) Composite tape curling The cold-rolled copper-nickel composite strip is then coiled to obtain the final copper-nickel composite strip coil.

2. The short-process continuous preparation method for copper-nickel composite strip according to claim 1, characterized in that: In step 1), the smelting method is vacuum induction melting or vacuum induction melting plus vacuum self-consumption, and further refining is used to control the composition of the nickel solution.

3. The short-process continuous preparation method for copper-nickel composite strip according to claim 1, characterized in that: In step 1), the superheat of the molten nickel at the end of smelting is 40-80°C.

4. The short-process continuous preparation method for copper-nickel composite strip according to claim 1, characterized in that: In step 3), after the molten nickel is smelted, the vacuum must be broken and an inert gas must be blown in to prevent the nickel from oxidizing.

5. The short-process continuous preparation method for copper-nickel composite strip according to claim 1, characterized in that: In step 3), the surface of the concave crystallizing roller is plated with a nickel-chromium alloy coating with a thickness of 20-60 μm; the nickel content in the nickel-chromium alloy coating is 50-80%, and the balance is chromium.

6. The short-process continuous preparation method for copper-nickel composite strip according to claim 1, characterized in that: In step 4), after the copper-nickel composite cast thin strip exits the crystallizing roll, it is first cooled to 800-900℃ by spraying inert gas through a high-pressure air-cooling nozzle at a cooling rate of 50-100℃ / s, and then immediately followed by online hot rolling with a hot rolling reduction rate of ≤70%.

7. The short-process continuous preparation method for copper-nickel composite strip according to claim 1, characterized in that: In step 5), the hot-rolled copper-nickel composite strip is subsequently cooled to room temperature using a high-pressure water nozzle at a rate of 60-150℃ / s; then it is cold-rolled with a total cold-rolling reduction rate of ≤80%.

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