Production of cages for prosthetic cardiac valves from commercially pure titanium
SUBSTANCE: proposed process of production of cages for prosthetic cardiac valves from commercially pure titanium comprises assembly and soldering of drawn wire and plate and thermal treatment. Prior to assembly, wire is annealed in vacuum furnace at 550-600°C for 30-40 minutes and cooled with furnace. After soldering, the cage is annealed in vacuum furnace at 550-600°C for 1.5-2 hours and cooled with furnace.
EFFECT: better manufacturability, lower labour input, high mechanical properties.
1 tbl, 1 ex
The invention relates to a method of manufacturing a welded products, mainly welded frames of artificial heart valves (X).
Known methods of manufacturing frames X machining (abroad - type Stellite Haynos) - see USSR author's certificate No. 1712459, C22F 1/10, publ. 15.02.1992. However, these methods are time consuming and do not allow to produce frames X complex forms.
A known method of manufacturing frames X titanium W 1-0 (α-β phase) (U.S. Pat. RF N 2012284 A61F 2/24, publ. 15.05.1994). The method includes the mechanical manufacture of the body and wings, Assembly, application of carbon coatings. The method includes heating rod, which is used to produce billets, forging and annealing. The heating rod is conducted to a temperature of ~900°C, forging full compression with double or triple draught of up to 30-50% with the subsequent drawing. Annealing forging during heat treatment produce electric chamber furnaces, heated to 670-680°C followed by cooling in air. The casing is secured in a fixed position and the sash is installed in the fixture, providing compression of the valves at the entry of the nest and smoothing when installed in the slot. The purpose is known of the invention is to improve the reliability of the valves. However, the patent does not contain indicators of these products. Furthermore, the method Trudie is OK.
The authors of this application tested tselnolitye samples made of titanium rod W 1-0 treated with the above method (the results are shown in the table).
As a prototype adopted a method of manufacturing a welded alloys of system cobalt-chromium-Nickel-molybdenum, mainly skeletons X as the most close to the sum of signs (ed. mon. The USSR № 1712459, C22F 1/10, publ. 15.02.1992). The method includes the Assembly and welded deformed wire drawing and plate heat treatment. Wire pre-deform the lug 50%. Spend electron beam welding wire to the plate at a voltage of 16 to 18 kV, a beam current of electrons 22-24 mA, the welding time is 0.9-1.2 s, the residual pressure in the vacuum chamber 133.10-4-135.10-5PA. Then carry out the tempering temperature 1100-1180°C in water, cold deformation by stretching with the degree of 15-20%, aged at 450-500°C for 10-15 hours
It should be noted the high complexity and duration of the method, which ultimately reduces its manufacturability. Mechanical characteristics quite high (see table).
There is a method of improving the proposed resolution.
The task is improving the way the prototype for the manufacture of frames X titanium as an alloy more technologically advanced, lightweight, which is important for such specific the products, as the frames of the IRS.
The technical result - improving the processability of the method by reducing the complexity and duration under high mechanical characteristics.
This technical result is achieved in that in the method of manufacturing frames X from commercially pure titanium, including the Assembly and welded deformed wire drawing and plates and heat treated prior to Assembly of the frame wire is annealed in a vacuum furnace at a temperature of 550-600°C for 30-40 minutes and cooled with the furnace, and after welding carry out the annealing of the frame in a vacuum furnace at a temperature of 550-600°C for 1.5-2 hours and cooling with the furnace.
The proposed method allows to produce frames X from commercially pure titanium, it is lighter, cheaper, has good weldability. The method is less time consuming for it excluded the operation of hardening, cold deformation and leave for 10-15 hours, weight reduction products, two times, at high fatigue characteristics.
The effect dovanojo annealing due to the fact that when passing it recrystallization makes the metal is thermodynamically more stable to the welding thermal cycle.
The purpose of the post-weld annealing is to reduce the level of internal stresses, the more homogeneous structure of the weld, reducing the hardness of the heat-affected zone, the training is a result of the removal work hardening, resulting from thermal deformation of the welding cycle, as well as the redistribution of hardening of the heat-affected zone during welding of the introduction of impurities of oxygen and nitrogen.
In the pre - and post-weld annealings achieves a more uniform distribution of properties in the influence zones of welding (weld and heat-affected zone).
The method is as follows.
Wire of commercially pure titanium deformed by the drawing and is annealed at a temperature of 550-600°C for 30-40 minutes, cooling with the furnace. Weld plates of the same material. After welding the frames is annealed at a temperature of 550-600°C in the same oven for 1.5-2 hours. Samples of finished frames X passed mechanical tests.
