Preparation method of microalloyed high-strength precise nickel-chromium resistance alloy material
阅读说明：本技术 微合金化的高强度精密镍铬电阻合金材料的制备方法 (Preparation method of microalloyed high-strength precise nickel-chromium resistance alloy material ) 是由 黄国平 马丁 刘海定 何曲波 曾羽 杨贤军 于 2020-06-08 设计创作，主要内容包括：本发明属于金属材料领域,特别涉及一种微合金化的高强度精密镍铬电阻合金材料,其制备方法为：真空感应熔炼→电渣重熔→真空自耗重熔→锻造开坯。采用本发明所述方法制备的材料电阻率高、电阻温度系数低,具有优异的耐热性能、耐腐蚀性能和力学性能以及良好的加工性能,可以满足高精度箔材、微细丝材的加工要求,提高成品的加工精度以及表面质量,用于制作高精密电子元件,采用VIM+ESR+VAR冶炼工艺制作的产品——精密电阻合金,由于精确控制了产品中合金元素以及杂质、气体含量,产品获得的电学性能以及加工性能均符合要求,可以面向国内外高端精密电阻合金市场。(The invention belongs to the field of metal materials, and particularly relates to a microalloyed high-strength precise nickel-chromium resistance alloy material, which is prepared by the following steps: vacuum induction melting → electroslag remelting → vacuum consumable remelting → forging cogging. The material prepared by the method has high resistivity, low resistance temperature coefficient, excellent heat resistance, corrosion resistance, mechanical property and good processing property, can meet the processing requirements of high-precision foils and micro wires, improves the processing precision and the surface quality of finished products, is used for manufacturing high-precision electronic elements, is a precision resistance alloy which is a product manufactured by adopting a VIM + ESR + VAR smelting process, and can be used for facing the high-end precision resistance alloy market at home and abroad because the contents of alloy elements, impurities and gases in the product are precisely controlled, and the electrical property and the processing property of the product meet the requirements.)
1. The preparation method of the microalloyed high-strength precise nickel-chromium resistance alloy material is characterized by comprising the following steps of:
1) preparing an electrode bar:
1-1) according to the proportion of a microalloyed high-strength precise nickel-chromium resistance alloy material, taking Ni, Cr and Fe components, drying for 6-8 hours at the temperature of 200 ℃, sequentially adding the components into a vacuum induction smelting furnace, and smelting until the Ni, Cr and Fe are melted, wherein the vacuum degree is less than 20 Pa; the power transmission power is 280kW, the temperature is raised until all substances in the smelting furnace are melted, and then slag is discharged; the power transmission power is reduced to 100 kW-130 kW, the temperature is maintained for 30 minutes, and the vacuum degree is less than or equal to 3 Pa; adding Si, Mn, Al, Zr, B and rare earth elements under the argon condition, improving the power transmission to 220kW, melting and stirring for 5-10 minutes; reducing the power transmission power to 70 kW-100 kW, keeping the vacuum degree less than or equal to 3Pa for 15 minutes;
1-2) controlling the temperature at 1450-1480 ℃, and casting; obtaining a vacuum electrode bar;
2) electroslag remelting:
carrying out surface treatment on the vacuum electrode bar obtained in the step 1); mixing CaF2-CaO-Al2O3The ternary slag is dried for 6 hours at the temperature of 600 ℃ according to the weight ratio of 80:15:5, and CaF2-CaO-Al2O3After the ternary slag is pre-melted, putting a vacuum electrode bar into a crystallizer, and under the conditions that the voltage is 50-55V and the current is 7-8 kA, adding CaF-CaO-Al2O3Remelting the ternary slag to obtain an electric slag ingot;
3) vacuum consumable remelting:
forging the electroslag ingot obtained in the step 2) into an electrode bar, removing surface oxide skin, cooling for 20-30 minutes after vacuum consumable remelting, and demolding to obtain a vacuum consumable remelting ingot;
4) forging and cogging:
heating the vacuum consumable remelting ingot obtained in the step 3) to 1160 ℃ along with a furnace, preserving heat for 2-2.5 hours, forging and cogging, and obtaining a finished product, wherein the final forging temperature is more than or equal to 900 ℃.
