Method for making tubular adapters of zirconium and steel sleeves

FIELD: processes and equipment for diffusion welding of tubular adapters of zirconium and steel sleeves.

SUBSTANCE: method comprises steps of placing sleeve of zirconium alloy inside steel sleeve and heating them in vacuum till diffusion welding temperature; then compressing welded surfaces due to expanding zirconium sleeve by means of roller expander; after diffusion welding cooling adapter in temperature range in which zirconium alloy has no phase containing α-zirconium and β-zirconium; subjecting zirconium sleeve to hot deformation by depth no less than 0.5 mm at reduction degree no less than 10%; cooling adapter till temperature range 540 - 580°C and keeping it in such temperature range no less than 30 min.

EFFECT: simplified method for making adapters having improved corrosion resistance in hot water and steam.

 

The invention relates to the field of diffusion welding of tubular adapter of zirconium and steel bushings, which are used as a bimetallic insertion when welding channels of nuclear reactors, which are tubes made of zirconium alloy, working in the reactor core, stainless steel pipes, which are located outside of the reactor core.

A tubular adapter is produced by means of diffusion welding sleeves of zirconium alloy and stainless steel, collected overlap, which is heated to a temperature of diffusion welding in the region of 950°and break them walls in the radial direction by giving inner sleeve.

Radial distribution carried out by means of a conical mandrel (see A.S. USSR №202404, 14.09.1967,, bull. No. 10), or by using a roller raskatikha (see asstr, CL 23 To 19/00, 05.08.79,, bull. No. 29).

In all known methods of fusion welding of zirconium alloy with stainless steel is carried out in vacuum at a temperature of more than 900°C.

The disadvantage of this method of diffusion welding reducers zirconium and steel bushings is a limited resource efficiency of the internal surface of the Zirconia part of the adapter due to its corrosion when operating in the active channel area of the uranium-graphite nuclear reactor. In the analy uranium-graphite reactor flows through the steam-water mixture at a temperature of about 300° Since, under the influence of which the inner surface of the adapter, consisting of a zirconium alloy, corrode, resulting in over time on the surface of Zirconia formed white oxide film, which as its growth showered that in the long run leads to clogging of the reactor radioactive corrosion products.

Increased corrosion of the internal surface of the Zirconia part of the adapter due to the fact that at diffusion welding the billet adapter is heated above 900°S, and when heated above 650°in zirconium phase transformations occur, which is formed of a two-phase structure consisting of alpha-zirconium and beta-zirconium, which is characterized by low corrosion resistance for long term use in hot water and steam at temperatures greater than 200 degrees Celsius.

A known method of manufacturing a tubular adapter of zirconium alloy and steel, in which the corrosion resistance of the surface of the Zirconia part of the adapter increases by deformation in a cold condition to a depth of not less than 200 μm, after which the adapter thermoablative in vacuum at 535-565°With not less than 15 hours (see patent No. 2085349, CL 23 To 20/00 from 27.07.97,, bull. No. 21).

The disadvantage of this method is its high complexity, since after the diff is precise welding in vacuum welded billet adapter is cooled from a temperature of 950° With up to the room and mechanical process with high purity, after which the Zirconia surface of the adapter is subjected to deformation by using the roller obsitnik by multiple passes. After that, the adapter again placed in the vacuum, where it is heated to 550°C and maintained at this temperature for at least 15 hours.

Also known a method of diffusion welding a lap joint in which the compression of the welded surfaces carried out by hand inner tube by rolling the roller raskatikha at a temperature of diffusion welding (see RF patent №2164198, CL 23 To 20/14 from 20.03.2001,, bull. No. 8).

This method for adapters zirconium-steel has the same drawback, that the method according to patent No. 2085349, because on this way to increase the corrosion resistance must also be subjected zirconium surface deformation using multiple roller running, after which you want the adapter annealed in vacuum for at least 15 hours. However, in this method, there are technological reserves due to the use of roller raskatikha to create a welding pressure at the temperature of diffusion welding. This method is taken as a prototype.

The problem to which the invention is directed, is to create a method of manufacturing the adapter method to trim the ion welding, which does not require post-weld cold-formed inner surface of the Zirconia sleeve and the subsequent long-term annealing in vacuum to increase its corrosion resistance in hot water and steam.

The technical result obtained by the proposed method is that it saves time, electricity and labor, as all the operations required to increase the corrosion resistance of zirconium surface of the adapter are in the process of cooling after the diffusion bonding by surface rolling of the roller raskatikha.

This technical result in the method of manufacturing a tubular adapter of zirconium and steel bushings is due to the fact that the sleeve of zirconium alloy are mounted inside a steel sleeve and heated them in a vacuum to a temperature of diffusion welding, then squeeze the welded surface by hand Zirconia sleeve roller raskatikha, and after diffusion welding the adapter is cooled to the range of temperatures at which the zirconium alloy is present dual phase consisting of alpha-zirconium and beta-zirconium, after which produce hot deformation of the inner surface of the sleeve of zirconium to a depth of not less than 0.5 mm when the degree of compression of not less than 10%, and flux is the adapter is cooled to the temperature range of 540 to 580° C and maintained in this range for at least 30 minutes.

