CN117385184A - VAR smelting method and smelting device for improving component uniformity of end part of ingot - Google Patents
VAR smelting method and smelting device for improving component uniformity of end part of ingot Download PDFInfo
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- CN117385184A CN117385184A CN202311451194.2A CN202311451194A CN117385184A CN 117385184 A CN117385184 A CN 117385184A CN 202311451194 A CN202311451194 A CN 202311451194A CN 117385184 A CN117385184 A CN 117385184A
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- 238000003723 Smelting Methods 0.000 title claims abstract description 118
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000001816 cooling Methods 0.000 claims abstract description 11
- 230000000087 stabilizing effect Effects 0.000 claims description 18
- 238000002844 melting Methods 0.000 claims description 13
- 230000008018 melting Effects 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 7
- 238000005520 cutting process Methods 0.000 claims description 3
- 239000007772 electrode material Substances 0.000 claims description 3
- 230000002349 favourable effect Effects 0.000 claims description 2
- 230000002708 enhancing effect Effects 0.000 claims 3
- 238000003756 stirring Methods 0.000 abstract description 22
- 230000000694 effects Effects 0.000 abstract description 9
- 238000000265 homogenisation Methods 0.000 abstract description 8
- 230000001737 promoting effect Effects 0.000 abstract description 2
- 238000010891 electric arc Methods 0.000 description 9
- 241001062472 Stokellia anisodon Species 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 6
- 239000002245 particle Substances 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000001788 irregular Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910001069 Ti alloy Inorganic materials 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 229910001257 Nb alloy Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000003708 edge detection Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- RJSRQTFBFAJJIL-UHFFFAOYSA-N niobium titanium Chemical compound [Ti].[Nb] RJSRQTFBFAJJIL-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/20—Arc remelting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1295—Refining, melting, remelting, working up of titanium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/003—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals by induction
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/04—Refining by applying a vacuum
Abstract
The invention provides a VAR smelting method for improving the uniformity of components at the end part of an ingot, which comprises the following steps: placing the bottom pad at the bottom of the crucible, and keeping the groove of the bottom pad downward; placing the consumable electrode in the crucible, and keeping the end of the electrode and the bottom pad out of contact; smelting; after the molten pool establishment stage is finished, maintaining the normal smelting stage and the feeding stage for smelting until the smelting is finished; the invention uses the concave bottom pad with the lower end, which not only promotes the current to flow to the side wall of the crucible instead of the crucible base in the stage of arc striking and establishing a molten pool, enhances the electromagnetic stirring effect and promotes the homogenization of the components of the molten pool, but also reduces the contact area between the bottom pad and the crucible base, thereby more effectively reducing the cooling intensity in the stage of arc striking and establishing the molten pool, increasing the depth of the molten pool, further promoting the homogenization of the components of the molten pool and leading the components of the bottom of the solidified cast ingot to be more uniform.
Description
Technical Field
The invention relates to the technical field of VAR smelting, in particular to a VAR smelting method and a VAR smelting device for improving uniformity of components at the end part of an ingot.
Background
VAR smelting: the method comprises the steps of vacuum consumable arc melting, welding a consumable electrode and an auxiliary electrode together, clamping the auxiliary electrode on an electrode rod, generating an electric arc between the auxiliary electrode and an arc starting material on a water-cooled copper crucible base in a vacuum or inert gas atmosphere, melting the consumable electrode by means of the heat of the electric arc, enabling the melted electrode to enter the crucible in a molten drop mode to form a molten pool, heating the surface of the molten pool by the electric arc, always forming a liquid state, and cooling the bottom and the periphery by the forced cooling of crucible cooling water to form a bottom-up crystallization process, continuously descending the electrode at a proper speed, and keeping continuous arc melting until the consumable electrode is melted and exhausted and melted.