2. The method of claim 1, wherein: 1-1), heating the smelting for 5 times, respectively controlling the power transmission power to be 30kW, 60kW and 100kW in the first three times, and controlling the heat preservation time to be 5-10 minutes each time; then controlling the power transmission power to be 150kW, heating, and keeping the temperature for 60-90 minutes; then the power transmission power is controlled to be 180kW, and the heat is preserved for 60-90 minutes.
3. The method of claim 1, wherein: the electromagnetic stirring in the step 1-2) is more than or equal to 5 times.
4. The method of claim 1, wherein: step 3) the forging method comprises the following steps: the forging temperature is 900-1160 ℃, the single pressing amount is 15-30 mm, and the final firing pass pressing amount is 10-20 mm.
5. The method of claim 1, wherein: step 3), controlling the smelting current in the vacuum consumable process: 4.8 ± 0.1kA, voltage: 22 +/-2V, vacuum degree less than 1Pa, smelting speed: 3.2-3.5 kg/min.
6. The method of claim 1, wherein: during forging and cogging in the step 4), if the forging of the blank is not finished and the temperature is lower than 900 ℃, tempering and heat preservation treatment are required, wherein the tempering system is to preserve heat for 1-1.5 hours at 1160 ℃, and then the rest part is forged.
7. The method of claim 1, wherein: in the forging and cogging process of the step 4), the rolling reduction controlled in the primary pass and the intermediate pass is 15-30 mm, and the rolling reduction controlled in the final firing pass is 10-20 mm.
8. The method of claim 1, wherein: the high-strength precise nickel-chromium resistance alloy material microalloyed in the step 1) comprises the following components in percentage by mass: cr: 19-21%; al: 2.0-3.5%; fe: 2-3%; 1.2-2.5% of Mn; 0.02-0.5% of Si; b: 0.001-0.08%; zr: 0.05-0.2%; rare earth elements: 0.01-0.5%; ni: and (4) the balance.
9. The method according to claim 1 or 8, characterized in that: the rare earth element is Ce.
Technical Field
The invention belongs to the field of metal materials, and particularly relates to a preparation method of a microalloyed high-strength precise nickel-chromium resistance alloy material.
Background
The resistance electrothermal alloy material is a series of products of electronic and electric appliance functional materials, wherein the consumption is the largest, and the most extensive related range is nickel-based alloy (Ni-Cr, Ni-Cr-Fe, Ni-Cr-Cu series) and iron-based alloy (Fe-Ni, Fe-Cr-Al series). The resistance electrothermal alloy material is used for manufacturing precise resistance elements and electrothermal elements in the forms of wires, strips, pipes, sections and the like, and is widely applied to industries such as household appliances, aerospace, ships, war industry and the like. With the progress of science and technology, the performance requirements of high and new electronic products on the resistance alloy are higher and higher. The resistive alloy material is required to have excellent electrical properties as well as good processability.
Resistance alloys are mainly divided into several categories:
(1) electric heating alloy: the electric heating element is widely applied to electric heating elements in the fields of machinery, metallurgy, chemical industry, food and the like, and the working temperature is 500-1400 ℃.
(2) Precision resistance alloy: generally has high resistivity and small temperature coefficient of resistance, and is mainly used as a precision resistance element.
(3) Strain resistance alloy: generally, the alloy is a resistance alloy with large resistance strain sensitive coefficient and small absolute value of resistance temperature coefficient.
The main direction of recent research in China is focused on the direction of electrothermal alloy, such as resistance electrothermal alloy developed by Chenjunda, which has higher resistivity, good surface oxidation resistance, high temperature level and higher strength at high temperature; the precipitation strengthening electrothermal alloy developed by Guoka and the like has good tensile strength, high-temperature creep strength and oxidation resistance, and has wide prospects in industrial application. However, for the precision resistance alloy, the performance requires that the resistance temperature coefficient is very small, and simultaneously, impurity elements and gas content of the material are strictly controlled and the material has good processing performance so as to meet the requirement of increasingly miniaturization of electronic products. Due to the limitation of a component control technology, a smelting technology and a subsequent processing technology, after the current domestic nickel-chromium precision resistance alloy is processed into an ultrathin foil (the thickness is less than 0.2mm), the mechanical property, the resistivity, the resistance temperature coefficient, the surface quality of the foil and the like can not meet the precision processing requirement.