An example of the method.
Wire of commercially pure titanium W 1-0 deformed by drawing on 55% of the diameter 2±0.01 mm, length 45 mm and annealed at a temperature of 550-600°C for 30-40 minutes, cooled with the furnace. Made from the same material plate size of 12×12×1. Carried out the welding wire to the plate. Heat treatment and welding is carried out in vacuum with a residual pressure 133.10-4-135.10-5. Welding mode: accelerating voltage of the electrons 16-18 kV, a beam current of electrons 18-20 mA, welding 1,0-1,2 (as in the prototype).
After welding the frames were heat treatment - annealing in vacuum at a temperature of 550-600°C for 1.5-2 hours cooling with the furnace.
After annealing, the carcasses were subjected to mechanical and electrochemical polishing, and then testing the alternating symmetric cyclic bending with the determination of the endurance limit based on trials N=107cycles and intensity of accumulation of cyclic damage, characterized by the indices β1that β2in physiological solution of ringer-Locke.
The results of the mechanical tests are shown in table.
The table shows that the temperature of 600°C dovanojo annealing and 600°C post weld annealing provide the best combination of strength and plastic (relative elongation δ, relative narrowing Ψ) characteristics and better fatigue characteristics: the maximum value of the fatigue limit σ-1=235 MPa on the basis of trials N=107cycles, the minimum angles of the left (β1) and right (β2) branches of the fatigue curve in the double logarithmic coordinates.
With decreasing temperature dovanojo annealing below 550°C (500°C) decreases the limit of endurance and high angles of fatigue curves. Some reduction in fatigue limit compared to the prototype, due to the difference in the properties of titanium and alloys of the cobalt-chromium-Nickel-molibden.
With increasing temperature dovanojo annealing above 600 is C (650°C) observed the same result.
Decreasing the exposure time when devroom annealing less than 30 minutes (25 minutes) the process of crystallization is less full and less grain is resistant to growth in the welding process.
Increasing the exposure time when devroom annealing over 40 minutes (45 minutes) can lead to grain growth, which will adversely affect durability.
With decreasing temperature and post weld annealing below 550°C (500°f) less than fully reduced level of internal stresses, uneven distribution of properties in the welded joints.
With increasing temperature and post weld annealing above 600°C (650°C) decreases the limit of endurance.
Decreasing the exposure time when the post-weld annealing is less than 1.5 hours (1 hour) is incomplete reduction of internal stresses, the uneven distribution of properties along the length of the welded joints, partial removal of work hardening resulting from thermal deformation of svarochno cycle.
Increasing the exposure time when the post-weld annealing for more than 2 hours leads to lower level of mechanical properties due to grain growth.
A pilot batch of frames X has been tested on fiziologicheskii stands in conditions close to operational, and showed an increase in the durability of 1.4-1.5 times in comparison with frames that have not undergone the proposed treatment - annealing.
The proposed method allows to produce frames X more technological way, lighter, cheaper, with higher fatigue limit, which increases their durability.
The method meets the criteria of novelty, inventive step and industrial applicability.
|Mode TMO||Mechanical properties|
|T dovanojo annealing °C||T post weld annealing °C||σin, MPa||σin, MPa||σ-1, MPa||β1||β2||δ, %||Ψ, %|
|time 30 min||time 1.5 hours|
|1400-1525 N/mm2||1295-1415 N/mm2||540-560 N/mm2||0,153-0,146||0,286-0,280||16-22||51,5 is 54.5|
|tselnolitye frames X||40||384||230||0,131||0,034||35||78|
A method of manufacturing frames of artificial heart valves from commercially pure titanium, including the Assembly and welded deformed wire drawing and plate and heat treatment, characterized in that prior to Assembly of the frame wire is annealed in a vacuum furnace at a temperature of 550-600°C for 30-40 minutes and cooled with the furnace, and after welding carry out the annealing of the frame in a vacuum furnace at a temperature of 550-600°C for 1.5-2 hours and cooling with the furnace.
FIELD: process engineering.
SUBSTANCE: invention relates to metal forming and can be used for production of turbo machine thermomechanical part from beta- and/or alpha/beta-titanium alloy. Forged piece of the part is made from titanium alloy ingot with temperature Tβ of conversion into beta-phase. Note here that at least one ingot rough forging step is effected at temperature T1 lower than temperature Tβ of conversion into beta-phase. In forging, the ingot is plastically deformed to ensure local deformation at all points of at least 0.2. Produced ingot is cooled down and subjected to final fording at T2 higher than temperature Tβ of conversion into beta-phase. Produced forged piece is cooled down.