Electromagnetic stirring: when VAR smelting, the electric arc is disturbed by surrounding air flow and magnetic field, the electric arc is distorted and deflected in different degree and uncontrollable, in order to make the electric arc controllable during operation of the electric arc furnace, an electromagnetic coil (arc stabilizing coil) wound outside a water-cooled crystallizer (copper crucible) of the electric arc furnace is utilized to establish a longitudinal magnetic field along the axial direction of an electrode to stabilize the electric arc, and simultaneously, stirring effect, namely electromagnetic stirring, is generated on a molten metal pool, and the electromagnetic stirring can make the molten metal components in the pool more uniform.
When the prior titanium alloy VAR is smelted, the problem of uneven components at the end part exists, and besides the reason of uneven mixing during the preparation of a consumable electrode, the problem is mainly caused by insufficient electromagnetic stirring of a molten pool forming the end part during smelting:
the VAR smelting process can be divided into three stages of arc striking and melting pool establishment, normal smelting and head feeding. In the stage of arc striking and establishing a molten pool (corresponding to the bottom of an ingot), the depth of the molten pool is smaller, namely the distance between the upper part of the molten pool and a crucible base is smaller, the resistance of a copper crucible is smaller, current in the molten pool flows not to the side wall of the crucible but to the bottom of the crucible, namely the current vertically passes through the molten pool along the direction of a magnetic field (as shown in figure 3), the arc stabilizing current is small, the magnetic field is weak, the generated Lorentz force is smaller, the electromagnetic stirring effect is smaller, the components of the molten pool are not easily homogenized, and in addition, the molten pool is shallower, the molten pool is less in the molten pool quantity, the cooling is strong, the molten pool is rapidly cooled and solidified, and the molten pool with uneven components is rapidly fixed, so that the components are unfavorable for homogenization. In the head feeding stage, the smelting power is reduced sharply, and the magnetic field stirring effect is required to be reduced to reduce the shrinkage cavity depth, so that the uniformity of the components of the head of the ingot is also poor. Therefore, the electromagnetic stirring in the arc striking and establishing molten pool stage (corresponding to the tail part of the ingot) and the head feeding stage (corresponding to the head part of the ingot) has poor homogenization effect on the molten pool, and even though the ingot is subjected to multiple smelting, the uniformity of the head and tail components of the ingot is still poor.
In the prior art, a method (CN 201910532447.6) for improving solidification structure of a large-size TC4 titanium alloy cast ingot is disclosed, wherein a bottom pad is used for reducing cooling strength of the bottom of the cast ingot; in addition to preventing damage to the crucible base, a method for producing a superconducting NbTiTa alloy ingot (CN 202310573088.5) in which a backing is used to prevent the electrode molten droplets from chilling on the backing by preheating the backing, resulting in the formation of inclusions of high melting point metals with a titanium niobium alloy ingot (CN 20221067328. X), is improved for a third smelting feed using a backing. In these techniques, it is described that the bottom pad is prevented at the bottom of the crucible, but in these techniques, the conventional design of the bottom pad is not sufficient to change or control the current direction, to guide the stirring of the molten pool in a plurality of directions, to enhance the electromagnetic stirring of the molten pool, and to promote homogenization of the components of the molten pool.
Disclosure of Invention
In view of the above drawbacks, the invention provides a VAR melting method for improving the uniformity of components at the end of an ingot, comprising the following steps:
preparing a bottom pad with a groove at one end, putting the bottom pad into the bottom of the crucible, and keeping the groove of the bottom pad downward;
placing the consumable electrode in a crucible, and performing arc-starting smelting after welding the consumable electrode;
initial stage of establishing a molten pool: setting initial smelting current of 3-8kA, voltage of 20-40V and arc stabilizing current of 3-15A, and establishing the end stage of a molten pool stage: smelting current is 6-40kA, voltage is 30-40V, and arc stabilizing current is 8-30A;
after the molten pool establishment stage is finished, the normal smelting stage and the feeding stage are switched to smelting until the smelting is finished.