Empirically, it was determined that the surface deformation of the sleeves of zirconium and its alloys using roller raskatikha when the temperature of the phase transition, when the zirconium alloy is present dual phase consisting of alpha-zirconium and beta-zirconium increases the corrosion resistance of the deformed surface, if it is subjected to subsequent vacuum annealing in the temperature range from 540 to 980°C. it was Also found that changing the depth of deformation and the degree of compression of the surface layer, and the time of annealing in the temperature range from 540 to 580°you can get corrosion the internal resistance of zirconium surface of the adapter in hot water and steam is not worse than cold-formed roller and subsequent annealing for 15 hours. At this time of annealing in the temperature range from 540 to 580°can be shortened to 45 minutes without a noticeable decrease in corrosion resistance.

The savings are achieved due to the fact that the surface deformation is carried out immediately after diffusion welding, while not spending energy and time on heating, and uses a process of cooling the welded billet adapter in vacuum with the temperature of diffusion welding (≈900° (C) to the temperature range at which the missile is going intensive phase transformations (750-650° C). Surface deformation and compression of the surface layer produced roller obcutekom. After surface deformation and compression temperature is reduced due to natural cooling of the adapter to the temperature range of 540 to 580°C. When chosen from this range of temperatures produce annealing for at least 30 minutes. The selected temperature is maintained automatically by periodically switching on and off high-frequency heater by including in the circuit of the heating automatic pyrometer. As a result of installation for diffusion welding in vacuum, adapted for hot surface deformation of the internal surface of the Zirconia sleeve adapter and high-frequency annealing, goes adapter, suitable for prolonged use in piping hot water and steam with a temperature of over 200°C.

A method of manufacturing a tubular adapter of zirconium and steel bushings, which consists in the fact that the sleeve of zirconium alloy are mounted inside a steel sleeve and heated them in a vacuum to a temperature of diffusion welding, then squeeze the welded surface by hand Zirconia sleeve roller raskatikha, characterized in that after diffusion welding the adapter is cooled in the interval of the temperature, where in zirconium alloy is present dual phase consisting of alpha-zirconium and beta-zirconium, after which produce hot deformation of the inner surface of the sleeve of zirconium to a depth of not less than 0.5 mm when the degree of compression of not less than 10%, then the adapter is cooled to the temperature range 540-580°C and maintained in this range for at least 30 minutes



 

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FIELD: non-ferrous metallurgy; methods of titanium alloy bricks production.

SUBSTANCE: the invention is pertaining to the field of non-ferrous metallurgy, in particular, to the brick made out of α+β titanium alloy and to a method of its manufacture. The offered brick consists of the following components (in mass %): aluminum - 4-5, vanadium - 2.5-3.5, iron - 1.5-2.5, molybdenum - 1.5-2.5, titanium - the rest. At that the alloy out of which the brick is manufactured, contains - 10-90 volumetric % of the primary α-phase. The average grain size of the primary α-phase makes 10 microns or less in a cross-section plain parallel to the brick rolling direction. Elongation of grain of the primary α -phase is the four-fold or less. The offered method of manufacture of the given brick includes a stage of a hot rolling. At that before the stage of the hot rolling conduct a stage of the alloy heating at the surfaces temperature (Tβ-150)- Tβ°C. During realization of the stage of the hot rolling the surface temperature is kept within the range of (Tβ-300)-( Tβ -50)°C, and the final surface temperature, that is a surface temperature directly after the last rolling, makes (Tβ-300)-( Tβ-100)°C, where Tβ is a temperature of α/β-transition. The technical result of the invention is formation of a brick out of the high-strength titanium alloy having a super pliability, excellent fatigue characteristics and moldability.

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FIELD: processes and equipment for diffusion welding of tubular adapters of zirconium and steel sleeves.

SUBSTANCE: method comprises steps of placing sleeve of zirconium alloy inside steel sleeve and heating them in vacuum till diffusion welding temperature; then compressing welded surfaces due to expanding zirconium sleeve by means of roller expander; after diffusion welding cooling adapter in temperature range in which zirconium alloy has no phase containing α-zirconium and β-zirconium; subjecting zirconium sleeve to hot deformation by depth no less than 0.5 mm at reduction degree no less than 10%; cooling adapter till temperature range 540 - 580°C and keeping it in such temperature range no less than 30 min.

EFFECT: simplified method for making adapters having improved corrosion resistance in hot water and steam.

FIELD: plastic metal working, possibly manufacture of intermediate blanks of titanium alloys by hot deforming.

SUBSTANCE: method comprises steps of deforming ingot at temperature in β -range and combination type operations of deforming blank temperature of (α + β) and β-ranges; at final deforming stage at temperature in (α + β) range realizing at least one forging operation after heating blank till temperature that is lower by 50 - 80°C than polymorphous conversion temperature of alloy; at least one time cooling blank in water; before deforming blank for final size, heating blank till temperature that is lower by 20 - 40°C than polymorphous conversion temperature for time period providing globule formation of α - phase; fixing formed structure by cooling in water; again heating blank till temperature that is lower by 20 - 40°C than polymorphous conversion temperature and finally deforming blank.

EFFECT: possibility for producing blank with globular-plate microstructure, lowered level of structural defects at ultrasonic flaw detection of turned blank.

1 ex

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