SU1787687A1 - Method of manufacturing compact billets from titanium alloy pipelines - Google Patents

Description

The invention relates to powder metallurgy, and in particular to methods for producing compact blanks with simultaneous compaction and sintering.

In powder metallurgy, various methods are known for producing compact blanks from metal granules, such as hot isostatic pressing, hot hydrostatic pressing, a combined process of compacting and stamping, hot isostatic stamping.

A known method of manufacturing products from hard-pressed metal powders, nickel-based powders, including filling the powder into a capsule, its evacuation. heating, uniaxial compaction to a density of 0.93-0.98, sludge with lateral extrusion and radial backing of at least 1.7 the yield strength of the material is sealed, heated and compacted by sludge under conditions of uneven compression with radial outflow of material in superplastic temperature and speed conditions deformation of the alloy with a maximum degree of compact deformation of at least 40% for the standard fraction and at least 50% for screenings. The capsule is sheathed into the shell and deformed together with it with a degree of compact deformation of at least 20% for the standard fraction and at least 30% for screenings with a radial support for the standard ¹ fraction of at least 0.5 of the axial force that goes to the joint deformation of the capsule and shells, and not less than 0.4 - for screenings. 1 zpf .. 1 tab. 1 ill.

division and subsequent firmware. The disadvantages of this method are: the complexity of the process, the need. the use of powerful forging and pressing equipment to create high: hydrostatic pressure and compacted material, the absence of isothermal conditions, which also contributes to an increase in required efforts.

The closest technical solution is the method of hot isostatic pressing (HIP) of granular titanium alloys, including filling granules into a capsule, evacuating, degassing, sealing, heating, compacting under conditions of comprehensive uniform compression, holding under pressure in isothermal conditions to obtain a finished compact. However, the known method has the following disadvantages: bottom

SU „n 1787687 A1 level of mechanical properties due to small non-uniformly distributed deformation and practically undeformed initial structure in zones corresponding to the central regions of the initial granules, sensitivity to foreign inclusions, a significant amount of which is in screenings, which are waste products of granular production and therefore not suitable for obtaining high-quality compacts by the GUI method; the use of sophisticated and expensive equipment - a gas thermostat: low productivity of the process, due to the long exposure for several hours under pressure, and the useful cycle time, i.e. holding at specified temperatures and pressure is .2025% of the duration of the entire cycle.

The aim of the invention is to increase the mechanical properties of compacts, the use of screenings to obtain compact billets, increase process productivity, simplify and reduce the cost of technology ......

This goal is achieved in that in the known method, which includes filling granules of a titanium alloy into a capsule, evacuating, degassing, sealing, heating and compacting under isothermal conditions, compacting is carried out by sedimentation under conditions of uneven compression with radial outflow of the material under temperature and speed conditions of superplastic deformation ( SPD) alloy on hydraulic presses. For compacts from granules of the standard fraction, the deformation should be at least 40% and at least 50% for compacts from screenings. For compacts from granules of the standard fraction having an ultimate degree of deformation of less than 40% and less than 50% for compacts from screenings, the capsule is sheathed in a shell providing a radial support for the standard fraction of at least 0.5 from the axial force P, which goes to the joint deformation of the capsule and shell and not less than 0.4 for screenings, provided that in order to obtain a high-quality compact with a level of mechanical properties exceeding the level of the ISU, the degree of deformation should be at least 20% for compacts from granules of a standard fraction and at least 30% for compacts from screenings.

The known GUI method combines a long-term effect of temperature and pressure, and after the formation of physical contact and setting of the granule surfaces, it is similar to diffusion welding carried out under creep conditions (constant stress and temperature), which leads to volumetric interaction and the formation of common grains at the granule interface. The HIP compaction is carried out by comprehensive uniform compression with shearless deformation of the peripheral zones of the granules and preservation of the original structure in the central zones of the granules. Surface defects and foreign inclusions are pressed into the product volume and are subsequently stress concentrators,

The proposed method of manufacturing compact billets from granules of titanium alloys was implemented as follows. The granules a + β of the VT23 titanium alloy of the standard fraction + 125-500 μm were compacted and the granules of the -125 μm fraction taken from the waste bin after magnetic and aerodynamic separation. G ranules of each fraction were poured into welded capsules made of 12Kh18N YuT steel.