Disclosure of Invention
The invention aims to provide a preparation method of a microalloyed high-strength nickel-chromium precise resistance alloy material, the material prepared by the method has high resistivity, low resistance temperature coefficient, excellent heat resistance, corrosion resistance, mechanical property and good processing property, can meet the processing requirements of high-precision foil materials and micro wires, improves the processing precision and surface quality of finished products, and is used for manufacturing high-precision electronic elements. The precise resistance alloy which is a product manufactured by adopting VIM + ESR + VAR smelting process (wherein VIM is a vacuum induction smelting process, ESR is an electroslag remelting process, and VAR is a vacuum consumable remelting process) meets the requirements on electrical properties and processing properties of the product due to the fact that the contents of alloy elements, impurities and gases in the product are precisely controlled, and can be oriented to the domestic and foreign high-end precise resistance alloy market.
The purpose of the invention is realized by adopting the following scheme:
the preparation method of the microalloyed high-strength precise nickel-chromium resistance alloy material comprises the following steps:
1) preparing an electrode bar:
1-1) according to the proportion of a microalloyed high-strength precise nickel-chromium resistance alloy material, taking Ni, Cr and Fe components, drying for 6-8 hours at the temperature of 200 ℃, sequentially adding the components into a vacuum induction smelting furnace, and smelting until the Ni, Cr and Fe are melted, wherein the vacuum degree is less than 20 Pa; the power transmission power is 280kW, the temperature is raised until all substances in the smelting furnace are melted, and then slag is discharged; the power transmission power is reduced to 100 kW-130 kW, the temperature is maintained for 30 minutes, and the vacuum degree is less than or equal to 3 Pa; adding Si, Mn, Al, Zr, B and rare earth elements under the argon condition, improving the power transmission to 220kW, melting and stirring for 5-10 minutes; reducing the power transmission power to 70 kW-100 kW, keeping the vacuum degree less than or equal to 3Pa for 15 minutes;
1-2) controlling the temperature at 1450-1480 ℃, and casting; obtaining a vacuum electrode bar;
2) electroslag remelting:
carrying out surface treatment on the vacuum electrode bar obtained in the step 1); mixing CaF2-CaO-Al2O3The ternary slag is dried for 6 hours at the temperature of 600 ℃ according to the weight ratio of 80:15:5, and CaF2-CaO-Al2O3After the ternary slag is pre-melted, putting a vacuum electrode bar into a crystallizer, and under the conditions that the voltage is 50-55V and the current is 7-8 kA, adding CaF-CaO-Al2O3Remelting the ternary slag to obtain an electric slag ingot;
3) vacuum consumable remelting:
forging the electroslag ingot obtained in the step 2) into an electrode bar, removing surface oxide skin, cooling for 20-30 minutes after vacuum consumable remelting, and demolding to obtain a vacuum consumable remelting ingot;
4) forging and cogging:
heating the vacuum consumable remelting ingot obtained in the step 3) to 1160 ℃ along with a furnace, preserving heat for 2-2.5 hours, forging and cogging, and obtaining a finished product, wherein the final forging temperature is more than or equal to 900 ℃.
1-1), heating the smelting for 5 times, respectively controlling the power transmission power to be 30kW, 60kW and 100kW in the first three times, and controlling the heat preservation time to be 5-10 minutes each time; then controlling the power transmission power to be 150kW, heating, and keeping the temperature for 60-90 minutes; then the power transmission power is controlled to be 180kW, and the heat is preserved for 60-90 minutes.
The electromagnetic stirring in the step 1-2) is more than or equal to 5 times.
Step 3) the forging method comprises the following steps: the forging temperature is 900-1160 ℃, the single pressing amount is 15-30 mm, and the final firing pass pressing amount is 10-20 mm.
Step 3), controlling the smelting current in the vacuum consumable process: 4.8 ± 0.1kA, voltage: 22 +/-2V, vacuum degree less than 1Pa, smelting speed: 3.2-3.5 kg/min.
