Preparation method of metal material with multiphase heterostructure

Abstract

The invention provides a preparation method of a metal material with a multi-phase heterostructure, which comprises the following steps of: weighing metal raw materials according to the components of the metal material, smelting to obtain molten metal, carrying out electric pulse treatment on the molten metal to obtain a melt, carrying out directional crystallization on the melt to obtain a cast ingot with an inclined splayed columnar crystal structure, carrying out hot working to obtain a blank, and carrying out heat treatment on the blank to obtain the metal material with the multi-phase heterostructure. And then the blank is subjected to cold machining treatment, a cold machined part is obtained, finally, the cold machined part is subjected to micro-area electric treatment, and the metal material with the multi-phase heterostructure is obtained. According to the method, a structure of a core columnar crystal and an edge equiaxed crystal is obtained through hot working, the hard outside and the tough inside are achieved, then more dislocation and deformation twin crystals are obtained through large-deformation cold working treatment, finally, the material is subjected to zoning treatment through micro-zone electric treatment, a structure with a softening zone and a hardening zone alternated is obtained, and tough alternation is achieved; under the synergy of the process, the multiphase heterostructure metal material which is hard outside and tough inside and has excellent mechanical properties is obtained, and the toughness of the multiphase heterostructure metal material is alternated.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material preparation and processing, and in particular relates to a method for preparing a metal material with a multi-phase heterogeneous structure. Background Art

[0002] Metal materials are key structural functional materials in many high-tech fields due to their good mechanical properties, electrical properties, magnetic properties and thermal conductivity. They have been widely used in my country's electronic communications, aerospace, petrochemical, marine engineering, new energy and other high-tech fields, especially copper alloys, aluminum alloys, titanium alloys, magnesium alloys and other materials are widely used in the manufacture of integrated circuit lead frames, precision electronic components, connectors, etc. With the rapid development of modern industry, especially in high-tech industries such as computers, semiconductors, instrumentation, information and communications, high load, high reliability and high service life have become the main development direction of conductor functional devices, which makes the service conditions of alloys used for signal transmission, structural support and thermal management systems more demanding, and therefore puts forward higher requirements on the comprehensive performance of materials.

[0003] Improving the strength and plastic toughness of metal materials at the same time is an important way to develop high-performance metals. Fine grain strengthening and precipitation strengthening are important means to improve the mechanical properties of metal materials. By adding modifiers or rapid solidification during the smelting process, ingots with fine grains can be prepared. Through strong plastic deformation processing technologies such as equal channel extrusion, multi-directional compression, and large deformation extrusion, a fine and uniform structure of grains can be obtained. The strength and plasticity of the material can be improved at the same time by refining the grains, but the degree of strengthening is limited. Therefore, it is usually necessary to undergo appropriate heat treatment to form a large number of dispersed fine second phase particles in the alloy.

[0004] At present, there are many methods for preparing and processing high-performance metal materials, which mainly focus on the research of overall material preparation, while there are few studies on the microstructure control process of materials. Patent No. ZL201210209072.8 discloses a CuNiSiMg alloy material and its preparation method and a method for preparing strips from the alloy material; Patent No. CN200810235978.0 discloses a modified preparation method for Cu-Cr-Zr alloy plates and strips. Both of the above methods adopt the "semi-continuous casting-hot rolling-milling / grinding-cold rolling-(solid solution-cold rolling)-aging" process. These processes have the problems of long process, low yield rate, poor product quality, high production cost, etc. in the production process; Patent No. CN107716885B discloses a short-process production method for high-strength and high-conductivity copper alloy strips. This method adopts the "hot and cold combined casting horizontal continuous casting-cold rolling-solid solution-cold rolling-aging" process to produce strips. This method greatly reduces the process flow and has the characteristics of high yield rate and low production cost; Patent No. CN111424224B discloses a preparation method for high-strength and high-toughness conductive copper alloy strips. This method adopts the "solid solution-cold rolling-electric pulse heat treatment-cold rolling-aging treatment" process route, so that the alloy obtains a matrix with fine and uniform grains, high-density dislocations and dispersed distribution of precipitated phases, which greatly improves the mechanical properties of the alloy. However, the above method still uses deformation + traditional heat treatment process, which is limited by the size of the furnace chamber, long heat treatment time and low production efficiency in the traditional heat treatment process on the one hand; on the other hand, due to the treatment of the alloy as a whole, only a single and evenly distributed organization can be obtained. Patent No. CN110343993A discloses a hard alloy surface treatment method and application, which adopts carburizing or nitriding treatment on the alloy surface, which can effectively improve the mechanical properties of the alloy surface. However, the process has high requirements on the thickness of the alloy. If the thickness of the substrate is too thin, the coating structure will be loose, resulting in coating failure, or coating penetration. The above process is difficult to meet the growing requirements of high life and high stability of the alloy during service. Therefore, how to overcome the shortcomings of the traditional production process of metal materials and develop a method for preparing metal materials with specific performance requirements (such as hard outside and tough inside, strong and tough alternating) that is not limited by material size is very important. Summary of the invention

[0005] In view of the above-mentioned shortcomings that currently exist, the purpose of the present invention is to provide a method for preparing a metal material with a multi-phase heterogeneous structure. First, a columnar crystal structure with an "oblique eight-shaped" structure is obtained through directional solidification, and then a structure of core columnar crystals + edge equiaxed crystals is obtained through hot working, so as to achieve external hardness and internal toughness and improve the mechanical properties. Subsequently, more dislocations and deformation twins are obtained through large deformation cold working treatment, so that the material obtains more second phase nucleation sites and better mechanical properties. Finally, the material is partitioned by micro-area current treatment to obtain a structure with periodic alternation of softening zones and hardening zones, so as to achieve strong and tough alternation in the micro-areas of the metal material. With the cooperation of the above-mentioned processes, a multi-phase heterogeneous structure metal material with excellent comprehensive performance and hardness on the outside and toughness on the inside and strong and tough alternation is obtained.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention discloses a method for preparing a metal material with a multi-phase heterogeneous structure. The method comprises the following steps: selecting metal raw materials according to the composition of the metal material for smelting to obtain molten metal, subjecting the molten metal to electric pulse treatment to obtain a melt, subjecting the melt to directional crystallization to obtain an ingot with an oblique eight-shaped columnar crystal structure, subjecting the ingot to hot processing to obtain a blank, subjecting the ingot to cold processing to obtain a cold-processed part, and finally subjecting the cold-processed part to micro-area electric processing to obtain the metal material with a multi-phase heterogeneous structure.

