CN112371996A

CN112371996A - Method for preparing K418 nickel-based superalloy supercharging turbine based on selective laser melting forming technology

Info

Publication number: CN112371996A
Application number: CN202011103105.1A
Authority: CN
Inventors: 刘邦涛; 陈卓; 田操; 李�浩; 张鑫浩
Original assignee: Aerospace Hiwing Harbin Titanium Industrial Co Ltd
Current assignee: Aerospace Hiwing Harbin Titanium Industrial Co Ltd
Priority date: 2020-10-15
Filing date: 2020-10-15
Publication date: 2021-02-19

Abstract

The invention discloses a method for preparing a K418 nickel-based superalloy supercharging turbine based on a selective laser melting forming technology, and belongs to the technical field of laser additive manufacturing of nickel-based superalloys. The invention solves the problems of more defects, high cost, long period and the like in the traditional casting process at the stage of developing the booster turbine. The method comprises the steps of firstly preprocessing a material to be formed, then selecting proper forming powder, constructing a model of the K418 supercharging turbine, preparing a program file before forming and setting processing technological parameters, guiding the program file and the processing technological parameters into SML equipment, selectively melting the forming powder material on a workbench by the SML equipment according to a scanning path and the technological parameters in the program under the argon atmosphere, then reducing the thickness of the workbench by one layer according to the set layer thickness, then spreading powder, continuously melting the forming powder by selecting the region, repeating the action, and gradually stacking and forming the forming into the supercharging turbine. The method reduces the warping deformation risk of the turbine blade of the supercharging turbine and avoids the part defects caused by stress shrinkage.

Description

Method for preparing K418 nickel-based superalloy supercharging turbine based on selective laser melting forming technology

Technical Field

The invention relates to a method for preparing a K418 nickel-based superalloy supercharging turbine based on a selective laser melting forming technology, and belongs to the technical field of laser additive manufacturing of nickel-based superalloys.

Background

Compared with the traditional mechanical processing means, the selective laser melting forming (SLM) technology has the advantages of strong 'design-forming' quick response capability, low complex structure processing process limitation, high material utilization rate, great advantages in the aspects of product processing cycle control, cost control and the like, and is very suitable for quick development of small-batch, complex structure and difficult-to-process material products.

The booster turbine belongs to a core part of a high-performance engine, has advantages in the aspects of increasing the power per liter of the engine, improving the emission of the engine, improving the fuel economy and reducing the oil consumption, and the huge market demand leads a design unit to face the pressure in the aspects of shortening the research and development period, improving the product performance and the like. The structure of the booster turbine is complex, the K418 nickel-based high-temperature alloy belongs to a difficult-to-machine material, so that the booster turbine has the characteristics of difficult-to-machine material and difficult-to-machine structure, the booster turbine blade is thin and has large curvature change, and when the booster turbine blade is produced by adopting an investment casting process, the defects of heat cracking, deformation and the like are easily generated, so that a large amount of waste of alloy and shell materials is caused, and the production of qualified parts is difficult to complete under the conditions of short cycle, low cost and the like by adopting the traditional manufacturing process. Therefore, it is necessary to provide a method for preparing the K418 nickel-based superalloy supercharging turbine based on the selective laser melting forming technology to solve the problems of multiple defects, high cost, long period and the like in the development stage of the traditional casting process.

Disclosure of Invention

The invention provides a method for preparing a K418 nickel-based high-temperature alloy supercharged turbine based on a laser selective melting forming technology, aiming at the problems of multiple defects, high cost, long period and the like in the development stage of the supercharged turbine in the traditional casting process.

