Treatment method of titanium-nickel alloys with nickel content of 49-51 at % with shape memory effect and reversible shape memory effect (versions)

FIELD: metallurgy.

SUBSTANCE: invention is related to the treatment method of titanium-nickel alloys with nickel content of 49-51 at % with shape memory effect and reversible shape memory effect (versions). The above method involves thermomechanical treatment combining deformation and annealing after deformation in the temperature range of 350-500°C till the accumulated deformation degree of 25-40% annealing after deformation in the temperature range of 350-500°C is obtained; thermomechanical guiding of shape memory effect (SME) and reversible shape memory effect (RSME) the annealing after deformation is performed during 1.5-10 h, and guiding of SME and RSME is performed by means of loading of the alloy as per the bending pattern with deformation of 12-20% at temperature Ak -10 ≤ T ≤ Ak +10, exposure at that temperature during 0.25-5 minutes, cooling to the end temperature of martensitic transformation; after that, alloy is unloaded and thermally cycled in the temperature range of Ak to -196°C with exposures during 0.25-5 minutes. According to the second version of the method, after the deformation is completed, first, recrystallisation annealing is performed at the temperature of 700°C during 0.20-120 minutes, and then, annealing after deformation is performed.

EFFECT: improving functional properties of the alloy.

2 cl, 1 dwg, 3 ex

 

The present invention relates to metallurgy, namely thermomechanical processing of alloys with shape memory (PCF), and can be used in any industry and medicine, where to apply materials with shape memory effect (APF). Actually APF is implemented when the form is reset when heated after deformation martensite stress and/or deformation of the reorientation of the existing cooling martensite or martensite stress. Reversible APP (OAPF) is spontaneous reversible shape change during thermal Cycling through the range of martensitic transformations.

SPF - functional materials. The most important service characteristics include the following: the value of reversible deformation εrthe magnitude of the reversible effect εTWreactive stress σr, the characteristic temperature of martensitic transformations Mn(the temperature at which the martensite transformation), Mto(the temperature of the end of martensitic transformation), TR(temperature R-transformation), Andn(temperature of the beginning of the reverse martensite transformation), Andto(the temperature of the end of the reverse martensite transformation).

Functional properties (FS) PCF, including options APP and OAPF, determined by the composition and structure of the alloy. izvestno, thermal and thermomechanical treatment are effective ways of regulating structures, and, consequently, FS SPF (V.Brailovski, S.Prokoshkin, P.Terriault, F.Troshu (Ed.), Shape Memory Alloys: Fundamentals, Modeling and Applications, Québec, Canada, 2003, 844 p.).

Hover APP and OAPF are largely influenced by the parameters of external influences: schematic of loading (tension - compression, torsion, bending), the degree of deformation, load, etc.

Known methods of thermomechanical processing of titanium alloys, Nickel to improve their mechanical and functional properties. For example, the method of identifying the effects of shape memory alloys based on titanium nickelide (RF patent No. 2115760, C22F 1/18, 20.07.1988) includes hardening, deformation and subsequent heating.

There is also known a method of manufacturing a hyperelastic alloy Nickel-titanium (JP 6065741, C22F 1/10), according to which the alloy containing at 50-51.% Ni, the rest - Ti, are annealed, cold-formed 15-60%, and then define the shape and heated to 175-600°C.

In the known methods is implemented by only one mechanism of increasing complex properties - creating dislocation Polynesians substructure.

There is a method of targeting APP and OAPF [Whitelouis, Haapanen, Ostankevych. The influence of deformation degree on the shape memory effect and the structure of martensite in nickelide titanium. Dilatometric effects martensite is of reversine. FMM, 1996, volume 81, issue 3, pg.107-116 (gsverdlovsk)], according to which in the alloy Ti-50.5% of Ni, subjected to recrystallization annealing at 800°C, EPF and OAPF made by rolling and stretching. Deformation was induced at room temperature, which corresponds to a two-phase condition B2+B19', with degrees induced deformation εt=4,7-16%. Maximum reversible strain εr=4,3% was obtained when εt=12%, the maximum value of OAPF εTW=1,6% at εt=16%. In the known method is implemented only one mechanism for improving properties - pointing ("training") APP.

On the influence of the exposure time during aging on the functional properties no information available.

