Manufacturing method of Ti6242 compressor drum

Abstract

A Ti6242 compressor drum manufacturing method comprises the following steps that an alpha + beta state Ti6242 bar serves as a raw material to be upset into a cake blank, the cake blank is machined into different shapes to be forged into a plurality of drum test pieces, and the multiple drum test pieces have different equivalent strain; carrying out solid solution and aging treatment on the drum test piece; obtaining an equivalent strain distribution cloud picture of the drum test piece through test and / or simulation calculation; cutting samples with different equivalent strain for mechanical property testing and microscopic structure analysis, and determining equivalent strain constraints meeting the mechanical property and the structure property; and the shape of the cake blank and the forging procedure are adjusted according to equivalent strain constraint, and a compressor drum finished product is obtained through forging. According to the method, the Ti6242 compressor drum with the uniform basket structure can be obtained, the comprehensive performance of the compressor drum is improved, and the reliability and economical efficiency of an engine are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engines, and particularly relates to a Ti6242 compressor drum manufacturing method. BACKGROUND

[0002] The engine of commercial wide-body technology has high working temperature and large working load. The high-temperature and high-stress working conditions of the compressor assembly in the engine put higher performance requirements on the performance of parts. At present, Ti6242 (TA19) alloy has good high-temperature mechanical properties, creep resistance and fatigue durability, and therefore can be used to manufacture compressor disc parts and drum cylinders and the like. The conventional process of Ti6242 is alpha + beta forging. Under this process condition, the titanium alloy organization mainly alternately distributes in the form of alpha phase and beta phase organization in layered sheets, and can be used for service conditions at about 200 DEG C. However, under higher temperature conditions, the alpha + beta forging organization cannot meet the performance requirements of high-temperature strength, thermal creep resistance, fracture toughness and stress-rupture sensitivity. Further, the drum cylinder manufactured by Ti6242 needs to be welded with a titanium alloy part having a basket weave organization, and the Ti6242 drum cylinder should also have a basket weave organization to achieve better organization uniformity, but the alpha + beta forging process cannot meet the requirements of this organization form. Therefore, it is of positive significance to further improve the overall performance of the aero-engine to provide a forging method capable of improving the high-temperature performance of Ti6242 alloy and forming a basket weave organization. SUMMARY

[0003] The application aims to provide a Ti6242 compressor drum manufacturing method, and improve the high-temperature mechanical properties of the compressor drum.

[0004] According to an embodiment of the application, a Ti6242 compressor drum manufacturing method is provided, comprising the following steps: providing alpha + beta state Ti6242 bars, upsetting the bars into patty blanks after heat preservation at 40 DEG C below the phase transition point for 100 min ± 5 min, the final forging temperature being not lower than 800 DEG C, and air cooling; processing a plurality of the patty blanks into different shapes, respectively heating the patty blanks to 25 DEG C above the phase transition point by using soft sleeves, heat preservation for 1 h ± 5 min, forging a plurality of drum test pieces having different equivalent strains, the final forging temperature being controlled to be not lower than 960 DEG C, and water cooling; performing solid solution treatment and aging treatment on the drum test pieces; obtaining strain distribution cloud maps of the plurality of drum test pieces by using tests and / or simulation calculation; cutting samples in regions having different equivalent strains to perform mechanical property tests and microstructure analysis; determining an equivalent strain range meeting the mechanical property and organization requirements of the compressor drum to obtain equivalent strain constraints; adjusting the shapes of the patty blanks and the forging process according to the equivalent strain constraints, and forging a compressor drum finished product, the organization strain of the compressor drum finished product meeting the equivalent strain constraints.

[0005] Ti6242 alloy is a near α titanium alloy, which has a high content of Al element. Compared with β titanium alloy, Ti6242 is more likely to generate coarse α phase along the grain boundary in β forging, which will cause adverse effects on the mechanical properties of the material, such as static strength and fatigue performance. The method controls the equivalent strain of the titanium alloy during the forging process, so that the flat and coarse α phase structure along the grain boundary is broken, and finally a uniform basket structure is formed, which can effectively improve the high-temperature mechanical properties and service life of the Ti6242 compressor drum.