A method for preparing a K418 nickel-based superalloy supercharging turbine based on a selective laser melting forming technology comprises the following steps:

step one, selecting formed powder: the particle size range of the formed powder is as follows: d50 is more than or equal to 30 mu m and less than or equal to 40 mu m, the proportion of fine powder with the particle size of less than 15 mu m is less than 5 percent, and the proportion of coarse powder with the particle size of more than 53 mu m is less than 5 percent;

step two, constructing a model of the K418 supercharged turbine, preparing a program file before forming and setting processing technological parameters, and importing the program file and the processing technological parameters into SML equipment, wherein the processing technological parameters are as follows: the preset temperature of the substrate is 100-200 ℃, the laser power is 220-280W, the thickness of the powder layer is 30-60 μm, the scanning speed is 800-1250 mm/s, and the scanning interval is 0.08-0.11 μm;

step three, selecting a laser area to melt and form the booster turbine, which specifically comprises the following steps: under the argon atmosphere and under the condition that the oxygen content in the forming cabin is not more than 0.1%, according to the program file and the parameters of the SML equipment introduced in the step two, the SML equipment selectively melts the forming powder material on the workbench according to the scanning path and the process parameters in the program, then the workbench reduces the thickness of one layer, then the powder is spread, the selective melting of the forming powder is continued, the action is repeated, and the forming is gradually stacked to form a supercharged turbine;

and step four, carrying out heat treatment, linear cutting and surface treatment on the supercharged turbine processed in the step three in sequence to obtain a final product.

Further, the shaped powder is a spherical K418 nickel-base superalloy powder.

Further, the specific components of the shaped powder are: c: 0.08 to 0.16 wt%, Cr: 11.50 to 13.50 wt%, Mo: 3.8-4.80 wt%, Al: 5.50-6.40 wt%, Ti: 0.50-1.00 wt%, Fe is less than or equal to 1.00 wt%, Nb: 1.80-2.50 wt%, B: 0.008 to 0.020 wt%, Zr: 0.060-0.150 wt%, Mn is less than or equal to 0.50 wt%, Si is less than or equal to 0.50 wt%, P is less than or equal to 0.015 wt%, S is less than or equal to 0.010 wt%, and the balance is Ni.

Further, the particle size distribution of the shaped powder was: 24.57 μm for D10, 36.27 μm for D50, and 49.22 μm for D90; the bulk density of the shaped powder was 4.47g/cm³Tap density of 5.12g/cm³。

Further, in the fourth step of heat treatment, the temperature is raised from room temperature to 1000-1200 ℃ at the temperature raising rate of 6-10 ℃/min, and then the temperature is kept for 15-16 h, and then the air cooling is carried out to the room temperature.

Further, the wire cutting in the fourth step adopts a repeated wire-moving electric spark wire-electrode cutting machine to carry out the wire cutting, and the cutting speed is 10 mm/s.

Further, the surface treatment in the fourth step comprises surface cleaning, surface grinding and surface sand blasting.

Further, the pre-forming process file includes a process support addition to the booster turbine: and performing analog simulation on the melting forming stress deformation of the laser selective area of the K418 supercharged turbine by adopting Magics software, analyzing a stress deformation simulation result, disclosing a control method of residual stress and buckling deformation under the action of a temperature field and a stress field in the melting forming process of the laser selective area, and performing local support structure design on a forming process digifax.

Further, the local support structure design process is as follows: according to the simulation result, the support adding position, the support shape, the support and part contact form and the support process parameters are optimally designed, the stress deformation is guaranteed to be controlled, the adding quantity of the process supports is reduced, and the purposes of saving raw materials and reducing the part surface roughness are achieved.

Furthermore, the processing parameters in the second step are as follows: the preset temperature of the substrate is 200 ℃, the laser power is 220W, the thickness of the powder layer is 0.03mm, the scanning speed is 750mm/s, and the scanning interval is 0.11 mm.

The invention has the following beneficial effects: the method for preparing the K418 nickel-based high-temperature alloy supercharged turbine based on the selective laser melting forming technology can solve the problems of more defects, high cost, long period and the like in the development stage of the traditional casting process, realizes the rapid development and verification of supercharged turbine products, and ensures the product performance, weakens the buckling deformation risk of blades and avoids the part defects caused by stress shrinkage by the reasonable process scheme and the support optimization design scheme provided by the method.

Drawings

FIG. 1 is a schematic view of a single vane of a turbo-charger prepared by the method of example 1;

FIG. 2 is a schematic diagram of a sample of a small square block formed for effect verification in example 1;

FIG. 3 is a schematic view of the forming of tensile test bar for mechanical property test

FIG. 4 is a drawing of the dimensions of a tensile bar for mechanical property testing;

FIG. 5 is a graph comparing the mechanical property curves of samples A #, B #, C # and D #.

Detailed Description

The experimental procedures used in the following examples are conventional unless otherwise specified. The materials, reagents, methods and apparatus used, unless otherwise specified, are conventional in the art and are commercially available to those skilled in the art.

Example 1:

firstly, selecting spherical K418 nickel-based superalloy powder with good powder fluidity and chemical components meeting the national standard requirements as a raw material for selective laser melting forming. The concrete components are as follows: 0.08 to 0.16 wt%, Cr: 11.50 to 13.50 wt%, Mo: 3.8-4.80 wt%, Al: 5.50-6.40 wt%, Ti: 0.50-1.00 wt%, Fe is less than or equal to 1.00 wt%, Nb: 1.80-2.50 wt%, B: 0.008 to 0.020 wt%, Zr: 0.060-0.150 wt%, Mn is less than or equal to 0.50 wt%, Si is less than or equal to 0.50 wt%, P is less than or equal to 0.015 wt%, S is less than or equal to 0.010 wt%, and the balance is Ni; the particle size distribution is as follows: d10 is 24.57 mu m, D50 is 36.27 mu m, D90 is 49.22 mu m, and the requirement of particle size distribution of the powder formed by selective laser melting is met; it is loose and denseThe degree is 4.47g/cm³Tap density of 5.12g/cm³。

Secondly, the first step of the method is to perform the following steps, building a model of a K418 supercharged turbine, introducing an STL part of the supercharged turbine to a Magics RP interface, checking and repairing various model errors in an STL file, building an FS271M virtual printing platform, placing the part, and designing a basic supporting structure (the specific process of the supporting structure design is that UG three-dimensional modeling software is used for building a structural model of a required target part, the structural model is stored in an STL format, and additive process support is carried out on the part of the supercharged turbine blade through additive manufacturing processing software. Then, processing by adopting selective laser melting forming equipment, ensuring that the raw materials of the powder cabin are sufficient before starting, setting processing technological parameters in the selective laser melting forming processing process, and carrying out selective laser melting forming processing under argon atmosphere to ensure that the oxygen content in the forming cabin is not more than 0.1%; the substrate is a Q235 steel plate, and the processing technological parameters are as follows: the preset temperature of the substrate is 200 ℃, the laser power is 220W, the powder layer thickness is 0.03mm, the scanning speed is 750mm/s, the scanning interval is 0.11mm, the formed powder material on the workbench is selected to be melted, then the workbench is reduced by one layer thickness, the powder is spread, the formed powder is continuously melted in a selected area, the action is repeated, and the formed powder is gradually stacked to form the design of the support structure in the booster turbine, as shown in figure 1.

And thirdly, performing line cutting on the machined part by using a repeated wire-moving electric spark wire cutting machine tool at the cutting speed of 10mm/s, performing heat treatment in a vacuum sintering furnace, heating the part from room temperature to 1180 ℃ at the heating rate of 8 ℃/min, preserving heat at the temperature for 2 hours, then performing air cooling to 450 ℃, then heating the part at the heating rate of 8 ℃/min, keeping the temperature at 930 ℃ for 16 hours, and performing air cooling to room temperature. Taking out the part and then carrying out surface treatment to obtain the K418 nickel-based superalloy supercharging turbine; the surface treatment comprises surface cleaning, surface polishing and surface sand blasting in sequence, and the final k418 nickel-based superalloy supercharging turbine is obtained.

The following performance characterization tests were performed:

firstly, selecting spherical K418 nickel-based superalloy powder with good powder fluidity and chemical components meeting the national standard requirements as a raw material for selective laser melting forming. The concrete components are as follows: 0.08 to 0.16 wt%, Cr: 11.50 to 13.50 wt%, Mo: 3.8-4.80 wt%, Al: 5.50-6.40 wt%, Ti: 0.50-1.00 wt%, Fe is less than or equal to 1.00 wt%, Nb: 1.80-2.50 wt%, B: 0.008 to 0.020 wt%, Zr: 0.060-0.150 wt%, Mn is less than or equal to 0.50 wt%, Si is less than or equal to 0.50 wt%, P is less than or equal to 0.015 wt%, S is less than or equal to 0.010 wt%, and the balance is Ni; the particle size distribution is as follows: d10: 24.57 μm, D50: 36.27 μm, D90: 49.22 μm, meeting the requirement of particle size distribution of powder formed by selective laser melting; the apparent density is 4.47g/cm³Tap density of 5.12g/cm³。

And secondly, optimally designing the parameters of the laser melting forming process. In the laser melting forming process, the technological parameters which have important influence on the final performance of the test piece mainly comprise laser power p, scanning speed v, scanning interval s and powder laying thickness h, and multiple technological parameters act on the part in a synergistic mode. By analyzing the physical and chemical properties of the K418 high-temperature alloy and by orthogonal tests, 16 groups of experiments are designed for comparison. The laser power p determines 4 sets of process parameters: 220W, 240W, 260W, 280W, the scanning speed v determines 4 sets of process parameters: 800mm/s, 950mm/s, 1100mm/s, 1250mm/s, and 4 sets of process parameters are determined by the scanning spacing s: 0.08mm, 0.09mm, 0.10mm and 0.11mm, setting the powder spreading thickness as an invariant according to the empirical value of 0.03mm, and performing laser forming on a small square sample with the size of 15 multiplied by 15mm after 16 groups of printing parameters are determined, as shown in figure 2. And (3) carrying out density and hardness value tests on the 16 groups of small square samples. The compactness of an alloy sample is an important reference index for representing the structure and the mechanical property of a material, and the high compactness usually means that the structure is compact, the defects of shrinkage cavities, shrinkage porosity, gaps and the like in the alloy sample are few, and the corresponding mechanical property is also excellent. According to the test result of the final comparison group test, 4 groups of better laser printing process parameters with high density and less internal defects are finally determined, and the details are shown in the following table 1:

the tensile bars were formed according to these 4 sets of process parameters, and the tensile bar samples were formed in the X-Y direction or the Z direction according to the deposition direction, as shown schematically in FIG. 3, and the dimensions of the tensile bars are shown in FIG. 4.

And (3) carrying out heat treatment on the formed tensile test bar, wherein the test heat treatment system specifies the solution treatment and the aging treatment according to the heat treatment standard of the K418 high-temperature alloy part in the heat treatment JB/T7712-1995 standard of the high-temperature alloy: heating to 1180 ℃, preserving the heat for 2 hours, and cooling to 450 ℃ in air; heating to 930 deg.C, holding for 16 hr, and air cooling. And respectively carrying out tensile test on the tensile test bars formed by the four parameters after heat treatment. And (3) performing tensile test on the sample by using a universal material testing machine, and performing the tensile test at room temperature according to GB/T228.1 to obtain the tensile strength Rm, the yield strength Rp0.2 and the elongation A of the sample. The mechanical property curves are shown in fig. 5. The room temperature tensile property test results are shown in table 2 below;

TABLE 2 results of tensile properties at room temperature for selective laser melting

Detecting parameters	R_m(MPa)	R_p0.2(MPa)	A％
				Technical index	≥755	≥685	≥3
A#	1295	796	12.13
				B#	1144	737	9.67
C#	1068	760	6.87
				D#	1256	773	10.47

And (4) performing tensile test under a high-temperature condition according to GB/T228.2 to obtain the tensile strength Rm, the yield strength Rp0.2, the elongation A and the reduction of area Z of the sample. The mechanical test results are shown in table 3.

TABLE 3 results of tensile properties test at high temperature (800 ℃ C.) in selective laser melting

Detecting parameters	R_m(MPa)	R_p0.2(MPa)	A％	Z％
					Technical index	≥755	-	≥4	≥6
A#	958	822	6	7
					B#	939	803	3.5	10
C#	898	733	3	4
					D#	961	841	8.5	14

According to the test result, a forming process parameter D # with higher density, less internal defects and excellent comprehensive performance is selected.