[0008] The preparation method of the present invention comprises the following steps: preparing various metal raw materials according to the designed proportion, placing them into an electric pulse directional solidification crucible in order from high to low melting points, placing a covering agent on the surface of the crucible to melt the metal, and subjecting the molten metal liquid to electric pulse treatment to obtain a melt with uniform composition and purity, and then subjecting the melt to directional crystallization to obtain an ingot with uniform composition and an "oblique eight-shaped" slender columnar crystal structure; then placing the ingot with uniform composition into a box-type resistance furnace for heating and heat preservation, and then subjecting the ingot to heat treatment to eliminate internal looseness, pores, The hot-worked material is then subjected to large deformation cold working to introduce a large number of dislocations, which provide more driving force and nucleation sites for the precipitation of the second phase. Finally, the designated positions of the plate and strip after large deformation cold working are subjected to micro-area electrical treatment to regulate the multiphase heterogeneous structure in the material microstructure, and obtain an organizational structure with periodic alternation of softening zones and hardening zones, thereby obtaining a multiphase heterogeneous structural metal material with excellent comprehensive performance that is hard on the outside and tough on the inside and strong and tough alternation.

[0009] In a preferred embodiment, the metal material is one of copper alloy, iron alloy, aluminum alloy, magnesium alloy, zinc alloy and titanium alloy.

[0010] In the present invention, the shape of the metal material is not subject to too many restrictions, such as plates, strips, wires, tubes, special-shaped materials, etc.

[0011] A preferred solution is to put the metal raw materials into a crucible in order from high to low melting points, place a covering agent on the surface of the crucible, and smelt them at 500-2000°C to obtain molten metal, wherein the covering agent is selected from at least one of sodium carbonate, borax, sodium fluoride, cryolite, and graphite powder.

[0012] In a preferred embodiment, the pulse current frequency of the electric pulse treatment is 200-5000 Hz, and the current density is 0.1-10 A / cm 3 .

[0013] Preferably, the pulse current frequency of the electric pulse treatment is 400-2000 Hz, and the current density is 0.5-5 A / cm 3 .

[0014] By applying electric pulse treatment during the smelting process, the melt composition can be made more uniform.

[0015] According to a preferred embodiment, the directional crystallization process is to use a casting speed of 1 to 100 mm / s to make the molten metal pass through the rapid cooling section and the slow cooling section of the water-cooled crystallizer in sequence, the length of the rapid cooling section is 50 to 200 mm, the length of the slow cooling section is 20 to 80 mm, the cooling water flow rate of the rapid cooling section is 600 to 2000 L / h, preferably 600-1000 L / h, and the cooling water flow rate of the slow cooling section is 100 to 400 L / h.

[0016] In the present invention, by controlling the water flow rate of the water-cooled crystallizer, a cooling temperature gradient of first rapid cooling and then slow cooling is achieved, so that the grains form "epitaxial oblique eight-shaped" columnar crystals. Based on this structure, subsequent hot processing is carried out to allow the "eight-shaped foot" columnar crystals in the outermost circle to be recrystallized, and a structure of core columnar crystals + edge equiaxed crystals is achieved (the inside of the eight-shaped shape is columnar crystals, and the outside of the eight-shaped shape is equiaxed crystals). This structure has higher mechanical properties than single equiaxed crystals or parallel columnar crystals, achieving "hard outside and tough inside".

[0017] In a preferred embodiment, the hot working process is as follows: firstly, the ingot is heated to 400-1200°C, preferably 600-1100°C, and kept warm for 1-60 minutes, preferably 30-60 minutes, and then multiple hot working is performed, and the deformation of each pass is controlled to be 5%-60%, preferably 10%-30%, and heat treatment is performed between passes, and the heat treatment temperature is 400-1200°C, preferably 600-1100°C, and the holding time is 30 minutes, preferably 5-10 minutes.

[0018] In actual operation, the ingot is placed in a box-type resistance furnace for heating and insulation, and then subjected to heat treatment (such as hot rolling) to eliminate defects such as internal looseness, pores, and microcracks.

[0019] In a preferred embodiment, during the thermal processing, the processing direction is controlled to be the direction of the temperature gradient. In the present invention, by processing along the direction of the temperature gradient, the internal stress of the sample on the processing surface is in a uniform state.

[0020] In a preferred embodiment, the hot working is selected from hot rolling, hot drawing, hot forging, hot rotary forging, hot radial forging, hot extrusion and hot upsetting, preferably hot rolling.

[0021] Preferably, the direction of the cold working treatment is consistent with the direction of the hot working treatment.

[0022] In a preferred embodiment, the cold working treatment is selected from one of cold rolling, cold drawing, cold forging, cold rotary forging, cold radial forging, cold extrusion and cold heading, preferably cold rolling.

[0023] In a preferred solution, during the cold working treatment, the deformation amount of a single pass is controlled to be 5-30%, and the total deformation amount is controlled to be 70-99%.