A VAR melting apparatus for improving uniformity of end composition of an ingot, comprising: crucible and inside bottom pad that sets up, the inside consumable electrode that is used for preventing to treat smelting of crucible, consumable electrode and crucible insert smelting power respectively, the inside water-cooling jacket that sets up of crucible for cool off the inside molten pool of crucible, still set up solenoid in the crucible outside to make the inside magnetic field that produces vertical direction of crucible, the material of bottom pad is the same with consumable electrode material, and the below of bottom pad sets up the empty slot, so that bottom pad lower surface intermediate position and crucible bottom do not contact.
The invention uses the concave bottom pad with the lower end, which not only promotes the current to flow to the side wall of the crucible instead of the crucible base in the stage of arc striking and establishing a molten pool, enhances the electromagnetic stirring effect and promotes the homogenization of the components of the molten pool, but also reduces the contact area between the bottom pad and the crucible base, thereby more effectively reducing the cooling intensity in the stage of arc striking and establishing the molten pool, increasing the depth of the molten pool, further promoting the homogenization of the components of the molten pool and leading the components of the bottom of the solidified cast ingot to be more uniform.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention.
FIG. 2 is a schematic top view of the molten pool of FIG. 1.
Fig. 3 is a schematic structural diagram of the prior art.
FIG. 4 is a schematic diagram of an embodiment of the detection method.
In the figure: crucible 10, electrode 20, non-solidified melt pool 21, solidified ingot 22, bottom pad 30, groove 31.
Detailed Description
See fig. 1 and 2. A VAR smelting method for improving the uniformity of components at the end part of an ingot comprises the following steps:
placing the bottom pad 30 into the bottom of the crucible, keeping the bottom pad groove 31 downward;
placing a consumable electrode in a crucible 10, welding an electrode 20 and an auxiliary electrode, and then transmitting power for smelting;
initial stage of establishing a molten pool: setting initial smelting current of 3-8kA, voltage of 20-40V and arc stabilizing current of 3-15A, and establishing the end stage of a molten pool stage: smelting current is 6-40kA, voltage is 30-40V, and arc stabilizing current is 8-30A;
after the molten pool establishment stage is finished, the normal smelting stage and the feeding stage are switched to smelting (the smelting process is a conventional process) until the smelting is finished. The normal smelting stage and the molten pool stage are the same, the feeding stage smelting process is supplemented with specific process, conventional process or other patent technology.
Further, VAR smelting comprises at least two times of smelting, and the ingot is put into a furnace after being inverted from head to tail in the next smelting, so that smelting is sequentially performed according to a molten pool establishment, a normal smelting stage and a feeding stage until smelting is finished in the smelting of two ends of the ingot.
Further, the bottom pad is a cylinder, the outer circle size of the bottom pad is matched with the inner wall of the crucible of the smelting furnace, and the lower end of the bottom pad is provided with a concave groove which is concave inwards, so that the thickness of the edge position of the bottom pad is larger than that of the middle position.
As described in the background, fig. 3 shows that, at the beginning of smelting, since copper has a much lower resistivity than titanium, the current direction (which should be the negative charge moving direction, for ease of understanding, is identified by e, and the same applies below) passes vertically through the unset melt pool 21, the set ingot 22, the bottom of the crucible, and then back from the crucible side walls, forming a passageway. It can be seen that the current direction vertically passes through the molten pool, and the current direction is parallel to the magnetic field direction, so that the charged particles are not acted by Lorentz force, namely, the stirring effect on the molten pool is not realized, and only the radial current direction at the bottom of the crucible is acted by the Lorentz force, but the acting force cannot act on the charged particles in the molten pool, so that the stirring effect cannot be realized.
