CN104846441A - Cutting preparation method of nickel-based single-crystal alloy seed crystal for casting - Google Patents

Abstract

The invention discloses a method for cutting and preparing a nickel-based single-crystal alloy seed crystal for casting. In the method, a test bar or a test plate used for preparing the seed crystal is mechanically processed to obtain a test block with upper and lower parallel sections. , one of the parallel sections of the test block is polished to obtain a polished surface; the polished surface of the test block is fixed on the center of the turntable of the X-ray stress measuring instrument, and marked on the polished surface of the test block direction; determine the X-ray diffraction angle of the test block material, and use the X-ray stress measuring instrument to measure the ψ angle and Scan the angle; use the wire cutting machine to realize the removal of ψ, Off-angle single crystal directional cutting; finally, the preparation of the seed crystal. The invention has very low requirements on the orientation of the original single crystal test rod, and can directly obtain seed crystals with (001), (011), (111) orientation characteristics by cutting; the processing cost is low; the seed crystal obtained by cutting has high precision and can be repeated Good properties; the surface finish of the seed crystal is high, no further processing is required.

Description

A kind of cutting preparation method of nickel base single crystal alloy seed crystal for casting

technical field

The present invention relates to Ni-based and Ni ₃ Al-based single-crystal superalloy casting seed crystal precise directional cutting preparation method, further said to make the Ni-based single-crystal alloy with any orientation into (001), (011) by measuring and mechanical processing ) or (111) crystallographic orientation characteristics of the seed crystal.

Background technique

The key to improving the performance of aviation gas turbine engines is to improve the performance of service materials. The Ni-based single crystal turbine blade is a key component with the most technically difficult service conditions in the turbine engine, and the service requirements for its materials are extremely stringent. Due to the anisotropy of Ni single crystal alloys, turbine blades with (111) orientation along the axis will have higher and more stable high-temperature performance. The research shows that the fracture life of Ni-6.8Al-13.8Mo-6W alloy (111) crystal orientation is 9 times longer than that of (001) crystal orientation at 980 ° C and 280 MPa, and the time to produce 1% creep is (001) crystal orientation. The elastic modulus of (111) orientation at room temperature is almost twice that of (001) orientation, even at high temperatures of 1000-1100°C, the durable strength of (111) orientation is 10% higher than that of (001) orientation More than 15%, the durable life is 3 times higher. However, the growth direction of the single crystal blade obtained by the spiral crystal selection method shows an obvious preferred orientation (generally along the direction of the temperature gradient: (001) direction), and the preferred orientation often has a certain off-angle with the axial direction, so that the single crystal blade The high temperature service performance is obviously reduced. Production practice shows that the reject rate of turbine blades directional solidified by the spiral crystal selection method due to the deviation from (001) exceeding 20° accounts for more than 30% of the production volume. In addition, it is difficult to obtain blades with an orientation of (111) by this method .

The seed crystal method refers to a single crystal grown by melting the top surface of the seed crystal and growing epitaxially. The orientation of the single crystal obtained by this method is strictly consistent with the orientation of the seed crystal. At present, the preparation of the seed crystal method generally involves cutting and preparing a seed crystal from a single crystal with (001), (011) or (111) orientation characteristics. It is random and uncontrollable.

Contents of the invention

The purpose of the invention is to provide a method for preparing (001), (011) and (111) seed crystals with high precision, high efficiency and high reliability for directional solidification Ni-based single crystal superalloy casting by seed crystal method. The test bar (or test plate) used to prepare the seed crystal can be a Ni-based single crystal superalloy with any orientation. In addition, the orientation of the seed crystal obtained after cutting has a high degree of consistency and repeatability, thereby improving the casting performance and orientation stability of the Ni-based single crystal superalloy obtained by the seed crystal method.