EFFECT: forged piece with fine and homogeneous grain size of about 50-100 mcm.
14 cl, 3 dwg
SUBSTANCE: workpieces are made in the form of rings; deformed so that thicknesses of their walls are reduced and their diameter is increased, and then, their ends are butt welded till a pipe is obtained. Deformation of rings with wall thickness reduction is performed by rolling on a ring-rolling mill or by forging on a mandrel using forging equipment. Radial texture is preserved throughout the pipe length.
EFFECT: producing a pipe from technically pure titanium with radial texture.
3 cl, 6 dwg, 2 ex
SUBSTANCE: invention relates to metallurgy. proposed method of treatment of said allows completely hardening in β-phase containing alloying elements, at least, boron and elements stabilising β-phase comprises cooling the blanks from temperatures of β-phase region. Blanks are cooled immediately after gardening or after heating and curing at temperatures of β-phase region. Note here that blanks are cooled to temperatures of (α+γ)- or (α+β+γ)-phase depending on size in air or in air in container to form thermodynamically nonequilibrium structure but at the rate smaller than that of cooling at tempering of alloy selected composition. The, blanks are cooled from temperatures of (α+γ)- or (α+β+γ)-phase region to room temperature together with the furnace or cooled in air with subsequent annealing at temperatures of (α+γ)- or (α+β-γ)-phase region and cooling after annealing together with the furnace.
EFFECT: higher performances and processing ductility.
5 cl, 5 dwg, 7 tbl, 3 ex
SUBSTANCE: proposed alloy features structure of nanocrystalline grains of B2-phase wherein volume fraction of 0.1 mcm-size grains and those of shape factor of 2 in mutually perpendicular planes makes at least 90%. Over 50% of grains have large angular boundaries misaligned relative to adjacent grains through 15 to 90 degrees. Method of making the bar from said alloy comprises thermomechanical processing including plastic straining and recovery annealing. Intensive plastic straining is made in two steps. At first step, equal-channel angular pressing is made to accumulated strain e≥4. At second step, forge ironing and/or drawing are made. Annealing is carried out either in process and/or after every straining step. Equal-channel angular pressing is performed at 400°C. Forge drawing and ironing are made to total reduction of over 60% at gradual decrease of temperature to t=450-200°C, while annealing is performed at t=400-200°C.
EFFECT: higher mechanical and functional properties.
2 cl, 2 dwg, 1 ex
SUBSTANCE: heat treatment method of castings from alloys based on gamma titanium aluminide involves hot isostatic pressing, cooling to room temperature and further heating at temperature below eutectoid alloy conversion. Hot isostatic pressing is performed at the temperature above eutectoid alloy conversion in α+β+γ phase area at the following number of phases in alloy, wt %: beta phase (β) 7 to 18, gamma phase (γ) 5 to 16, and alpha phase (α) is the rest.
EFFECT: shortening the time required for heat treatment; with that, alloys have high level of mechanical properties.
2 cl, 2 dwg, 1 tbl, 1 ex
SUBSTANCE: prior to drawing a wire heating method involving dosed heating with infrared emission flow before a drawing block differs by the fact that dosed heating is performed by selecting semiconductor emitting diodes located around the drawing block and having directed emission characteristic, the maximum of which is oriented to wire axis; with that, dosed heating is performed by changing feed current of emitting diodes.
EFFECT: improving wire quality owing to reducing probability of occurrence of defects and breaks.
SUBSTANCE: proposed method comprises processing the workpiece in explosive accelerator by high-velocity Ti powder particle flow in the mode of super deep penetration of particles. Note here that Ti particles are arranged under explosive with air gap. Acceleration of articles is carried out by shock wave in accelerator guide channel coupled with processed workpiece. Processing is performed by flow of particles with dispersity of 20 mcm at flow rate of 1.5-2.5 km/s, density of 1 g/cm3, pressure of collision of particles with workpiece material of 12-15 GPa and their interaction time of 5-7·10-5 s.
EFFECT: higher strength and homogeneity of titanium workpiece structure.
