CN115287463A - Slag system for electroslag remelting N06625 nickel-based alloy welding material, preparation method and use method - Google Patents

Abstract

The invention relates to a slag system for electroslag remelting N06625 nickel-based alloy welding material, a preparation method and a use method. The above-mentioned slag system includes the following components by mass percentage: CaF ₂ : 58-62%, Al ₂ O ₃ : 15-19%, CaO: 15-19%, Na ₂ O: 2.0-4.0%, TiO ₂ : 2.0-4.0%; the balance is impurities, the content of impurities is less than or equal to 1%, and the sum of the foregoing items is 100%; the impurities include SiO ₂ , and the content of SiO ₂ accounts for less than 1% of the total slag system. The present invention adjusts the proportion of each component in the slag system so that the melting point, density and viscosity of the slag system can meet the production of electroslag remelting N06625 nickel-based alloy welding material, which can reduce impurity elements such as N, O gas and S, and control the The number of inclusions can also control the burning loss of easily oxidizable elements Al and Ti in the alloy and ensure the uniformity of the head and tail of the welding material.

Description

A kind of slag system for electroslag remelting N06625 nickel-based alloy welding material, preparation method and use method

technical field

The invention belongs to the technical field of metallurgy, and in particular relates to a slag system for electroslag remelting N06625 nickel-based alloy welding consumables, a preparation method and a use method.

Background technique

As environmental emission requirements become more and more stringent, the service conditions of oil well pipes, cracking furnace pipes, heat exchangers, gasifiers, and waste incinerators used in petrochemical, energy, and environmental protection industries are more stringent, and the materials used for key equipment and key components are from the current The transformation of austenitic and super austenitic stainless steel into high-end nickel-based alloys has led to an increase in high-end nickel-based alloy welding consumables matched with nickel-based alloys. At present, the total consumption of nickel-based alloys in the world is about 300,000 tons, of which high-end nickel-based alloy welding consumables are mainly N06625, accounting for about 20,000 tons. The annual apparent consumption of nickel-based alloys in my country is about 40,000 tons, and the corresponding high-end nickel-based alloy N06625 welding consumables account for about 8,000 tons, and more than 80% of them need to be imported.

The product quality of high-end nickel-based alloy N06625 welding consumables in my country still has a certain gap compared with foreign countries. For example, in terms of purity, the gas content of the product can only be stably controlled at O≤30ppm, and the sum of inclusion grades≤1.5. The invention application with the application number 201810734346.2 records a high-purity and non-segregation-free electroslag remelting smelting process of N06625 alloy. The sum is not greater than 2.0, but the specific composition range of the relevant slag-based components is not given. The invention application with the application number 201810610467.6 records a method for electroslag remelting of N06625 nickel-based alloy and the slag system used. The mass percentage between the raw material of the slag system and the raw material is CaF ₂ : 55-65%, Al ₂ O ₃ : 15-25%, CaO: 8-15%, MgO: 5-10%, TiO ₂ : 2-5%. The document "Five-element Slag Density and Its Application in Nickel-based Alloy Industrial Melting" reports a slag-based component for electroslag remelting Inconel625 nickel-based alloy: CaF ₂ : 65%, CaO: 9%, Al ₂ O ₃ : 18%, SiO ₂ : 8%, MgO: 7%. However, there is a certain difference between N06625 welding consumables and Inconel625 alloy in alloy composition. The current typical finished product composition of Inconel625 alloy is Cr: 21.5, Ni: 61, Mo: 9, Nb: 3.6, Fe: 2, C: 0.05, Al: 0.2, Ti : 0.2, Si: 0.2, Mn: 0.2, S≤0.015, P: 0.001; typical N06625 welding consumable finished composition is Cr: 21.7, Mo: 8.9, Nb: 3.6, Fe: 0.01, C: 0.03, Al: 0.15, Ti: 0.01, Si: 0.02, Mn: 0.2, S: 0.001, P: 0.001. The content of main deoxidizing elements C, Si and Al in N06625 welding material is very low, so it is more difficult to control the oxygen content in the alloy. At the same time, the typical Inconel625 alloy Al:Ti content ratio is 1:1, and the uniformity of Al and Ti in the remelting process is easier to control; while the low level of Al+Ti content in the N06625 welding consumables reduces the "clamping" of oxides and nitrides during welding. The generation of "slag" improves the welding performance of the alloy, but it is difficult to control the uniformity of Al and Ti in the remelting process. In addition, S exists as a harmful element in nickel-based alloys. When the mass fraction of S in the alloy is high, it will have an adverse effect on the hot workability, weldability, corrosion resistance, and high-temperature oxidation resistance of the alloy. Especially for high-quality N06625 welding consumables, the requirements for S content are more stringent.

