A nickel-based superalloy and a laser selective melting preparation method thereof

Abstract

The application provides a nickel-based superalloy and a laser selective melting preparation method thereof, and specifically comprises the following steps: (1) fully mixing and uniformly mixing weldable Inconel718 nickel-based superalloy powder and non-weldable K447A nickel-based superalloy powder according to different component proportions; (2) drying and removing moisture from the mixed alloy powder in an oven; (3) printing and forming the mixed powder by using a laser selective melting method, and adjusting process parameters including laser power, scanning speed, layer thickness and scanning strategy; and (4) obtaining a nickel-based superalloy component with few defects and good performance by adjusting the content of different alloy powders and the printing process parameters. The application obtains a nickel-based superalloy with good printing performance and mechanical performance by adjusting the content of different alloy powders, and compared with the existing nickel-based superalloy preparation method, the method has the characteristics of being simple and easy to implement and wide in application range.

Description

Technical Field

[0001] This invention relates to nickel-based superalloys prepared by additive manufacturing methods, specifically a novel nickel-based superalloy and its laser selective melting preparation method. This invention belongs to the fields of nickel-based superalloys and laser additive manufacturing. Background Technology

[0002] Selective laser melting (SLM) is an additive manufacturing technology that uses laser as an energy source. Also known as laser powder bed melting, it involves slicing a workpiece into two-dimensional thin layers based on its three-dimensional data. Using computer-aided technology, the workpiece is sliced ​​into these two-dimensional layers based on the three-dimensional data. A fine laser beam is then used to melt the powder in selected areas, creating a strong metallurgical bond between the layers and ultimately obtaining a three-dimensional bulk material. SLM offers several advantages: it eliminates the need for specific tooling and molds, has a short production cycle, high material utilization, and produces high-quality workpieces with minimal or no machining required. The raw materials used can be alloy powders, pure metal powders, ceramic powders, or combinations of these powders. Besides direct printing of complex structures, it can also be used to develop new alloy materials. With the development of modern aerospace technology, the demand for high-performance, lightweight, and environmentally friendly high-temperature alloy components capable of withstanding increasingly harsh environments is growing. SLM can meet this requirement for fabricating complex high-temperature alloy components. To date, laser additive manufacturing technology has been used to process various nickel-based superalloys. Among them, Inconel 718 is the most studied alloy. This alloy exhibits excellent mechanical properties and good structural stability at 650℃. It has low titanium and aluminum content (total content 1.6%), good weldability, and is suitable for additive manufacturing. Compared to alloys with good weldability like Inconel 718, nickel-based superalloys with high γ' phase strengthening have superior high-temperature strength but poor weldability, making them unsuitable for laser additive manufacturing. For example, K447A alloy, a typical precipitation-strengthened nickel-based superalloy, can operate at temperatures up to 1000℃. It has good casting properties, mechanical properties, and resistance to high-temperature oxidation and corrosion, making it suitable for manufacturing key hot-end components such as turbine disks and guide vanes for aero-engines. However, due to its high titanium and aluminum content (total content 6.55%), its weldability is very poor, classifying it as an unweldable alloy. This leads to numerous cracks during additive manufacturing, significantly limiting its practical applications. Therefore, fully utilizing the advantages of laser additive manufacturing while combining the characteristics of different types of weldable nickel-based superalloys to process and manufacture nickel-based superalloy components with both good additive manufacturing performance and excellent mechanical properties is an important direction for the development of superalloys. In view of this, this invention proposes to borrow the principle of material composites and use laser additive manufacturing to mix and print different types (weldable and non-weldable alloys) of nickel-based superalloy powders, thereby obtaining a novel nickel-based superalloy with both good printing performance and excellent mechanical properties. Summary of the Invention

[0003] The purpose of this invention is to utilize the principle of material composites and laser selective melting technology to prepare a novel nickel-based high-temperature alloy that has both good printing performance and mechanical properties.

[0004] The objective of this invention is achieved as follows:

[0005] This invention involves fully mixing nickel-based superalloy powders with different welding properties in different proportions using a ball mill, and then using laser selective melting technology to prepare a novel nickel-based superalloy with good printing performance and mechanical properties.

[0006] A method for preparing nickel-based superalloys by selective laser melting includes the following steps:

[0007] (1) IN718 nickel-based superalloy powder and K447A nickel-based superalloy powder were designed and mixed according to different component ratios;

[0008] (2) The alloy powder is mixed evenly by ball milling, and then dried in an oven at 100±10℃ for 6±2 hours to remove moisture from the powder.

[0009] (3) The alloy powder that has been thoroughly mixed and dried is prepared using a laser selective melting device. The process parameters are: laser power 200-280W, scanning speed 600-900mm / s, powder layer thickness 40μm, and scanning spacing 80μm. Finally, a printed nickel-based high-temperature alloy is obtained.

[0010] The laser selective melting scanning strategy in step (3) includes strip scanning, island scanning and spiral scanning; the interlayer rotation angle includes 0°, 45°, 67° and 90°.

