RU2302476C2 - Method of production of zirconium-based alloys - Google Patents

Abstract

FIELD: metallurgy; industrial production of high-quality zirconium-based alloys used in atomic industry.

SUBSTANCE: proposed method includes screening the briquettes made from mixture of zirconium-based material and alloying elements; making the billets from briquettes, molding the consumable electrodes from billets, iodide bars and zirconium wire and melting the ingot by repeated vacuum arc remelting; part of billet corresponding to bottom part of ingot of first remelting process and/or gating part of ingot of final remelting process is formed from depleted briquettes into which alloying elements are introduced in the following amount: C=K₁xC_r, where K₁ is coefficient taking into account the tendency of alloying element to liquation K₁=0.5-1.0, C_r is rated content of alloying element in alloy; total mass of depleted briquettes M=K₁xD, where K₂ is coefficient taking into account the mass of molten metal at the initial moment of melt depending on length of ingot K₂=0.04-0.12 kg/mm, D is diameter of final melt ingot, mm.

EFFECT: improved quality of alloys due to enhanced chemical homogeneity of ingot.

6 cl, 1 tbl, 1 ex

Description

The invention relates to the field of metallurgy, and in particular to methods for producing zirconium-based alloys, and can be used to obtain zirconium-based alloys that are homogeneous in chemical composition by vacuum arc remelting (VDP).

A known method of producing alloys based on zirconium, which includes pressing from a mixture of zirconium powder, alloying elements and pieces of iodide zirconium hollow briquettes, into the holes of which are inserted rods of reverse metal, sintering the prefabricated in this way vacuum blanks. From the obtained blanks, iodide rods and zirconium wire, a consumable electrode is formed and the ingot is melted by multiple vacuum - arc remelting (Shikov A.K., Nikulin A.D., Nikulina A.V., Arzhakova V.M., Bezumov V.N. , Rozhdestvensky VV, Lositsky AF, Shtutsa MG, Kuzmenko NV The development perspective and current state of production of zirconium, its alloys and products from them / Physics and Chemistry of Materials Processing, No. 1, 2003) .

The disadvantage of this method is the significant heterogeneity in the chemical composition in the gating part of the ingot of the second remelting associated with the advanced melting of the powder base of the alloy and, as a consequence, the enrichment of the bottom of the ingot of the first remelting in terms of the content of alloying components.

The problem to which the invention is directed is to improve the quality of the resulting alloys by increasing the chemical uniformity of the ingot.

The technical result is achieved by the fact that in the proposed method for producing zirconium-based alloys, comprising pressing briquettes from a mixture of zirconium-containing material and alloying elements, making a workpiece from briquettes, forming a consumable electrode from the workpiece, iodide rods and zirconium wire and smelting the ingot with multiple vacuum-arc , in the manufacture of the billet, the part that corresponds to the bottom of the ingot of the first remelting and / or the gating part of the ingot of the final remelting are made up of depleted briquettes into which each of the alloying elements is introduced in an amount of:

C = K ₁ × C _p ,

where K ₁ - coefficient taking into account the tendency of the alloying element to segregation, K ₁ = 0.5-1.0;

With _p - the estimated content of the alloying element in the alloy, and the total mass of depleted briquettes is:

M = K ₂ × D,

where K ₂ - coefficient taking into account the mass of liquid metal at the initial moment of melting, depending on the length of the deposited ingot,

K ₂ = 0.04 ÷ 0.12 kg / mm;

D is the diameter of the ingot of the final remelting, mm

In a particular embodiment of the method, a mixture of zirconium-containing material and alloying elements is prepared by portion weighing, and then by averaging.

As the zirconium-containing material, metal zirconium powder and / or ground zirconium sponge, pieces of iodide zirconium and reverse zirconium in the form of chips can be used.

As the zirconium-containing material, metal zirconium powder and / or a zirconium sponge, pieces of zirconium iodide can be used, and the briquettes are pressed with central holes into which a reverse zirconium rod is inserted into the workpiece.

In a particular embodiment of the method, briquettes are connected by sintering in the manufacture of a preform.

In a particular embodiment of the method, in the manufacture of a preform, the briquettes are connected by electron beam or plasma-arc welding.