Therefore, in order to effectively alleviate the dependence on the import of high-end nickel-based alloy welding consumables, meet the needs of various industries for high-quality nickel-based alloys, speed up the localization of key equipment, reduce production costs, and promote green development, develop a high-cleanliness The slag system for electroslag remelting high-end nickel-based alloy N06625 welding consumables is an urgent problem to be solved at present.

Contents of the invention

(1) Technical problems to be solved

In order to solve the problems of insufficient purity and insufficient product quality of N06625 nickel-based alloy welding materials in the prior art, the present invention provides a slag system for electroslag remelting N06625 nickel-based alloy welding materials. In order to solve the above problems, the present invention also provides a method for preparing and using a slag system for electroslag remelting N06625 nickel-based alloy welding consumables.

(2) Technical solution

In order to achieve the above object, the main technical solutions adopted in the present invention include:

In the first aspect, the present invention provides a slag system for electroslag remelting N06625 nickel-based alloy welding material, which comprises the following components in terms of mass percentage:

CaF ₂ : 58-62%, Al ₂ O ₃ : 15-19%, CaO: 15-19%, Na ₂ O: 2.0-4.0%, TiO ₂ : 2.0-4.0%;

_The balance is impurities, the content of which is _≤1 %, and the sum of the above items is 100%.

The above-mentioned slag system for electroslag remelting N06625 nickel-based alloy welding consumables, preferably, in terms of mass percentage, the slag system includes the following components:

CaF ₂ : 59%, Al ₂ O ₃ : 17%, CaO: 17%, Na ₂ O: 3.0%, TiO ₂ : 3.0%;

The impurity is 1%, and the content of _SiO2 in the impurity accounts for 0.8% of the total amount of the slag system.

The slag system for electroslag remelting N06625 nickel-based alloy welding consumables mentioned above, preferably, in the slag system, (CaO+Na ₂ O)/SiO ₂ ≥ 20.

The above-mentioned slag system for electroslag remelting N06625 nickel-based alloy welding material, preferably, in terms of mass percentage, the N06625 nickel-based alloy welding material includes the following components:

C≤0.10%, Si≤0.2%, Mn≤0.5%, S≤0.015%, P≤0.015%, Cr: 20.0-23.0%, Mo: 8.0-10.0%, Nb: 3.15-4.15%, Al≤0.2% , Ti≤0.2%, and the balance is Ni.

In a second aspect, the present invention provides a method for preparing the slag system for the electroslag remelting N06625 nickel-based alloy welding material, comprising the following steps:

S1: Using CaF ₂ , Al ₂ O ₃ , CaO, Na ₂ O and TiO ₂ as raw materials, mix and stir each component evenly, and prepare a slag system with the following mass percentage components: CaF ₂ : 58-62%, Al ₂ O ₃ : 15-19%, CaO: 15-19%, Na ₂ O: 2.0-4.0%, TiO ₂ : 2.0-4.0%; the rest is impurities, the content of impurities ≤ 1%, the sum of the above items 100%; the impurity contains SiO ₂ , and the content of SiO ₂ accounts for ≤1% of the total amount of slag;

S2: putting the ingredients obtained in step S1 into an electric arc furnace for melting and refining;

S3: After refining, casting is performed, and then cooled to room temperature to obtain pre-melted slag block;

S4: crushing and screening the pre-slag blocks obtained in step S3 to prepare pre-slag for electroslag remelting N06625 nickel-based alloy welding consumables with the above composition content.

According to the above-mentioned preparation method, preferably, the refining temperature in step S2 is 1550-1580° C., and the refining time is 30-50 minutes.

According to the above-mentioned preparation method, preferably, in step S4, the pre-slag block is broken into 1-10 mm to produce pre-slag for electroslag remelting for N06625 nickel-based alloy welding consumables.

In a third aspect, the present invention also provides a method for using the slag system for the electroslag remelting N06625 nickel-based alloy welding material, comprising the following steps:

S1: Put the slag system for electroslag remelting N06625 nickel-based alloy welding material after premelting into the slag feeder of the electroslag furnace, and the slag feeder of the electroslag furnace is electrically connected with the protective atmosphere;

S2: Pass argon gas into the electroslag furnace;

S3: Turn on the power of the electroslag furnace, send power to start the arc, and at the same time control the slag feeder of the electroslag furnace to add slag to the electroslag furnace;

S4: The consumable electrode, slag and bottom water tank form a closed loop, and start to prepare electroslag remelting N06625 nickel-based alloy welding consumables.

(3) Beneficial effects

The beneficial effects of the present invention are:

The present invention makes the melting point, density and viscosity of the slag system satisfy the production of electroslag remelting N06625 nickel-based alloy welding consumables by adjusting the ratio of each component in the slag system, which can not only reduce N, O gas and S and other impurity elements, but also control The number of inclusions can also control the burning loss of easily oxidized elements Al and Ti in the alloy, and ensure the uniformity of the head and tail of the welding material.

Specifically, the present invention adds a relatively high amount of CaO and Na ₂ O to the slag to reduce the activity of SiO ₂ in the slag, and adds an appropriate amount of TiO ₂ to suppress the burning loss of easily oxidizable elements such as Al and Ti, and control Ingot longitudinal uniformity. In addition, a higher amount of CaO and Na ₂ O increases the basicity and sulfur capacity of slag, improves the ability of removing inclusions and desulfurization during the slag-gold reaction process, and reduces the content of O, S elements and O, S inclusions quantity.

Detailed ways

In order to better explain the present invention and facilitate understanding, the present invention will be described in detail below through specific embodiments.

In the first aspect, the present invention provides a slag system for electroslag remelting N06625 nickel-based alloy welding material, which comprises the following components in terms of mass percentage:

CaF ₂ : 58-62%, Al ₂ O ₃ : 15-19%, CaO: 15-19%, Na ₂ O: 2.0-4.0%, TiO ₂ : 2.0-4.0%. _The balance is impurities, the content of which is _≤1 %, and the sum of the above items is 100%.

In terms of mass percentage, the above-mentioned N06625 nickel-based alloy welding consumables include the following components:

C≤0.10%, Si≤0.2%, Mn≤0.5%, S≤0.015%, P≤0.015%, Cr: 20.0-23.0%, Mo: 8.0-10.0%, Nb: 3.15-4.15%, Al≤0.2% , Ti≤0.2%, and the balance is Ni. Among the above-mentioned welding consumable components, the content of Al+Ti elements is low, the purpose is to reduce the generation of oxide and nitride "slag inclusion" during welding, and improve the welding performance of the alloy. The content of harmful elements such as S and P is low, which can avoid hot cracks in the weld.

Among them, CaF ₂ can reduce the melting point, viscosity and surface tension of the slag system.

The element composition of electroslag remelting N06625 nickel-based alloy welding material often contains relatively low content of easily oxidized elements such as Al and Ti. In order to suppress the burning loss of Al and Ti elements and maintain the longitudinal uniformity of the ingot, the present invention uses 2.0%-4.0% TiO ₂ is added to the N06625 nickel-based alloy welding consumables to prevent the phenomenon of "burning titanium to increase aluminum" or "burning aluminum to increase titanium" in formula (1).

3[Ti]+2(Al ₂ O ₃ )=4[Al]+3(TiO ₂ ) (1)

Al ₂ O ₃ can significantly reduce the electrical conductivity of the slag system, reduce power consumption, and improve production efficiency.

There is about 1%, generally 0.8%, of SiO ₂ in industrial slag. Studies have shown that when SiO ₂ is contained in the slag system, Al and Ti elements will react in formula (2) and formula (3):

4[Al]+3(SiO ₂ )=3[Si]+2(Al ₂ O ₃ ) (2)

[Ti]+(SiO ₂ )=[Si]+(TiO ₂ ) (3)

In order to suppress or weaken the reaction in formula ( ₂ ) and formula (3), the present invention adds relatively high amount of CaO and Na2O at the same time, so that the binary alkalinity (CaO ₊ Na2O)/ _SiO2≥20 , with This reduces the activity of _SiO2 in the slag. At the same time, due to the addition of Al ₂ O ₃ and TiO ₂ to the slag system, it can further inhibit the positive progress of the above reaction and prevent the burning loss of Al and Ti elements.

In addition, in order to control the oxygen content in the N06625 nickel-based alloy welding material, the present invention uses argon as a protective atmosphere to carry out electroslag remelting. Under the condition of argon protection, the gasification desulfurization reaction is suppressed, and the S element in the welding material alloy is mainly removed through the reaction of formula (4):

[S]+(O ^2- )＝[O]+(S ^2- ) (4)

The invention adds relatively high content of CaO and Na ₂ O to the slag system, increases the sulfur capacity of the electroslag remelting slag, and improves the removal capacity of S.

The preferred composition of the above-mentioned slag system for electroslag remelting N06625 nickel-based alloy welding material includes the following components: CaF ₂ : 59%, Al ₂ O ₃ : 17%, CaO: 17%, Na ₂ O: 3.0%, TiO ₂ : 3.0%, impurity 1%, the content of SiO ₂ in the impurity accounts for 0.8% of the total amount of the slag system.

In a second aspect, the present invention provides a method for preparing the slag system for the electroslag remelting N06625 nickel-based alloy welding material, comprising the following steps:

S1: Using CaF ₂ , Al ₂ O ₃ , CaO, Na ₂ O and TiO ₂ as raw materials, mix and stir each component evenly, and prepare a slag system with the following mass percentage components: CaF ₂ : 58-62%, Al ₂ O ₃ : 15-19%, CaO: 15-19%, Na ₂ O: 2.0-4.0%, TiO ₂ : 2.0-4.0%, the rest is impurities, the content of impurities ≤ 1%, the sum of the above items 100%; the impurities include SiO ₂ , and the content of SiO ₂ accounts for ≤1% of the total amount of slag.

S2: melting the ingredients obtained in step S1 in an electric arc furnace, and refining at 1550-1580° C. for 30-50 minutes.

S3: After refining, cast into cast iron pans, and then cool to room temperature to obtain pre-melted slag blocks.

S4: Crushing and screening the pre-slag block obtained in step S3, and sifting out the part with a particle size of 1-10 mm to prepare the pre-slag for electroslag remelting N06625 nickel-based alloy welding material with the above-mentioned composition content.

In a third aspect, the present invention also provides a method for using the slag system for the electroslag remelting N06625 nickel-based alloy welding material, comprising the following steps:

S1: Put the slag system for electroslag remelting N06625 nickel-based alloy welding material after premelting into the slag feeder of the electroslag furnace, and the slag feeder of the electroslag furnace is electrically connected with the protective atmosphere.

