WO2021135223A1

WO2021135223A1 - Crystallizer for metal electroslag remelting, electroslag remelting device and electroslag remelting method

Info

Publication number: WO2021135223A1
Application number: PCT/CN2020/107065
Authority: WO
Inventors: 吕广奇
Original assignee: 浙江正达模具有限公司
Priority date: 2019-12-31
Filing date: 2020-08-05
Publication date: 2021-07-08
Also published as: CN111118302B; CN111118302A

Abstract

A crystallizer for metal electroslag remelting, an electroslag remelting device and an electroslag remelting method, belonging to the technical field of metal smelting and solving the problem that large electroslag ingots cannot be produced at present. The crystallizer (5) for metal electroslag remelting comprises an upper crystallization chamber (7), a middle crystallization chamber (8), and a lower crystallization chamber (9) which are sequentially stacked from top to bottom; the upper crystallization chamber (7), the middle crystallization chamber (8), and the lower crystallization chamber (9) are each provided with an upper smelting cavity (71), a middle smelting cavity (81), and a lower smelting cavity (91) which vertically penetrate through the corresponding crystallization chamber separately; the middle smelting cavity (81) is in an inverted cone shape, the largest end of the middle smelting cavity (81) is in butt joint with the upper smelting cavity (71), and the smallest end of the middle smelting cavity (81) is in butt joint with the lower smelting cavity (91). Solidified electroslag ingots are extracted from the crystallizer, the stability of the whole electroslag process is not affected, the high-temperature electroslag ingots are directly subjected to water cooling, and the cooling speed is increased. Due to the special crystallizer structure, it can be guaranteed that when the electroslag ingots are subjected to water cooling, the temperature field of molten slags in a high-temperature molten pool is influenced by generated large cooling, and thus electroslag remelting can be smoothly carried out.

Description

Crystallizer for metal electroslag remelting, electroslag remelting device and electroslag remelting method

Technical field

The invention belongs to the technical field of metal smelting, and relates to a crystallizer for metal electroslag remelting, an electroslag remelting device and an electroslag remelting method.

Background technique

High-speed steel is a high-alloy tool steel containing carbon (C), tungsten (W), molybdenum (Mo), chromium (Cr), vanadium (V), cobalt (Co) and other elements. After heat treatment, it has high heat resistance and toughness. , When the use temperature is as high as 600 ℃, there is no obvious decrease in hardness. High-speed steel can be divided into ordinary high-speed steel and high-performance high-speed steel according to the chemical composition. According to the manufacturing process, it is divided into smelting high-speed steel and powder metallurgy high-speed steel. The main production processes of smelting high-speed steel are electric arc furnace smelting, electroslag remelting, forging, and rolling.制等。 System and so on. Powder metallurgy high-speed steel has not been produced in China due to its high technical difficulty.

The main application areas of high-speed steel are machinery and tool manufacturing. It is mainly used to manufacture various cutting tools, such as turning tools, drills, hobs, machine saw blades and demanding molds. In recent years, high-speed CNC machine tools have been commonly used in machining. They have good thermal toughness, wear resistance, and impact toughness. High-speed steel bears great pressure and grinding during work. Traditional high-speed steel, it The advantage is that the thermal strength is good, but the disadvantage is that the toughness is not enough and easy to crack, the thermal conductivity is poor, and the plasticity and thermal fatigue performance are not ideal, especially for large specifications (

The above) high-speed steel has poor carbide unevenness, which has seriously affected its own performance. Therefore, most of the domestic tool manufacturers (M35) large-size high-speed steel have used imported materials.