The invention uses the bottom pad with the 'concave' bottom end, the vacuum or inert gas atmosphere is arranged between the groove and the crucible base, no heat conduction medium is arranged in the groove, and only the edge is subjected to heat conduction, so that the current can actively avoid due to the larger resistance in the middle of the cushion block and move towards the edge direction, namely, the current flows towards the side wall of the crucible, and the current direction is offset towards the side wall of the crucible from the center of a molten pool, so that the liquid in the molten pool flows from the center of the circle to the edge, namely, the liquid is offset towards the X direction, and the current direction is offset in the X plane of the first direction. As shown in the direction of the current e in the figure, and as the magnetic field B exists in the vertical direction, the direction of the lorentz force is in the horizontal plane X and is perpendicular to the current direction, and as shown in fig. 1 and 2, under the action of the force F, the current direction of the charged particles is deviated along the direction of the F, and is deviated along the Z plane in the second direction, so that the current flows in the Z plane, a large amount of the flowing charged particles form stirring power, vortex stirring is formed in a molten pool, homogenization of the molten pool components is promoted, and the components at the end of an ingot are uniform. Therefore, according to the scheme, through the design of the bottom pad structure, charged particles are offset in at least two directions, so that the offset in the two directions of X, Z is formed, and then the upward, downward, front, rear, left and right omnibearing movement is formed in the molten pool, so that the purpose of uniform stirring is achieved.
Moreover, the design of the bottom pad lengthens the distance between the molten pool and the bottom of the crucible, raises the height of the molten pool, avoids the bottom of the molten pool from being rapidly cooled by a water cooling system at the bottom of the crucible, prolongs the liquid state maintaining time, and ensures the continuous stirring; the design of the middle groove of the bottom pad further lengthens the cooling time of the molten pool due to the fact that the inside is hollow and no heat transfer medium exists.
The invention also provides a VAR smelting device for improving the uniformity of components at the end part of an ingot, which comprises the following steps: the crucible and the inside bottom pad that sets up, the consumable electrode of waiting to smelt is placed to the crucible inside, and consumable electrode and crucible insert smelting power respectively, the inside water-cooling jacket that sets up of crucible for cool off the inside molten pool of crucible, still set up solenoid in the crucible outside, so that the inside magnetic field that produces of crucible vertical direction, the material of bottom pad is the same with consumable electrode material, and the below of bottom pad sets up the empty slot, so that bottom pad lower surface intermediate position and crucible bottom do not contact.
Further, the bottom pad is a cylinder, the outer circle size of the bottom pad is matched with the inner wall of the crucible, the bottom pad is placed inside the crucible, the lower end of the bottom pad is provided with a groove which is concave inwards, and therefore the thickness of the edge position of the bottom pad is larger than that of the middle position. Thereby making the resistance of the middle position of the base pad larger.
Further, the electrode to be smelted is the same in material of the base pad.
Further, the thickness of the bottom pad is not less than 30mm, the depth of the concave groove is not less than 10mm, the thickness of the thinnest part of the concave bottom pad is not less than 20mm, and the diameter of the bottom pad is 3-20mm smaller than the inner diameter of the crucible, so that the bottom pad is favorable for being smoothly placed into the bottom of the crucible.
Example 1: the embodiment provides a method for improving the uniformity of components at the bottom of a TA15 cast ingot in VAR smelting.
1) The TA15 cast ingot in the embodiment is a three-time smelting cast ingot, wherein the first smelting uses a crucible with the specification phi 650mm, the second smelting uses a crucible with the specification phi 720mm, and the third smelting uses a crucible with the specification phi 820mm.
2) In the embodiment, the first smelting adopts a conventional method of smelting niobium and titanium, and the concave-shaped bottom pad is not used.
