阅读说明：本技术 一种超低气体含量镍基合金690的制备方法 (Preparation method of nickel-based alloy 690 with ultralow gas content ) 是由 王方军 吴畏 刘应龙 李永友 刘海定 于 2019-11-21 设计创作，主要内容包括：本发明涉及超低气体含量镍基合金690的制备方法,该方法采用真空感应熔炼+电渣重熔的双联工艺,制备的镍基合金690中(O+N+H)气体总含量小于60ppm,并且锻造性能好。(The invention relates to a preparation method of a nickel-based alloy 690 with ultralow gas content, which adopts a duplex process of vacuum induction melting and electroslag remelting, wherein the total content of (O + N + H) gas in the prepared nickel-based alloy 690 is less than 60ppm, and the forging performance is good.)

1. A preparation method of an ultra-low gas content nickel-based alloy 690 is characterized by comprising the following steps:

1) self-fusing electrode bar

Taking the components according to the proportion of 690 alloy, carrying out vacuum induction melting, casting the components into round bars in a vacuum environment of more than or equal to 2Pa, keeping the vacuum environment for more than or equal to 24 hours, cooling the components to be below 100 ℃ in the vacuum environment, and taking out steel ingots to obtain self-melting electrode bars subjected to electroslag remelting;

2) pre-melted slag of electroslag remelting

The weight portions are as follows: al: 5-15 parts of Fe: 85-95 parts of each component, taking the Fe-Al steel ingot prepared by vacuum induction melting as a round rod, finishing and using the round rod as a Fe-Al self-melting electrode for slag washing;

the slag material proportion of the electroslag remelting is as follows according to parts by weight: CaF₂: 65-175 parts of CaO: 6 to 112 portions of Al₂O₃: 10-13 parts of MgO: 12-115 parts;

firstly, adding a small amount of slag (the slag amount is determined by the size of the crystallizer) into the crystallizer, heating the slag to a molten state by carbon electrode arcing, then removing the carbon electrode, slowly descending Fe-Al from the molten electrode into molten electroslag remelting slag, electrifying to strike an arc to form a molten pool, and slowly and uninterruptedly adding the rest slag into the molten pool to be molten;

cooling the melted slag in a crystallizer, taking out to form solid pre-melted slag, and crushing to obtain pre-melted slag of the electroslag remelting 690 alloy;

3) electroslag remelting

Baking the pre-melted slag obtained in the step 2) at 800 ℃, putting the pre-melted slag into a crystallizer, heating the pre-melted slag to a molten state, slowly lowering the self-melting electrode obtained in the step 1) into the molten pre-melted slag, electrifying, arcing and cooling the pre-melted slag, introducing argon into the top of the crystallizer, adjusting the voltage of the self-melting electrode rod to 45-55V and the current to 3000-7500A, slowly melting the self-melting electrode rod, and passing the molten liquid drops of the self-melting electrode rod through a molten slag pool to recrystallize at the bottom of the crystallizer to obtain an electroslag ingot with a smooth surface.

2. The method of claim 1, wherein: the diameter of the self-fluxing electrode rod in the step 1) is 100 mm-200 mm.

3. The method of claim 1, wherein: and 2) the granularity of the slag of the crushed pre-melted slag is less than 10 mm.

4. The method of claim 1, wherein: and 2) the liquid slag melted by the electroslag is in a clear and uniform state.

5. The method of claim 1, wherein: and 2) heating in the crystallizer by adopting a graphite electrode bar.

6. The method of claim 1, wherein: and 3) baking the pre-melted slag for more than or equal to 4 hours.

7. The method of claim 1, wherein: the step 3) is to cool the crystallizer and the bottom plate by adopting water.

8. The method of claim 1, wherein: and 3) the flow rate of the argon in the step 3) is 200-400 l/min.

9. The method of claim 1, wherein: and 3) the diameter of the electroslag ingot is 160-300 mm.

Technical Field

The invention relates to the field of metal material smelting, in particular to a preparation method of a nickel-based alloy 690 with ultralow gas content.

Background

The 1E-level thermocouple thermometer is mainly used for measuring the temperature of the reactor core outlet of the reactor of the advanced pressurized water reactor nuclear power station, and in order to protect thermocouple elements and simultaneously cooperate with a thermocouple to normally work in the high-temperature and high-pressure environment, the thermocouple needs to be matched with a sleeve for use, so that the service life of the thermocouple can be prolonged, and the thermocouple can also play a role in supporting and fixing a hot electrode and increasing the strength of the hot electrode. Considering the long-term high temperature of the reactor core and the long-term use of the reactor core above 650 ℃ in partial working conditions, a UNS N06690 alloy material with better high temperature resistance is selected, and the nickel-based alloy 690 is a nickel-based heat-resistant corrosion-resistant alloy and is an American alloy number UNS N06690 alloy.