After analyzing and comparing large-scale high-speed steel products at home and abroad, it is found that: foreign high-speed steel

The carbide unevenness of round steel is (3-4) grade, domestic

The carbide unevenness of round steel is (5-6) grade, and other indicators are basically equivalent. The decisive factor of carbide unevenness is the forging ratio, which is generally between 20-30 in foreign countries and around 15 in China. The forging ratio is determined by the size of the electroslag ingot. The fundamental reason why domestic manufacturers do not adopt a large forging ratio is the limitation of the electroslag remelting process. To

Take the round steel as an example. According to 20 forging ratios, the diameter of the electroslag ingot must be

the above. But domestically produced

The above high-speed steel electroslag ingots have a coarse as-cast structure due to the slow cooling rate. Therefore, the domestic production experience is that the use of large ingots and large forging ratios is not as good as the use of medium ingots and large round steels with medium forging ratio. The fundamental reason for the coarse as-cast structure of large-size electroslag ingots is that the ingot is too large and the cooling is slow. Therefore, in order to produce high-performance large-size high-speed steel, it is necessary to start with solving the electroslag remelting process and equipment.

Summary of the invention

The first object of the present invention is to solve the above-mentioned problems of the existing electroslag remelting, and propose a metal electroslag remelting mold capable of producing large-sized electroslag ingots.

The first objective of the present invention can be achieved through the following technical solutions:

A crystallizer for metal electroslag remelting, comprising an upper crystallization chamber, a middle crystallization chamber, and a lower crystallization chamber superimposed from top to bottom. The three types of crystallization chambers have an upper smelting cavity, a middle smelting cavity and a lower smelting cavity through which the upper and lower ends are penetrated. The middle smelting cavity is in an inverted cone shape, the largest end of the middle smelting is butted with the upper smelting cavity, and the smallest end of the middle smelting is butted with the lower smelting cavity.

In the above-mentioned crystallizer for metal electroslag remelting, the crystallizer further includes a rapid cooling device, and the rapid cooling device includes a sprayer arranged one above the other in multiple layers, and the sprayer includes a spray pipe And multiple spray heads arranged on the corresponding spray pipe at intervals, and multiple spray heads in the same sprayer are arranged around.

In the above-mentioned crystallizer for metal electroslag remelting, the spraying direction of the nozzles are all inclined inwards and downwards, the spraying inclination angle of the nozzles in the upper sprayer is the largest, and the spraying inclination angle of the nozzles in the bottom sprayer is the smallest . In the above-mentioned crystallizer for metal electroslag remelting, the upper crystallizing chamber, the middle crystallizing chamber, and the lower crystallizing chamber all include the inner wall of the crystallizer and the outer wall of the crystallizer. The inner wall of the crystallizer encloses the respective corresponding crystallizing chambers. A closed interstitial space is formed between the inner wall and the corresponding outer wall of the crystallizer. The upper crystallization chamber, the middle crystallization chamber and the lower crystallization chamber are respectively provided with water outlet pipes and water outlets communicating with the corresponding interstitial spaces on the upper and lower parts of the corresponding interstitial spaces. Inlet pipe.

The second purpose of the present invention is to solve the above-mentioned problems of the existing electroslag remelting, and propose an electroslag remelting device capable of producing large-size electroslag ingots.

The second objective of the present invention can be achieved through the following technical solutions:

An electroslag remelting device, comprising an upper column, an upper lifting arm, an upper lifting drive device, a chuck, a crystallizer, a bottom water tank, a lower column, a lower lifting drive device and a lower lifting arm. The bottom water tank is fixedly connected with the lower lifting arm And it is directly opposite to the lower exit of the crystallizer. The lower lifting drive device drives the bottom water tank and the lower lifting arm to lift up and down along the lower column. The chuck is fixedly connected with the upper lifting arm and is directly opposite to the upper inlet of the crystallizer. The device drives the upper lifting arm and the chuck to move up and down along the upper column. The crystallizer includes an upper crystallization chamber, a middle crystallization chamber and a lower crystallization chamber superimposed from top to bottom, the upper crystallization chamber, the middle crystallization chamber and the lower crystallization chamber. It has an upper melting chamber, a middle melting chamber, and a lower melting chamber penetrating through the upper and lower ends. The middle melting chamber has an inverted cone shape, the largest end of the middle melting is butted with the upper melting chamber, and the smallest end of the middle melting is connected to the lower melting chamber. Docking.