[0024] In the present invention, after obtaining the structure of core columnar crystals + edge equiaxed crystals through hot working, more dislocations and deformation twins are obtained through cold working with a large deformation amount, so that the material obtains more second phase nucleation sites and better mechanical properties.

[0025] A preferred solution is that the process of micro-area electrical treatment is to divide the metal material into several parallel hardening zones and softening zones along the length direction or the width direction, wherein the hardening zones and the softening zones are distributed alternately in a periodic manner, and a blank zone is provided between the hardening zones and the softening zones, and then the hardening zones and the softening zones are subjected to micro-area electrical treatment in turn, wherein the micro-area electrical treatment parameters of the hardening zone are: voltage 0.01~8V, current 100~500A; the micro-area electrical treatment parameters of the softening zone are: voltage 8~20V, current 800~2000A.

[0026] In the present invention, by obtaining a metal material with more dislocations and deformation twins during cold working, the metal material is divided into hardening and softening zones, and a high current is used to cause a large thermal effect on the alloy, so that the temperature acting on the metal zone is higher at the instantaneous action, and a violent recovery and recrystallization occur at the position where the dislocations are accumulated, thereby obtaining a softening zone. A low current acts on the alloy zone at a lower temperature at the instantaneous action, and a recovery and second phase precipitation occur at the position where the dislocations are accumulated, thereby obtaining a hardening zone.

[0027] Further preferably, the width of the blank area is greater than 5 mm, preferably 5 to 15 mm. A certain spacing needs to be set in the division between the hardening zone and the softening zone, and the spacing needs to be controlled. If a lower spacing is selected, heat overlap may occur in the target area due to metal heat conduction, resulting in the second phase precipitation and growth rate in the hardening zone being too fast, resulting in weakened strengthening effect in the hardening zone, and even recrystallization. If the spacing is too large, the final strengthening effect is weakened.

[0028] In a preferred solution, the current in the micro-area electrical treatment process is in the form of any one of pulse current, constant current, alternating current and direct current, preferably pulse current.

[0029] According to a preferred embodiment, the micro-area electrical treatment process applies current to the metal material through a movable electronic probe, firstly placing the movable electronic probe at a certain point in any hardening zone or softening zone of the metal material, applying current once within the area of ​​the electronic probe, and then moving the electronic probe in parallel to apply current to the next area of ​​the electronic probe. After one hardening zone or softening zone is treated, the electronic probe is moved to another untreated hardening zone or softening zone to repeat the above process; when current is applied to the hardening zone, the treatment time of any single point is 5 to 60 seconds, and when current is applied to the softening zone, the treatment time of any single point is 10 to 300 seconds.

[0030] Further preferably, the shape of the electronic probe is any one of rectangular, circular, elliptical and linear.

[0031] Preferably, the area of ​​the electronic probe is 0.01 to 10 mm 2 .

[0032] In the prior art, for example, when performing electric pulse treatment on a material, usually only the material can be processed as a whole. However, the present invention uses a movable electronic probe to control the area of ​​the electronic probe on the metal material to realize the application of current in a micro-area. In the actual operation process, for the sake of ease of operation, the electronic probe is first placed at the starting end of a hardening zone or a softening zone. When the current application within the area range of a certain electronic probe is completed, the electronic probe is moved to apply the current within the area range of the next electronic probe. After the path of the treatment of this zone is completed, the electronic probe is moved to the starting end of another zone for operation, that is, the current is applied step by step and in a controllable manner by moving the electronic probe, so as to controllably obtain the desired heterogeneous phase structure. Of course, in the actual operation process, the movement of the electronic probe is relative, that is, it can be directly by moving the electronic probe, or by moving the material to be processed, which is equivalent to the position of the electronic probe and the processed material being changed.

[0033] Principles and advantages

[0034] The preparation method of the present invention comprises the following steps: preparing various metal raw materials according to a designed ratio, placing them into an electric pulse directional solidification crucible in order from high to low melting points, placing a covering agent on the surface of the crucible to melt the metal, and subjecting the molten metal liquid to electric pulse treatment to obtain a uniform and pure melt, and then subjecting the molten metal liquid to directional crystallization to obtain an ingot with a uniform composition and an "oblique eight-shaped" slender columnar crystal structure; then subjecting the ingot with uniform composition to a box-type resistance furnace for heating and heat preservation, and then subjecting the ingot to heat treatment to eliminate internal defects such as internal looseness, pores, and microcracks, and forming a structure of core columnar crystals + edge equiaxed crystals to achieve "hard outside and tough inside", and then subjecting the hot-processed material to large deformation cold processing to introduce a large number of dislocations to provide more driving force and nucleation sites for the precipitation of the second phase; finally subjecting the designated position of the plate and strip material after large deformation cold processing to micro-area electrical processing to regulate the multiphase heterogeneous structure in the material microstructure, and obtain a structure in which the softening zone and the hardening zone are periodically alternately distributed, thereby obtaining a multiphase heterogeneous structure metal material with hard outside and tough inside and alternating strength and toughness.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) Compared with the prior art, the present invention uses electric pulse directional solidification technology to prepare an ingot with a uniformly distributed "oblique eight-shaped" slender columnar crystal structure, replacing the equiaxed crystal structure in the traditional process. At the same time, the electric pulse directional solidification melting and micro-area electrical processing are organically combined, and the electric pulse directional solidification is used to eliminate the agglomeration of the metal during the melting process, accelerate the atomic diffusion, and obtain a metal liquid with uniform composition; at the same time, the segregation phenomenon generated during the cooling and solidification process is suppressed; through subsequent hot processing and large deformation cold processing, the defects such as looseness, pores, and microcracks inside the ingot are further eliminated, and a large number of dislocations are introduced to provide more driving force and nucleation sites for the precipitation of the second phase; finally, micro-area electrical processing is used to change the input energy at different metal material positions to greatly promote the precipitation of multiple second phases, forming a "soft / hardening alternating, soft and hard coating" heterogeneous structure, and realizing the precise design of material microstructures oriented to performance requirements.