During forging and cogging in the step 4), if the forging of the blank is not finished and the temperature is lower than 900 ℃, tempering and heat preservation treatment are required, wherein the tempering system is to preserve heat for 1-1.5 hours at 1160 ℃, and then the rest part is forged.
In the forging and cogging process of the step 4), the rolling reduction controlled in the primary pass and the intermediate pass is 15-30 mm, and the rolling reduction controlled in the final firing pass is 10-20 mm.
The high-strength precise nickel-chromium resistance alloy material microalloyed in the step 1) comprises the following components in percentage by mass: cr: 19-21%; al: 2.0-3.5%; fe: 2-3%; 1.2-2.5% of Mn; 0.02-0.5% of Si; b: 0.001-0.08%; zr: 0.05-0.2%; rare earth elements: 0.01-0.5%; ni: and (4) the balance.
The rare earth element is Ce.
According to the invention, the corresponding blank is produced by adopting VIM + ESR + VAR technology through the precise control of microalloying elements in the resistance alloy and the adjustment of the melting technology and the precise control of impurity elements and gas content in the alloy material, so that the alloy is ensured to have lower resistance temperature coefficient and higher processing performance.
Compared with the prior art, the invention has the beneficial effects that:
1. the material is added with trace elements such as Si, Mn, Zr, B, rare earth elements and the like, so that the material has the performance meeting the use requirement; the high-temperature strength and the fatigue life of the resistance alloy can be improved by adding elements such as Zr, B, rare earth elements and the like, and the mechanical property and the processability of the alloy can be improved by adding Si, Mn and the like.
2. Compared with the VIM + ESR + VAR smelting process, the VIM + ESR + VAR smelting process can reduce the content of impurity elements and gas in the material to the maximum extent, change the organization structure of the alloy and obtain a precise resistance alloy product with higher purity, good processing performance and low resistance temperature coefficient.
When the material prepared by the method is used for processing foil with the thickness of 20 mu m and micro wire with the diameter of 0.08mm, the surface quality is good, surface defects such as bubbles, folds, looseness and the like on the surface are avoided, and simultaneously, because the inclusion content is low, the components are more uniform, the processing performance is good, the final metallographic structure of the product is more uniform, the size, tolerance and surface quality can be better, and the tolerance of the finished product material can be controlled within +/-5% of the thickness of the foil.
The material of the invention has the advantages of small heat productivity, low power consumption, small noise and the like, and can be widely applied to electrical equipment such as precision resistors, regulators, potentiometers and the like.
Detailed Description
In the embodiment, the microalloyed high-strength precise nickel-chromium resistance alloy material provided by the invention comprises the following components in proportion as shown in table 1:
TABLE 1 chemical composition TABLE (wt%)
1) Preparing an electrode bar:
taking the components according to the table 1, and drying the components at the temperature of 200 ℃ for 6-8 hours; ni, Cr and Fe are used as main materials, Si, Mn, Al, Zr, B and rare earth elements are used as auxiliary materials, and the rare earth element is Ce.
Taking and smelting a large material, heating the large material by 5 times, respectively controlling the power transmission power to be 30kW, 60kW and 100kW in the first three times, and controlling the heat preservation time to be 5-10 minutes each time; then controlling the power transmission power to be 150kW, heating, and keeping the temperature for 60-90 minutes; then controlling the power transmission power to be 180kW, preserving the heat for 60-90 minutes until the large materials are melted, and ensuring that the vacuum degree is less than 20 Pa; after the materials in the furnace meet the requirements, the power transmission power is increased to 280kW from 180kW as soon as possible, so that the temperature in the furnace is increased to the melting temperature of the large materials, and after the materials added in the vacuum induction melting furnace are completely melted, the impurities float upwards at the moment because the density of the impurities is smaller than that of the raw materials, and the impurities are removed by deslagging; then reducing the power transmission power, controlling the power transmission power between 100kW and 130kW, keeping for 30 minutes, pumping high vacuum, and controlling the vacuum degree to be less than or equal to 3 Pa.