3) In the embodiment, a concave bottom pad at the lower end is placed on a crucible base before secondary smelting, the bottom pad is prepared by a riser with TA15 phi 705mm, the thickness of the edge of the bottom pad is 95mm, a pit is irregular in the middle, and the thickness of the bottom pad at the deepest part of the pit is 85mm. The furnace chamber vacuum is 1.5Pa, the leakage rate is 0.6Pa/min, the power transmission smelting is started, the initial current is 5kA, the voltage is 28V, the arc stabilizing current is 6A/AC for 45s, the smelting current at the end stage of the molten pool stage is 12-25kA, the voltage is 30-36V, and the arc stabilizing current is 8-25A/AC for 15-40s. And after the molten pool establishment stage is finished, continuing to smelt in the normal smelting stage and the feeding stage until smelting is finished. Sawing and removing the bottom pad after secondary smelting and discharging, and using the flat head as an electrode for third smelting.
4) In the embodiment, a concave bottom pad at the lower end is placed on a crucible base before third smelting, the bottom pad is prepared by a riser with TA15 phi 800mm, the middle is provided with irregular pits, the edges are machined to be smooth, the thickness of the bottom pad is 130mm, and the thickness of the bottom pad at the deepest part of the pits is 100mm. The furnace chamber vacuum is 1Pa, the leakage rate is 0.2Pa/min, the power transmission smelting is started, the initial current is 6kA, the voltage is 28V, the arc stabilizing current is 8A/AC for 40s, the smelting current at the end stage of the molten pool stage is 15-30kA, the voltage is 30-38V, and the arc stabilizing current is 8-25A/AC for 15-30s. And after the molten pool establishment stage is finished, continuing to smelt in the normal smelting stage and the feeding stage until smelting is finished.
5) Flaw detection and cutting of shrinkage cavity of the head of the ingot, sawing and removing the bottom pad from a position 150mm away from the bottom of the ingot (containing the bottom pad), and sampling and detecting from 9 points of end faces of sawing positions of the head and the bottom of the ingot respectively, wherein the results are shown in the following table (mass percent).
The detection method adopted by the scheme is as follows: the end face of the ingot which was cut was trimmed to a smooth plane, 9 points were taken as in fig. 4, and the above data were obtained by inspection. 1. And 6, 5 and 9 are edge detection positions, 3 is a circle center position, and 2, 4, 7 and 8 are radius positions.
In this embodiment, the thickness of the bottom pad is 130mm, the thickness of the bottom pad after smelting is cut off is 150mm, the difference of components on the cross section is small, namely the components are uniform, especially for Cr element, because the specific gravity of the element is final, in the stage of establishing a molten pool, the molten pool is less, the fluidity is poor, the element has the worst fluidity, and after being melted and fallen from an electrode, the element falls into the molten pool and is easily concentrated in a certain position, when the original smelting process is adopted, electromagnetic stirring is not obvious, especially in the diameter range, the positions close to the edge, such as the positions of 1, 6, 5 and 9 points, have lower Cr content, and the positions of 2, 3, 4, 7 and 8 have higher Cr content, namely because the electromagnetic stirring effect in the original process is not obvious, especially the stirring in the X, Z plane cannot be formed, so that the components of Cr in the plane are not uniform. In the present invention, the Cr component is uniform especially in the X, Z plane by stirring in two directions, the head component deviation is (2.12-2.04)/2.12=0.03, and the head component deviation is (2.19-2.15)/2.19=0.018.
Example 2: the embodiment provides a method for improving the uniformity of components at the bottom of a VAR smelting TC1 ingot.
1) The TC1 cast ingot in the embodiment is a three-time smelting cast ingot, wherein the first smelting uses a crucible with the specification phi 440mm, the second smelting uses a crucible with the specification phi 530mm, and the third smelting uses a crucible with the specification phi 650mm.
2) In the embodiment, the first smelting and the third smelting adopt a conventional method, and the concave bottom cushion is not used.
3) In the embodiment, a concave bottom pad at the lower end is placed on a crucible base before secondary smelting, the bottom pad is prepared by a riser with the same brand of phi 615mm, the edge thickness is 60-65 mm, the middle is an irregular pit, and the maximum depth of the pit is 15mm.