[0037] (2) Compared with the existing metal material preparation process, the present invention organically combines electric pulse directional solidification, hot rolling, large deformation cold processing and micro-area electrical treatment, which greatly shortens the heat treatment and processing steps in the existing metal material preparation process "hot and cold combined casting horizontal continuous casting-cold rolling-solid solution-cold rolling-aging" and "semi-continuous casting-solid solution-cold rolling-electric pulse treatment-cold rolling-aging"; at the same time, since the traditional aging process is to put the material into a heat treatment furnace for insulation to promote the precipitation of second phase particles. However, due to the limitation of the furnace cavity size and the long heat treatment time, the production flow time is increased, which seriously reduces the production efficiency; at the same time, since the material is processed as a whole, only a single distribution of organization can be obtained, and some specific performance requirements can only be processed by surface treatment, which greatly increases the production cost. The present invention proposes a micro-area electrical treatment process, which aims to precisely control different microstructures in local areas or tiny areas, and realize mass production of some metal materials with specific performance requirements (such as hard outside and tough inside, alternating strength and toughness) that are not restricted by material size, thereby solving the problems of complicated and cumbersome existing process flow, difficult processing and high cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a process flow chart of the present invention.

[0039] Figure 2 This is the microstructure diagram of the alloy ingot in Example 1. The oblique S-shaped columnar crystal structure can be clearly observed from the diagram.

[0040] Figure 3 This is a microstructure diagram of the metal material with a multi-phase heterogeneous structure provided in Example 1. It can be seen from the figure that the left area is a second phase with a large amount of dispersed distribution, the right side is the original structure, the right side is the softening zone, and the left side is the hardening zone. DETAILED DESCRIPTION

[0041] To make the present invention easier to understand, the present invention is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in the field; unless otherwise specified, the raw materials and equipment involved in this article can be purchased from the market or prepared by known methods.

[0042] Example 1

[0043] A method for preparing a metal material with a multi-phase heterogeneous structure, the process flow is as follows Figure 1 As shown, the following steps are included:

[0044] This embodiment takes Cu-Ni-Sn alloy as the object.

[0045] (1) Electric pulse directional solidification: Prepare electrolytic copper sheets, nickel sheets and tin blocks with a purity of 99.99% or more according to the mass ratio of Ni: Sn: Cu = 15: 8: 77, and put Ni, Cu, and Sn into the electric pulse directional solidification crucible in order from high to low according to the melting point, and then put 20g of graphite powder with a particle size of 5 mesh to cover the metal surface. The crucible is induction heated by an electromagnetic coil, and the heating temperature is controlled at 1350°C. After the metal block in the crucible is melted into liquid metal, the electromagnetic stirrer is turned on for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 2500Gs and the stirring speed is 200r / min. Then the temperature is lowered to 1180°C for insulation. After 5 minutes of insulation, the pulse power supply is turned on, and the pulse frequency is set to 1200Hz and the current density is 2.0A / cm through the central controller. 3 After 5 minutes of processing time, the pulse power supply is turned off to obtain molten metal with uniform composition. Then, the molten metal is pulled out from the center hole of the crystallizer at a speed of 1 mm / s by using a mechanical arm linked to a traction rod. During the pulling process, the molten metal passes through a 150 mm rapid cooling section and a 50 mm slow cooling section in sequence. The circulating water flow rate of the crystallizer in the rapid cooling section is 800 L / h, and the circulating water flow rate of the crystallizer in the slow cooling section is 400 L / h, forming a 60×20 mm alloy ingot with "oblique eight-shaped" slender columnar crystals.

[0046] (2) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 820°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 50%, and the deformation of a single pass is 20%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0047] (3) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 10%, and the plate thickness reaches 1 mm after multiple rolling.

[0048] (4) Micro-area electrical processing: The metal material is divided into parallel hardening zones and softening zones along the X-axis direction, where the hardening zones and softening zones are alternately distributed. At the same time, a blank zone is set between the hardening zones and softening zones. The width of the hardening zone and the softening zone is the width of the probe, and the width of the blank zone is 10 mm. Then, the cold-rolled alloy plate is subjected to micro-area electrical processing using an oxygen-free copper electronic probe. The probe uses a linear contactor with a contact area of ​​0.1 mm. 2, select low-frequency high-peak pulse power supply, move the electronic probe linearly along the X direction (relative movement, or moving metal materials) to gradually perform micro-area scanning electrical treatment. In the hardening area, apply an equivalent voltage of 8V, a current of 200A, and a single treatment time of 30s. After the X direction is treated, move the electronic probe parallel to the Y axis for 10mm, and continue to move the electronic probe in the X direction for micro-area scanning electrical treatment. Apply an equivalent voltage of 8V, a current of 1000A, and a treatment time of 30s. Repeat the above process until the entire material is treated.

[0049] The performance indicators of the alloy plate and strip in this implementation case are:

[0050] Tensile strength: 1680MPa

[0051] Elongation at break: 10.6%

[0052] Electrical conductivity: 15.4% IACS

[0053] Embodiment 2:

[0054] A method for preparing a metal material with a multi-phase heterogeneous structure, the process flow is as follows Figure 1 As shown, the following steps are included:

[0055] This embodiment takes silicon steel alloy as the object.