The drawing shows a view of the capsule and shell for compacting granules. The item numbers in the figure correspond to: 1

- top cover with a hole for filling granules. 2 - bottom cover, 3 - shell, 4

- a stub, 5 - a shell.

Capsules with granules were evacuated: degassed, sealed by welding the plug with an electron beam. Then they were placed in a resistance furnace heated to a temperature of 850 ° C, kept in an oven 4

h. The deformation was carried out by flat unpolished dies of the ZhS6U alloy in an isothermal deformation unit heated to the optimum temperature of the alloy SPD mounted on a hydraulic press with a force of 1600 tp The optimum temperature-and-speed regime of the SPD of VT23 titanium alloy: T = 850 ° C, έ = 10 ~ ⁴ s' ¹ . The studies showed that for the granulated VT23 titanium alloy, the optimum temperature and speed regime of the SPD is: T = 850 ° C, έ = 10 ^_3 -10 ⁴ s. The value of the strain rate in the beginning at the end of the compaction process for various degrees of deformation is given in the table. The degree of deformation was calculated by the formula:

ro But where e is the average relative altitudinal deformation;

But - the initial height of the compact;

Hk - the final height of the compact;

ro is the initial density of the backfill.

The order of the strain rate of 10 ~ ³ s ” ¹ was realized on a press with a force of 1600, i.e. with a strain rate of 0.2 mm / s and corresponds to the SPD speed interval of granulated VT23 granular titanium alloy (table: examples 1-3, 6-8, 11-16, 19-24). Outrageous values of the strain rate in the order of 10 ¹ s ¹ were realized on a press with a force of 1000 i.e. with a strain rate of 13 mm / s (examples 4,9,17, 18, 25, 26). The compaction of the blanks from the granules of the standard fraction was carried out in the temperature and speed conditions of the SPD of the VT23 alloy with the ultimate degrees of deformation equal to 20.40 and 50% (examples 1-3), for compacts from screenings 30, 40, 60% (examples 6-8) .

To determine the effect of the strain rate on the quality of the compacts obtained by depositing capsules without a shell), compacting was carried out in the optimum temperature regime of the SPD of the VT23 alloy, but with strain rates not corresponding to the SPD speed range with the degrees of deformation of 60% (Example 4) for the standard fraction and 65% (example 9) for screenings, and for compacts obtained by precipitation of capsules in the shell with degrees of deformation of 20, 60% (examples 17, 18). for the standard fraction and 30, 65% (examples 25, 26) for plumb.

To determine the effect of radial support on) the quality of the workpieces from granules of the standard fraction and its limit value, providing a level of mechanical properties above the level of the ISU, was compacted in the temperature and speed conditions of the SPD alloy with various degrees of deformation and radial support less than 0.5 (example 11) equal to 0.5 (examples 12-15) and more than 0.5 (example 16) from the axial force going to joint deformation of the capsule with the material and the shell. For this, a capsule with granules of a standard fraction was sheathed in a shell with a wall thickness of 10, 20, 25 mm, respectively, given the value of the radial support. Similarly, capsules with screenings were sheathed in a shell with a wall thickness of 5, 10, 20 mm, providing a radial support respectively less than 0.4 (example 19), equal to 0.4 (examples 20-23) and more than 0.4 (example 24).