[0011] In step (3), argon is used as a protective gas for the printing process.

[0012] The particle size range of the alloy powder selected in step (1) is 15-53 μm.

[0013] In step (1), K447A alloy powder and IN718 alloy powder are fully mixed by ball milling for 8 hours.

[0014] In step (1), the ratio of IN718 nickel-based superalloy powder to K447A nickel-based superalloy powder is 6:4.

[0015] In step (1), the ratio of IN718 nickel-based superalloy powder to K447A nickel-based superalloy powder is 8:2.

[0016] In step (1), the ratio of IN718 nickel-based superalloy powder to K447A nickel-based superalloy powder is 9:1.

[0017] The printed nickel-based superalloy has a yield strength of 784 MPa, a tensile strength of 1105 MPa, an elongation of 23.7% at room temperature, a Vickers hardness of 324 HV0.5, and a defect rate of 0.1%.

[0018] A nickel-based superalloy, characterized in that it is prepared by any of the methods described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] This invention utilizes the advantages of weldable and non-weldable nickel-based high-temperature alloys, which respectively possess excellent printing performance and mechanical properties. Drawing on the principle of material composites, different types of alloy powders are mixed and processed into shapes using laser selective melting technology to prepare a novel high-temperature alloy with both good printing performance and mechanical properties.

[0021] The printed nickel-based superalloy obtained by this invention has a yield strength of 784 MPa, a tensile strength of 1105 MPa, an elongation of 23.7% at room temperature, a Vickers hardness of 324 HV0.5, and a defect rate of 0.1%. Its mechanical properties are superior to those of single alloy powder printed alloys.

[0022] The technical means used in this invention is laser selective melting additive manufacturing technology, which has advantages such as short production cycle, high material utilization rate and large design freedom compared with traditional processing methods. Attached Figure Description

[0023] Figure 1a -e represents the microstructure of K447A / IN718 alloy after selective laser melting;

[0024] Figure 2a -e represents the molten pool morphology of K447A / IN718 alloy in selective laser melting;

[0025] Figure 3 Mechanical properties of K447A / IN718 alloy obtained by selective laser melting. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] The steps for preparing nickel-based superalloys according to the present invention are as follows: different types of weldable nickel-based superalloys are weighed according to different mass percentage ratios, and thoroughly mixed using a ball mill for 8 hours;

[0028] (1) Dry the mixed alloy powder in an oven at a temperature of 100±10℃ and keep it at that temperature for 6±2 hours.

[0029] (2) The dried alloy powder is loaded into the laser selective melting equipment. The selected printing process parameters are: laser power 200-280W, scanning speed 600-900mm / s, powder layer thickness 40μm, scanning spacing 80μm, scanning strategy is bar scanning strategy, interlayer rotation 67°, substrate temperature is set to 160℃, and argon gas is filled into the forming chamber as a protective gas.

[0030] (3) The particle size range of the mixed alloy powder is 15-53 μm;

[0031] (4) After printing, the sample is cut off from the substrate and the microstructure and mechanical properties of the sample are characterized.

[0032] Furthermore, the additive manufacturing technology for the alloy is not limited to laser selective melting technology, but also includes electron beam additive manufacturing technology or electric arc additive manufacturing technology, as well as combinations of the above additive manufacturing technologies.

[0033] Furthermore, the ball mill mixing equipment can be any ball mill equipment with a mixing function.

[0034] Furthermore, the laser selective melting equipment can optimize the printing performance and mechanical properties of the alloy by adjusting process parameters such as laser power, scanning speed, layer thickness, and scanning strategy.

[0035] Furthermore, the substrate temperature is set to 160°C during the laser selective melting process, and argon is used as the printing protective gas.

[0036] Furthermore, the composite principle and preparation process proposed above are not only applicable to nickel-based superalloys, but also to the additive manufacturing of other alloys such as titanium alloys, stainless steel and their composite materials.

[0037] A nickel-based superalloy and its laser selective melting preparation method include the following steps:

[0038] (1) K447A alloy powder and IN718 alloy powder were thoroughly mixed by ball milling. The total content of Al and Ti was controlled, and three alloy compositions were designed: KI46 (K447A (40%) / IN718 (60%)), KI28 (K447A (20%) / IN718 (80%)), and KI19 (K447A (10%) / IN718 (90%)). K447A and IN718 printed with single alloy powders were used as control groups.

[0039] (2) The two alloy powders with different proportions were fully mixed using a planetary ball mill. The stainless steel grinding balls used in the mixing process had diameters of 10 mm and 6 mm, a ball-to-material ratio of 3:1, a ball mill speed of 200 r / min, and a mixing time of 8 hours.

[0040] (3) Place the mixed alloy powder in an oven to dry at 100℃ for 6 hours. This thoroughly removes moisture from the alloy, improves the fluidity of the mixed alloy powder, and allows the mixed powder to spread better during the printing process.