[0056] (1) Electric pulse directional solidification: prepare iron particles and silicon wafers with a purity of 99.99% or more according to the mass ratio of Fe:Si=96:4, and put Cu and Zn into the electric pulse directional solidification crucible in order from high to low according to the melting point, and then put 20g of graphite powder with a particle size of 5 mesh to cover the metal surface. The crucible is induction heated by an electromagnetic coil, and the heating temperature is controlled at 1580℃. After the metal block in the crucible is melted into liquid metal, turn on the electromagnetic stirrer for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 1500Gs and the stirring speed is 200r / min. Then lower the temperature to 1520℃ for insulation. After 5 minutes of insulation, turn on the pulse power supply, set the pulse frequency to 1200Hz and the current density to 1.0A / cm through the central controller. 3 After 5 minutes of processing time, the pulse power supply is turned off to obtain molten metal with uniform composition. Then, the molten metal is pulled out from the center hole of the crystallizer at a speed of 10 mm / s by using a mechanical arm linked to a traction rod. During the pulling process, the molten metal passes through an 80 mm rapid cooling section and a 50 mm slow cooling section in sequence. The circulating water flow rate of the crystallizer in the rapid cooling section is 600 L / h, and the circulating water flow rate of the crystallizer in the slow cooling section is 300 L / h, forming a 60×20 mm alloy ingot with "oblique eight-shaped" slender columnar crystals.

[0057] (2) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 880°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 70%, and the deformation of a single pass is 30%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0058] (3) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 20%, and the slab thickness reaches 1 mm after multiple rolling.

[0059] (4) Micro-area electrical processing: The metal material is divided into parallel hardening zones and softening zones along the X-axis direction, where the hardening zones and softening zones are alternately distributed. At the same time, a blank zone is set between the hardening zones and softening zones. The width of the hardening zone and the softening zone is the width of the probe, and the width of the blank zone is 5 mm. Then, the cold-rolled alloy sheet is subjected to micro-area electrical processing using an oxygen-free copper electronic probe. The probe uses a linear contactor with a contact area of ​​0.1 mm. 2 , select low-frequency high-peak pulse power supply, move the electronic probe linearly along the X direction to gradually perform micro-area scanning electrical treatment. In the hardening area, apply an equivalent voltage of 10V, a current of 250A, and a treatment time of 30s. After the X direction is treated, move the electronic probe parallel to the Y axis for 1mm, and then continue to move the electronic probe horizontally along the X direction for micro-area scanning electrical treatment, apply an equivalent voltage of 10V, a current of 1200A, and a treatment time of 30s. Repeat the above process until the entire material is treated.

[0060] The performance indicators of the alloy plate and strip in this implementation case are:

[0061] Tensile strength: 1450MPa

[0062] Elongation at break: 15.6%

[0063] Embodiment 3:

[0064] A method for preparing a metal material with a multi-phase heterogeneous structure, the process flow is as follows Figure 1 As shown, the following steps are included:

[0065] This embodiment takes Ti-6Al-4V alloy as the object.

[0066] (1) Electric pulse directional solidification: Prepare titanium particles, aluminum particles and vanadium blocks with a purity of 99.99% or more according to the mass ratio of Ti:Al:V=90:6:4, and put V, Ti, and Al into the electric pulse directional solidification crucible in order from high to low according to the melting point, and then put 20g of graphite powder with a particle size of 5 mesh to cover the metal surface. The crucible is induction heated by an electromagnetic coil, and the heating temperature is controlled at 1380℃. After the metal block in the crucible is melted into liquid metal, turn on the electromagnetic stirrer for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 2000Gs and the stirring speed is 200r / min. Then reduce the temperature to 1100℃ for insulation. After 5 minutes of insulation, turn on the pulse power supply, set the pulse frequency to 1200Hz and the current density to 1.0A / cm through the central controller. 3 After 5 minutes of processing time, the pulse power supply is turned off to obtain molten metal with uniform composition. Then, the molten metal is pulled out from the center hole of the crystallizer at a speed of 2 mm / s by using a mechanical arm linked to a traction rod. During the pulling process, the molten metal passes through a 100 mm rapid cooling section and a 30 mm slow cooling section in sequence. The circulating water flow rate of the crystallizer in the rapid cooling section is 800 L / h, and the circulating water flow rate of the crystallizer in the slow cooling section is 200 L / h, forming a 60×20 mm alloy ingot with equiaxed crystals + slender columnar crystals.

[0067] (2) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 880°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 70%, and the deformation of a single pass is 30%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0068] (3) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 20%, and the slab thickness reaches 1 mm after multiple rolling.

[0069] (4) Micro-area electrical processing: The metal material is divided into parallel hardening zones and softening zones along the X-axis direction, where the hardening zones and softening zones are alternately distributed. At the same time, a blank zone is set between the hardening zones and softening zones. The width of the hardening zone and the softening zone is the width of the probe, and the width of the blank zone is 5 mm. Then, the cold-rolled alloy sheet is subjected to micro-area electrical processing using an oxygen-free copper electronic probe. The probe uses a linear contactor with a contact area of ​​0.1 mm. 2, select low-frequency high-peak pulse power supply, move the electronic probe linearly along the X direction to gradually perform micro-area scanning electrical treatment. In the hardening area, apply an equivalent voltage of 6V, a current of 400A, and a treatment time of 30s. After the X direction is treated, move the electronic probe parallel to the Y axis for 1mm, and then continue to move the electronic probe horizontally along the X direction for micro-area scanning electrical treatment, apply an equivalent voltage of 10V, a current of 800A, and a treatment time of 30s. Repeat the above process until the entire material is treated.

