阅读说明：本技术 一种镍铬电热合金及其制备方法 (Nickel-chromium electrothermal alloy and preparation method thereof ) 是由 沙国伟 于 2019-12-18 设计创作，主要内容包括：本发明涉及合金材料领域,尤其涉及一种镍铬电热合金及其制备方法。为了解决常规方法所制备的镍铬电热合金的电阻率较低,最高工作温度仅为1200℃的问题,本发明提供一种镍铬电热合金,通过对镍铬电热合金的成分和含量进行合理设计以及采用特殊加工工艺,使得所制备的镍铬电热合金具有较好的高温强度和电阻率(1.3Ωmm<Sup>2</Sup>/m以上),其工作温度可达到1350℃。(The invention relates to the field of alloy materials, in particular to a nickel-chromium electrothermal alloy and a preparation method thereof. In order to solve the problems that the resistivity of the nickel-chromium electrothermal alloy prepared by the conventional method is low and the highest working temperature is only 1200 ℃, the invention provides the nickel-chromium electrothermal alloy, and the prepared nickel-chromium electrothermal alloy has better high-temperature strength and resistivity (1.3 omega mm) by reasonably designing the components and the content of the nickel-chromium electrothermal alloy and adopting a special processing technology 2 More than m), the working temperature can reach 1350 ℃.)

1. The nickel-chromium electrothermal alloy is characterized by comprising the following components (in percentage by mass of element components):

Cr 20-21%

Fe 0.4-0.6%

Al 0.1-0.2%

Mn 0.02-0.06%

Ti 0.08-0.12%

Zr 0.2-0.5%

C 0.02-0.04%

Si 0.8-1%

P 0.01-0.012%

S 0.01-0.012%

N 0.01-0.02%

V 1-2%

Mo 0.5-1%

0.3 to 0.4 percent of rare earth elements

The balance of Ni.

2. The nichrome electrothermal alloy of claim 1, wherein: the rare earth element is one or more of La, Ce, Y and Nb.

3. The preparation method of the nickel-chromium electrothermal alloy according to the claims 1-2, characterized by comprising the following steps:

step (1): vacuum low-temperature freeze drying of nickel-chromium electrothermal alloy powder

Placing alloy component powder to be dehydrated into a vacuum freeze dryer, setting the vacuum degree to be 10-15Pa, pre-freezing for 0.5-1h at-20 ℃, then freezing at-45 ℃, then sublimating water at-5 ℃, and packaging the alloy powder when the water content is lower than 0.5 percent after sublimation is finished;

step (2): ingredients

The nickel-chromium electrothermal alloy component powder dried at low temperature in vacuum is mixed according to the proportion in the claim 1.

And (3): bottom-blown rare earth element dispersion strengthening technology for electrothermal alloy smelting furnace

Preparing the prepared nickel-chromium electrothermal alloy powder into fine powder, wherein the granularity of the nickel-chromium electrothermal alloy powder is 300 meshes, Ar is used as a carrier, the nickel-chromium electrothermal alloy powder is pressed into an air brick at the bottom of a vacuum induction smelting furnace by using a conventional injection system under high pressure, and is injected into the smelting furnace for vacuum induction smelting, the powder flow is 5kg/h, the smelting temperature is 1520 plus material 1560 ℃, the smelting time is 20-30min, and the vacuum degree is 1 multiplied by 10^-3Pa, tapping temperature is 1520-1560 ℃;

and (4): electroslag refining, namely performing electroslag refining on the steel ingot obtained in the step (3), wherein the temperature in the refining period is controlled to be 1520-1580 ℃, the smelting voltage is 45-50V, and the smelting current is 2500-;

and (5): forging at the forging temperature of 900-1180 ℃ and the forging starting temperature of 1150 ℃, and heating by adopting natural gas;

and (6): hot rolling the wire rod, wherein the forged square rod is subjected to hot rolling at the temperature of 900-1180 ℃, the initial rolling temperature of 1170 ℃ and the final rolling temperature of 900 ℃;

and (7): annealing at 950-1050 ℃ for 2 h;

and (8): rinsing, namely performing acid pickling-water washing on the hot-rolled wire rod and the annealed blank;

and (9): and (4) ash-coating and drying the rinsed wire rod for multiple passes, and drawing → annealing → drawing to obtain a finished product of the high-resistance electrothermal alloy material.

4. The method for preparing the nickel-chromium electrothermal alloy according to claim 3, characterized in that: and (4) drawing in the step (9) is carried out at a low speed by a single vehicle, and the linear speed is 8-10 m/mint.

5. The method for preparing the nickel-chromium electrothermal alloy according to claim 3, characterized in that: and (4) annealing in the step (9) by adopting bright heat treatment annealing, wherein the annealing temperature is 950-1050 ℃.

6. The method for preparing the nickel-chromium electrothermal alloy according to claim 3, wherein the acid solution in the rinsing and pickling steps in the step (8) is HNO (HNO)₃：HF：H₂O = 1.5: 0.8: 100, the temperature of the acid liquor is 40-60 ℃, and the acid leaching time is 10-15 min.

Technical Field

The invention relates to the field of alloy materials, in particular to a nickel-chromium electrothermal alloy and a preparation method thereof.

Background

The electrothermal alloy is a functional electrothermal engineering alloy material which converts electric energy into heat energy through joule heat generated by a metal resistor. As an important classification of high-temperature alloy materials, the high-temperature alloy materials have good oxidation resistance, corrosion resistance, high-temperature strength and other comprehensive properties, are mainly used for manufacturing precise resistance elements and electric heating elements with the working temperature of 500-1400 ℃ in the forms of wires, strips, pipes, sections and the like, and are widely applied to the fields of electronics, military industry, aerospace, automobiles, household appliances, buildings, petrochemical industry, metallurgy and the like. With the continuous advancement of science and technology and the development of economic globalization, electrification has deepened all corners of the world, the demand of electrothermal alloy materials is increasing day by day, and the electrothermal alloy materials become important engineering alloy materials and play an important role in national economy at present.

The nickel-based electrothermal alloy has austenite structure at room temperature and high temperature, and the alloy structure is stableThe high-temperature strength is high, the high-temperature brittleness is avoided, and the electric performance is uniform and stable because the high-temperature-strength high-temperature-brittleness-free material is a uniform solid solution structure; the cold and hot processing performance is good, and the wire can be made into thin wires and thin strips; the welding performance is excellent, and the maintenance is convenient; the nickel-based electrothermal alloy has the advantages of low resistivity, high maximum working temperature of 1200 ℃, high nickel and chromium content in the alloy, high cost, poor chemical stability and easy corrosion and failure particularly when used in a sulfur-containing atmosphere. For improving the high temperature strength and the resistivity of the nickel-based alloy, the design and the processing technology of the components of the nickel-based alloy are mainly started at present, for example, Chinese invention patent CN 101899593A discloses a nickel-based electrothermal alloy Cr20Ni80Zr, the maximum service temperature of which reaches 1300 ℃, and the surface load of which reaches 5W/cm²(ii) a The Chinese invention patent CN108998635A discloses a nickel-chromium electrothermal alloy, the maximum service temperature of which reaches 1300 ℃.

With the progress and development of science and technology, the requirements of consumers on performance indexes of products are higher and higher, and the materials for manufacturing the resistance elements are required to have high and stable resistance characteristics, particularly the resistance electric heating alloy materials for manufacturing the electric heating elements are required to have higher high-temperature endurance strength and creep resistance, and have longer safe service life. Therefore, for the nickel-based electrothermal alloy, the development is directed to higher use temperature, longer service life and higher thermal efficiency.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the resistivity of the nickel-chromium electrothermal alloy prepared by the conventional method is lower, and the highest working temperature is only 1200 ℃, so that the nickel-chromium electrothermal alloy provided by the invention has better high-temperature mechanical property and higher resistivity through reasonable design of the components and content of the nickel-chromium electrothermal alloy and a special smelting heat treatment processing process, and the working temperature of the nickel-chromium electrothermal alloy can reach 1350 ℃.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the invention provides a nickel-chromium electrothermal alloy, which comprises the following components (in percentage by mass of element components):

specifically, the rare earth element is one or more of La, Ce, Y and Nb.