[0006] Further, in some embodiments, the method for determining the equivalent strain constraint is: cutting samples from regions with different equivalent strains for mechanical property testing, fitting the test results of the mechanical properties with the equivalent strain to obtain an equivalent strain-strength function, determining the range of equivalent strain according to the mechanical property requirements of the compressor drum to obtain a first constraint condition; verifying the microstructure characteristics of the samples within the first constraint condition to obtain the range of equivalent strain that meets the organizational requirements of the compressor drum as the equivalent strain constraint.

[0007] Further, in some embodiments, the transfer time of the water cooling treatment of the drum test piece is not more than 45s.

[0008] Further, in some embodiments, the temperature of the solid solution treatment is 25℃ below the phase transition point, the holding time is 1h±5min, and the air cooling is performed.

[0009] Further, in some embodiments, the temperature of the aging treatment is 595±6℃, the holding time is 8h±15min, and the air cooling is performed.

[0010] Further, in some embodiments, when cutting samples on the drum test piece, at least three samples with different radial positions are cut at the same axial position.

[0011] Further, in some embodiments, when cutting samples on the drum test piece, at least four samples with different axial positions are cut at the same radial position.

[0012] Further, in some embodiments, the mechanical property test includes chordwise strength test perpendicular to the grain flow line and axial strength test parallel to the grain flow line.

[0013] Further, in some embodiments, the method for processing the plurality of the cake blanks into different shapes is machining the cake blanks.

[0014] Further, in some embodiments, the cake blank is obtained by three or four fire processing of the Ti6242 bar. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1aFigure 1 is a schematic diagram of the cross-sectional structure of a cake a in one embodiment;

[0016] Figure 1b Figure 2 is a cloud plot of the equivalent strain distribution during forging of a drum test piece a in one embodiment;

[0017] Figure 1c Figure 3 is a schematic diagram of sampling locations for a drum test piece a in one embodiment;

[0018] Figure 2a Figure 4 is a schematic diagram of the cross-sectional structure of a cake b in one embodiment;

[0019] Figure 2b Figure 5 is a cloud plot of the equivalent strain distribution during forging of a drum test piece b in one embodiment;

[0020] Figure 2c Figure 6 is a schematic diagram of sampling locations for a drum test piece b in one embodiment;

[0021] Figure 3 Figure 7 is a chord-wise equivalent strain-strength distribution plot in one embodiment;

[0022] Figure 4 Figure 8 is a chord-wise and axial equivalent strain-strength distribution plot in another embodiment;

[0023] Figure 5 Figure 9 is a metallographic photograph of a microstructure with an equivalent strain of 0.625 in one embodiment;

[0024] Figure 5 Figure 10 is a metallographic photograph of a microstructure with an equivalent strain of 0.625 in another embodiment;

[0025] Figure 5 Figure 11 is a metallographic photograph of a microstructure with an equivalent strain of 0.875 in one embodiment;

[0026] Figure 5 Figure 12 is a metallographic photograph of a microstructure with an equivalent strain of 0.875 in another embodiment;

[0027] Figure 5 Figure 13 is a metallographic photograph of a microstructure with an equivalent strain of 1 in one embodiment;

[0028] Figure 5 Figure 14 is a metallographic photograph of a microstructure with an equivalent strain of 1 in another embodiment;

[0029] Figure 5 Figure 15 is a metallographic photograph of a microstructure with an equivalent strain of 1.2 in one embodiment.

[0030] The above embodiments are intended to make a detailed description of the present application so that those skilled in the art can understand the technical concept of the present application, and are not intended to limit the present application. For the sake of brevity, the structures in the above drawings are only schematically drawn with respect to the technical features of the present application, and the complete structures and all details are not strictly drawn according to the actual proportions. DETAILED DESCRIPTION

[0031] The present application will be further described in detail by specific embodiments in conjunction with the drawings.