[0070] The performance indicators of the alloy plate and strip in this implementation case are:

[0071] Tensile strength: 1320MPa

[0072] Elongation at break: 15.6%

[0073] Comparative Example 1

[0074] This comparative example uses a directional solidification process followed by hot rolling, large deformation cold working, and micro-area electrical treatment to process Cu-Ni-Sn alloy plates and strips, including the following steps:

[0075] (1) Directional solidification: Prepare electrolytic copper sheets, nickel sheets and tin blocks with a purity of 99.99% or more according to the mass ratio of Ni: Sn: Cu = 15: 8: 77, and put Ni, Cu and Sn into the directional solidification crucible in descending order according to their melting points. Turn on the water cooling circulation system, set the circulating water flow rate to 600 L / h (quenching section) and 400 L / h (slow cooling section), close the furnace door and air inlet valve, turn on the mechanical pump, vacuum gauge and molecular pump to reduce the vacuum degree in the furnace (5×10 -4 Pa), induction heating the graphite crucible through the induction coil, induction heating the crucible through the electromagnetic coil, the melting temperature is controlled at 1350 ° C, and after the metal block in the crucible is melted into liquid metal, the electromagnetic stirrer is turned on for mechanical stirring, the magnetic field strength of the electromagnetic stirring is set to 2500Gs, and the stirring speed is 200r / min. Then the temperature is lowered to 1180 ° C for insulation. After insulation for 10 minutes, the mechanical turbine is started to drive the metal connecting rod to pull the crucible from the induction coil to the condenser (16° gallium-indium alloy coolant) at an axial movement speed of 0.01mm / s for cooling and forming, forming a 60×20mm ingot with a columnar crystal structure in microscopic morphology.

[0076] (2) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 820°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 50%, and the deformation of a single pass is 20%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0077] (3) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 10%, and the plate thickness reaches 1 mm after multiple rolling.

[0078] (4) Micro-area electrical processing: The metal material is divided into parallel hardening zones and softening zones along the X-axis direction, where the hardening zones and softening zones are alternately distributed. At the same time, a blank zone is set between the hardening zones and softening zones. The width of the hardening zone and the softening zone is the width of the probe, and the width of the blank zone is 10 mm. Then, the cold-rolled alloy plate is subjected to micro-area electrical processing using an oxygen-free copper electronic probe. The probe uses a linear contactor with a contact area of ​​0.1 mm. 2 , select low-frequency high-peak pulse power supply, move the electronic probe linearly along the X direction to gradually perform micro-area scanning electrical treatment. In the hardening area, apply an equivalent voltage of 8V, a current of 200A, and a single treatment time of 30s. After the X direction is treated, move the electronic probe parallel to the Y axis for 10mm, and then continue to move the electronic probe horizontally along the X direction for micro-area scanning electrical treatment. Apply an equivalent voltage of 8V, a current of 1000A, and a treatment time of 30s. Repeat the above process until the entire material is treated.

[0079] The performance indicators of the alloy plate and strip in this implementation case are:

[0080] Tensile strength: 1520MPa

[0081] Elongation at break: 8.4%

[0082] Electrical conductivity: 13.4% IACS

[0083] Comparative Example 2

[0084] This comparative example uses electric pulse ordinary melting process followed by hot rolling, large deformation cold working and micro-area electrical treatment process to process Cu-Ni-Sn alloy plates and strips, including the following steps:

[0085] (1) Electric pulse ordinary smelting: Use an industrial frequency induction furnace for smelting in a non-vacuum environment. Prepare electrolytic copper sheets, nickel sheets and tin blocks with a purity of 99.99% or more according to the mass ratio of Ni: Sn: Cu = 15: 8: 77, and put Ni, Cu, and Sn into the smelting crucible in order from high to low according to the melting point. The smelting temperature is 1350°C. After the metal blocks in the crucible are melted into molten metal, turn on the electromagnetic stirrer for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 2500Gs and the stirring speed is 200r / min. Then lower the temperature to 1180°C for insulation. After 5 minutes of insulation, turn on the pulse power supply, set the pulse frequency to 1200Hz and the current density to 2.0A / cm3 through the central controller, and after 5 minutes of processing time, turn off the pulse power supply and start casting to form a 60×20mm alloy ingot.

[0086] (2) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 820°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 50%, and the deformation of a single pass is 20%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0087] (3) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 10%, and the plate thickness reaches 1 mm after multiple rolling.

[0088] (4) Micro-area electrical processing: The metal material is divided into parallel hardening zones and softening zones along the X-axis direction, where the hardening zones and softening zones are alternately distributed. At the same time, a blank zone is set between the hardening zones and softening zones. The width of the hardening zone and the softening zone is the width of the probe, and the width of the blank zone is 10 mm. Then, the cold-rolled alloy plate is subjected to micro-area electrical processing using an oxygen-free copper electronic probe. The probe uses a linear contactor with a contact area of ​​0.1 mm. 2 , select low-frequency high-peak pulse power supply, move the electronic probe linearly along the X direction to gradually perform micro-area scanning electrical treatment. In the hardening area, apply an equivalent voltage of 8V, a current of 200A, and a single treatment time of 30s. After the X direction is treated, move the electronic probe parallel to the Y axis for 10mm, and then continue to move the electronic probe horizontally along the X direction for micro-area scanning electrical treatment. Apply an equivalent voltage of 8V, a current of 1000A, and a treatment time of 30s. Repeat the above process until the entire material is treated.