S2: Pass argon gas into the electroslag furnace.

S3: Turn on the power of the electroslag furnace, send power to start the arc, and at the same time control the slag feeder of the electroslag furnace to add slag to the electroslag furnace.

S4: The consumable electrode, slag and bottom water tank form a closed circuit, and start to prepare electroslag remelting N06625 nickel-based alloy welding consumables. The steady-state melting rate is controlled at 0.40-0.55kg/h.

Example 1

In this example, fluorite, lime, industrial alumina, sodium oxide and titanium dioxide are used as raw materials, according to CaF ₂ : 59%, Al ₂ O ₃ : 17%, CaO: 17%, Na ₂ O: 3.0%, TiO ₂ : The ratio of 3.0% is mixed and stirred evenly, melted in an electric arc furnace, and refined at 1550°C for 35 minutes. Then pour it into a cast iron pan and cool it to room temperature, and use a crusher to crush and screen out the part with a particle size of 1-10mm to make pre-melted slag for electroslag remelting N06625 nickel-based alloy welding consumables.

The melting point of the slag system is 1448K, the density (2.605g·cm ^-3 ), and the viscosity of the slag system at 1873K is 0.02Pa·s, which can satisfy the production of electroslag remelting N06625 nickel-based alloy welding consumables.

Remelting is carried out in a protective atmosphere electroslag remelting furnace, with an electrode diameter of 75 mm and a crystallizer diameter of 140 mm. First, put 3.2kg of pre-melted electroslag remelting N06625 nickel-based alloy welding consumable slag system into the protective atmosphere electroslag furnace slag feeder, and the electroslag furnace slag feeder is connected with the protective atmosphere electroslag furnace. Then, argon gas is introduced into the protective atmosphere electroslag furnace, and then the power supply of the electroslag furnace is turned on, and the arc is started by power transmission. At the same time, slag is added to the furnace through the slag feeder, and the consumable electrode forms a closed circuit with the slag and the bottom water tank. , The process of electroslag remelting N06625 nickel-based alloy welding consumables officially started. The voltage in the remelting stable period is 34V, the remelting current is 2.2kA, and the melting speed is 65kg/h.

The above-mentioned slag system for electroslag remelting nickel N06625 nickel-based alloy welding consumables has stable properties in the electroslag remelting process, and the inner and outer surfaces of the obtained ingots are of good quality, without obvious defects such as slag grooves and nodules. Composition analysis was carried out on the samples taken from the head, middle and tail of the ingot. Refer to Table 1 for specific data. It was found that the composition of easily oxidizable elements in the head, middle and tail of the ingot was uniform and within the target range, the content of S element was low, and the composition was qualified, and the sum of A+B+C+D inclusions in the ingot was not more than 1.0.

Comparative example 1

This comparative example provides a general slag system, which includes: CaF ₂ : 70%, Al ₂ O ₃ : 30% in terms of mass percentage. Using this slag system, using this slag system to prepare N06625 nickel-based alloy welding consumables, the sum of A+B+C+D inclusions in the obtained ingot is 2.5, the burning loss of Ti element is serious, and the desulfurization effect is poor. The content of each element is shown in Table 1.

Table 1N06625 Nickel-based alloy welding material alloy part chemical composition (mass fraction/%)

It can be seen from Table 1 that the slag system for electroslag remelting N06625 nickel-based alloy welding consumables in Example 1 can effectively suppress the burning loss of Ti element by optimizing the slag system components and the ratio of each component, and improve the concentration of each element in the ingot. The uniformity of the distribution in the medium, thus ensuring the uniformity of the alloy structure and properties.

In addition, the S element content in the ingot is controlled in a low range, and the composition is qualified. However, the sum of A+B+C+D inclusions in the ingot is not greater than 1.0, which significantly reduces the number of inclusions, improves the purity of the nickel-based alloy N06625 welding consumable and the performance of the nickel-based alloy N06625 welding consumable.