[0032] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that the phrase in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of one another. Those skilled in the art will recognize that the embodiments of the present application can be combined with other embodiments in a manner that is not structurally inconsistent. The terms "first", "second", and the like in the description do not necessarily connote any relative importance or particular order of the described features, structures, or characteristics. The term "a plurality" in the description means at least two.

[0033] The compressor drum made of Ti6242 alloy (Ti-6Al-2Sn-4Zr-2Mo alloy, domestic brand TA19) has good mechanical properties and welding properties, and has good fatigue durability and creep properties at above 200°C, and has been well applied in the manufacture of narrow-body aircraft engine. However, for high-power wide-body aircraft engines, due to the increase in thrust requirements, the working load and temperature of the engine are further increased, and higher requirements are put forward for the comprehensive performance of the compressor drum. For wide-body aircraft high-pressure compressors, the size of the disc and the drum is larger, and the inter-stage service temperature and stress difference is larger, and the high-temperature strength, creep properties, fracture toughness and load retention fatigue sensitivity of the metal under different working stresses and temperatures need to be considered. The titanium alloy net basket structure has high high-temperature tensile properties, fracture toughness and good creep properties, and is therefore suitable for the manufacture of high-pressure compressor parts. Considering the mechanical performance requirements of the drum and the need for welding connection with other titanium alloy parts with net basket structure, the Ti6242 compressor drum should also have a uniform net basket structure to improve the high-temperature strength and creep properties of the drum and improve the coordination of stress and strain between the welded parts.

[0034] However, there are certain technical difficulties in forging the compressor drum of Ti6242 alloy with basketweave structure. At present, in the field of aviation, Ti6242 alloy is widely used in α+β forging process for workpiece manufacturing, and the development of β forging process is not sufficient. Since the forging window of Ti6242 alloy itself is narrow, and the content of Al element in the structure is high, flat and coarse grain boundary α phase or large size feather-like structure is easily formed in the grain boundary region of Ti6242 alloy during forging. Compared with β titanium alloy such as Ti17 alloy or two-phase titanium alloy such as Ti-6Al-4V alloy, it is more difficult for Ti6242 alloy to obtain uniform basketweave structure by β forging. The flat and coarse grain boundary α phase and the large size feather-like structure are not conducive to the consistency of the comprehensive high-temperature performance and the performance of the forged piece of the Ti6242 compressor drum.

[0035] To solve the above problems, an embodiment of the present application provides a Ti6242 compressor drum manufacturing method. The method comprises the following steps:

[0036] Firstly, the α+β state Ti6242 bar is forged into a cake blank, and the temperature is kept at 40℃ below the phase transition point for 100min±5min during forging, the final forging temperature is controlled to be not lower than 800℃, and air cooling is used for cooling. In the preferred embodiment, the process of forging the bar into a cake blank is controlled to be three or four fires.

[0037] Next, the cake blank is processed into different shapes, the cake blank is heated to 25℃ above the phase transition point for 1h±5min by using a soft sleeve, and is forged into a drum test piece, the final forging temperature is controlled to be not lower than 960℃, and water cooling is used for cooling. In the preferred embodiment, the water cooling transfer temperature is not more than 45s. The specific shape of the cake blank is determined according to simulation calculation or test, so as to make the drum test piece have different equivalent strain.

[0038] Next, the drum test piece is subjected to solid solution treatment and aging treatment. In the preferred embodiment, the solid solution treatment temperature is 25℃ below the phase transition point, the holding time is 1h±5min, and air cooling is used for cooling. The aging treatment temperature is 595℃±6℃, the holding time is 8h±15min, and air cooling is used for cooling.

[0039] Subsequently, the equivalent strain distribution of each drum test piece in the final forging process is analyzed through test or numerical simulation, and the strain distribution cloud diagram of the drum test piece is obtained. Among them, the test can analyze the flow lines on the cross section of the drum test piece through metallographic analysis, and the simulation test can analyze the flow state of the drum test piece material in the forging process through simulation software.