[0089] The performance indicators of the alloy plate and strip in this implementation case are:

[0090] Tensile strength: 1360MPa

[0091] Elongation at break: 5.3%

[0092] Electrical conductivity: 10.6% IACS

[0093] Comparative Example 3

[0094] This comparative example uses a directional solidification process followed by hot rolling, large deformation cold working and traditional aging process to process Cu-Ni-Sn alloy plates and strips on the basis of the embodiment, including the following steps:

[0095] (1) Electric pulse directional solidification: Prepare electrolytic copper sheets, nickel sheets and tin blocks with a purity of 99.99% or more according to the mass ratio of Ni: Sn: Cu = 15: 8: 77, and put Ni, Cu and Sn into the electric pulse directional solidification crucible in order from high to low according to the melting point, and then put 20g of graphite powder with a particle size of 5 mesh to cover the metal surface. The crucible is induction heated by an electromagnetic coil, and the heating temperature is controlled at 1350°C. After the metal block in the crucible is melted into liquid metal, the electromagnetic stirrer is turned on for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 2500Gs and the stirring speed is 200r / min. The temperature is then lowered to 1180°C for insulation. After 5 minutes of insulation, the pulse power supply is turned on, and the pulse frequency is set to 1200Hz and the current density is 2.0A / cm3 through the central controller. After a processing time of 5 minutes, the pulse power supply is turned off to obtain molten metal with uniform composition. The molten metal is then pulled out of the center hole of the crystallizer at a speed of 1mm / s using a robotic arm-linked traction rod. During the pulling process, the molten metal passes through a 150mm rapid cooling section and a 50mm slow cooling section in sequence. The circulating water flow rate of the crystallizer in the rapid cooling section is 800L / h, and the circulating water flow rate of the crystallizer in the slow cooling section is 400L / h, forming a 60×20mm alloy ingot with "oblique eight-shaped" slender columnar crystals.

[0096] (1) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 820°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 50%, and the deformation of a single pass is 20%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0097] (2) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 10%, and the plate thickness reaches 1 mm after multiple rolling.

[0098] (3) Traditional aging process: The plates and strips after large deformation and cold working are placed in a box-type resistance furnace for aging and insulation treatment. The insulation temperature is 400℃ and the insulation time is 2h.

[0099] The performance indicators of the alloy plate and strip in this implementation case are:

[0100] Tensile strength: 1360MPa

[0101] Elongation at break: 5.3%

[0102] Electrical conductivity: 10.6% IACS

[0103] Comparative Example 4

[0104] This comparative example uses a directional solidification process followed by hot rolling, large deformation cold working and electric pulse aging process to process Cu-Ni-Sn alloy plates and strips on the basis of the embodiment, including the following steps:

[0105] (1) Electric pulse directional solidification: Prepare electrolytic copper sheets, nickel sheets and tin blocks with a purity of 99.99% or more according to the mass ratio of Ni: Sn: Cu = 15: 8: 77, and put Ni, Cu, and Sn into the electric pulse directional solidification crucible in order from high to low according to the melting point, and then put 20g of graphite powder with a particle size of 5 mesh to cover the metal surface. The crucible is induction heated by an electromagnetic coil, and the heating temperature is controlled at 1350°C. After the metal block in the crucible is melted into liquid metal, the electromagnetic stirrer is turned on for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 2500Gs and the stirring speed is 200r / min. Then the temperature is lowered to 1180°C for insulation. After 5 minutes of insulation, the pulse power supply is turned on, and the pulse frequency is set to 1200Hz and the current density is 2.0A / cm through the central controller. 3 After 5 minutes of processing time, the pulse power supply is turned off to obtain molten metal with uniform composition. Then, the molten metal is pulled out from the center hole of the crystallizer at a speed of 1 mm / s by using a mechanical arm linked to a traction rod. During the pulling process, the molten metal passes through a 150 mm rapid cooling section and a 50 mm slow cooling section in sequence. The circulating water flow rate of the crystallizer in the rapid cooling section is 800 L / h, and the circulating water flow rate of the crystallizer in the slow cooling section is 400 L / h, forming a 60×20 mm alloy ingot with "oblique eight-shaped" slender columnar crystals.

[0106] (1) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 820°C. After keeping warm for 30 minutes, it is taken out and rolled along the temperature gradient. The total deformation is 50%, and the deformation of a single pass is 20%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0107] (2) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 10%, and the plate thickness reaches 1 mm after multiple rolling.

[0108] (3) Electric pulse aging process: The plates and strips after large deformation and cold working are placed in the electric pulse heat treatment circuit for electric pulse aging. A low-frequency and high-peak pulse power supply is selected, with an equivalent voltage of 8V, a current of 200A, and a processing time of 5 minutes.

[0109] The performance indicators of the alloy plate and strip in this implementation case are:

[0110] Tensile strength: 1360MPa

[0111] Elongation at break: 5.3%

[0112] Electrical conductivity: 10.6% IACS

[0113] Comparative Example 5

[0114] This comparative example uses a common smelting process followed by hot rolling, large deformation cold working and aging process to process Cu-Ni-Sn alloy plates and strips on the basis of the embodiment, including the following steps:

[0115] (1) Ordinary smelting: Use an industrial frequency induction furnace to carry out smelting in a non-vacuum environment, prepare electrolytic copper sheets, nickel sheets and tin blocks with a purity of 99.99% or more according to the mass ratio of Ni: Sn: Cu = 15: 8: 77, and put Ni, Cu, and Sn into the smelting crucible in order from high to low according to the melting point. The smelting temperature is 1350°C. After the metal blocks in the crucible are melted into molten metal, turn on the electromagnetic stirrer for mechanical stirring. The magnetic field strength of the electromagnetic stirring is set to 2500Gs and the stirring speed is 200r / min. Then reduce the temperature to 1180°C for insulation. After the insulation time is 10 minutes, start casting to form a 60×20mm alloy ingot.