The above embodiments are only used to explain the present invention, and do not constitute a limitation to the protection scope of the present invention. Those skilled in the art can make various changes or modifications within the scope of the claims, all of which belong to the essence of the present invention.

Claims (8)

1. A slag system for electroslag remelting N06625 nickel-based alloy welding consumables, characterized in that, by mass percentage, comprising the following components: _CaF2 : 58-62%, _Al2O3 : 15-19%, CaO: 15-19%, Na2O _: 2.0-4.0%, _{TiO2 :} 2.0-4.0%; _The balance is impurities, the content of which is _≤1 %, and the sum of the above items is 100%. 2. the slag system for electroslag remelting N06625 nickel-base alloy welding material according to claim 1, is characterized in that, by mass percentage, described slag system comprises following components: _CaF2 : 59%, _Al2O3 : ₁₇ %, CaO: 17%, Na2O: 3.0%, _{TiO2 :} 3.0%; The impurity is 1%, and the content of _SiO2 in the impurity accounts for 0.8% of the total amount of the slag system. 3. The slag system for electroslag remelting N06625 nickel-based alloy welding material according to claim 1, characterized in that, in the slag system, (CaO+Na ₂ O)/SiO ₂ ≥ 20. 4. The slag system for electroslag remelting N06625 nickel-based alloy welding material according to claim 1, characterized in that, by mass percentage, said N06625 nickel-based alloy welding material comprises the following components: C≤0.10%, Si≤0.2%, Mn≤0.5%, S≤0.015%, P≤0.015%, Cr: 20.0-23.0%, Mo: 8.0-10.0%, Nb: 3.15-4.15%, Al≤0.2% , Ti≤0.2%, and the balance is Ni. 5. A preparation method of slag system for electroslag remelting N06625 nickel-based alloy welding material according to any one of claims 1-4, characterized in that, comprising the steps of: S1: Using CaF ₂ , Al ₂ O ₃ , CaO, Na ₂ O and TiO ₂ as raw materials, mix and stir each component evenly, and prepare a slag system with the following mass percentage components: CaF ₂ : 58-62%, Al ₂ O ₃ : 15-19%, CaO: 15-19%, Na ₂ O: 2.0-4.0%, TiO ₂ : 2.0-4.0%; the rest is impurities, the content of impurities ≤ 1%, the sum of the above items 100%; the impurity contains SiO ₂ , and the content of SiO ₂ accounts for ≤1% of the total amount of slag; S2: putting the ingredients obtained in step S1 into an electric arc furnace for melting and refining; S3: After refining, casting is performed, and then cooled to room temperature to obtain pre-melted slag block; S4: crushing and screening the pre-slag blocks obtained in step S3 to prepare pre-slag for electroslag remelting N06625 nickel-based alloy welding consumables with the above composition content. 6. The preparation method according to claim 5, characterized in that the refining temperature in step S2 is 1550-1580°C, and the refining time is 30-50min. 7. The preparation method according to claim 5, characterized in that in step S4, the pre-slag block is broken into 1-10mm to make pre-slag for electroslag remelting for N06625 nickel-based alloy welding material. 8. A method for using the slag system for electroslag remelting N06625 nickel-based alloy welding material according to any one of claims 1-4, characterized in that, comprising the steps of: S1: Put the slag system for electroslag remelting N06625 nickel-based alloy welding material after premelting into the slag feeder of the electroslag furnace, and the slag feeder of the electroslag furnace is electrically connected with the protective atmosphere; S2: Pass argon gas into the electroslag furnace; S3: Turn on the power of the electroslag furnace, send power to start the arc, and at the same time control the slag feeder of the electroslag furnace to add slag to the electroslag furnace; S4: The consumable electrode, slag and bottom water tank form a closed loop, and start to prepare electroslag remelting N06625 nickel-based alloy welding consumables.