To compare the proposed method With the prototype spent ISU capsules with granules of the standard fraction (example 5) and screenings (example 10) according to the mode T = 850 ° C, the pressure in the container 1600 atm, exposure under pressure of 4 hours

Analysis of the quality of the workpieces depending on the conditions of compaction5 showed the following. Carrying out the compaction of a capsule without a shell under isothermal conditions and temperature conditions of SPD of a granular titanium alloy and with a degree of compact deformation of at least 40% for the standard fraction and at least 50% for screenings provides a level of mechanical properties higher than the properties of compacts obtained by the ISU for standard fraction 15 by 4.7-5.2% for Oe.2, by 3.9-4.5% for σ _β , by 1% for <5, by 34.5-51.4% for ψ, by

2,2-17,4% for KCU, and for compacts prepared from screenings, respectively 5,47,0% to Oo 2, in 4.7-6,3% for σ _Β. at 1% 20 for d. 23.8-38.4% for ψ, 1.8-3.5% for KCU. An increase in the degree of deformation above 40% for the standard fraction and above 50% for screenings does not lead to a noticeable increase in mechanical properties. The compacting of capsules without a shell in high-speed regimes that do not correspond to the SPD speeds of the alloy, with degrees of deformation of 60% for the standard fraction and 65% for screenings, leads to a decrease in the level of 30 mechanical properties below the level of the ISU. Compaction of capsules in the shell with strain rates not corresponding to the SPD rates of the alloy, with degrees of deformation of 20. 60% for granules of the standard fraction and 30. 35 65% for screenings compared to compaction of capsules in the shell and in the high-speed mode of SPD alloy leads to a decrease in the level mechanical properties below the level of the ISU. Compaction in the shell in the temperature and speed conditions of the SPD alloy for compacts from granules of the standard fraction having a maximum degree of deformation of less than 40% and for compacts from screenings, respectively, less than 50% with a radial support of at least 0.5 of the axial force and the degree of compact deformation at least 20% for the standard fraction and, accordingly, with a radial support of at least 0.4 and a strain of at least 30% for 50 screenings provides a level of mechanical properties above the level of the ISU. For the standard fraction, 0.7–4.6% for dp, 2, 1.4–2.7% for σ _β , 20–30% for <5, and 31.8_ 45.0% for y , by 13.0-21.7% for KCU, and for screenings by 4.8-7.0% for Cfo. 2. by 3.3-5.9% for σ _Β , by 0 .8-7.9% for ό, by 34.4-54.3% for ul by 1.8% for KCU. The degree of deformation for compacts from granules of a standard fraction of less than 20% and less than 30% for compacts 1787687 compacts from screenings leads to a decrease in the level of mechanical properties below the level of the ISU. Radial support of less than 0.5 for the standard fraction and less than 0.4 for screenings leads to a decrease in the level of mechanical properties below the level of the ISU. An increase in radial heading above 0.5 for the standard fraction and above 0.4 for screenings does not lead to a noticeable increase in properties.

Using the proposed method for producing compact blanks from granules of titanium alloys provides, in comparison with the prototype, the following advantages:

increase the mechanical properties of compacts;

the use of screenings (fraction less than 125 microns), which are irrevocable wastes of the granular production, to obtain high-quality compact billets with a level of properties comparable to the level of compacts from granules of the standard fraction in terms of strength characteristics and exceeding it in terms of plasticity;

an increase in productivity by 2-14 times, which increases with an increase in the overall dimensions of the capsules;

simplification and cheaper technology by eliminating the operation of hot isostatic pressing.