The invention provides a method for cutting and preparing a nickel-based single crystal alloy seed crystal for casting, which comprises the following steps:

In the first step, the test bar or test plate used for preparing the seed crystal is machined to obtain a test block with upper and lower parallel sections, and one of the parallel sections of the test block is polished to obtain a polished surface.

The second step is to fix the polished surface of the test block on the center of the turntable of the X-ray stress tester stably, and mark the polished surface of the test block with straight lines and arrows. The marking direction is the same as that on the X-ray stress tester. direction parallel.

The third step is to determine the X-ray diffraction angle of the test block material, and set the parameters of the X-ray stress measuring instrument.

The fourth step is to measure the ψ angle and corner to scan.

Rough scan method: fix 2θ and set the scan range of ψ angle and Angular scan range. In order to reduce the amount of cutting as much as possible, the test block that deviates from a specific angle by more than 30° is generally not cut, that is, the scanning range of the ψ angle is 0 to 30°, Angular scan range is 0° to 360°; coarse scan ψ and Each increment of the angle is 0.5° and 5° respectively, that is: every time the ψ angle is fed, The angle is rotated from 0° to 360° in increments of 5°. Record the two angles ψ,

Fine scan method: fixed 2θ and ψ angle recorded in rough scan, for Angle carried out scan within the range. The scan step is 0.5°, and the record occurs when the strongest X-ray diffraction occurs horn.

The fifth step is to use the wire cutting machine to realize the removal of ψ, Off-angle single crystal directional cutting;

In the sixth step, the seed crystal is prepared for the test block obtained after the single crystal directional cutting.

Preferably, a centerless grinder is used to grind the surface of the seed crystal prepared in the sixth step to improve the surface quality of the seed crystal.

The advantages of the present invention are:

1. The requirements for the orientation of the original single crystal test rod are extremely low (in order to reduce the amount of cutting, the deviation from the orientation to be cut should not exceed 45°).

2. The cutting equipment is simple and there is no need to import foreign equipment, and the seed crystals with (001), (011) and (111) orientation characteristics can be obtained directly by cutting.

3. Low processing cost.

4. The seed crystal obtained by cutting has high precision and good repeatability.

5. The surface finish of the seed crystal is high, no further processing is required.

Description of drawings

Fig. 1 is a schematic diagram of parallel section cutting of a Ni-based single crystal superalloy with arbitrary orientation.

Figure 2 is a point-to-point Schematic diagram of the test principle of the X-ray stress tester 350AC for the function of the connecting mechanism of the corner.

Figure 3 is a schematic diagram of the relationship between the normal direction of the test block and the crystallographic orientation (the (001) orientation sample is taken as an example in this figure) and the cut surface.

Fig. 4 is the schematic diagram of clamp and test piece clamping that adopt among the present invention;

Fig. 5A and Fig. 5B are schematic diagrams showing the details of the indexing plate and the test block chuck used in the fixture of the present invention, respectively.

Fig. 6A and Fig. 6B are the screenshots of orientation analysis of Lauey's spots of seeds with (001) and (111) crystal orientations prepared by the method of the present invention, respectively.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The method for cutting and preparing the nickel-based single crystal alloy seed crystal for casting provided by the present invention has the following specific steps:

In the first step, the test bar or test plate used to prepare the seed crystal is machined to obtain a test block with upper and lower parallel sections. As shown in Figure 1, the test bar or test plate is cut along the dotted line to obtain the upper and lower surfaces Parallel test blocks. One of the parallel sections of the test block is polished to obtain a polished surface.

Polishing treatment conditions: use 60#, 180#, 400#, 800#, 1500# water-grinding sandpaper to polish one side of the parallel section of the test block in order to remove the processing residual stress on the surface.

In the second step, the test block is fixed on the X-ray stress measuring instrument (manufactured by Handan Est Stress Technology Application Co., Ltd. The X-ray stress tester 350AC with the function of the connection mechanism of the angle) The center of the turntable, as shown in Figure 2, and use a fine marker to mark the polished surface of the test block with a straight line and an arrow, and the marking direction is the same as that on the X-ray stress tester. direction parallel.