In the above-mentioned electroslag remelting device, the crystallizer further includes a rapid cooling device, and the rapid cooling device includes a sprayer arranged one above the other in multiple layers, and the sprayer includes a spray pipe and a spacer. Multiple spray heads arranged on the corresponding spray pipe, and multiple spray heads in the same sprayer are arranged around.

In the above-mentioned electroslag remelting device, the spraying direction of the nozzles are all inclined inwards and downwards, the spraying inclination angle of the spraying heads in the upper sprayer is the largest, and the spraying inclination angle of the spraying nozzles in the bottom spraying device is the smallest.

In the above-mentioned electroslag remelting device, the upper crystallization chamber, the middle crystallization chamber and the lower crystallization chamber all include the inner wall of the crystallizer and the outer wall of the crystallizer. The inner wall of the crystallizer encloses the respective corresponding crystallization chambers, the inner wall of the crystallizer and the inner wall of the crystallizer. A closed interstitial space is formed between the outer walls of the corresponding crystallizer. The upper crystallization chamber, the middle crystallization chamber and the lower crystallization chamber are respectively provided with outlet pipes and water inlet pipes communicating with the corresponding interstitial spaces on the upper and lower portions of the corresponding gap spaces. .

The third objective of the present invention is to solve the above-mentioned problems of the existing electroslag remelting, and propose a metal electroslag remelting method capable of producing large-size electroslag ingots.

The third objective of the present invention can be achieved by the following technical solutions:

A metal electroslag remelting method, which is performed by using the above crystallizer and electroslag remelting device, is characterized in that the method includes the following steps:

1: Anneal the electrode rod to eliminate part of the stress (heat preservation temperature 830℃, time 5-7h, furnace installation method: no requirement).

2: Sanding the electrode rod to ensure that the surface of the electrode rod is basically whitened, and to remove the oxidation and crack defects on the electrode rod surface.

3: Weld the electrode rod and the dummy electrode:

Cleaning the electrode rod before welding: clean the contact surface of the electrode rod with the dummy electrode to a plane to ensure the conductivity of the electrode rod

Welding method & position: Ensure that the dummy electrode and the electrode rod are in a straight line.

4: Choose a reasonable metal electroslag ratio (through the quaternary slag system ratio, the slag material can meet the requirements of moderate conductivity γ, high boiling point, low melting point, good chemical stability, low viscosity and specific surface tension σ).

5: Drying slag (requirement: the composition of the slag material meets the requirements, is pure and free of impurities, and the particle size is appropriate)

Equipment: Box-type resistance furnace

Process: Baking temperature 550℃, time: 24h.

6: Slagging (current: 600A, the amount of slag in each slagging furnace: determined by the amount)

7: Clamping of the electrode rod: it must be clamped upright. When clamping, the contact surface of the electrode rod and the fixture should be polished clean, and the connecting bolts of the conductive part of the electrode rod and the fixture should be detected to ensure that there is no looseness or poor contact.

8: Prepare the crystallizer, rapid cooling device, starter plate and bottom water tank: install the rapid cooling device under the crystallizer, ensure that the panel of the bottom water tank is level, coat the bolts fixing the starter plate with conductive paste, and screw it into the bottom water tank Inside the threaded hole.

9: Raise the bottom water tank to the center of the crystallizer, and add asbestos rope to seal the edge of the bottom water tank.

10: Lower the electrode rod to a reasonable height in the center of the crystallizer, and put in the metal electroslag. The amount of slag is determined according to the size of the electrode rod, and the rapid cooling device is turned on.

11: Turn on the current to increase the metal electroslag temperature. After the metal electroslag temperature rises to a reasonable temperature, start the metal electroslag smelting.

12: Fast cooling ingot extraction: Control the height of the metal electroslag liquid level on the inner wall of the mold by adjusting the smelting current, voltage and ingot extraction speed to ensure that there is a reasonable ratio between the ingot extraction speed and the melting speed to prevent metal electroslag from appearing Liquid overflow from the top of the crystallizer, difficulty in ingot extraction, or leakage of metal electroslag liquid; control the cooling rate of remelted electroslag ingots by controlling the water pressure of the rapid cooling device to prevent insufficient cooling rate of electroslag ingots during the smelting process or Cracking due to too fast cooling rate.