4) The furnace chamber is subjected to vacuum 1Pa, leakage rate 0.5Pa/min, power transmission smelting is started, initial current is 4kA, voltage is 25V, arc stabilizing current is 6A/AC for 50s, argon is started to be filled into the furnace chamber until the furnace chamber pressure is 8000-13000Pa after power transmission, smelting current at the end of a smelting pool stage is 13-20kA, voltage is 32-42V, and arc stabilizing current is 8-20A/AC for 15-45s. And after the molten pool establishment stage is finished, continuing to smelt in the normal smelting stage and the feeding stage until smelting is finished.
5) After the bottom pad was removed by sawing from a position 85mm away from the bottom of the ingot, the end face 9 points at the sawing position of the ingot were sampled and examined, and the results are shown in the following table (mass percent).
| Element(s) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Al | 2.05 | 2.10 | 2.08 | 2.07 | 2.08 | 2.04 | 2.06 | 2.02 | 2.00 |
| Mn | 1.62 | 1.56 | 1.62 | 1.58 | 1.54 | 1.50 | 1.51 | 1.51 | 1.50 |
| Fe | 0.096 | 0.09 | 0.085 | 0.096 | 0.087 | 0.087 | 0.087 | 0.090 | 0.087 |
Example 3: the embodiment provides a method for improving the uniformity of components at the bottom of a VAR smelting Nb47Ti ingot.
1) The Nb47Ti ingot in the embodiment is a three-time smelting ingot, wherein the first smelting uses a crucible with the specification phi 365mm, the second smelting uses a crucible with the specification phi 440mm, and the third smelting uses a crucible with the specification phi 530mm.
2) In this example, the first smelting was performed by a conventional method without using a backing pad.
3) In the embodiment, a concave bottom pad at the lower end is placed on a crucible base before secondary smelting, the bottom pad has the same composition as an electrode to be smelted, the diameter of the bottom pad is 435mm, the thickness is 80mm, a pit with the diameter of 350mm is arranged in the middle, and the pit depth is 1-10mm. The furnace chamber vacuum is 1Pa, the leakage rate is 0.3Pa/min, the power transmission smelting is started, the initial current is 4kA, the voltage is 25V, the arc stabilizing current is 5A/AC for 30s, the smelting current at the end stage of the molten pool stage is 8-20kA, the voltage is 28-36V, and the arc stabilizing current is 6-20A/AC for 15-30s. And after the molten pool establishment stage is finished, continuing to smelt in the normal smelting stage and the feeding stage until smelting is finished. And after the secondary smelting is discharged from the furnace, removing molten knots at the positions of the bottom pad and the cast ingot joint, and using the flat head as an electrode for the third smelting.
4) In the embodiment, a concave bottom pad at the lower end is placed on a crucible base before third smelting, the bottom pad has the same composition as an electrode to be smelted, the diameter of the bottom pad is 525mm, the thickness of the bottom pad is 60mm, a pit with the middle phi of 400mm is formed, and the pit depth is less than or equal to 10mm. The furnace chamber vacuum is 1Pa, the leakage rate is 0.2Pa/min, the power transmission smelting is started, the initial current is 5kA, the voltage is 28V, the arc stabilizing current is 8A/AC for 40s, the smelting current at the end stage of the molten pool stage is 12-25kA, the voltage is 30-38V, and the arc stabilizing current is 8-25A/AC for 15-60s. And after the molten pool establishment stage is finished, continuing to smelt in the normal smelting stage and the feeding stage until smelting is finished.
5) Flaw detection and cutting of shrinkage cavity of the head of the ingot, sawing and removing of the bottom pad from a position 80mm away from the bottom of the ingot, sampling and detecting from 9 points of end faces of sawing positions of the head and the bottom of the ingot, and obtaining the results in the following table (mass percent).
| Position of | Element(s) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Head | Ti | 46.78 | 47.00 | 47.27 | 46.96 | 46.86 | 46.86 | 47.06 | 47.07 | 46.79 |
| Bottom | Ti | 47.53 | 47.35 | 47.31 | 47.33 | 47.44 | 47.49 | 47.28 | 47.31 | 47.49 |
The present invention is not limited to the above-described embodiments, and various changes can be made without departing from the spirit of the invention within the knowledge of one of ordinary skill in the art.