The third step is to determine the X-ray diffraction angle of the test block material by consulting relevant literature (SSCS or related Pdf cards), and input the corresponding parameters (diffraction angle 2θ, counting time, counting range, etc.) in the supporting software of the X-ray stress tester parameter).

The fourth step is to measure the ψ angle and corner to scan.

Rough scan method: fix 2θ and set the scan range of ψ angle and Angular scan range. In order to reduce the amount of cutting as much as possible, the test block that deviates from a specific angle by more than 30° is generally not cut, that is, the scanning range of the ψ angle is 0 to 30°, Angular scan range is 0° to 360°; coarse scan ψ and Each increment of the angle is 0.5° and 5° respectively, that is: every time the ψ angle is fed, The angle is rotated from 0° to 360° in increments of 5°. Record the two angles ψ,

Fine scan method: fixed 2θ and ψ angle recorded in rough scan, for Angle carried out scan within the range. The scan step is 0.5°, and the record occurs when the strongest X-ray diffraction occurs horn.

The fifth step is to use a wire cutting machine (DK7732 wire cutting machine produced by Beijing Deli Machine Tool Equipment Co., Ltd.) to realize the removal of ψ, Off-angle single crystal directional cutting;

Clamp and fix the test block on the fixture to realize directional cutting of single crystal.

Described fixture is shown in Figure 4, comprises rectangular parallelepiped base 1, support 2, rotating bar 3, locking knob 4 and collet 5, and described rectangular parallelepiped base 1 and support 2 form an integral structure, and support 2 is perpendicular to rectangular parallelepiped base 1 , in the shape of "⊥". The support 2 is vertical; the rotating rod 3 is a cylindrical structure with a horizontal axis. One end of the rotating rod 3 is fixed on the support 2, and the other end is provided with a chuck 5, as shown in Figure 5B. The chuck 5 includes two flat plates and two One of the flat plates is fixed on the rotating rod 3, and the other flat plate is a movable plate. When used to clamp the test block, the test block is clamped between the two flat plates and fixed by screw clamping; The top end is provided with a lock button 4 to fix the rotating rod 3, and the rotating rod 3 can be rotated around its own axis to adjust The corner is fixed by the lock button 4 after being adjusted to the set angle. The fixing method of the rotating rod 3 on the bracket 2 is that the bracket 2 is provided with a horizontal through hole or a horizontal blind hole, and the aperture is matched with the outer diameter of the rotating rod 3; it communicates with the horizontal through hole or the horizontal blind hole The vertical through hole is used to set the locking button 4, and one end of the rotating rod 3 is inserted into the horizontal through hole or the horizontal blind hole, and the rotating rod 3 is fixed by the locking button 4 after rotating at a suitable angle. At the end of the rotating rod 3, there is an indexing plate 6 concentric with the center of the cross section of the rotating rod 3, as shown in Figure 5A, the indexing plate 6 is drawn on the support 2, and the 0° scale direction of the indexing plate 6 is vertical to the support 2. parallel to the straight axis. The clamping requirements of the test block 7 on the fixture are: the normal direction of the polished surface of the test block 7 is parallel to the axis of the rotating rod 3, the marking direction on the polished surface of the test block 7 is in line with the 0° scale line on the index plate 6 Parallel; when fixing the cuboid base 1, the long side of the cuboid base 1 should be parallel to the straight line in the direction of the wire cutting guide rail. Put the rotating rod 3 along the X-ray stress measuring instrument Angle turntable scan direction rotated to corner position. Set the cutting direction on the wire cutting device as a straight line forming an angle ψ with the direction of the wire cutting wire guide rail (wire cutting device-x-axis direction), and perform the first cutting to obtain the first cutting surface. Then the other end of the test block is cut so that the second cutting plane is completely parallel to the first cutting plane. Requirements: The distance between two parallel sections after cutting is at least 20mm (the distance between two parallel sections before cutting is related to the size of the test block).