13: After the smelting is completed, cut off the electricity and water, remove the electroslag ingot and put it into a box-type resistance furnace for heat preservation to prevent the electroslag ingot from cracking during the subsequent cooling process.

14: Annealing: complete annealing, reduce stress, adjust hardness

15: Sanding to remove the oxide scale on the surface of the electroslag ingot

Forging: Electroslag ingots are forged and processed into various forgings.

Rolling: The forged billet is then hot-rolled or cold-rolled to obtain rolled products of various specifications.

Compared with the prior art, the present invention extracts the solidified electroslag ingot from the crystallizer without affecting the stability of the entire electroslag process, and directly water-cools the high temperature electroslag ingot to increase the cooling rate. The special crystallizer structure can ensure that the large drop in temperature generated when the electroslag ingot is water-cooled will not affect the temperature field of the slag in the high-temperature molten pool, so that the electroslag remelting can proceed smoothly.

Description of the drawings

Figure 1 is a schematic diagram of the structure of an electroslag remelting device.

Figure 2 is a schematic diagram of the structure of a mold for metal electroslag remelting.

In the figure, 1. Upper column; 2. Upper lifting arm; 3. Lower column; 4. Chuck; 5. Crystallizer; 6. Bottom water tank; 7. Upper crystallization chamber; 8. Middle crystallization chamber; 9. Lower crystallization Chamber; 71, upper melting chamber 71; 72, inner wall of crystallizer; 73, outer wall of crystallizer; 81, middle melting chamber; 91, lower melting chamber; 12, electrode rod; 13, lower lifting arm; 14, rapid cooling device; 15. Upper lift drive device; 16. Lower lift drive device; 17. Water inlet pipe; 18. Water outlet pipe; 21 spray pipe; 22 sprayer; 23 spray head.

Detailed ways

The following are specific embodiments of the present invention combined with the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

As shown in Figure 1, the electroslag remelting device includes an upper column 1, an upper lifting arm 2, an upper lifting drive device, a chuck 4, a crystallizer 5, a bottom water tank 6, a lower column 3, a lower lifting drive device 16 and The lower lifting arm 13, the bottom water tank 6 and the lower lifting arm 13 are fixedly connected with the lower end outlet of the crystallizer 5 up and down. The lower lifting drive device 16 drives the bottom water tank 6 and the lower lifting arm 13 to lift up and down along the lower column 3, and the chuck 4 is fixedly connected to the upper lifting arm 2 and directly opposite to the upper entrance of the crystallizer 5 up and down. The upper lifting driving device 15 drives the upper lifting arm 2 and the chuck 4 to move up and down along the upper column 1.

As shown in Fig. 2, the crystallizer 5 includes an upper crystallization chamber 7, a middle crystallization chamber 8 and a lower crystallization chamber 9 superimposed from top to bottom. The upper crystallization chamber 7, the middle crystallization chamber 8 and the lower crystallization chamber 9 have upper and lower ends running through The upper smelting cavity 71, the middle smelting cavity 81 and the lower smelting cavity 91, the middle smelting cavity 81 has an inverted cone shape, the largest end of the middle smelting cavity 81 is butted with the upper smelting cavity 71, and the smallest end of the middle smelting cavity 81 is connected to the lower smelting cavity 91 docking.

The crystallizer 5 also includes a rapid cooling device 14 that includes a sprayer 22 arranged one above the other in multiple layers. The sprayer 22 includes a spray pipe 21 and a spray pipe 21 arranged at intervals on the corresponding spray pipe 21. A plurality of spray heads 23, and a plurality of spray heads 23 in the same shower 22 are arranged around.

The spraying directions of the spray heads 23 are all inclined inward and downward. The spray head 23 in the upper sprayer 22 has the largest spray inclination angle, and the spray head 23 in the bottom sprayer 22 has the smallest spray inclination angle. The lower the shower 22 is, the flatter the spray tilt angle of the corresponding spray head 23 is.