[0040] Next, samples are cut from the region with different equivalent strains for mechanical property testing and microstructure analysis to determine the equivalent strain range that meets the mechanical property and microstructure requirements of the compressor drum, and the equivalent strain constraint condition is obtained. Specifically, the mechanical properties include the yield strength and tensile strength in the direction perpendicular to the flow line (chordwise) and the yield strength and tensile strength in the direction parallel to the flow line (axial). The microstructure should meet the requirements that the original β phase is broken and the deformation is uniform, there is no large-size feather-like structure or thick and flat α phase, and the net basket structure is complete and uniform. In a preferred embodiment, the first constraint condition of the equivalent strain of the compressor drum is first determined according to the mechanical property requirements, and then the final equivalent strain constraint condition is determined according to the microstructure analysis results.

[0041] After the equivalent strain constraint condition is determined, the shape of the cake blank and the forging process are adjusted, and the forging process is iterated to meet the equivalent strain constraint of the compressor drum as a whole, and the compressor drum finished product is obtained by forging.

[0042] This method controls the microstructure equivalent strain of the compressor drum during forging, adjusts the β phase original grain size during forging of Ti6242 alloy, fully breaks and breaks the grain boundary α phase, and avoids the α phase from growing again during subsequent heat treatment, so that uniform net basket structure can be formed in the microstructure of the compressor drum finished product, thereby meeting the mechanical property requirements of the compressor drum.

[0043] In a preferred embodiment, the process of manufacturing a Ti6242 compressor drum is as follows:

[0044] First, a Φ230 specification α+β state Ti6242 bar is used, and after being kept at 40℃ below the phase transition point for 100min, a cake is formed, the final forging temperature is controlled to be ≥800℃, and air cooling is performed. The cake forming process uses three fires or four fires, and a cake blank is obtained. The cake blank is machined to obtain cake blanks with different shapes as shown in Figure 1a and Figure 2a .

[0045] Next, die forging is performed. The cake blank is heated to 25℃ above the phase transition point in a soft sleeve in a heating furnace for 1h±5min, the die is preheated to 300-350℃, the final forging temperature is controlled to be ≥960℃, and water cooling is performed after forging, and the transfer time is not more than 45s, and a drum test piece is obtained.

[0046] Solid solution treatment is performed at 25℃ below the phase transition point for 1h±5min, and air cooling is performed. Aging treatment is performed at 595±6℃ for 8h±15min, and air cooling is performed.

[0047] The process of forging the cake blank to the drum test piece is simulated to obtain the equivalent strain distribution cloud diagram as shown in Figure 1b and Figure 2b . It can be seen that by using theFigure 1a The equivalent strain range of the cake blank during the forging process is 0.25-2.0. Figure 2a The equivalent strain range of the cake blank during the forging process is 0.5-1.5.

[0048] The samples are cut from the regions with different equivalent strains for mechanical property analysis and microstructure analysis, and the sample cutting positions are shown in Figure 1c and Figure 2c The samples are taken at least at three different radial positions (horizontal direction of Figure 1c and Figure 2c vertical direction) in the same axial position (axial direction of Figure 1c and Figure 2c horizontal direction), and at least at four different axial positions (axial direction of and

[0049] horizontal direction) in the same radial position. Figure 5 a- Figure 5 f.

[0050] In Figure 5 a and Figure 5 b, the equivalent strain of the microstructure is 0.625, and the original β grain deformation is small, Figure 5 a, the feather-like structure with large size appears, Figure 5 and in b, more straight and continuous coarse grain boundary α phase appears on the grain boundary.

[0051] Figure 5 c and Figure 5 d, the equivalent strain of the microstructure is 0.875, the original β phase grain boundary is broken, the deformation is uniform, and the in-grain network basket structure is well woven.