In the sixth step, the seed crystal is prepared for the test block obtained after the single crystal directional cutting.

Use superglue (502 quick-drying glue) to bond the first cut surface or the second cut surface of the test block to a 1mm thick conductive plate, and only glue the edge for fixing. The conductive plate is replaced by No. 45 steel plate or other conductive plates, and the purpose is to provide fixation. Place the conductive plate with the test block horizontally and fix it on the guide rail. At this time, the first cutting surface or the second cutting surface of the test block should be parallel to the XOY plane of the wire cutting guide rail (the coordinate axis of the DK7732 wire cutting machine itself, or the cutting surface is parallel to the horizontal plane). Cut a Φ3.2×20mm cylinder on the test block by programming, and the axis of the seed crystal obtained by cutting should be parallel to the normal direction of the surface of the test block, so that the axis direction is a specific orientation of the seed crystal rod.

The seventh step is to use a centerless grinder (centerless grinder MT1040A produced by Wuxi Yiji Grinding Machine Manufacturing Co., Ltd.) to grind the surface of the seed crystal rod to improve the surface quality of the seed crystal.

Example 1

The first step is to perform wire cutting on the cuboid test plate to be made into (001) direction seed crystals to obtain a test block (28×27×27mm) with upper and lower parallel sections, and one of the parallel sections of the test block is sequentially Use 60#, 180#, 400#, 800#, 1500# water abrasive paper to polish to obtain a polished surface.

In the second step, as shown in Figure 2, the test block is stably fixed on the X-ray stress measuring instrument (produced by Handan Este Stress Technology Application Co., Ltd. The center of the turntable of the X-ray stress tester-350AC) with the function of the connection mechanism of the corner, and use a fine marker pen to make an initial mark on the polished surface of the test block, and the mark is the same as same direction;

The third step is to confirm that the 2θ angle (X-ray diffraction angle) of the tested block material is set to 79.6° by consulting relevant literature (SSCS or related Pdf cards), and the scanning range of the ψ angle is 0 to 30°. Angle scanning range is 0° to 360°, ψ angle and Coarse scans were performed with angular increments of 0.5° and 5°, respectively. During the rough scan, it is found that ψ ₁ =18.5°, The strongest diffraction occurs. Fix the 2θ angle and ψ ₁ (=18.5°) angle to the test block, at turn around the angle corner (scan range), The angular rotation increment is 0.5° for fine scanning. By observing the X-ray diffraction peaks The strongest diffraction occurs at 59.5°.

In the fourth step, the normal direction of the polished surface of the test block is parallel to the axial direction of the rotating rod 3 and the marking direction on the polished surface is in the 0° direction of the index plate 6, and the test block is clamped (as shown in Figure 4). Put the rotating rod 3 of the test block 7 along the direction of the X-ray stress measuring instrument Rotate the scanning direction of the angle turntable to the 59.5° position. Set the cutting direction on the wire cutting device to be a straight line at 18.5° from the wire cutting device-XO axis direction, and perform the first cut to obtain the first cutting surface. After cutting, cut again at a position 20 mm away from the first cutting surface, so that the second cutting surface, the first cutting surface after cutting and the second cutting surface are parallel to each other, and the cutting profile is as shown in Figure 3.

The fifth step is to glue the first cutting surface of the test block to the No. 45 steel plate with a thickness of 1 mm with superglue (502 quick-drying glue), and fix the steel plate on the guide rail of the wire cutting machine. Cut a Φ3.2×20mm cylinder on the test block 7 by programming, and the axis of the seed crystal obtained by cutting should be parallel to the normal direction of the surface of the test block, so that the axis direction is a specific orientation of the seed crystal.

In the sixth step, the surface of the seed crystal is processed by a grinding machine to obtain a seed crystal with a high finish.