Claims

1. a method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology, is characterized in that, the method comprises the following steps:

Step 1, the selection of the forming powder: the particle size range of the forming powder is: 30μm≤D50≤40μm, the proportion of fine powder with a particle size smaller than 15μm<5%, and the proportion of coarse powder with a particle size larger than 53μm<5%;

Step 2: Build the model of the K418 supercharger turbine, prepare the pre-forming program files and processing technology parameter settings and import them into the SML equipment, where the processing technology parameters are specifically: the preset temperature of the substrate is 100-200°C, and the laser power is 220W-280W, The powder layer thickness is 30μm～60μm, the scanning rate is 800mm/s～1250mm/s, and the scanning distance is 0.08mm～0.11μm;

Step 3, laser selective melting and forming of the booster turbine, specifically: in an argon atmosphere, under the condition that the oxygen content in the forming chamber does not exceed 0.1%, according to the program files and processing parameters of the SML equipment imported in step 2, the SML equipment will According to the scanning path and process parameters in the program, the selected area melts the molding powder material on the worktable, and then the worktable is reduced by one layer thickness, and then powder is applied, and the selected area is continued to melt the molding powder. Repeat this action to gradually stack and form a supercharger turbine;

In step 4, heat treatment, wire cutting and surface treatment are sequentially performed on the supercharged turbine processed in step 3 to obtain a final product.

2 . A method for preparing a K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1 , wherein the shaped powder is spherical K418 nickel-based superalloy powder. 3 .

3. A method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1 or 2, wherein the specific composition of the forming powder is: C: 0.08-0.16 wt%, Cr: 11.50-13.50wt%, Mo: 3.8-4.80wt%, Al: 5.50-6.40wt%, Ti: 0.50-1.00wt%, Fe≤1.00wt%, Nb: 1.80-2.50wt%, B : 0.008-0.020wt%, Zr: 0.060-0.150wt%, Mn≤0.50wt%, Si≤0.50wt%, P≤0.015wt%, S≤0.010wt% and the balance Ni.

4. A method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 3, wherein the particle size distribution of the formed powder is: D10 is 24.57 μm, D50 is 36.27 μm, D90 is 49.22 μm; the bulk density of the formed powder is 4.47 g/cm ³ , and the tap density is 5.12 g/cm ³ .

5. A method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1, characterized in that, in the step 4, the heat treatment process is 6°C/min～10°C /min heating rate, from room temperature to 1000 ~ 1200 ℃, and then keep the temperature for 15 ~ 16h, air-cooled to room temperature.

6. a kind of method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1, is characterized in that, described step 4 middle wire cutting adopts repeated wire electric discharge wire cutting machine tool to carry out Wire cutting, the cutting speed is 10mm/s.

7. A method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1, wherein the surface treatment in the step 4 includes surface cleaning, surface grinding and surface spraying sand.

8. A method for preparing a K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1, wherein the pre-forming program file includes adding process support to the supercharged turbine: The Magics software was used to simulate the stress and deformation of K418 supercharged turbine laser selective laser melting and forming, and the simulation results of stress and deformation were analyzed. The numerical model of the forming process is used to design the local support structure.

9. A method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 8, characterized in that, the design process of the local support structure is: according to the simulation results, adding support to the support The optimal design of the position, support shape, the contact form of the support and the part, and the support process parameters, while ensuring the control of stress and deformation, reduces the number of process supports added, and achieves the purpose of saving raw materials and reducing the surface roughness of the parts.

10. A method for preparing K418 nickel-based superalloy supercharged turbine based on laser selective melting and forming technology according to claim 1, wherein the processing parameters in the second step are: the preset temperature of the substrate is 200 ℃, the laser power is 220W, the powder layer thickness is 0.03mm, the scanning rate is 750mm/s, and the scanning spacing is 0.11mm.