In order to ensure that the casing material does not affect the service life of the thermocouple and the accuracy and stability of measurement, 690 alloy material with ultralow gas content and total (O + N + H) gas content of less than 60ppm needs to be prepared.

The current patent with the patent number of 2012105744199 reports a process method for preparing 3 tons of ultra-pure I-690 alloy electroslag remelting ingots with the O content of 20ppm in the industrial production, and the patent with the patent number of 2014108094083 reports an electroslag remelting method for large-size, ultra-pure and high-performance nickel-based alloys 690 with the O content of 24ppm, but the 690 alloys prepared by the methods have a common characteristic: the content of N is as high as about 100 ppm. The total content of (O + N + H) gas is more than 120ppm, and the technical requirements of advanced nuclear-grade casing materials can not be met.

At present, the common method for reducing the total content of the gas of the nickel-based alloy 690 (O + N + H) is to adopt a vacuum consumable remelting mode when remelting alloy electrodes for the second time, but the surface quality of a steel ingot subjected to vacuum consumable remelting is poor, and when forging the steel ingot, the forging processability is poor, the surface of the steel ingot is easy to crack, and the yield of products is reduced.

Therefore, it is required to develop a preparation process method of an alloy steel ingot of the nickel-based alloy 690 with more excellent ultra-low gas content.

Disclosure of Invention

The invention aims to provide a preparation method of a nickel-based alloy 690 with ultralow gas content, which adopts a duplex process of vacuum induction melting and electroslag remelting, and the total content of (O + N + H) gas in the prepared nickel-based alloy 690 is less than 60ppm, and the forging performance is good.

The technical scheme of the invention is as follows:

the preparation method of the nickel-based alloy 690 with the ultralow gas content comprises the following steps:

1) self-fusing electrode bar

Taking the components according to the proportion of 690 alloy, carrying out vacuum induction melting, casting the components into round bars in a vacuum environment of more than or equal to 2Pa, keeping the vacuum environment for more than or equal to 24 hours, cooling the components to be below 100 ℃ in the vacuum environment, and taking out steel ingots to obtain self-melting electrode bars subjected to electroslag remelting;

2) pre-melted slag of electroslag remelting

The weight portions are as follows: al: 5-15 parts of Fe: 85-95 parts of each component, taking the Fe-Al steel ingot prepared by vacuum induction melting as a round rod, finishing and using the round rod as a Fe-Al self-melting electrode for slag washing;

the slag material proportion of the electroslag remelting is as follows according to parts by weight: CaF₂: 65-175 parts of CaO: 6 to 112 portions of Al₂O₃: 10-13 parts of MgO: 12-115 parts;

firstly, adding a small amount of slag (the slag amount is determined by the size of the crystallizer) into the crystallizer, heating the slag to a molten state by carbon electrode arcing, then removing the carbon electrode, slowly descending Fe-Al from the molten electrode into molten electroslag remelting slag, electrifying to strike an arc to form a molten pool, and slowly and uninterruptedly adding the rest slag into the molten pool to be molten;

cooling the melted slag in a crystallizer, taking out to form solid pre-melted slag, and crushing to obtain pre-melted slag of the electroslag remelting 690 alloy;

3) electroslag remelting

Baking the pre-melted slag obtained in the step 2) at 800 ℃, putting the pre-melted slag into a crystallizer, heating the pre-melted slag to a molten state, slowly lowering the self-melting electrode obtained in the step 1) into the molten pre-melted slag, electrifying, arcing and cooling the pre-melted slag, introducing argon into the top of the crystallizer, adjusting the voltage of the self-melting electrode rod to 45-55V and the current to 3000-7500A, slowly melting the self-melting electrode rod, and passing the molten liquid drops of the self-melting electrode rod through a molten slag pool to recrystallize at the bottom of the crystallizer to obtain an electroslag ingot with a smooth surface.

The diameter of the self-fluxing electrode rod in the step 1) is 100 mm-200 mm.

And 2) the granularity of the slag of the crushed pre-melted slag is less than 10 mm.

And 2) the liquid slag melted by the electroslag is in a clear and uniform state.

And 2) heating in the crystallizer by adopting a graphite electrode bar.

And 3) baking the pre-melted slag for more than or equal to 4 hours.

The step 3) is to cool the crystallizer and the bottom plate by adopting water.

And 3) the flow rate of the argon in the step 3) is 200-400 l/min.

And 3) the diameter of the electroslag ingot is 160-300 mm.