The orientation analysis of the end face of the obtained seed crystal was carried out by using a JF-2 X-ray crystal analyzer produced by Dandong Liaodong Ray Instrument Co., Ltd. Figure 6A is the Lloyd test analysis diagram of the sample cut in the (001) direction. It can be seen that the test block has been corrected from the original 18.5° deviation from the 001 direction to the current 2.5°.

Example 2

In the first step, as shown in Figure 1, wire-cut the cuboid-shaped test plate to be made into the (111) direction seed crystal, and obtain two test blocks (29×25×34mm) with parallel sections on the upper and lower sides, and the test block One of the parallel sections is polished with 60#, 180#, 400#, 800#, 1500# water-grinding sandpaper to obtain a polished surface.

In the second step, as shown in Figure 2, the test block is stably fixed on the X-ray stress measuring instrument (produced by Handan Este Stress Technology Application Co., Ltd. X-ray Stress Measuring Apparatus-350AC) with the function of the connecting mechanism of the angle, the center of the turntable, the polished side facing up, and use a fine marker pen to make initial marks on the polished surface of the test block, and the X-ray Stress Measuring Apparatus same direction;

The third step is to set the 2θ angle of the X-ray stress measuring instrument to 68.7°, and the scanning range of the ψ angle to be 0 to 30°, set The angular scan range is from 0° to 360°. ψ with The angle increments are 0.5° and 5°, respectively. During rough measurement, it was found that ψ ₂ = 28°, The strongest diffraction occurs. Fix the 2θ angle and ψ (=28°) angle to the test block respectively, rotate Angle (range 105~125°), the rotation increment is 0.5°. By observing the X-ray diffraction peaks is 113.5°.

In the fourth step, the normal direction of the polished surface of the test block is parallel to the axial direction of the rotating rod 3 and the initial marking direction is in the 0° direction of the indexing plate 6, and the test block is clamped (as shown in Figure 4). Put the rotating rod 3 of the test block along the X-ray stress measuring instrument The scanning direction of the angle turntable is rotated to the 113.5° position. Perform programming on the wire cutting equipment, set the cutting direction as a straight line at 28° from the wire cutting equipment-XO axis direction, and perform the first cutting to obtain the first cutting surface. After the cutting is completed, cut again at a position 20 mm away from the first cutting surface to obtain a second cutting surface, and the first cutting surface obtained after cutting is parallel to the second cutting surface.

The fifth step is to glue the first or second cutting surface of the test block to the 1mm thick No. 45 steel plate with superglue (502 quick-drying glue), and fix the steel plate on the guide rail of the wire cutting machine. Cut a Φ3.2×20mm cylinder on the test block by programming, and the axis of the seed crystal obtained by cutting should be parallel to the normal direction of the surface of the test block, so that the axis direction is the specific orientation of the seed crystal.

In the sixth step, the surface of the seed crystal is processed by a grinding machine to obtain a seed crystal with a size of Φ3.2×20mm.

The orientation analysis of the end face of the obtained seed crystal was carried out by using a JF-2 X-ray crystal analyzer produced by Dandong Liaodong Ray Instrument Co., Ltd. Fig. 6B is the Lloyd test analysis diagram of the sample cut in the (111) direction. It can be seen that the sample has been corrected from the original 28° deviation from the 111 direction to the current 3°.

The present invention uses a Ni-based single crystal superalloy with any orientation to prepare (001), (011) or (111) direction crystallographic orientation characteristic seed crystals, which can not only provide anisotropic single crystal test rods for laboratory testing The seed crystal with low deflection angle, high precision and high reliability can also provide high-quality seed crystal for casting for the production of turbine engine single crystal blades. Therefore, the technology of preparing single crystal seed crystal with specific orientation by cutting method can provide a strong guarantee for a large number of high-precision experiments and special production.

Claims (4)

1. cast the cutting preparation method with Crystal Nickel-based Superalloy seed crystal, it is characterized in that:

The first step, obtains the test block that has upper and lower parallel cut after carrying out mechanical workout for the preparation of the coupon of seed crystal or test plate (panel), carries out polishing process, obtain polished face to one of them parallel cut of test block;

Second step, is steadily fixed on the center of turntable of x-ray stress analyzer upward by test block polished face, and on test block polished face, carries out straight line and arrow mode marks, on label orientation and x-ray stress analyzer direction is parallel;

3rd step, determines the x-ray diffraction angle of test block material, carries out optimum configurations to x-ray stress analyzer;

4th step, utilize x-ray stress analyzer to the ψ angle of test block and angle is scanned;

Coarse scan method: fix 2 θ and the sweep limit setting ψ angle with the sweep limit at angle, record occur X diffraction the strongest diffraction time these two angle ψ,

Essence sweeps method: fix the ψ angle of recording in 2 θ and coarse scan, right angle is carried out scope in scanning; Scanning step is 0.5 °, record occur X diffraction the strongest diffraction time angle;

5th step, utilize wire cutting machine realize go ψ, the monocrystalline directional cutting of drift angle;

6th step, carries out the preparation of seed crystal to the test block obtained after monocrystalline directional cutting.

2. a kind of cutting preparation method cast with Crystal Nickel-based Superalloy seed crystal according to claim 1, it is characterized in that: in coarse scan method, ψ angular scan range is 0 to 30 °, angular scan range is 0 ° to 360 °; Coarse scan ψ with the each increment in angle is respectively 0.5 ° and 5 °, that is: often feed a ψ angle, namely angle rotates to 360 ° from 0 ° with increment 5 °.

3. a kind of cutting preparation method cast with Crystal Nickel-based Superalloy seed crystal according to claim 1, is characterized in that: use the surface of centerless grinding machine to the seed crystal that the 6th step prepares to carry out ground finish and improve seed crystal face quality.

4. a kind of cutting preparation method cast with Crystal Nickel-based Superalloy seed crystal according to claim 1, is characterized in that: the oriented monocrystalline described in the 5th step is cut into and test block is fixedly clamped on fixture, realizes monocrystalline directional cutting;

Described fixture comprises rectangular parallelepiped base, support, bull stick, cage knob and chuck, the described structure that is formed in one with support, and support is vertical with rectangular parallelepiped base, in " ⊥ " type; Rectangular parallelepiped base coordinates with the guide rail on wire cutting machine, and support is vertical; Bull stick is cylindrical structural, axis horizontal, one end of bull stick is fixed on support, the other end arranges chuck, and described chuck comprises two pieces of flat boards and two screw rods, and wherein one flat plate is fixed on bull stick, another one flat plate is portable plate, when being used for clamping test block, test block being clamped between two pieces of flat boards, and being fixedly clamped with screw rod; Arrange the cage knob of fixing bull stick on the top of support, one end of bull stick is inserted in described support, after rotating proper angle, is fixed by cage knob; Have an indexing plate concentric with the center of circle, cross section of bull stick at bull stick end, indexing plate is drawn on support, and 0 ° of scale direction of indexing plate is parallel with the vertical axis of support; The clamping requirement of test block on fixture is: the normal orientation of test block polished face and the axis being parallel of bull stick, and on test block polished face, label orientation is parallel with ° scale marks of 0 on indexing plate; During fixing rectangular parallelepiped base, the long limit of rectangular parallelepiped base should be parallel to the straight line in Linear cut guide rail direction; By bull stick along x-ray stress analyzer rotating disk scanning direction, angle rotates extremely angle Position; Cutting on line equipment setting cut direction is the straight line becoming ψ angle with Linear cut silk guide rail direction, carries out first time cutting, obtains the first cut surface; Afterwards the other end of test block is cut, make the second cut surface be parallel to the first cut surface completely; Two parallel cut spacing at least 20mm after cutting.