[0041] (4) The mixed alloy powder was loaded into the laser selective melting equipment. The oxygen content in the forming chamber was reduced to 500ppm by pumping and purging. Then, argon was introduced as a protective gas to prevent oxidation during processing. The substrate temperature was set to 160℃. The process parameters were: laser power 200-280W, scanning speed 600-900mm / s, powder layer thickness 40μm, scanning spacing 80μm, and a strip scanning strategy with interlayer rotation of 67°. A total of 9 sets of process parameters were obtained.

[0042] (5) After printing, the sample is cut off from the substrate using a wire cutting machine, and the microstructure and mechanical properties of each mixed component alloy are characterized.

[0043] Figure 1a -e represents the microstructure of K447A / IN718 alloy obtained by laser selective melting. Figure 1a The microstructure of a single K447A chromatographic alloy reveals numerous crack defects. Figure 1b -d are microstructure photographs of KI46, KI28, and KI19 alloys, respectively. It can be observed that with the increase of IN718 content, the number of cracks in the alloy gradually decreases, and the weldability gradually improves. Figure 1e The microstructure of a single IN718 printed alloy is shown in the photograph, revealing virtually no cracks. Figure 2a -e is a micrograph of the molten pool morphology of K447A / IN718 alloy obtained by laser selective melting. Figure 2a -e and Figure 1a The sample sequence corresponding to -e is consistent. The change in alloy molten pool morphology indicates that the addition of IN718 alloy changed the morphology of K447A alloy molten pool. The molten pool morphology changed from narrow and deep to wide and shallow, the area of ​​heat-affected zone gradually decreased, and the number of cracks decreased. Figure 3 Stress-strain curves of K447A / IN718 alloy prepared by laser selective melting were obtained. Among them, KI28 alloy had the best comprehensive performance. The yield strength of the printed alloy at room temperature was 784 MPa, the tensile strength was 1105 MPa, and the elongation reached 23.3%. Figure 1cThe microstructure of the KI28 alloy after polishing shows a defect rate of 0.1% calculated using Imagej software. Table 1 shows the mechanical properties of each component alloy printed under the same process parameters (laser power 240W, scanning speed 900mm / s, powder layer thickness 40μm, bar scanning strategy, interlayer rotation 67°). The experimental results show that the composite powder mixing printing method can obtain nickel-based superalloy bulk materials with both good printing performance and mechanical properties.

[0044] Table 1

[0045]

[0046] This invention provides a nickel-based superalloy and its laser selective melting preparation method. Specifically: (1) Weldable Inconel 718 nickel-based superalloy powder and non-weldable K447A nickel-based superalloy powder are thoroughly mixed in different proportions; (2) The mixed alloy powder is dried in an oven to remove moisture; (3) The mixed powder is printed into shape using laser selective melting, with adjusted process parameters including laser power, scanning speed, layer thickness, and scanning strategy; (4) By adjusting the content of different alloy powders and the printing process parameters, nickel-based superalloy components with fewer defects and better performance are obtained. This invention obtains nickel-based superalloys with both good printing performance and mechanical properties by controlling the content of different alloy powders. Compared with existing nickel-based superalloy preparation methods, this method is simple, easy to implement, and has a wide range of applications.

Claims

1. A method for laser powder bed fusion of a nickel-based superalloy, characterized in that, The method comprises the following steps: (1) mixing IN718 nickel-based superalloy powder and K447A nickel-based superalloy powder according to different component proportions; (2) uniformly mixing the alloy powder by using a ball milling method, then drying in an oven, setting the temperature to 100±10℃, and keeping the temperature for 6±2 hours to remove water in the powder; (3) preparing the alloy powder which is fully mixed and dried by using a laser selective melting device, the process parameters range from 200 to 280 W of laser power, 600 to 900 mm / s of scanning speed, 40 μm of powder layer thickness, and 80 μm of scanning interval; finally obtaining a printed nickel-based superalloy; the laser selective melting scanning strategy in the step (3) comprises strip scanning, island scanning and spiral scanning; the interlayer rotation angle comprises 0°, 45°, 67° and 90°; the step (3) uses argon as the protective gas in the printing forming process; the particle size of the alloy powder selected in the step (1) ranges from 15 to 53 μm; the step (1) fully mixes the K447A alloy powder and the IN718 alloy powder by using a ball milling method, and the mixing time is 8 hours; the proportion of the IN718 nickel-based superalloy powder and the K447A nickel-based superalloy powder in the step (1) is 6:4, 8:2 or 9:

1.

2. The method for preparing nickel-based superalloys by laser selective melting according to claim 1, characterized in that, The printed nickel-based superalloy has a yield strength of 784 MPa, a tensile strength of 1105 MPa, an elongation of 23.7%, a Vickers hardness value of 324 HV0.5, and a defect rate of 0.1% at room temperature.

3. A nickel-base superalloy characterized by, Prepared by any one of the methods in claims 1-2.

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