SUBSTANCE: high-strength pseudo-beta titanium alloy contains the following, wt %: aluminium 5.3-5.7, vanadium 4.8-5.2, iron 0.7-0.9, molybdenum 4.6-5.3, chrome 2.0-2.5, oxygen 0.12-0.16, and titanium and impurities are the rest, and when necessary, one or more additional elements chosen from N, C, Nb, Sn, Zr, Ni, Co, Cu and Si; with that, each additional element is present in the amount of less than 0.1%, and total content of additional elements is less than 0.5 wt %. At production of alloy, after it is obtained, homogenisation is performed at the temperature below temperature of beta-conversion and its disperse strengthening. An aviation system component represents a landing gear or a fastening part, which is made using titanium alloy.
EFFECT: alloy has high strength,ductility and ability for deep hardening.
25 cl, 4 dwg, 3 tbl, 3 ex
SUBSTANCE: method of processing the titanium alloy consisting of, at least, the following components, in wt %: iron - 0.2-0.5, oxygen - 0.02-0.12, silicon - 0.15-0.6, titanium and unavoidable impurities making the rest, comprises executing the first thermal treatment at first temperature to form the structure containing 50% of beta-phase, and, then, cold rolling. Second thermal treatment at second temperature is executed to produce second-phase precipitation while third thermal treatment is performed at third temperature for alloy recrystallisation without dissolution of precipitation.
EFFECT: high-strength titanium alloy with high resistance to oxidation and pliability at low temperatures.
18 cl, 6 dwg
SUBSTANCE: proposed method comprises hot forming of slab, hot rolling and teat treatment of plate, whereat hot forming if carried out in one step. Immediately after reaching required thickness in slab forming it is quickly cooled to the depth of 20-30 mm at the rate of at least 50°C/min. Subsequent hot lengthwise rolling at performed at first step in α+β-area by partial reduction with deformation degree εi varying from 3% to 5% to total deformation ε=25…30% with breaks between passes of 8 to 12 s. At second step, it is performed in β-area from heating temperature determined by definite formula. At the next step rolling is performed in α+β-are with breaks and heating in lengthwise or transverse directions with total degree of deformation e after every break to 60%.
EFFECT: homogeneous fine-grain microstructure, high and stable mechanical properties, high precision, no surface defects.
FIELD: process engineering.
SUBSTANCE: invention relates to welding, particularly, to electron beam welding vacuum of different-thickness parts. Said butt locking joint is made between large-depth part, lock base being made at weld edge end, and smaller-depth part to be jointed thereto. Note here that lock base is skewed at 45°≤α≤60°, while welding is effected with butt penetration through entire depth. Lock base can be skewed straightly or in zigzag manner.
EFFECT: higher quality of seam.
3 cl, 6 dwg
SUBSTANCE: joint of a pipeline from stainless steel with a vessel from titanium alloy comprises an adapter made in the form of a bushing, the lower part of which is made according to a spherical shell shape and is connected to it by means of electronic beam welding. The upper part of the bushing is installed coaxially inside the pipeline and is connected with it by means of high-temperature vacuum soldering. The adapter is made from a niobium-based alloy alloyed with at least one of the metals selected from the following group: tantalum, molybdenum, vanadium, titanium. Electronic beam welding of the adapter with the vessel shell is carried out with beam displacement along the shell joint surface with the adapter towards the adapter.
EFFECT: invention provides for tightness and high strength of connection.
6 cl, 2 dwg, 1 tbl
FIELD: process engineering.
SUBSTANCE: method may be used for making critical welded structures in machine building. Parts of be welded are arranged with clearance. Adding material is fed into said clearance. Grooves and adding material are washed by electron beam and common molten pool is produced. Clearance width is selected proceeding from the condition 1.1d≤h≤1.2d, where h is clearance width and d is adding material diameter.
EFFECT: higher quality of welded joints.
FIELD: process engineering.
SUBSTANCE: invention relates to electron-beam processing. Pre-welding is performed without grooving and with part-through penetration. Face bead width and height are defined. Grooving is made for main welding to prepare grooving cavity 5 and main welding is carried out on transmitting electron beam through grooving cavity 5. Grooving before main welding is performed to produce groove 6 nearby grooving cavity base with width and height, at least, 15% larger than those of face bead after pre-welding.
EFFECT: high-quality welded joints between large-thickness articles.
FIELD: machine building.
SUBSTANCE: invention relates to a device for retention of components during repair of a blade of a single-block turbine wheel by means of electron-beam welding of an insert with a blade along the joint plane. The device comprises facilities to retain the wheel and facilities for controlled retention of the blade and the insert. The facilities for controlled retention of the blade and the insert comprise a support, where facilities are placed to retain the blade and the insert so that the space above the joint plane makes it possible for the electron beam to pass through. The relative position of the blade and the insert is controlled with the help of facilities installed on a single support, letting the electron beam pass through.