Filling argon gas, adding small materials, increasing the power transmission power to about 220kW, heating and melting the materials, and performing electromagnetic stirring for more than 5 times, wherein the time is controlled to be 5-10 minutes; reducing the power again, controlling the power transmission power at 70 kW-100 kW, vacuumizing to a high vacuum degree of less than or equal to 3Pa, and keeping for 15 minutes;
furnace taking out by using ceramic samplerPerforming component analysis on the former sample, if the components are unqualified, performing vacuum material supplementing according to the requirement of the component range, then performing electromagnetic stirring, and repeating the sampling step in front of the furnace until the chemical components reach the requirement of the table 1; and controlling the temperature to be 1450-1480 ℃ to carry out vacuum electrode bar casting to obtain the electrode bar. Selecting
2) Electroslag remelting:
before electroslag, the electrode rod obtained in the step 1) needs to be subjected to surface sanding treatment to remove surface oxide skin, burrs, attachments and the like, so that impurity elements are prevented from being introduced in the electroslag process. Using CaF2-CaO-Al2O3And (3) slag, namely drying the slag in a furnace at 600 ℃ for more than 6 hours, pre-melting the slag, mashing the slag, putting the smashed slag into the bottom of a crystallizer, arcing and slagging through a graphite electrode bar, and putting a vacuum electrode bar into the crystallizer for corresponding electroslag remelting to obtain an electroslag ingot. The filling ratio of the electrode bar to the crystallizer is controlled to be 0.5-0.8, the remelting current is controlled to be 7-8 kA, and the remelting voltage is controlled to be 50-55V.
Pre-melting the slag with a graphite electrode rod, wherein the weight of the slag is 30-35 kg.
Electroslag remelting can further remove sulfur and phosphorus, and the content of harmful impurities is controlled to be low, and the content of S, P can be even lower than 0.005%. CaF-CaO-Al is adopted2O3The preparation method of the embodiment, such as 80:15:5 weight ratio of the ternary slag and control of the melting speed of the electrode bar, enables the components of the remelted alloy to be more uniform and obtains a better crystal structure.
3) Vacuum consumable remelting:
before vacuum consumable remelting, forging and cogging the electroslag ingot obtained in the step 2)
4) Forging and cogging:
and (3) heating the vacuum consumable re-melted ingot obtained in the step 3) along with a furnace, preserving heat for 2-2.5 hours at 1160 ℃, then starting forging, keeping the final forging temperature at not less than 900 ℃, if the blank is large and the forging of the blank is not finished, keeping the temperature below 900 ℃, carrying out tempering heat preservation treatment, keeping the temperature at 1160 ℃ for 1-1.5 hours, and then forging the rest.
In the forging process, the rolling reduction of the primary pass and the intermediate pass is 15-30 mm, the rolling reduction of the final fire pass is 10-20 mm, and the material is finally forged into a plate blank or a square blank.
In order to analyze the influence of two smelting processes of VIM + ESR and VIM + ESR + VAR on the material purity, the material components of the Ni-Cr alloy, the A-286 alloy and the Incoloy 901 alloy after the two smelting processes are analyzed, and the specific components are shown in tables 2-4.
TABLE 2 chemical compositions (wt%) of Ni-Cr alloy different smelting process materials
TABLE 3A-286 alloy different smelting process material chemical compositions (wt%)
Alloy element
C
Si
Mn
Ni
Cr
Al
Fe
Ti
VIM+ESR
0.063
0.18
0.15
24.72
14.72
0.29
Balance of
2.15
VIM+ESR+VAR
0.05
0.17
0.14
24.41
14.6
0.14
Balance of
2.06
Alloy element
B
Mo
P
S
O
N
H
V
VIM+ESR
0.0079
1.34
0.0095
0.001
0.0032
0.0082
0.0006
0.42
VIM+ESR+VAR
0.0076
1.34
0.0086
<0.001
0.0011
0.0033
0.0002
0.38
TABLE 4 Incoloy 901 alloy different smelting process material chemical composition (wt%)
Alloy element
C
Si
Mn
Ni
Cr
Al
Fe
Ti
VIM+ESR
0.039
0.17
0.12
41.82
12.19
0.24
Balance of
2.95
VIM+ESR+VAR
0.035
0.17
0.11
41.75
12.17
0.16
Balance of
2.83
Alloy element
B
Mo
P
S
O
N
H
Cu
VIM+ESR
0.015
6.11
0.0068
0.001
0.0029
0.0074
0.0003
0.017
VIM+ESR+VAR
0.015
5.84
0.0054
<0.001
0.0014
0.0041
0.0002
0.017
Compared with the material obtained by the VIM + ESR + VAR smelting process (preparation method), the material prepared by the VIM + ESR + VAR smelting process (preparation method) has the advantages that the content of main alloy elements is not changed greatly, and the content of C, O, N, H, S, P and other impurity elements are obviously reduced. The reason is that in the process of vacuum consumable remelting, the gas phase partial pressure of the material is reduced under the high vacuum condition, the solubility of partial impurity elements is reduced, and gas inclusions float, decompose and volatilize, so that the contents of gas and partial inclusions in the alloy melt can be obviously reduced.