As the closest analogue (prototype) selected guidance method APP and OAPF in alloys Ti-50.0 at.% Ni and Ti-at 50.7 at.% Ni, subjected to cold rolling with a true strain e=0,3 (ε=30%) with poslerevolyutsionnye by annealing (PDO) in the temperature range at 200-500°C, 1 h at 700°C, 30 min Hover APP and OAPF carried out according to the scheme of bending around mandrels of different diameter with full-induced deformation εt=3-10% at fixed temperatures near TRand Mndefined by the method of differential scanning calorimetry (DSC). After elastic unloading was determined induced deformation εiand after heat - set the th ε r[Incan KE Study the relationship between structure and functional properties of thermo-treated alloys with shape memory on the basis of Ti-Ni. The dissertation on competition of a scientific degree of candidate of technical Sciences. Moscow, MISiS, 2006]. The value OAPF εTWnot determined.

The disadvantage of this method is the relatively low values of reversible deformation APP εr=8% for the alloy Ti-50.0 at.% Ni (s) and εr=8,5% (s-116) for the alloy Ti-to 50.7 at.% Ni. In the known method implemented two mechanisms to improve functional properties: create Polynesians patterns (in the range of DTP 400-500°C) and the guidance APP.

In all known methods guidance APF carried out at a fixed temperature near the temperature of Mnor TRi.e. if the structure of martensite cooling. In the deformation process in the residual austenite is formed oriented martensite voltage and a reorientation of martensite cooling.

A large number of publications devoted to the study of the influence of parameters of external influences on the parameters APF and especially OAPF showed a considerable interest of researchers to this question, but the results of these studies are quite contradictory.

The reasons for this lie in the omission of the following are essential in the century

First, almost all published studies there is no information about the original (before pointing OAPF) the structure of the alloy used in the study, it can only indirectly be judged by the driven modes of heat treatment. At the same time, as the analysis of literature data, it is the initial structural state of the alloy is an important determinant of the resulting complex functional properties of the PCF.

Secondly, overlooked the importance of the source phase state and the possibility of implementing different mechanisms (sequences) transformations hover APP and APAP.

The objective of the invention is the improvement of functional properties of alloys with APP Ti-Ni content nicely 49-51 at.% due to the combined effect of the following factors: hardening during aging (only for alloys with Ni content above equiatomic), guidance APF during the deformation process B2→R→B19'transformation and increasing the degree of deformation hover APP.

This object is achieved in that the alloy is a titanium-Nickel APP with a Nickel content of from 49 to 51 at.% Ni is subjected to processing including pre-quenching and subsequent thermomechanical processing total accumulated deformation rate of 25-40%, then subjected to PDO in intervale temperatures of 350-500°C, unlike the prototype for 1.5-50 is (option 1). In the specified temperature range in parallel there are two processes: polygonization and aging. The result of this treatment, the alloy may have developed nanoscale Polynesian substructure with nanophase padding, which is implemented through released during the aging phase of Ti3Ni4.

The task is achieved by the fact that the alloy after TMO is subjected to recrystallization annealing at 700°C for 0.25 to 120 min, and then subjected to PDO in the temperature range of 350-500°C for 1.5-10 hours (option 2). The proposed method provides receiving of recrystallized structure with padding particle phase Ti3Ni4released during aging.

The task is achieved by the fact that the alloy subjected to TMO for option 1 and tempering for option 2, canevaluate in the region of existence of stable phase B2-austenite and benevolent state is cooled below the temperature of the end of martensite transformation Mto(the region of existence of stable martensite), after which the material is unloaded and thermocycling in the temperature range between the temperature Andtoand - 196°C. That is, the proposed method over APF is carried out during the deformation interval transformation B2→R→B19'. The proposed heat treatment for option 2 provides the receiving PE is kristallizovannyj structure with padding particle phase Ti 3Ni4released during aging.

The task is achieved by the fact that when you hover APP alloy is deformed according to the scheme of the curve with degrees of deformation in the range of 12-20%.

This goal is achieved by the fact that the time when senegalian is 0.5-5 minutes

The proposed method by conducting TMO for option (1) allows to realize the value of reversible deformation εr=14.8 and values OAPF εTW=2,5%. The proposed method by conducting TMO for option (2) allows to realize the value of reversible deformation εr=14.5% and values OAPF εTW=5,4%.