EFFECT: device differs by simplicity and reliability.
19 cl, 12 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to method of electron beam welding of nonmagnetic metals and alloys. Proposed method comprises penetrating the butt of parts 3 to be welded together by electron beam 2, inducing magnetic field inside said parts and forming presser geometry of electron beam and penetration channel in displacing electron beam over part thickness. Blind penetration of but 4 is performed. In welding, beam 2 is deflected across the butt to vary shape and sizes of seam root 6 at constant size of weld seam apex. For this, variable magnetic field is induced on the side of seam root.
EFFECT: higher quality of welded joints, control over weld seam shape.
FIELD: technological processes.
SUBSTANCE: invention relates to the method of electron-beam welding and is designed to produce non-detachable welded joints. The method includes generation of an electronic beam (3), its deflection and displacement relative to the gun axis, arrangement of the beam focus inside a welded part (1) and maintenance of the beam (3) focus position along the thickness of the welded joint as permanent. Deflection and displacement of the electronic beam (3) from the gun axis is carried out with alternating magnetic field. The field is developed with supply of AC current to the lower portion of the welded part via current contact jaws (4), which are arranged at two sides symmetrically to the joint at the distance between them, equal to the width of the welding joint in the upper portion of the welded part. The magnetic field is displaced in direction of welding with the speed equal to the speed of electronic beam. The value of the alternating current supplied via current contact jaws (4) is selected provided that the width of the joint in the root zone is equal to the width of the joint in the upper part of the welded joint.
EFFECT: method makes it possible to increase quality of the welded joint by improvement of the root part of the joint and elimination of the defect area in the middle part of the joint.
SUBSTANCE: procedure consists in local pad weld of coating on at least part of blade body and in dimensional processing. Regularly distributed crossing strips are pad-welded along surface of the blade body and form a net at their crossing.
EFFECT: raised operational characteristics of blades.
25 cl, 1 dwg
FIELD: process engineering.
SUBSTANCE: invention may be used for repair of parts made from high-alloy refractory steels and alloys in aircraft engineering, ship building and power engineering. Turbine blade body is, first, conditioned for powder to be applied thereon by microplasma evaporation, said powder containing 70% of nickel-based filler and 30% of high-temperature solder. High-temperature soldering is carried out. Blade body section, a transverse strip covering section to be repaired, is heated by scanning electron beam to solder solidus temperature all over blade thickness. Then, repaired section is heated to temperature 100°C-120°C higher than solder solidus temperature and said temperature is maintained in pulsed mode for 1 minute. Note here that intermittent heating is performed for 5-7 s and temperature is reduced to 1000°C and maintained for 10-15 s.
EFFECT: complete recovery of parts shape, higher efficiency of repair and longer life of recovered parts.
2 cl, 1 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to repair of turbo machine integral vaned disk. Vane repair is performed by method of electron-beam welding of insert. Vane repair begins from machining damaged zone to shape it as required. First sample piece is made. Second sample piece corresponding to insert is welded to first sample piece corresponding to insert and shaped as required to produce specimen for starting the work. Said specimen is checked for quality. Is quality complies with acceptance requirements, the insert is welded to zone to be repaired. Note here that the same electron-beam welding machine is used without changing its operating parametres. Now, repaired zone is again machined.
EFFECT: higher strength of vane.
14 cl, 7 dwg
SUBSTANCE: group of inventions relates to medicine. Intracardiac device for recovery of functional elasticity of cardiac structures, accumulating energy from cardiac structures and transmitting energy to cardiac structures during cardiac cycle, has elongated shape, is wound in spirals along specified section and can be fixed to cardiac structure. Spirals are selected by material, number and sizes in such a way as to make it possible for intracardiac device to be elastically elongated within the range from 10% to 50% of the length of intracardiac device in the state of rest, and are subjected to impact by blood flow in the process of exploitation. Device contains elongated link, made from metal wire of springs, wound in spirals along said specified section. At least one link is capable of direct fixation to cardiac structure, is fixed on elongated link, and has elongated shape, and is located near elongated link and along it. Fixed link includes tube from metal net, crisscrossing with said spirals. Tube is capable of stretching. Described is constructive variant of intracardiac device and holding instrument for intracardiac device.
EFFECT: inventions make it possible to minimise response of cardiac structures to foreign body in cardiac cavity.
10 cl, 27 dwg