An example of the implementation of the proposed method is to obtain double vacuum vacuum remelting of ingots used in the nuclear industry alloys Zr-Nb - (0.9-1.2 wt.%) - Fe (0.30-0.47 wt.%) - Sn (1.10-1 , 42 wt.%) - O (0.05-0.12 wt.%). To form a consumable electrode of the first remelting, the samples for briquettes corresponding to the bottom of the ingot of the first remelting and the sprue of the ingot of the second remelting contained a smaller amount of alloying elements, their content was determined from the ratio:

C = K ₁ × C _p ,

where K ₁ - coefficient taking into account the tendency of the alloying element to segregation, K ₁ = 0.5-1.0, was determined experimentally for each element;

With _p - the estimated content of the alloying component in the alloy,

As a result, for depleted briquettes forming the bottom of the ingot of the first remelting and the sprue of the ingot of the second remelting, the calculated content of the alloying elements was:

C _Nb -0.97 × C _pNb ; C _Sn -0.95 × C _pSn ; C _Fe -0.94 × C _pFe ; C _O -1.0 × C _pO

The total mass of lean briquettes was determined from the ratio:

M = K ₂ × D,

where K ₂ - coefficient taking into account the mass of liquid metal at the initial moment of melting, depending on the length of the deposited ingot, K ₂ = 0.04 ÷ 0.12 kg / mm;

D is the diameter of the ingot of the final remelting, mm

In the given example, for a final remelting ingot with a diameter equal to 450 mm and a deposited ingot length of 55 mm, the total mass of lean briquettes was 41.25 kg.

The working metal rods were inserted into the briquette holes, sintered in a vacuum furnace, a consumable electrode was formed from the obtained billet, iodide rods and zirconium wire and the ingot was melted by a double vacuum-arc remelting.

Samples were taken from the sprue, middle and bottom parts of the obtained ingot to determine the chemical composition, the results of which are shown in table 1.

To obtain comparative data, the ingot of an alloy of the same composition obtained by the closest method was similarly studied.

Comparison of the chemical composition of the ingots by the proposed and closest methods (table 1) indicate the solution of the problem of improving the quality of alloys by increasing the chemical uniformity of the ingot.

The proposed method can be used in the industrial production of ingots from zirconium-based alloys used as structural materials of nuclear reactors.

Table 1 The method of producing alloy Part of the ingot for the study of the composition The content of alloying elements,% Nb Sn Fe O Proposed Litnikovaya 1,0 1.26 0.35 0.08 Average 1,0 1.22 0.33 0.08 Donna 1,0 1.22 0.34 0.08 By the closest analogue Litnikovaya 1,2 1.4 0.42 0.08 Average 1,03 1.22 0.35 0.08 Donna 1,03 1.24 0.34 0.08

Claims (6)

1. A method of producing zirconium-based alloys, comprising pressing briquettes from a mixture of zirconium-containing material and alloying elements, making billets from briquettes, forming a consumable electrode from iodide rods, iodide rods and zirconium wire and smelting the ingot by multiple vacuum-arc remelting, characterized in that in the manufacture of a workpiece, that part thereof that corresponds to the bottom of the ingot of the first remelting and / or the gating part of the ingot of the final remelting is depleted x briquettes into which each of the alloying elements is introduced in an amount C = K ₁ × C _p , where K ₁ - coefficient taking into account the tendency of the alloying element to segregate K ₁ = 0.5-1.0; With _p - the estimated content of the alloying element in the alloy, and the total mass of depleted briquettes is M = K ₂ × D, where K ₂ - coefficient taking into account the mass of liquid metal at the initial moment of melting, depending on the length of the deposited ingot, K ₂ = 0.04 ÷ 0.12 kg / mm; D is the diameter of the ingot of the final remelting, mm 2. The method according to claim 1, characterized in that the mixture of zirconium-containing material and alloying elements is prepared by portion weighing, and then by averaging. 3. The method according to claim 1, characterized in that the metal zirconium powder and / or ground zirconium sponge, pieces of zirconium iodide and recycled metal in the form of chips are used as zirconium-containing material. 4. The method according to claim 1, characterized in that the metal zirconium powder and / or ground zirconium sponge, pieces of iodide zirconium are used as the zirconium-containing material, the briquettes being pressed with central holes into which the reverse zirconium rod is inserted. 5. The method according to claim 1, characterized in that in the manufacture of the preform, the briquettes are connected by sintering. 6. The method according to claim 1, characterized in that in the manufacture of the preform, the briquettes are connected by electron beam or plasma arc welding.