Thus, the proposed set of features of the process allows to obtain a new effect, leading to a significant improvement in the functional properties of PCF. This allows to make a conclusion on the conformity of the proposed method the criterion of "inventive step".

The method is as follows. In the first stage, the initial harvesting, in particular, from an alloy of titanium-Nickel (in the range of compositions from Ti - 49 at.% Ni to Ti - 51 at.% Ni) of recrystallized structure (i.e., after recrystallization annealing) is subjected to plastic deformation, in particular, for example, by drawing or rolling over multiple passes to obtain the total accumulated strain is 25-40% in the temperature range 25-600°C.

The choice of the criminal code is related to the range of compositions of the alloys Ti-Ni due to the fact, when the Ni content is below 49 at.% Ni in the alloy is present in a large number of globular phase composition of Ti2Ni (produced in the smelting process), which strongly affects all FS properties. In the alloy containing Ni above 51 at.% Ni in the alloy in the aging process is the phase of Ti3Ni4very large size and in large quantities, which limits the amount of martensitic transformations.

Deformation at temperatures below 25°C can lead to fracture of the material due to the low technology of plasticity, and the use of temperatures above 600°C is impractical due to the processes of dynamic recrystallization, which ultimately leads to lower total accumulated strain.

The next stage (for option 1) includes both PDO, aging and task forms. The material is subjected to annealing in the temperature range of 350-500°C for 1.5-10 am, the Efficiency of annealing at a temperature below 350°C is reduced due to the impossibility of obtaining advanced Polynesians substructure, weak processes of aging (in alloys saakvitne composition), as well as the impossibility of obtaining a given shape. Carrying out far above 500°C not effective due to the development of the processes of recrystallization and reduce the intensity of the aging process (Fig.1). The time when aged less than 1.5 h dostatochno for the selection phase of Ti 3Ni4the number of influencing the increase in FS. The exposure time of more than 10 h does not lead to further increase of εrand, in addition, is-low-tech.

The next stage (option 2) involves recrystallization annealing at 700°C for 0,20-120 min and subsequent annealing in the temperature range of 350-500°C for 1.5-10 hours; during the second annealing processes are aging and task forms.

The efficiency of annealing at a temperature below 350°C is reduced due to poor process of aging, as well as the impossibility of obtaining a given shape. Carrying out far above 500°C not effective due to the development of the processes of recrystallization and reduce the intensity of the aging process. The time when aged less than 2 hours is not enough to highlight phase Ti3Ni4the number of influencing the higher values of FS. The exposure time of more than 50 h does not lead to further increase of εrand, in addition, is-low-tech.

The material is subjected to annealing in the temperature range of 350-500°C for 1.5-50 hours the Efficiency of annealing at a temperature below 350°C is reduced due to the impossibility of obtaining advanced Polynesians substructure, weak processes of aging, as well as the impossibility of obtaining a given shape. Carrying out far above 500°C is inefficient, because the development process is in recrystallization and reduce the intensity of the aging process. The time when aged less than 1.5 hours is not sufficient for the selection phase of Ti3Ni4the number of influencing the increase in FS.

The next step is actually putting APP. Sample canevaluate on a special mandrel with deformation rate of 12-20% to the temperature T, which is in the interval Ato- 10≤T≥Andto+10, maintained at this temperature benevolent state of 0.25-5 min, slowly cooled to liquid nitrogen temperature - 196°C, maintained at this temperature benevolent state of 0.25-5 minutes, then release. Measure induced deformation εi. The sample is gradually heated to a temperature Andto'which is slightly higher initial temperature Andto(to bringing APF). Measure the residual strain εf. Determine the amount of reversible deformation εrif.

The choice of temperature range Andto- 10≤T≤Andto+10 due to the following reasons. Senegalian material should be in the region of existence of stable B2-austenite: at temperatures below Andto- 10 starts the R-transformation, and senegalian this will partly be due to the reorientation of the resulting R-phase, which will not allow to get the maximum possible value of εr. Senegalian material is use temperature And to+10 can lead to plastic deformation B2-austenite, resulting in increased residual value (irreversible) deformation εfand, as a consequence, the decrease of εr.

Senegalian material with a degree of deformation less than 12% and more than 20% allows to realize the value of εrnot more than 10% (figure 1).

The exposure time of less than 0.25 min is not enough for heating/cooling the alloy to the desired temperature; the exposure time for more than 5 min does not increase the achieved result and, in addition, is-low-tech.

Example No. 1 of a specific implementation.

Wire with a diameter of 0.45 mm alloy Ti - 50.7% of Ni is subjected to the homogenization annealing at 700°C for 20 minutes and Then the wire is subjected to drawing at a temperature of 25-400°C for 5-6 passes to a diameter of 0.3 mm (i.e. the total accumulated deformation ratio is 30%). The wire clear of graphite lubricants, cut-to-length harvesting and are annealed in a muffle furnace at a temperature of 430°C for 10 hours, the Samples are fixed on a special cylindrical mandrel with a diameter of 1.5 mm and bent around a mandrel at full turn at a temperature of 37°C (the total induced deformation εt15%); maintained at this temperature for 30 sec. Sample on the mandrel gradually cooled to a temperature of - 196°C and vyderjivaut this temperature for 30 s, then the sample is released from the mandrel. Measure induced deformation εishe 14,8%). Next, the sample is gradually heated to a temperature Andto'=45°C and measure the amount of residual deformation: εf=0%. The sample is cooled to a temperature of - 196°C and measure the value OAPF.

The result is the value of the reversible deformation εr=14,8%; the amount of OAPF εTW=2,0%.

Thus, the proposed method allows to implement complex properties unattainable by the application of known methods.

Example # 2 of a specific implementation.

The source material is a wire with a diameter of 0.45 mm alloy Ti - 50.7% of Ni. The wire is subjected to the homogenization annealing at 700°C for 20 minutes and Then the wire is subjected to drawing at a temperature of 25-400°C for 5-6 passes to a diameter of 0.3 mm (i.e. the total accumulated deformation ratio is 30%). The wire clear of graphite lubricants, cut into dimensional direct procurement and annealed at 700°C for 20 minutes, the Oxide layer is removed by etching. In a special matrix form patterns and are annealed in a muffle furnace at a temperature of 430°C for 10 hours, the Samples are fixed on a special cylindrical mandrel with a diameter of 1.5 mm and bent around a mandrel at full turn at a temperature of 37°C (the total induced the deformation is then ε t15%); maintained at this temperature for 3 minutes, the Sample on the mandrel gradually cooled to a temperature of - 196°C and kept at this temperature for 3 min, after which the sample is cut off from the mandrel. Measure induced deformation εi: it is equal to 14.5%). Next, the sample is gradually heated to a temperature Andto'=45°C and measure the amount of residual deformation: εi=0%. The sample is cooled to a temperature of - 196°C and measure the value OAPF.

The result is the value of the reversible deformation εr=14.5 percent. Value OAPF εTW=5,4%.

The proposed method allows to implement complex properties unattainable by the application of known methods.

Example No. 3 of specific performance.

Wire with a diameter of 0.45 mm alloy Ti - 50,0% Ni is subjected to the homogenization annealing at 700°C for 20 minutes and Then the wire is subjected to drawing at a temperature of 25-400°C for 5-6 passes to a diameter of 0.3 mm (i.e. the total accumulated deformation ratio is 30%). The wire clear of graphite lubricants, cut-to-length harvesting and are annealed in a muffle furnace at a temperature of 480°C for 1.5 hours, the Sample is fixed on a special cylindrical mandrel with a diameter of 1.5 mm and bent around a mandrel at full turn at a temperature of 45°C (total induced deformation εt 16%); maintained at this temperature for 30 sec. Sample on the mandrel gradually cooled to a temperature of 0°C and maintained at this temperature for 30 s, after which the sample is released from the mandrel. Measure induced deformation εi: it is equal to 11.9%). Next, the sample is gradually heated to a temperature Andto'=50°C and measure the amount of residual deformation: εf=0%. The sample is cooled to a temperature of 0°C and measure the value OAPF.

The result is the value of the reversible deformation εr=7,4%; the amount of OAPF εTW=4,5%.

The proposed method allows to implement complex properties unattainable by the application of known methods and exceeding crystallographic resource lattice deformation in the martensitic transformation. Structural mechanism of the obtained effects requires a special study.

1. Method of processing titanium alloys Nickel Nickel 49-51 at.% with shape memory effect and reversible shape memory effect, including thermomechanical processing, combining deformation and roledefinitions annealing in the temperature range of 350-500°C to obtain the accumulated strain is 25-40% and poslerevolyutsionnogo annealing in the temperature range of 350-500°C, thermo-mechanical guidance of the shape memory effect (APF) and reversible shape memory effect (OAPF), otlichayushiesya, what roledefinitions annealing is carried out for 1.5 to 10 h, and guidance APP and OAPF carried out by samevolume alloy according to the scheme of bending deformation 12-20% at temperaturesto-10≤T≤Andto+10, holding at this temperature for 0.25 to 5 min, cooling to the temperature of the end of martensite transformation, after which the alloy unload and thermocycling in the temperature range of from atoto -196°C With exposure times of 0.25-5 minutes

2. Method of processing titanium alloys Nickel Nickel 49-51 at.% with shape memory effect and reversible shape memory effect, including thermomechanical processing, combining deformation and roledefinitions annealing in the temperature range of 350-500°C to obtain the accumulated strain is 25-40% and poslerevolyutsionnogo annealing in the temperature range of 350-500°C, thermo-mechanical guidance of the shape memory effect (APF) and reversible shape memory effect (OAPF), characterized in that after deformation, first carry out recrystallization annealing at 700°C for 0,20-120 min, then hold roledefinitions annealing for 1.5-10 h, and guidance APP and OAPF carried out by samevolume alloy scheme bending deformation 12-20% at temperaturesto-10≤T≤Andto+10, holding at this temperature for 0.25 to 5 min, cooling to the temperature of the end of the martensite prevremeni is, then the alloy unload and thermocycling in the temperature range of from atoto -196°C With exposure times of 0.25-5 minutes



 

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EFFECT: the invention ensures production of the uniform fine-grained structure and a high level of general physical-mechanical properties of the blank and the item as a whole.

2 ex

FIELD: non-ferrous metallurgy; methods of thermal treatment of items or blanks made out of the two-phase titanium alloys titanium alloys.

SUBSTANCE: the invention is pertaining to the field of metallurgy, in particular, to the method of thermal treatment of an item or blanks made out of the two-phase titanium alloys titanium alloys. The offered method of thermal treatment of an item or a blanks made out of the two-phase titanium alloys provides for their heating, seasoning and chilling. At that the item or the blank is heated up to the temperature of (0.5-0.8)tag , where tag is the temperature of the alloy aging, and chilling is conducted from -10 up to -20°С at simultaneous action of a gas current and an acoustic field of an acoustical range frequency with a level of the sound pressure of 140-160 dB. The technical result is the invention ensures an increased strength of items or blanks at keeping the satisfactory plastic properties.

EFFECT: the invention ensures an increased strength of items or blanks at keeping the satisfactory plastic properties.

7 cl, 1 dwg, 1 tbl, 1 ex

FIELD: metallurgy, namely processes for forging titanium alloys and blank of such alloy suitable for forging.

SUBSTANCE: method comprises steps of preparing blank and forging it. Forging is realized at providing mechanical hardening factor equal to 1.2 or less and at difference of hardness values between central (along width) zone and near-surface zone equal to 60 or less by Vickers. Factor of mechanical hardening is determined as HV(def)/HV(ini), where HV(ini) - hardness of titanium alloy blank before forging; HV(def) -hardness of titanium alloy blank after forging at forging reduction 20%. Forging may be realized at deformation rate from 2 x 10 -4 s -1 to 1s-1 while keeping relations (T β - 400)°C ≤ Tm ≤ 900°C and 400°C ≤ Td ≤ 700°C, where Tβ (°C) -temperature of β-phase transition of titanium alloy, T m(°C) - temperature of worked blank; Td(°C) - temperature of die set. Blank has factor of mechanical hardening 1.2 or less and difference of hardness values between central (along width) zone and near-surface zone equal to 60 or less by Vickers.

EFFECT: possibility for forging titanium alloy blanks at minimum difference of material properties along depth, simplified finishing of blank surface after forging, reduced cracking of blank material, good workability of blank with favorable ductility and fatigue properties.

8 cl, 5 tbl, 6 dwg, 4 ex

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.

EFFECT: the invention ensures production of a brick out of the high-strength titanium alloy having a super pliability, excellent fatigue characteristics and moldability.

7 cl, 7 dwg, 21 tbl, 2 ex

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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