[0052] Figure 5 e and Figure 5 f, the equivalent strain of the microstructure is 1, the original β phase grain boundary is broken, the deformation is uniform, and the in-grain network basket structure is well woven, and the microstructure is uniform.

[0053] Figure 5 g, the equivalent strain of the microstructure is 1.2, and the grains are large elongated crystals, and more side-by-side α phases appear along the grain boundary, which affects the weaving effect of the network basket structure.

[0054] Based on simulation calculations and metallographic analysis, the equivalent strain value to meet the microstructure requirements of the compressor drum should be controlled within the range of 0.7-1.0. If the equivalent strain is too low, the original grains will not deform sufficiently, easily forming flat and coarse grain boundary α phases, making it difficult to form a well-woven basket structure. If the equivalent strain is too high, the microstructure of the forged and heat-treated Ti6242 alloy will be dominated by large-sized elongated grains, and the α phases on the grain boundaries will easily be distributed side by side, which is not conducive to the formation of a uniform basket structure.

[0055] In one embodiment, the test results of the chordal mechanical properties of samples with different equivalent strains are as follows: Figure 3 As shown, the blue dashed line represents the mechanical property requirement of the compressor drum's chordal yield strength, and the black solid line represents the mechanical property requirement of the compressor drum's chordal tensile strength (i.e., the first constraint condition). It can be seen that the chordal mechanical properties of samples with equivalent strains below 0.7 or above 1.1 exhibit significant dispersion, with some samples showing yield strength and / or tensile strength lower than the mechanical property requirements. Furthermore, combined with... Figure 5 a- Figure 5 The microstructure analysis results of f show that the final equivalent strain constraint range is 0.7-1.0.

[0056] In another embodiment, the test results of the chordal and axial mechanical properties of samples with different equivalent strains are as follows: Figure 4 As shown, the black dashed line represents the mechanical property requirement of the compressor drum's axial yield strength, and the red solid line represents the mechanical property requirement of the compressor drum's axial tensile strength. The equivalent strain and tensile strength / yield strength relationships for different samples were fitted and calculated, yielding the equivalent strain (x) - yield strength (y) fitting function as y = -199.36x + 1040.2, and the equivalent strain (x) - tensile strength (y) fitting function as y = -204.24x + 1162.3. With yield strength ≥ 825 MPa and tensile strength ≥ 900 MPa as the first constraint conditions, combined with... Figure 5 a- Figure 5 The microstructure analysis results of f show that the range of the final equivalent strain constraint is 0.7-1.0.

[0057] Finally, based on the above constraints, the shape of the compressor drum blank and the forging process were adjusted so that the overall equivalent strain within the microstructure of the compressor drum during the final forging process is within the range of 0.7-1.0. The specific adjustment process can be completed through process trial production combined with simulation calculations. Using the optimized forging method, a Ti6242 compressor drum with a uniform basket structure that meets the overall mechanical performance requirements of the compressor drum can be produced.

[0058] It should be understood that the manufacturing process of the compressor drum in the above embodiments is only provided for a specific structural design, and when the shape, size and structure of the compressor drum change or the composition of the alloy raw material differs, the calculation and analysis results may differ, and those skilled in the art can make reasonable adjustments within the scope of the method provided in the above embodiments.

[0059] In different embodiments, the use of different specifications of Ti6242 bars, the size of the cake blank and the difference in the forging process will also have different effects on the determined Ti6242 compressor drum forging method. In some embodiments, the microstructure plays a major role in constraining the range of equivalent strain, while in other embodiments, the mechanical property requirements play a major role in constraining the range of equivalent strain. Considering the overall performance requirements of the compressor drum, the range of equivalent strain is first constrained according to the mechanical property requirements.

[0060] In different embodiments, simulation calculations can be performed using general or specialized software, such as specialized forging analysis software or finite element analysis software, and those skilled in the art can make reasonable choices based on actual conditions. When adjusting the cake blank shape and forging process, automatic optimization can be performed using the functions of the simulation software, or manual adjustments can be made based on the specific forging process and the experience of technicians.