Vacuum induction melting is an effective means for preparing pure alloy steel ingots, but steel ingots which are directly demoulded after vacuum casting are still in a high-temperature state, and are in contact with the atmosphere, the surface of the steel ingots is easily oxidized to adsorb gas, if oxide layers of the steel ingots cannot be completely removed, the content of alloy gas prepared subsequently is often higher, while the surface of the steel ingots cooled in a vacuum environment is very clean, the purity of the whole steel ingots in a vacuum melting state is kept, and the content of the prepared alloy gas is lower.

The premelting slag prepared by the Fe-Al steel ingot and the slag charge in proportion has the following typical advantages: (1) the stable slag components avoid the defect of unstable components caused by uneven slag charge mixing during production; (2) when electroslag remelting production is carried out, the arc striking and slagging are easy, the time is short, the bottom of the steel ingot has good quality, and the yield is high; (3) greatly simplifies and even cancels the slag baking, reduces the power consumption of the slag baking; (4) the water content in the slag is extremely low, so that a large amount of hydrogen is effectively prevented from being increased in the remelting process, the slag collapse phenomenon in the slag melting process can be prevented, and the operation safety is ensured; (5) the granular slag is adopted, so that the dust is less, the environmental pollution is less, and the abrasion to a transmission part of mechanical equipment is particularly small; (6) the Fe-Al steel ingot can effectively remove impurities and other impurity elements in slag, wherein the impurities and other impurity elements are easy to combine with gas into the alloy through chemical reaction, so that the gas content of the alloy is increased.

Electroslag remelting is an important metallurgical process technology for purifying materials to improve structures, and has great influence on the performance of the materials. The electroslag remelting can effectively reduce harmful elements, refine impurities to make impurities uniformly distributed, refine tissues to make tissues uniformly distributed and the like. The proper electroslag remelting process can also greatly improve the hot processing performance of the alloy, ensure that the alloy is not cracked during hot processing, and further improve the yield.

The preparation method of the nickel-based alloy 690 material with the ultra-low gas content has the beneficial effects that the gas content of the nickel-based alloy 690 is lower by the preparation method, the requirement of the advanced nuclear-grade thermocouple sleeve material on the total gas content of the alloy (O + N + H) is less than 60ppm is met, the improvement of the nuclear power technology in China is facilitated, and the economic benefit and the social benefit are very obvious.

The nickel-based alloy 690 prepared by the method of the present invention has O, N, H gas content weight percent as follows: o is less than 20ppm, N is less than 30ppm, H is less than 10ppm, O + N + H is less than 60ppm, and the nickel-based alloy 690 with ultra-low gas content is obtained.

Detailed Description

Example 1

A preparation method of an ultra-low gas content nickel-based alloy 690 comprises the following steps:

a) preparation of self-fluxing electrode rod

The nickel-based alloy 690 comprises the following electrode rods in parts by weight: 0.03 part of C, 0.3 part of Mn, 10 parts of Fe, 28 parts of Cr and 61.67 parts of Ni, and is prepared by adopting 50kg of vacuum induction melting. The alloy smelted by vacuum induction is cast into a round bar with the diameter of 100mm under the vacuum environment of 2Pa, and the cast round bar is continuously cooled for 24 hours under the vacuum environment of 2Pa, so that the alloy steel ingot is prevented from being oxidized to the maximum extent. Taking out the steel ingot when the alloy round bar is cooled to below 100 ℃ in a vacuum environment, wherein the surface of the steel ingot is bright metallic;

b) preparation of electroslag remelting premelting slag

And preparing Fe-Al steel ingots by vacuum induction melting for preparing remelting slag materials. The chemical component proportion of the Fe-Al steel ingot is as follows by weight: al: 5 parts of Fe: 85 parts of the raw materials. The Fe-Al steel ingot prepared by vacuum induction melting is a round bar with the diameter of 170mm, and the surface of the round bar is sanded to remove oxide skin and is used as a self-melting electrode for slag washing after finishing.

The slag material proportion of the electroslag remelting is as follows according to parts by weight: CaF₂: 65 parts of CaO: 11 parts of Al₂O₃: 12 parts of MgO: 12 parts.

Heating the proportioned slag in a crystallizer with the diameter of phi 280mm to a molten state through a graphite electrode rod, then moving out a graphite electrode, slowly descending the Fe-Al from the molten electrode into molten electroslag remelting slag, electrifying and arcing to form a molten pool, slowly and uninterruptedly adding the slag into the molten pool for melting, and ensuring that the molten liquid slag is in a clear and uniform state in the melting process.

