Method of titanium-based alloys production

FIELD: metallurgy.

SUBSTANCE: production of titanium-based allot with content of boron of 0.002-0.008 wt % comprises smelting in vacuum arc skull furnace with consumable electrode without extra vacuum port for addition of modifying additives. Preform of modifier B4C wrapped in aluminium foil is fitted in consumable electrode bore drilled from alloyable end to distance defined by electrode fusing interval.

EFFECT: titanium-based alloy of equiaxed structure and grain size smaller than 15 mcm.

1 tbl, 1 ex

 

The technical field

The invention relates to the field of metallurgy, in particular to a method for producing alloys based on titanium, melting and casting are carried out in a vacuum arc skull furnaces not equipped with a separate vacuum port for the introduction of components of the alloy (mixture) during melting.

Known solutions and the purpose of the invention

Titanium alloys are used for details of responsible assignments in aircraft construction, shipbuilding, chemical engineering and other fields that require a combination of high mechanical properties (strength, ductility, fracture toughness and other) and corrosion resistance at a relative low weight [Ilyin A.A., Kolachev B.A., Polkin I.S. Titanium alloys. The composition, structure, properties. The Handbook. M: VILS-MATI, 2009, 520 S.]. Quality parts, largely determined by the quality of titanium casting (ingot or shaped casting, which, in turn, depends on the method of producing the alloy.

Known methods for producing titanium alloy by vacuum arc remelting electrode made of titanium sponge, pressed into him alloying elements, the method of producing an alloy by plasma melting of the mixture supplied to the combustion zone of the plasma, electron beam melting [Neustroev A.A., Chodorowski "Vacuum skull furnace", M "metallurgy", 1967].

These methods of obtaining ingots do not provide for the modification of alloys.

Closest to the proposed method is a method of obtaining alloys based on titanium-aluminum (U.S. Pat. US5311655 from 17.05.1994). This method involves melting the charge materials (pieces) in the crucible by heating due to the rotating electrode or plasma or electron beam. Is arc remelting (preferably vacuum-arc remelting) after melting of the source material.

This method allows you to get in the ingot grain size of about 100 microns, however, these ingots are used only as consumables when the shaped casting in arc skull furnaces. Obtaining a specific structure of the ingot is not necessary. The process of manufacturing ingots with a certain grain structure is produced in a special oven.

The aim of the invention is to provide a method of producing alloys based on titanium, which allows to obtain a grain size less than 15 microns and equiaxial structure in the molded castings and ingots.

The goal has been achieved by the fact that the method of introduction into the melt alloying component modifier when performing melting reactive alloys in vacuum arc skull furnaces with consumable the electrode during arc without an additional vacuum port for the introduction of additives, characterized in that on the basis of the estimated data on weight melt parameters, velocity fusion of the alloy, the program operating the heat is preparing and laying in the body of a consumable electrode prior to welding at a certain distance from fusion-bonded butt hanging alloying component modifier, which leads to melting it in a certain moment of melting and uniform distribution in the melt.

The invention

The basis purpose of the invention is to develop a method of introduction into the melt when burning arc in a certain time melting a precisely calculated amount of material mixture (alloy component, a modifier).

To achieve this objective, the following tasks were solved.

1. To determine the input method

2. To determine the type of packaging additives.

3. To determine the weight supplements

4. To make the calculation scheme of melting components and additives.

5. To determine the place of installation Supplement.

6. To calculate the time of entry.

An example of executing

For experimental validation of the proposed invention was implemented 4 options for obtaining modified titanium alloy, which are listed in table 1.

The composition of the alloy, wt.%
Became the dominant elements Impurity, not more than
TiAlBCFeSiONHOther
Base4,7000,160,300,190,210,050,010,3
Base4,710,0020,170,290,200,210,050,010,3
Base4,690,0080,190,300,180,200,050,010,3
Base 4,700,0100,190,290,190,210,050,010,3

Casting of shaped castings with wall thickness from 10 to 100 mm in order to obtain a fine grain structure and uniform (isotropic) mechanical properties of all sections and areas of the casting.

As boron modifying material on the empirical data of the selected micro-powder of boron carbide (B4C) 4-25 microns.

As the melting unit selected vacuum arc skull install NIAT D designed for melting and casting of refractory and reactive alloys by fusion of the electrode prepared in the chemical composition, the collection of the melt in the crucible and drain into the mold. During melting the electrode has a negative electric charge, and the skull crucible is positive. Current 12-17 kA, voltage 34-40 B, DC.

Crucible capacity 120 kg on Titan. Electrode diameter 280 mm Electric power Luga 650 kW. The vacuum in the chamber of 1.33×10-2-5×10-3mm Hg From practical data manual installation of the program holding the bottoms depending on the amperage when rent is nom voltage and type of charge (amount of waste used as lining in the crucible, one of the conditions of skull melting). According to the program of melting required time of operating the heat depending on the total weight of the weld metal. The modifying effect is achieved by the introduction of the modifier for 1.5-2 minutes to drain metal in the mold.

Operations according to the task.

1. Input method - tab hanging modifier in consumable electrode.

2. Packaging foil of alloy AD according to GOST 12592-67.

3. Weight modifier 0,002-0,008% of the total weight of the heat.

4. The scheme of calculating the weight melting and modifier.

G kg drain G kg waste=G kg electrode

Tbottomsmin-(1,5-2) min=T1the time of melting of the electrode to the installation location of the bookmark.

Tbottomsfrom the program of melting, to determine the length of the electrode, made at time T1,

to do this:

- determine the weight of 1 cm electrode length

3.14×282×4,5=P PV=280 mm (for the installation),

the proportion of alloy - 4.5 g/cm

the amount of metal, fusion-bonded at time T1

Rconstx T1=G*kg

where Rconst is a value determined empirically for a given installation, thus, G*/Rconst=Hcmwhere Hcm- the distance from the fusion-bonded to the end face of the electrode to bookmark hanging modifier.

5. Note the resulting size of the electrode. Produced sverlov the electrode has a drill with a diameter of 20 mm at a depth equal to half the diameter of the electrode. In the resulting hole lay out a portion of the modifier, wrapped in aluminum foil. On the electrode running drill for the following heats and sent electrode for welding.

As a result of experiments shows that when the content of boron 0,002-0,008% identified fine-grained structure in different thicknesses casting (with a grain size of 10-15 μm) and with maintaining the strength characteristics, as a result, the ductility of the alloy uvelichivaya up to 30%. When the boron content of more than 0,008% high probability of its location mainly at the grain boundaries, which reduces the mechanical properties.

The method of producing an alloy based on titanium with boron 0,002-0,008 wt.%, including melting in vacuum arc skull furnaces with consumable electrode without an additional vacuum port for the introduction of modifying additives, characterized in that a portion of the modifier B4C, wrapped in aluminum foil, placed into the hole of a consumable electrode, which drill from fusion-bonded to the end face of the electrode at a distance determined depending on the time of its melting.



 

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