[0116] (2) Hot rolling: The ingot is placed in a box-type resistance furnace for heating with the furnace, and the temperature is controlled at 820°C. After keeping warm for 30 minutes, it is taken out and rolled. The total deformation is 50%, and the deformation of a single pass is 20%. After each pass, it is quickly placed in a box-type resistance furnace for continued insulation. After keeping warm for 10 minutes, it is taken out for the next rolling deformation. After multiple rolling, the thickness of the slab reaches 10 mm.

[0117] (3) Large deformation cold processing: The hot-rolled slab is placed in a six-roll rolling mill for cold rolling. The deformation direction is consistent with the hot rolling direction. The total deformation is 90%, the single-pass deformation is 10%, and the plate thickness reaches 1 mm after multiple rolling.

[0118] (4) Traditional aging process: The plates and strips after large deformation and cold working are placed in a box-type resistance furnace for aging and insulation treatment. The insulation temperature is 400℃ and the insulation time is 2h.

[0119] The performance indicators of the alloy plate and strip in this implementation case are:

[0120] Tensile strength: 1220MPa

[0121] Elongation at break: 2.73%

[0122] Electrical conductivity: 7.6% IACS.

Claims

1. A method for preparing a metal material having a multi-phase heterogeneous structure, characterized in that: Metal raw materials are selected according to the composition of the metal material for smelting to obtain molten metal, the molten metal is subjected to electric pulse treatment to obtain a melt, the melt is directionally crystallized to obtain an ingot with an oblique S-shaped columnar crystal structure, the ingot is hot-processed to obtain a billet, the billet is then cold-processed to obtain a cold-processed part, and finally the cold-processed part is subjected to micro-area electrical treatment to obtain a metal material with a multi-phase heterogeneous structure.

2. The method for preparing a metal material having a multi-phase heterogeneous structure according to claim 1, characterized in that: Metal raw materials are placed into a crucible in descending order according to their melting points, a covering agent is placed on the surface of the crucible, and smelting is performed at 500-2000°C to obtain molten metal, wherein the covering agent is selected from at least one of sodium carbonate, borax, sodium fluoride, cryolite, and graphite powder.

3. The method for preparing a metal material having a multi-phase heterogeneous structure according to claim 1, characterized in that: The pulse current frequency of the electric pulse treatment is 200-5000 Hz, and the current density is 0.1-10 A / cm 3 .

4. The method for preparing a metal material having a multi-phase heterogeneous structure according to claim 1, characterized in that: The process of directional crystallization is to use a casting speed of 1 to 100 mm / s to make the molten metal pass through the rapid cooling section and the slow cooling section of the water-cooled crystallizer in sequence, the length of the rapid cooling section is 50 to 200 mm, the length of the slow cooling section is 20 to 80 mm, the cooling water flow rate of the rapid cooling section is 600 to 2000 L / h, and the cooling water flow rate of the slow cooling section is 100 to 400 L / h.

5. The method for preparing a metal material with a multi-phase heterogeneous structure according to claim 1, characterized in that: The process of the hot working is: firstly heating the ingot to 400-1200°C, keeping the temperature for 1-60 minutes, and then performing multiple hot working, controlling the deformation of each pass to be 5%-60%, and performing heat treatment between passes, the heat treatment temperature is 400-1200°C, and the holding time is 30 minutes, During the thermal processing, the processing direction is controlled to be the direction of the temperature gradient; The hot working is selected from one of hot rolling, hot drawing, hot forging, hot rotary forging, hot radial forging, hot extrusion and hot upsetting.

6. The method for preparing a metal material with a multi-phase heterogeneous structure according to claim 1, characterized in that: The direction of the cold working treatment is consistent with the direction of the hot working; The cold working treatment is selected from one of cold rolling, cold drawing, cold forging, cold rotary forging, cold radial forging, cold extrusion and cold heading. During the cold working treatment, the deformation amount of a single pass is controlled to be 5-30%, and the total deformation amount is controlled to be 70-99.9%.

7. The method for preparing a metal material with a multi-phase heterogeneous structure according to claim 1, characterized in that: The process of the micro-area electrical treatment is to divide the metal material into a plurality of parallel hardening zones and softening zones along the length direction or the width direction, wherein the hardening zones and the softening zones are periodically alternately distributed, and a blank zone is provided between the hardening zones and the softening zones, and then the hardening zones and the softening zones are subjected to micro-area electrical treatment in turn, wherein the micro-area electrical treatment parameters of the hardening zones are: voltage 0.01-8V, current 100-500A, and the micro-area electrical treatment parameters of the softening zones are: voltage 8-20V, current 800-2000A; The width of the blank area is >5mm.

8. The method for preparing a metal material with a multi-phase heterogeneous structure according to claim 1 or 7, characterized in that: The current form in the micro-area electrical treatment process is any one of pulse current, constant current, alternating current and direct current.

9. The method for preparing a metal material with a multi-phase heterogeneous structure according to claim 1 or 7, characterized in that: The micro-area electrical treatment process applies an electric current to the metal material through a movable electronic probe. The movable electronic probe is first placed at a certain point in any hardening zone or softening zone of the metal material, and a current is applied once within the area of ​​the electronic probe. Then, the electronic probe is moved in parallel to apply current to the next area of ​​the electronic probe. After the treatment of one hardening zone or softening zone is completed, the electronic probe is moved to another untreated hardening zone or softening zone to repeat the above process. When the current is applied to the hardening zone, the treatment time of any single point is 5 to 60 seconds, and when the current is applied to the softening zone, the treatment time of any single point is 10 to 300 seconds.

10. The method for preparing a metal material with a multi-phase heterogeneous structure according to claim 8, characterized in that: The shape of the electronic probe is any one of a rectangular, circular, elliptical, and linear shape; the shape of the electronic probe is any one of a rectangular, circular, elliptical, and linear shape; The area of ​​the electronic probe is 0.01 to 10 mm 2 .

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