Claims (8)
1. A VAR smelting method for improving the uniformity of components at the end part of an ingot is characterized by comprising the following steps:
placing the bottom pad at the bottom of the crucible, and keeping the groove of the bottom pad downward;
placing the consumable electrode in the crucible, and keeping the end of the electrode and the bottom pad out of contact;
initial stage of establishing a molten pool: setting initial smelting current of 3-8kA, voltage of 20-40V and arc stabilizing current of 3-15A, and establishing the end stage of a molten pool stage: smelting current is 6-40kA, voltage is 30-40V, and arc stabilizing current is 8-30A;
after the molten pool establishment stage is finished, the normal smelting stage and the feeding stage are maintained for smelting until the smelting is finished.
2. The method for increasing the uniformity of end-of-ingot composition VAR melting of claim 1, wherein: the VAR smelting comprises at least two times of smelting, wherein the head and the tail of an ingot are inverted and then are put into a furnace when two adjacent times of smelting are performed, so that smelting is performed sequentially according to a molten pool establishment, a normal smelting stage and a feeding stage when two ends of the ingot are smelted until the smelting is finished.
3. The method for increasing the uniformity of end-of-ingot composition VAR melting of claim 1, wherein: the bottom pad is an end material formed by cutting off the end part of the cast ingot after smelting, and the end material is processed into a groove.
4. The method for increasing the uniformity of end-of-ingot composition VAR melting of claim 1, wherein: the bottom pad is a cylinder, the outer circle size of the bottom pad is matched with the inner wall of the crucible of the smelting furnace, and the lower end of the bottom pad is provided with a concave groove which is concave inwards, so that the thickness of the edge position of the bottom pad is larger than that of the middle position.
5. VAR smelting device for improving component uniformity of end part of cast ingot, which is characterized by comprising: crucible and inside bottom pad that sets up, the inside consumable electrode that is used for preventing to treat smelting of crucible, consumable electrode and crucible insert smelting current respectively, the inside water-cooling jacket that sets up of crucible for cool off the inside molten pool of crucible, still set up solenoid in the crucible outside to make the inside magnetic field that produces vertical direction of crucible, the material of bottom pad is the same with consumable electrode material, and the below of bottom pad sets up the empty slot, so that bottom pad lower surface intermediate position and crucible bottom do not contact.
6. The ingot end composition uniformity enhancing VAR melting method of claim 5, wherein: the bottom pad is a cylinder, the outer circle size of the bottom pad is matched with the inner wall of the crucible, the bottom pad is placed inside the crucible, the lower end of the bottom pad is provided with a concave groove which is concave inwards, and the thickness of the edge position of the bottom pad is larger than that of the middle position.
7. The ingot end composition uniformity enhancing VAR melting method of claim 5, wherein: the electrode to be smelted is made of the same material as the base pad.
8. The ingot end composition uniformity enhancing VAR melting method of claim 5, wherein: the thickness of the bottom pad is not less than 30mm, the depth of the concave groove is not more than 10mm, the thickness of the thinnest part of the bottom pad at the concave bottom is not less than 20mm, and the diameter of the bottom pad is 3-20mm smaller than the inner diameter of the crucible, so that the bottom pad is favorable for being smoothly placed into the bottom of the crucible.
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| CN202311451194.2A CN117385184A (en) | 2023-11-03 | 2023-11-03 | VAR smelting method and smelting device for improving component uniformity of end part of ingot |
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| CN202311451194.2A CN117385184A (en) | 2023-11-03 | 2023-11-03 | VAR smelting method and smelting device for improving component uniformity of end part of ingot |
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