And cooling the melted slag in a crystallizer, taking out the cooled slag to form solid pre-melted slag, crushing the solid pre-melted slag by using a jaw crusher, wherein the granularity of the crushed slag is less than 10mm, and preparing the pre-melted slag required by the electroslag remelting nickel-based alloy 690.

c) Electroslag remelting

Weighing 8kg of the premelting slag, baking for 4 hours at 800 ℃, heating the premelting slag in a phi 160mm crystallizer through a graphite electrode rod to a molten state, then removing the graphite electrode, slowly descending the nickel-based alloy 690 from the molten electrode into molten electroslag remelting slag, electrifying and arcing, cooling a crystallizer and a bottom plate in the crystallizer by water, introducing argon gas at the flow rate of 200-250 l/min at the top of the crystallizer to isolate air, and adjusting the remelting voltage of the self-melting electrode rod obtained in the step 1) to 45V and the current to 3500A. The self-melting electrode bar is slowly melted by resistance heat, and the liquid drops of the melted self-melting electrode bar pass through the melted slag layer to be recrystallized at the bottom of the crystallizer, so that the phi 160mm electroslag ingot with compact and uniform tissue, purity and smooth surface is obtained.

The steel ingot is sampled after forging processing, and is sent to the mechanical industry so as to be detected by functional material detection of Chongqing instruments of material product quality supervision and detection centers, and the result is O: 15ppm, N: 29ppm, H: 6.6ppm, O + N + H: 50.6 ppm.

The alloy produced by the method described in example 1 was an ultra low gas content nickel based alloy 690.

Example 2

a) Preparation of self-fluxing electrode rod

The nickel-based alloy 690 comprises the following electrode rods in parts by weight: 0.03 part of C, 0.3 part of Mn, 10 parts of Fe, 28 parts of Cr and 61.67 parts of Ni, and is prepared by 500kg of vacuum induction melting. The alloy smelted by vacuum induction is cast into a round bar with the diameter of 200mm under the vacuum environment of 2Pa, and the cast round bar is continuously cooled for 48 hours under the vacuum environment of 2Pa, so that the alloy steel ingot is prevented from being oxidized to the maximum extent. Taking out the steel ingot when the alloy round bar is cooled to below 100 ℃ in a vacuum environment, wherein the surface of the steel ingot is bright metallic;

b) preparation of electroslag remelting premelting slag

And preparing Fe-Al steel ingots by vacuum induction melting for preparing remelting slag materials. The chemical component proportion of the Fe-Al steel ingot is as follows by weight: al: 10 parts of Fe: and 90 parts. The Fe-Al steel ingot prepared by vacuum induction melting is a round bar with the diameter of 170mm, and the surface of the round bar is sanded to remove oxide skin and is used as a self-melting electrode for slag washing after finishing.

The slag material proportion of the electroslag remelting is as follows according to parts by weight: CaF₂: 70 parts of CaO: 8 parts of Al₂O₃: 9 parts of MgO: 13 parts.

Heating the proportioned slag in a crystallizer with the diameter of phi 280mm to a molten state through a graphite electrode rod, then moving out a graphite electrode, slowly descending the Fe-Al from the molten electrode into molten electroslag remelting slag, electrifying and arcing to form a molten pool, slowly and uninterruptedly adding the slag into the molten pool for melting, and ensuring that the molten liquid slag is in a clear and uniform state in the melting process.

And cooling the melted slag in a crystallizer, taking out the cooled slag to form solid pre-melted slag, crushing the solid pre-melted slag by using a jaw crusher, wherein the granularity of the crushed slag is less than 10mm, and preparing the pre-melted slag required by the electroslag remelting nickel-based alloy 690.

c) Electroslag remelting

Weighing 30kg of the premelting slag, baking for 6 hours at 800 ℃, heating the premelting slag in a crystallizer with the diameter of 300mm to a molten state through a graphite electrode rod, then removing the graphite electrode, slowly descending the self-melting electrode obtained in the step 1) into molten electroslag remelting slag, electrifying and arcing, cooling a crystallizer and a bottom plate in the crystallizer by water, introducing argon gas with the flow rate of 300-400 l/min to isolate air into the top of the crystallizer, and adjusting the remelting voltage of the nickel-based alloy 690 from the melting electrode rod to 55V and the current of 7500A. The self-melting electrode bar is slowly melted by resistance heat, and the liquid drops of the melted self-melting electrode bar pass through the melted slag layer to be recrystallized at the bottom of the crystallizer, so that the phi 300mm electroslag ingot with compact and uniform tissue, purity and smooth surface is obtained.

The steel ingot is sampled after forging processing, and is sent to the mechanical industry so as to be detected by functional material detection of Chongqing instruments of material product quality supervision and detection centers, and the result is O: 18ppm, N: 26ppm, H: 2.8ppm, O + N + H: 46.8 ppm.

The alloy produced using the method described in example 2 was an ultra low gas content nickel based alloy 690.