[0061] Through the method provided in the above embodiments, the deformation range of Ti6242 for manufacturing a compressor drum through β forging can be quantitatively determined through microstructure analysis and mechanical property testing, improving the manufacturing efficiency of the compressor drum, improving the performance consistency of the forged drum, and improving the overall reliability and economy of the engine. Further, the method provided in the above embodiments can avoid the formation of coarse α phase in the Ti6242 microstructure during the β process, and by controlling the equivalent strain, the α phase can be broken and fragmented, while avoiding the retention or growth of flat, coarse grain boundary α phase during subsequent heat treatment, improving the room temperature and high temperature mechanical properties, fatigue durability and creep properties of the Ti6242 compressor drum. At the same time, through the above method, the forging process parameters for a specific structure of Ti6242 compressor drum can be accurately determined, which is beneficial to the mass production of compressor drums and improves production efficiency.

[0062] The purpose of the above embodiments is to further illustrate the present application in conjunction with the drawings, so that those skilled in the art can understand the technical concept of the present application. Within the scope of the present disclosure, the method steps involved are optimized or equivalently replaced, and the embodiments in different embodiments are combined without structural and principle conflicts, all of which fall within the scope of the present application.

Claims

1. A method for manufacturing a Ti6242 compressor drum, characterized in that, Includes the following steps: Provide α+β state Ti6242 bars, hold at 40℃ below the phase transformation point for 100min±5min, then upset into billets, with a final forging temperature of not less than 800℃, and air-cooled; Multiple blanks are processed into different shapes, and each blank is heated to 25°C above the phase transformation point using a soft sleeve, held for 1 hour ± 5 minutes, and forged into multiple drum test pieces with different equivalent strains. The final forging temperature is controlled to be no less than 960°C, and then water-cooled. The drum test piece was subjected to solution treatment and aging treatment; Equivalent strain distribution cloud maps of multiple drum test specimens were obtained using experimental and / or simulation calculations; Samples were cut from regions with different equivalent strains for mechanical property testing and microstructure analysis. The equivalent strain range that satisfies the mechanical properties and microstructure requirements of the compressor drum is determined, and the equivalent strain constraint is obtained; The shape and forging process of the blank are adjusted according to the equivalent strain constraint to forge the compressor drum finished product, and the microstructure strain of the compressor drum finished product satisfies the equivalent strain constraint.

2. The method for manufacturing a compressor drum according to claim 1, characterized in that, The method for determining the equivalent strain constraint is as follows: samples are cut from regions with different equivalent strains and their mechanical properties are tested. The test results of the mechanical properties are fitted with the equivalent strain to obtain the equivalent strain-intensity function. The range of equivalent strain is determined according to the mechanical performance requirements of the compressor drum to obtain the first constraint condition. The microstructure characteristics of the samples within the first constraint condition are verified to obtain the range of equivalent strain that meets the microstructure requirements of the compressor drum, which is used as the equivalent strain constraint.

3. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, The transfer time for the water cooling treatment of the drum test piece shall not exceed 45 seconds.

4. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, The solution treatment temperature is 25°C below the phase transition point, the holding time is 1h±5min, and then air cooling is performed.

5. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, The aging treatment was performed at a temperature of 595±6℃, with a holding time of 8h±15min, followed by air cooling.

6. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, When cutting samples from the drum test piece, at least three samples at different radial positions should be cut from the same axial position.

7. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, When cutting samples from the drum test piece, at least four samples at different axial positions should be cut from the same radial position.

8. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, The mechanical property tests include chordal strength tests perpendicular to grain streamlines and axial strength tests parallel to grain streamlines.

9. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, The method for processing multiple dough blanks into different shapes involves machining the dough blanks.

10. The method for manufacturing a compressor drum according to claim 1 or 2, characterized in that, The blank is obtained by processing the Ti6242 bar stock through three or four heat treatments.

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