Chip Granules Way SPD speed mode T instrumental Strain rate, ε, s ε Example ^ 0.1 9 kg / mm ¹ kgf / mm ² G h i * Xi, kg / s ^a Standard- Offers 3.2-6.2 .10 “* 20 Ί. 105.1 108.8 8.3 16.1 4.0 may pulled Yes 8 S0 3.2-8.3-10 ’ 4ο 2 114.1 118.7 10.0 29.6 4.7 fraction 3.2-9.8-10- ’ fifty 3 114.7 118.0 10.1 33.3 5,4 100 2.2-8.1.10 60 4 105,2 106.0 .5.7 4.3 2.0 Not·. - - Famous - - 5 109.0 of, b 10.0 22.0 ’M Not 3.2-7.1-10- ’ thirty 6 98.1 101,2 10.8 20.3 4.3 Proposal Yes 850 3.2-9.8-10- ’ fifty 7 105,4 106.9 12.7 37,4-  5.8 being 3.2-10 ^ - 60 8 107.0 108,5 12.8 4t, 8 5.9 Screenings 1,2 -10-2 Not . 100 2.2-9.2-10- ’ 65 9 92.4 93.0 6.0 7.5 2.0 Famous 850 - • * 10 ' 1 (10.0 '102.1' 12.7 ' 30,2 5.7 ' Table continuation Obols ^ ka Granules Value Speed T tool Speed .ε, At- Lo.1 ί, 9, • xi, radial no mode cop, * C deformations % measures kgf / mn ^g kg / mm ^s ' X kgcm / cm ^a moto under spd ε, “-’ it's time from p Standard- <0.5 P 3.2-6.1.10- ’ 20 eleven 106.0 108.8 9.8 19.6 4.2 3.2-5.5'i0 ~ ’ 10 12 106.3 108,2 7.3 19.5 4.2 fraction = 0.5 P Yes 850 3.2-6.2.10- ’ 3.2-8.3.10- ’ 20 40 thirteen 14 109.8 110.0 115.3 115,2 10.3 10,2 31.2 31.9 5,6 5,4 3.2-3.8-10- " fifty fifteen 114.0 116.7 10,2 29.0 5.2 - -. 3.2-9.9-10 '’ fifty 1b 114.5 118.2 10.3 33.0 5.5 > 0.5 P Not 100 2.2-4.0-10 ' 20 17 103, '2 103.3 5.7 ' 7.3 2,8 there is 2.2-8.1-10 60 18 107.1 107.5 7.6 11.1 3.3 <0.4 P 3.2> 7L Ί0- * zo 19 99.1 101.6 11.6 27.9 4.4 3.2-6.2Ί0 “ ⁵ 20 20· 98.7 101.3 9,4 26.1 4.2 Screenings 3.2-7.1-10- ’ 'thirty 21 104.8 105.5 13.7 46.6 5.8 • oh, p Yes 850 3.2-3.8-10- ’ fifty 22 '08, 9 107.0 12.8 40.7 5.7 3.2 40 "- 60 23 107.G. 108.1 13,2 40.6 5.8 1,240-a * _and" 60 24 U7.5 108,4 13.3 40.8 5.9 > OD p Not 100 2,2-4 / 6-ΙΟ ' ¹ thirty 25 92.2 93.8 6.3 U.9 3,1 2.2-9.2 .10 ’’ 65 26 94.1 ' 95.7 6.2 17.5 3.3

Claims (2)

Claim 1. A method of manufacturing compact for ¹ cooking from granules of titanium alloys, comprising filling granules into a capsule, evacuating, degassing, sealing, heating and compacting in isothermal conditions, characterized in that, in order to increase the mechanical properties of compacts obtained from granules of different particle size distribution including screenings, increasing process productivity, simplifying and reducing the cost. The technology and compaction are carried out by sedimentation under conditions of uneven compression with radial outflow of material in temperature and speed conditions of superplastic deformation of the alloy with a maximum degree of compact deformation of at least 40% for the standard fraction and at least 50% for screenings. 2: The method according to claim 1, characterized in that, in order to obtain high-quality compacts having an ultimate degree of deformation of less than 40% for the standard fraction and less than 50% for screenings, the capsule is sheathed into the shell and deformed together with it with the degree of deformation a compact of at least 20% for the standard fraction and at least 30% for screenings with radial support for the standard fraction of at least 0.5 of the axial force that goes to joint deformation of the capsule and shell, and at least 0.4 for screenings. .->: