Method of diffusion welding of billets made of ot4-1 titanium alloy

FIELD: process engineering.

SUBSTANCE: invention relates to pressure welding, particularly, to diffusion welding at low-intensity power effects and may be used for making thin-wall structures from OT4-1 titanium alloy. Proposed method comprises heating to welding temperature, jointing two work pieces for time sufficient for making a physical contact between surfaces to be jointed together. Heating at first stage is performed with application of welding pressure for development of 3D interaction. At second stage, heating is performed with application of welding pressure. At said first stage heating is performed in conversion temperature range α+β→β for time τw defined as follows: τw=k·p-n·exp(E/RT)·lnRa, where k is empirical factor describing kinetics of the development of physical contact area between surfaces to be jointed equal to 1.75·10-7 s, p is numerical magnitude of welding pressure, MPa, n is empirical factor describing material creepage equal to 1,2, E is activation energy, J/mol, R is gas constant, J/(K·mol), T is heating temperature, K, Ra is numerical value of surface roughness.

EFFECT: decreased accumulates strain in work pieces, power savings.

1 ex

 

The invention relates to the welding of pressure, namely the diffusion welding of low power influence, and can be used for the manufacture of thin-walled structures made of titanium alloy AT-1.

The formation of the diffusion of compounds under conditions of low power influence titanium alloys limited by the stage of formation of physical contact, during which there is convergence of the welded surfaces. The formation of physical contact is accompanied by crushing of asperities on the joined surfaces and the formation of discontinuities. For the further development of contact require large deformation, leading to the accumulation of residual deformations of welded blanks.

The reduction of the accumulated deformation of the welded workpieces is one of the factors that determine the quality and operational properties of the welded connection.

To improve the quality and operational properties of a welded joint may manage the processes and the application of pressure (Karakozov AS welding of metals by pressure. - M.: Mashinostroenie, 1986, 280 S.).

Closest to the claimed method is a method for pressure welding of workpieces made of titanium alloy AT-1, comprising placing between the billet intermediate strip of titanium alloy with the original RA is the mayor of grains less than 1 μm and the connection blanks and strips by the application of pressure to the workpieces. Connection blanks and spacers carried out in two stages. At the first stage pressure is applied at a temperature below the temperature of the second stage and close to the lower limit of temperature range, providing appropriate conditions of superplasticity is the strain-rate, in a period of time sufficient for the formation of physical contact between the joined surfaces of the blanks and strips. The second stage is carried out at a temperature and time required for development volume interaction (the description of the patent RU 2415738 IPC B23K 20/16 (2006.01) B23K 20/22 (2006.01), published on 10.04.2011).

In the known method the formation of physical contact and development volume interaction between the joined surfaces of the blanks and strip contact accompanied by a hardening of the latter, which is a consequence of the application of pressure and friction.

In addition, the intermediate strip with the grain size less than 1 μm thermal-deformation processing operation is energy-intensive and time-consuming.

The objective of the invention is to simplify technology for production and improving the quality of welded joints manufactured in titanium welded thin-walled structures.

The technical result - the reduction of accumulated deformation in welded blanks and lower energy and labor made the I.

The technical result is achieved in the claimed method of diffusion welding of workpieces made of titanium alloys. The method includes heating to a temperature of welding, the connection of workpieces in two stages in a period of time sufficient for the formation of physical contact between the joined surfaces of the workpieces at the first stage with the application of welding pressure and for the development of the volume interaction in the second stage without the application of welding pressure. At the first stage heating is carried out in the temperature interval α+β→β transformation and during the time τStwhich is determined from the conditions:

τSt=k·p-n·exp(E/RT)·lnRawhere

k is an empirical coefficient, characterizing the kinetics of the development area of physical contact between the joined surfaces of the workpieces, equal to 1.75·10-7sec;

R is the numerical value of the welding pressure, measured in MPa;

n is an empirical coefficient, characterizing the creep of material, equal to 1.2;

E - the activation energy, j/mol;

R is the universal gas constant, j/(K·mol);

T - temperature, K;

Ra- the numerical value of the roughness of the welded surfaces, measured in microns.

The relationship is established from the condition of convergence in the first stage of the welded surfaces by a distance commensurate with the height of the fact deformation of the ion reliefs, formed under the action of its own (internal) stresses. The selected time at a selected temperature ensures the creation in the contact clearance centers (foci), around which develops the processes occurring during the sintering of metals. Contact discontinuities formed in the collapse of Microsystem, the development of strain reliefs under the action of internal stresses are divided into smaller ones that are commensurate with the height of substructural relief and heal due to viscous flow of a substance matrix in time without the application of pressure during the second stage of welding.

An example of the method. Was welded cylindrical specimens with a height of 30 mm and a diameter of 16 mm alloy OT, in which the roughness of the welded surface is determined as equal to Ra=10 ám.

The process of diffusion welding lead in two stages by mode:

stage 1 - heating to welding temperature T=950°C, the welding pressure p=2 MPa support during the time τStcalculated by the dependence of τSt=k·p-n·exp(E/RT)·lnRa.taking for computing the estimated value of the coefficients k=1,75·10-7sec and n=1,2, values E=230000 j/mol, R=8,3 j/(K·mol) and T=1223 K.

Calculate the values of the coefficients k and n by studying the regularities of high-temperature deformation for a particular Titus the new alloy under compression by well-known methods, described in the book. Diffusion welding of titanium ed.: AS Karakozov, L. Orlov, V.V. Peshkov, V. Grigoriev, metallurgy, 1977, p.42-47. For each specific titanium alloy empirical coefficients k and n correspond to approximating the coefficients of the equation of the rate of creepε'=kpnexp(E/RT).

According to the numerical calculation of the exposure time is 20 minutes.

τSt=1,75·10-7-2-1,2·exp(230000/(8,3·1223)·ln 10≈1198 s≈20 minutes

stage 2 - the welding pressure is removed, the heat at the welding temperature continued for 40 minutes - the time required for the formation of the welded connection.

The method of diffusion welding of workpieces made of titanium alloy AT-1, including heating to welding temperature, the connection of workpieces in two stages in a period of time sufficient for the formation of physical contact between the joined surfaces of the workpieces at the first stage with the application of welding pressure and for the development of the volume interaction in the second stage without the application of welding pressure, characterized in that the first stage heating is carried out in the temperature interval α+β→β transformation and during BP is when τ Stwhich is determined from the condition: τSt=k·R-n·exp(E/RT)·lnRawhere
k is an empirical coefficient, characterizing the kinetics of the development area of physical contact between the joined surfaces of the workpieces, equal to 1.75-10-7;
R is the numerical value of the welding pressure, measured in MPa;
n is an empirical coefficient, characterizing the creep of material, equal to 1.2;
E - the activation energy, j/mol;
R is the universal gas constant, j/(K·mol);
T - temperature, K;
Ra- the numerical value of the roughness of the welded surfaces, measured in microns.



 

Same patents:

FIELD: metallurgy.

SUBSTANCE: "ЖС32" or "ЖС32МОНО" alloy is used for bonding of at least two part fragments from said alloy by diffusion conglomeration with application of 11 g/mm2 load in vacuum at 1320°C for 40 min to 1 hour.

EFFECT: high mechanical strength and accurate sizes.

7 dwg, 3 ex

FIELD: process engineering.

SUBSTANCE: invention may be used for production of semiconductor micromechanical devices, for example, sensors of integrated transducers. Laminate pack of glass and monocrystal silicon is compressed at specified force and heated. Compressed laminate pack is isothermally cured at temperature exceeding that of sealing. After cooling of compressed pack to temperature lower than that of sealing constant voltage is applied to the pack with subsequent current control unless its termination.

EFFECT: higher precision of sensors, normal mechanical strength.

FIELD: process engineering.

SUBSTANCE: invention relates to permanent connection of parts made of alloys based of titanium nickelid (TiNi, nitinol), particularly, to to diffusion welding using liquid phase. Proposed method comprises cleaning parts surfaces of oxides and bringing them in contact. Then, they are heated in vacuum and cooled down. Parts are heated to 990-1130°C and cured for 10 s - 5 minutes. In compliance with first version, parts are bonded via substrate from alloys based of titanium nickelid. Said alloy contains 0.05-0.2 wt % of oxygen. In compliance with second one or both parts contain 0.05-0.2 wt % of oxygen.

EFFECT: higher mechanical properties, higher process efficiency.

4 cl, 1 dwg, 1 tbl, 5 ex

FIELD: process engineering.

SUBSTANCE: invention relates to production of laminar composite material in diffusion welding of metal sheets. Proposed material is used for producing aircraft and spacecraft components with high strength requirements. Proposed method comprises assembling initial blanks into stack. Aluminium foil in laid between blank surfaces to be welded together in assembly of said stack. Aluminium foil thickness may not exceed 0.3 mm. Then, said stack is heated to apply pressure thereto for diffusion welding of blanks. In welding, blank surfaces to be welded together are subjected to aluminium cementation prior to reaching physical contact between said surfaces.

EFFECT: higher strength and quality of joint.

2 cl, 4 tbl, 1 ex

Diffusion joint // 2455138

FIELD: process engineering.

SUBSTANCE: inventions may be used in diffusion joints of components with nonplanar shape, particularly, aircraft engine parts. Firs component of pressure side with first joint surface and second component on rarefaction side with second joint surface are arranged to make butt joint on mandrel. Outline of mandrel first surface complies, at least, partially, with first component surface portion while mandrel second surface outline is aligned with second component portion. Components are jointed together at separate positions along their lengthwise line. First and second components are positioned together with mandrel at die assembly. Said surfaces are jointed by diffusion in furnace by applying uniform pressure along joint surfaces. Male and female dies may be jointed together by multiple fasteners with lower thermal expansion factor. Flexible pneumatic conveyor is arranged between male or female die and one of joint surfaces.

EFFECT: higher quality of joint.

46 cl, 23 dwg, 1 tbl

FIELD: technological processes.

SUBSTANCE: invention relates to equipment for welding with heating, in particular to installations for diffusion welding of semiconductors with dielectrics and may be used in radio engineering, electronic and instrument-making industry. Installation comprises heating chamber (1), heaters (2), current-conducting busbars (3), insulators (4) and packet device, which consists of system for compression of units-billets (5), lower (8) and upper (9) current-conducting plates. Bimetallic plate (11) is fixed in heating chamber (1) and is arranged from materials with various temperature coefficients of linear expansion. One end of metal insert (10) is connected to bimetallic plate (11), and its other end is installed between units-billets (5).

EFFECT: invention is aimed at improvement of quality of connected parts due to provision of required extent of vacuum.

2 dwg

FIELD: metallurgy.

SUBSTANCE: invention can be used for welding of multi-layered items consisting of martensitic steels of 12X13 type and having magnetic properties, and austenitic steels of X18H10T type, which are not susceptible to magnetisation, namely for welding of housings of magnetic conductors of step motors. In order to decrease the creep value of layers from martensitic steel, diffusion welding is carried out in two steps: First, welded surfaces are heated to the temperature of not more than 700°C; after that they are compressed with force of more than 2 kgf/mm2 and kept in such state for not less than 15 minutes. At the second step compression force is decreased to the value of less than 0.1 kgf/mm2, and heating temperature of welded surfaces is increased up to 1050-1100°C, and they are kept at this temperature for not less than 15 minutes. In order to accelerate diffusion processes, welded surfaces of workpieces from martensitic steels are covered before welding with galvanic nickel layer with thickness of not less than 1.5 mcm.

EFFECT: method provides obtaining of welded joints equal in strength at manufacture of multi-layered items and at maintaining the axial size of each layer.

2 cl, 1 dwg

FIELD: technological processes.

SUBSTANCE: invention may be used to manufacture shells from sheet billets of titanium alloy by superplastic moulding. Sheet billets are assembled in packet with account of rolling direction in them. Each half of packet is assembled from at least two sheet billets, which are installed one versus another with arrangement of angle between directions of rolling in them. Sheet billets are combined in each half of packet by means of pressure welding. Connection of billets in packet is realised by welding along perimetre. Forming of produced billet is executed by pressure of working medium generated in cavity of packet produced by its halves. In a particular case of method realisation, in process of each packet half assembly, between billets, having larger grain size, billets are arranged, which have smaller grain size, besides welding temperature is selected taking into account billets with smaller grain size. Billet having smaller grain size is preferably arranged to produce internal surface of shell. Connection of billets in both halves of packet may be executed simultaneously, for this purpose gasket is inserted between packet halves with anti-welding coating applied on it on both sides, for instance on the basis of boron nitride, and after connection of billets gasket is removed.

EFFECT: reduction of rolled sheet metal anisotropy impact at shell quality.

7 cl, 7 dwg, 1 tbl, 3 ex

FIELD: welding.

SUBSTANCE: method can be used while manufacturing of lamellar cell panel from titanium alloys. Honeycomb is manufactured from strip, subject to preliminary thermal processing by means of heating up to the temperature for 20-50°C higher the temperature of polymorphic transformation during 5-40 sec. Except strip for width of 2-4 of its thickness it is subject to deformation parallel to strip plane and it is shaped fringe region of sediment with fine-grained microstructure, and then perpendicularly to strip plane for restoration of geometrics of strip. It is implemented diffusion welding of honeycomb with panels.

EFFECT: heat-treated strip of honeycomb stably keeps steadiness during the process of diffusion welding, and fringe region of sediment provides receiving of high-quality connection, close by strength balance to main metal.

FIELD: welding jobs.

SUBSTANCE: invention can be used for jointing ceramic elements made from sintered non-oxide ceramics. The elements are brought in contact and jointed by diffusion welding in a low-deforming way, in the presence of protective gas and with a forced applied to form a monolith. Welding temperature makes at least 1600°C, preferably, over 1800°C, most desirable, over 2000°C. The method makes the elements to be jointed subjected to plastic strain less that 5%, and preferably less than 1%.

EFFECT: producing seamless monolith with shape complying with that of finished workpiece that allows rejecting subsequent mechanical processing.

19 cl, 7 dwg, 6 ex

FIELD: metallurgy.

SUBSTANCE: "ЖС32" or "ЖС32МОНО" alloy is used for bonding of at least two part fragments from said alloy by diffusion conglomeration with application of 11 g/mm2 load in vacuum at 1320°C for 40 min to 1 hour.

EFFECT: high mechanical strength and accurate sizes.

7 dwg, 3 ex

FIELD: process engineering.

SUBSTANCE: invention relates to electric welding of primarily thin-sheets articles from different-thickness and chemically inhomogeneous pipes. Pipes are aligned. Edges are arc tacked and annular seam is arc welded over pipe end face by short-time current pulses. Tacking and welding are made simultaneously by several fixed heat sources composed of torches or electrodes. Heat sources are spaced apart so that heat contact between live arcs is inhibited. Every heat source is connected separately to its power supply.

EFFECT: better geometry of welded structure and higher quality of weld joint.

1 ex

FIELD: process engineering.

SUBSTANCE: invention relates to oil and oil-refining industries and may be used in development of oil processing equipment, particularly, in assembly of large-sized metallic tanks, say, separators, settlers, oil storage tanks, etc. Proposed method comprises butt hidden-arc welding of metal sheets with forced feed of flux from above and below of weld seam. Then cylinders are rolled from welded sheets. Then butt is welded long the cylinders with forced feed of melt from above and below of weld seam to produce cylindrical shell. Cylindrical shells are arranged at rolls to make their end surfaces face each other. Butt hidden-arc welding of cylindrical shells is carried out with forced feed of flux from above and below of weld seam. Note here that arc zone is filled with the melt between the shells by feeding the melt from inside of shells. In welding the shells are rotated.

EFFECT: higher strength and quality of weld seam.

2 dwg, 1 ex

FIELD: process engineering.

SUBSTANCE: proposed method comprises applying the LF-vibrations by appropriate vibrators to in welding. Said LF vibrations are applied at frequency equal to intrinsic frequency of pipeline section with welded joint defined by define formula. Said frequency is calculated with allowance for pipeline section OD and ID, and spacing between the points of stiff attachment of pipeline section with welded joint.

EFFECT: higher quality of weld joint and metal near-seam layer.

2 dwg, 1 ex

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used for increasing wear resistance of outer cylindrical surfaces. Proposed method comprises arranging the article to be surfaced horizontally. Note here that two plates are fitted atop the article in symmetry about vertical and radially relative to the article. Said plates are made of heat-resistant non-metal. Spacing between said plates equals the width of a single built-up layer. Portion of surfacing metal is applied between said plates and treated by inductor. Melt hardened the article is turned through surfacing pitch. Then, first plate as seen along turning direction is moved to the place occupied by the second plate. Second plate is removed. Surfacing material is applied between surfacing layer and rearranged plate and processed by inductor. Then, surfacing cycles are repeated over the article circle. Now the built-up surface is turned to required diameter.

EFFECT: optimised surfacing.

3 dwg

FIELD: process engineering.

SUBSTANCE: invention may be used in welding complex structures of titanium alloys, in particular, of 3D panels. Before welding, content of hydrogen is defined in billet titanium alloy surface layer by spectral analysis. First, surfaces are degreased and dehydrated. Obtained values of hydrogen content are compared with that in parent metal. Obtained values may not exceed 0.0015%.

EFFECT: higher accuracy of estimation, ruled out porosity in seam metal, higher strength and reliability.

1 tbl

FIELD: process engineering.

SUBSTANCE: invention relates to machine building. Proposed method comprises placing the article in retainer for them to revolve with aligned article rotation axis and mirror axis. Spreader is arranged inside article inner cylindrical surface bottom section. Spreader is fixed relative to revolving article and with clearance relative to its surface. Then inductor is installed to start the article to revolve. The inductor is switched on to feed facing material gradually onto revolving surface to required thickness of facing layer over the entire surface area. Here speed of rotation equals that whereat facing material crumbling and melt spreading are prevented. After facing said inductor is switched off. Note that revolution is continued unless hardening of the melt. Now the built-up surface is turned to required diameter.

EFFECT: optimised process, higher quality of built-up layer.

1 dwg

FIELD: process engineering.

SUBSTANCE: invention maybe used in production of heat exchangers composed of tube plates connected to tubes by friction welding. Friction consumable rod 2 of friction tool revolves and is displaced into open end of tube 11 along tube axis, said tube being surrounded by tube plate 10. Ring 3 arranged behind friction rod 2 features OD exceeding friction rod diameter and is furnished with bead 4 to make transition between said ring and said friction rod. Ring 3 is pressed against surfaces of tube end 12 and that of tube plate 10. Said surfaces are softened to produced weld seam there between. Ring bead 4 features, at least, one section acting on end of tube and tube plate being welded together. Said section may be concave if seen from friction rod side, or have semicircular, or rectangular, or triangular cross section.

EFFECT: high quality circular weld seam.

5 cl, 2 dwg

FIELD: process engineering.

SUBSTANCE: invention may be used for making articles with inner cavities by explosion welding. Two three-layers stacks are composed with aluminium and copper-nickel plates arranged there between with preset thickness of layers to be welded by explosion. Anti-welding substance is applied to bottom copper layer surface. Hydraulic pressure is used to form inner cavities between copper layers of welded six-layer workpiece to be sintered to obtain intermetallide diffusion interlayers between aluminium and nickel layers. Now workpiece is heated to aluminium melting point to remove fused aluminium from its surface and cured at said point to transform aluminium residues in intermetallides.

EFFECT: continuous heat-resistant 50-70 mcm-thick intermetallide layer to resist high temperature in oxidising gases.

5 dwg, 1 tbl, 3 ex

FIELD: process engineering.

SUBSTANCE: invention may be used for making articles with inner cavities by explosion welding. Two three-layers stacks are composed with aluminium and copper-nickel plates arranged there between with preset thickness of layers to be welded by explosion. After explosion welding stack of produced three-layers stacks are composed with aluminium and copper-nickel plates arranged there between with preset thickness of layers and anti-welding composition applied thereto. After forming of inner cavities between copper layers, seven-layer workpiece is annealed to produce intermetallide diffusion layers between those of aluminium and nickel. Workpiece is heated to temperature exceeding aluminium melding point to remove aluminium from its surface and cured at said temperature.

EFFECT: high heat resistance and durability in oxidising gases.

5 dwg, 1 tbl, 3 ex

FIELD: metallurgy, namely metal welding, possibly butt welding of hot rolled steel strips designed for further cold rolling.

SUBSTANCE: method comprises steps of drawing together end edges of strips; welding them by passing electric current through them and upsetting them; determining value of welding current according to relation Iw = isp x V, where I w - welding current value, A; i sp - specific density of electric current equal to 0.52 -0.56 A/cub. mm; V - volume of melt metal of strip, cub. mm. Upsetting value after welding is determined according to relation Δ c = K x δ, where Δ c -upsetting value, mm; K - empiric coefficient equal to 1.45 - 1.75; δ - strip thickness, mm.

EFFECT: enhanced possibility for rolling welded joints due to optimal structure of metal in zone of welding joints.

1 ex

Up!