Meanwhile, the content of the non-metallic inclusions in the alloy material after different smelting processes are adopted is analyzed, and the results are shown in tables 5-7.
TABLE 5 non-metallic inclusions in Ni-Cr alloy materials for different smelting processes
TABLE 6 non-metallic inclusions in different smelting process materials of A-286 alloys
TABLE 7 non-metallic inclusions in different smelting process materials of Incoloy 901 alloy
Compared with the VIM + ESR smelting process, the VIM + ESR + VAR smelting process (preparation method) can effectively reduce the content of non-metallic inclusions in the material. Because the VIM + ESR + VAR smelting process removes S, P and other impurities in most materials through electroslag remelting, and simultaneously, the vacuum consumable remelting process can further remove gas impurities and volatile elements in the materials, the purity of the materials is ensured, the non-metal inclusions in the materials are further reduced, and the processing performance of subsequent finished products of the materials is ensured.
The electrical properties of the material were then analyzed, as shown in table 8.
TABLE 8 Electrical Properties of the materials
The resistance temperature coefficient refers to the change degree of the alloy resistance value when the temperature changes, and the positive and negative change directions are different, for example, the higher the temperature is, the larger the resistance value of the positive resistance alloy is, and the smaller the resistance value of the negative resistance alloy is. The more the absolute value of the resistance temperature coefficient is close to 0, the smaller the influence of temperature change on the resistance value change of the resistance alloy is, the more stable the performance of the resistance alloy is, and the resistance temperature coefficient is a performance index of the resistance alloy.
The nickel-chromium resistance alloy produced by the VIM + ESR + VAR smelting process further removes gas impurities and volatile elements in the material due to the vacuum consumable remelting process, ensures the purity of the material, further reduces non-metallic inclusions in the material, reduces the absolute value of the resistance temperature coefficient from 34 to 5, and meets the use requirement of the material specified by the standard, and after the material produced by the VIM + ESR smelting process is subjected to aging treatment, the absolute value of the resistance temperature coefficient is improved from 12 to 36 and deviates from 0 value too much, namely the resistance value of the material is greatly influenced by the temperature and cannot meet the use requirement.
In the subsequent precision processing process of the material, the defects of subcutaneous bubbles, folds, looseness and the like can be found on part of the surface of the material produced by the VIM + ESR smelting process when the material is rolled to a strip with the thickness of 0.2mm, and the use requirement of high-precision electrical appliance elements can not be met.
The material produced by the VIM + ESR + VAR smelting process has good surface quality when being processed into a foil with the thickness of 20 mu m and a fine wire with the diameter of 0.08mm, has better processing performance compared with the material produced by the VIM + ESR smelting process due to low inclusion content and more uniform components, has more uniform final metallographic structure, and more accurate control on parameters such as the size, tolerance, surface quality and the like of the processed product, and can control the tolerance of the finished product material to +/-5% of the thickness of the foil.
The material prepared by the VIM + ESR + VAR process has more uniform tissue and less impurity elements and gas content, so that the material can be subjected to high-precision processing and has good surface quality and stable and reliable performance, and has wide prospect when being applied to the aspect of precise electronic components.
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