Specifically, the preparation method of the nickel-chromium electrothermal alloy comprises the following steps:

step (1): vacuum low-temperature freeze drying of nickel-chromium electrothermal alloy powder

Placing alloy component powder to be dehydrated into a vacuum freeze dryer, setting the vacuum degree to be 10-15Pa, pre-freezing for 0.5-1h at-20 ℃, then freezing at-45 ℃, then sublimating water at-5 ℃, and packaging the alloy powder when the water content is lower than 0.5 percent and the sublimation is finished;

step (2): ingredients

The nickel-chromium electrothermal alloy component powder after vacuum low-temperature drying is mixed according to a certain proportion.

And (3): bottom-blown rare earth element dispersion strengthening technology for electrothermal alloy smelting furnace

Preparing the prepared nickel-chromium electrothermal alloy powder into fine powder, wherein the granularity of the nickel-chromium electrothermal alloy powder is 300 meshes, Ar is used as a carrier, the nickel-chromium electrothermal alloy powder is pressed into an air brick at the bottom of a vacuum induction smelting furnace by using a conventional injection system through high pressure, and is injected into the smelting furnace for vacuum induction smelting, the powder flow is 5Kg/h, the smelting temperature is 1520 plus materials 1560 ℃, the smelting time is 20-30min, and the vacuum degree is 1 multiplied by 10^-3Pa, tapping temperature is 1520-1560 ℃;

and (4): electroslag refining, performing electroslag refining on the steel ingot obtained in the step (3), wherein the temperature in the refining period is controlled to be 1520-1580 ℃, the smelting voltage is 45-50V, and the smelting current is 2500-;

and (5): forging, namely forging the steel ingot obtained in the step (4), wherein the forging temperature is 900-1180 ℃, the forging starting temperature is 1150 ℃, and natural gas is adopted for heating;

and (6): hot rolling the wire rod, wherein the forged square rod is subjected to hot rolling at the temperature of 900-1180 ℃, the initial rolling temperature of 1170 ℃ and the final rolling temperature of 900 ℃;

and (7): annealing at 950-1050 ℃ for 2 h;

and (8): rinsing, namely performing acid pickling-water washing on the hot-rolled wire rod and the annealed blank;

and (9): and (4) ash-coating and drying the rinsed wire rod for multiple passes, and drawing → annealing → drawing to obtain a finished product of the high-resistance electrothermal alloy material.

Specifically, the drawing in the step (9) is carried out at a single slow speed, and the linear speed is 8-10 m/mint.

Specifically, the annealing in the step (9) adopts bright heat treatment annealing, and the annealing temperature is 950 ℃ to 1050 ℃.

Specifically, the acid solution in the rinsing and acid washing step in the step (8) is HNO in parts by weight₃：HF：H₂O ═ 1.5: 0.8: 100, the temperature of the acid liquor is 40-60 ℃, and the acid leaching time is 10-15 min.

The invention has the beneficial effects that:

(1) in order to improve the strengthening effect of the rare earth element on the electrothermal alloy and improve the deoxidation efficiency of the nickel-chromium electrothermal alloy and the yield of the rare earth element, the bottom blowing rare earth element dispersion strengthening technology of the electrothermal alloy smelting furnace is adopted, the problem that the rare earth element is not easy to add in the smelting process is solved, the strong stirring is caused to the molten pool by controlling the impact effect of high-pressure powder airflow, the dynamic condition of metallurgical reaction is greatly improved, the alloying time is shortened, the homogenization degree of the alloy element in steel is promoted, the yield of the alloy is improved, the effective discharge of desulfurization (deoxidation) products is ensured, the non-metallic inclusions and the like remained in the molten pool are uniformly distributed, the uniformity and the cleanliness of alloy components are improved, and the improvement of various performances of the nickel-chromium electrothermal alloy is very facilitated;

(2) the invention adopts the vacuum low-temperature freeze drying technology to carry out drying treatment on the nickel-chromium electrothermal alloy, prevents the oxidation of alloy elements from influencing the quality of the electrothermal alloy, ensures that the water content of the alloy powder is lower than 0.5 percent after the alloy powder is subjected to vacuum low-temperature freeze drying, has no oxidation browning phenomenon in the drying process, has no adhesion or agglomeration phenomenon among powder particles after drying, has good dispersibility and has less influence on the performance of the alloy powder;

(3) the nickel-chromium electrothermal alloy prepared by reasonable component design and special processing technology of the nickel-chromium electrothermal alloy has better high-temperature mechanical property and higher resistivity of 1.3 omega mm²And/m, the working temperature can reach 1350 ℃.

Detailed Description

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