The upper crystallization chamber 7, the middle crystallization chamber 8 and the lower crystallization chamber 9 all include the inner wall 72 of the crystallizer and the outer wall 73 of the crystallizer. The inner wall 72 of the crystallizer encloses the corresponding crystallizing chamber, and the inner wall of the crystallizer 72 and the corresponding outer wall of the crystallizer 73 A closed interstitial space is formed. The upper crystallization chamber 7, the middle crystallization chamber 8 and the lower crystallization chamber 9 are respectively provided with a water outlet pipe 17 and a water inlet pipe 18 at the upper and lower portions of the respective corresponding gap spaces.

A metal electroslag remelting method: using the above electroslag remelting device, the method includes the following steps:

3: Weld the electrode rod and the dummy electrode:

4: Choose a reasonable metal electroslag ratio (through the quaternary slag system ratio, the slag material can meet the requirements of moderate conductivity γ, high boiling point, low melting point, good chemical stability, low viscosity and specific surface tension σ). Through the compound addition of rare earths (rare earth ratio: 40% yttrium heavy rare earth + 20% cerium light rare earth + 40% calcium particles), the cracking sensitivity of the material is improved;

Equipment: Box-type resistance furnace

Process: Baking temperature 550℃, time: 24h.

14: Annealing: complete annealing, reduce stress, adjust hardness

15: Sanding to remove the oxide scale on the surface of the electroslag ingot

Forging: Electroslag ingots are forged and processed into various forgings.

The cooling method of electroslag remelting in this process is direct water cooling outside the crystallizer. The metal electroslag liquid is quickly cooled from high temperature to low temperature to obtain electroslag ingots with fine carbide structure. Ordinary electroslag remelting is passed through the crystallizer. The copper wall is indirectly water-cooled, and the cooling rate is slow. The carbides accumulate and grow during the slow cooling process. The uniqueness of our process is that it can not only realize the rapid cooling of the metal electroslag remelting, but also avoid the easy production in this process. Of cracking defects.

It should be understood that in the claims and specification of the present invention, all "including..." should be understood as an open-ended meaning, that is, its meaning is equivalent to "containing at least...", and should not be understood as a closed-ended meaning. Meaning, that is, its meaning should not be understood as "only containing...".

The specific embodiments described herein are merely examples to illustrate the spirit of the present invention. Those skilled in the technical field of the present invention can make various modifications or additions to the specific embodiments described or use similar alternatives, but they will not deviate from the spirit of the present invention or exceed the definition of the appended claims. Range.

Claims

A crystallizer for metal electroslag remelting, which is characterized in that it comprises an upper crystallization chamber, a middle crystallization chamber and a lower crystallization chamber superimposed from top to bottom. The upper crystallization chamber, the middle crystallization chamber and the lower crystallization chamber have upper and lower crystallization chambers. The upper smelting cavity, the middle smelting cavity and the lower smelting cavity penetrate through the ends, the middle smelting cavity is in an inverted cone shape, the largest end of the middle smelting is butted with the upper smelting cavity, and the smallest end of the middle smelting is butted with the lower smelting cavity.
The crystallizer for metal electroslag remelting according to claim 1, characterized in that the crystallizer further comprises a rapid cooling device, and the rapid cooling device comprises a multi-layer sprayer arranged one above the other. The sprinkler includes a sprinkler pipe and a plurality of sprinklers arranged on the corresponding sprinkler pipe at intervals, and the plurality of sprinklers in the same sprinkler are arranged around.
The mold for metal electroslag remelting according to claim 2, characterized in that the spray direction of the nozzles are all inclined inward and downward, the spray nozzle of the upper sprayer has the largest spray inclination angle, and the spray nozzle of the bottom spray The jet tilt angle of the nozzle in the device is the smallest.
The crystallizer for metal electroslag remelting according to claim 1, wherein the upper crystallizing chamber, the middle crystallizing chamber and the lower crystallizing chamber all comprise an inner wall of the crystallizer and an outer wall of the crystallizer, and the inner wall of the crystallizer surrounds The respective corresponding crystallization chambers form a closed interstitial space between the inner wall of the mold and the corresponding outer wall of the mold. The upper, middle, and lower crystallization chambers are connected to the upper and lower parts of the corresponding interstitial spaces. The outlet pipe and the inlet pipe of the corresponding clearance space.
An electroslag remelting device, comprising an upper column, an upper lifting arm, an upper lifting drive device, a chuck, a crystallizer, a bottom water tank, a lower column, a lower lifting drive device and a lower lifting arm. The bottom water tank is fixedly connected with the lower lifting arm And it is directly opposite to the lower exit of the crystallizer. The lower lifting drive device drives the bottom water tank and the lower lifting arm to lift up and down along the lower column. The chuck is fixedly connected with the upper lifting arm and is directly opposite to the upper inlet of the crystallizer. The device drives the upper lifting arm and the chuck to move up and down along the upper column, and is characterized in that the crystallizer includes an upper crystallization chamber, a middle crystallization chamber, and a lower crystallization chamber that are sequentially superimposed from top to bottom, the upper crystallization chamber and the middle crystallization chamber The upper and lower crystallization chambers have an upper melting chamber, a middle melting chamber and a lower melting chamber through which the upper and lower ends are penetrated. The middle melting chamber is in an inverted cone shape, the largest end of the middle melting is butted with the upper melting chamber, and the smallest end of the middle melting Docking with the lower melting chamber.
An electroslag remelting device according to claim 5, wherein the crystallizer further comprises a rapid cooling device, and the rapid cooling device comprises a sprayer arranged one above the other in multiple layers, and the spray The sprayer includes a spray pipe and a plurality of spray heads arranged on the corresponding spray pipe at intervals, and the multiple spray heads in the same sprayer are arranged around.
The electroslag remelting device according to claim 6, wherein the spray direction of the nozzles are all inclined inward and downward, the spray nozzles in the upper sprayer have the largest spray inclination angle, and the spray nozzles in the bottom sprayer have the largest spray inclination angle. The jet tilt angle is the smallest.
The electroslag remelting device according to claim 5, wherein the upper crystallization chamber, the middle crystallization chamber and the lower crystallization chamber all comprise an inner wall of the crystallizer and an outer wall of the crystallizer, and the inner wall of the crystallizer is surrounded by respective corresponding In the crystallization chamber, a closed interstitial space is formed between the inner wall of the mold and the corresponding outer wall of the mold. The upper, middle and lower crystallization chambers are respectively provided with corresponding gaps on the upper and lower parts of the corresponding gap spaces. Outlet and inlet pipes of the space.
A metal electroslag remelting method, which is performed by using the above crystallizer and electroslag remelting device, is characterized in that the method includes the following steps:

(1): Anneal the electrode rod;

(2): Sanding the electrode rod;

(3): Weld the electrode rod and the dummy electrode:

(4): Choose a suitable metal electroslag ratio;

(5): Baking residue;

(6): Slagging;

(7): Clamping of electrode rods;

(8): Prepare the crystallizer, rapid cooling device, starter plate and bottom water tank: install the rapid cooling device under the crystallizer, ensure the level of the bottom water tank panel, coat the bolts that fix the starter plate with conductive paste, and screw in In the threaded hole of the bottom tank;

(9): Raise the bottom water tank to the center of the crystallizer, and add asbestos rope to seal the edge of the bottom water tank;

(10): Lower the electrode rod to the center of the crystallizer, put in the metal electroslag, and turn on the rapid cooling device at the same time;

(11): Turn on the current to start the smelting of metal electroslag;

(12): Quick-cooling ingot extraction: by controlling the water pressure of the rapid cooling device, the cooling rate of the remelted electroslag ingot is controlled to prevent the electroslag ingot from being insufficiently cooled during the smelting process or cracking due to too fast cooling;

(13): After the smelting is completed, cut off the electricity and water, unload the electroslag ingot and put it into a box-type resistance furnace for heat preservation to prevent the electroslag ingot from cracking during the subsequent cooling process.

(14): Annealing:

(15): Sanding to remove the oxide scale on the surface of the electroslag ingot.