Alloy powder for selective laser melting, alloy steel and preparation method thereof

Abstract

The present invention discloses an alloy powder for selective laser melting, wherein the raw materials include, by weight percentage: C≤0.03%, Si≤0.10%, Mn≤0.10%, P≤0.01%, S≤0.01%, O≤0.08%, Mo 3‑6%, Ni 15‑21%, Al 0.02‑0.18%, Co 8‑15.75%, Ti 0.7‑1.95%, and the remainder is Fe. The present invention also discloses a method for preparing alloy steel by selective laser melting, comprising the following steps: performing selective laser melting on the alloy powder to form a blank, cooling the blank to room temperature in a nitrogen atmosphere, and then heat treating the blank to obtain the alloy steel. The present invention also discloses an alloy steel, which is prepared by the selective laser melting method for preparing the alloy steel. The application of the alloy steel is also disclosed. The alloy steel obtained by the present invention has good mechanical properties and greatly shortens the production cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of alloys, and in particular to alloy powder for selective laser melting, alloy steel and a preparation method thereof. Background Art

[0002] 18Ni350 ultra-high strength steel has a wide range of applications in the field of high-strength steel due to its excellent strength and toughness. However, the traditional production and heat treatment of 18Ni350 materials often require multiple cumbersome processes such as solid solution treatment, aging treatment and cyclic heat treatment, resulting in a long production cycle and high processing costs. In addition, traditional casting or forging methods often cause cracking problems during the molding process, affecting the quality and application range of the material. In recent years, with the development of selective laser melting (SLM) technology, 3D printing technology has provided a new solution for the manufacture of high-performance metal materials. SLM technology can accurately control the melting process, form complex structures, and solve the problem of material cracking to a certain extent. However, the existing SLM molding 18Ni350 material heat treatment method has not been perfected. How to further improve material performance, shorten production cycle, and reduce costs by optimizing the heat treatment system is still a technical problem that needs to be solved urgently. Summary of the invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes an alloy powder for selective laser melting, an alloy steel and a preparation method thereof. The present invention adjusts the alloy composition and screens appropriate selective laser melting parameters and heat treatment parameters to enable the alloy steel to have good mechanical properties, density and no cracks. Compared with the existing process that requires multiple solid solution and aging treatments, the production cycle is greatly shortened and the production cost is reduced.

[0004] The invention provides an alloy powder for selective laser melting, wherein the raw materials thereof include, by weight percentage, C≤0.03%, Si≤0.10%, Mn≤0.10%, P≤0.01%, S≤0.01%, O≤0.08%, Mo 3-6%, Ni 15-21%, Al 0.02-0.18%, Co 8-15.75%, Ti 0.7-1.95%, and the balance is Fe.

[0005] Preferably, the raw materials include, by weight percentage: C≤0.03%, Si≤0.10%, Mn≤0.10%, P≤0.01%, S≤0.01%, O≤0.08%, Mo 3.5-4.5%, Ni 17-19%, Al 0.05-0.15%, Co 9-11%, Ti 1.0-1.2%, and the balance is Fe.

[0006] Preferably, the raw materials include, by weight percentage, C 0.02%, Si 0.08%, Mn 0.05%, P 0.005%, S 0.005%, O 0.01%, Mo 4%, Ni 18%, Al 0.1%, Co 10%, Ti 1.1%, and the balance is Fe.

[0007] The present invention also proposes a method for preparing alloy steel by selective laser melting, comprising the following steps: performing selective laser melting on the alloy powder to form a blank, cooling the blank to room temperature in an inert atmosphere, and then heat treating the blank to obtain the alloy steel.

[0008] The inert atmosphere may be one or more of a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere.

[0009] Preferably, the parameters of the selective laser melting are: scanning layer thickness of 30-50 μm, scanning speed of 800-1000 mm / s, laser power of 270-310 W, scanning spacing of 0.08-0.11 mm, and inter-layer rotation angle of 16-18°.

[0010] Preferably, the parameters of the selective laser melting are: scanning layer thickness of 30-40 μm, scanning speed of 850-950 mm / s, laser power of 290-310 W, scanning spacing of 0.09-0.10 mm, and inter-layer rotation angle of 16-18°.

[0011] Preferably, the heat treatment parameters are: temperature of 460-500° C. and time of 4-8 h.

[0012] Preferably, the heat treatment parameters are: temperature of 460-480°C and time of 4-6h.

[0013] The present invention also provides an alloy steel, which is prepared according to the selective laser melting preparation method of the alloy steel.

[0014] The invention also proposes the application of the alloy steel in aerospace and automobile manufacturing.

[0015] The present invention improves the crack resistance and toughness of the alloy steel by reducing the carbon content, and selects a suitable content of Ni to cooperate with Ti, Mo and Al to form a Ni3Ti aging strengthening phase, an aging phase Ni3Mo with a close-packed hexagonal structure, a NiAl phase and an η-Ni3 (Ti, Al) phase, so that the alloy steel improves its strength while maintaining good toughness, and Ni can keep the austenite stable; a suitable amount of Co is selected to cooperate with Mo to promote the precipitation of a molybdenum-containing precipitation phase, and Co itself can be distributed in the alloy structure in the form of atoms, further improving the strength of the alloy and hindering the coarsening of the aging phase; in addition, a suitable amount of Mo is easily enriched at the grain boundary, hindering the precipitation of the aging phase therefrom, reducing the risk of fracture along the grain boundary, and improving the toughness level of the alloy; and Al can also effectively prevent oxidation of the material.

[0016] In addition, the present invention adjusts the alloy composition and selects appropriate selective laser melting parameters to obtain a blank, which can make the blank have a high density and is not easy to crack during the selective laser melting forming process, which has great advantages in expanding the application range of the alloy; and the blank obtained by the present invention only needs to undergo a single heat treatment step to obtain good mechanical properties, which greatly shortens the production cycle and reduces production costs compared to the existing process that requires multiple solid solution and aging treatments, and is suitable for industrial production. The obtained alloy steel can be used in aerospace, automobile manufacturing, high-end equipment and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 These are photos of the alloy steels prepared in Examples 1-5, wherein ae are Examples 1-5 respectively.

[0018] Figure 2-6 The photographs of the alloy steels prepared in Comparative Examples 1, 3, 5, 7 and 9 are shown in sequence. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described in detail below through specific embodiments.

[0020] Examples 1-3 and Comparative Examples 1-4

[0021] A selective laser melting preparation method for alloy steel comprises the following steps: taking alloy powder with a formula as shown in Table 1 and performing selective laser melting to prepare a blank, cooling the blank to room temperature in a nitrogen atmosphere, then heat treating the blank, and naturally cooling the blank to room temperature to obtain alloy steel;

[0022] The parameters of the selective laser melting are: scanning layer thickness of 30 μm, scanning speed of 1000 mm / s, laser power of 300 W, scanning spacing of 0.1 mm, and interlayer rotation angle of 17°; the heat treatment parameters are: temperature of 460 °C and time of 4 h.

[0023] Table 1 Formula of each combination of alloy powder (weight percentage, balance is Fe)

[0024] Grouping Mo Ni Al Co Ti C Si Mn P S O Example 1 3 21 0.02 15.75 0.7 0.02 0.08 0.05 0.005 0.005 0.01 Example 2 6 15 0.18 8 1.95 0.02 0.08 0.05 0.005 0.005 0.01 Example 3 4 18 0.1 10 1.1 0.02 0.08 0.05 0.005 0.005 0.01 Comparative Example 1 7 18 0.1 10 1.1 0.02 0.08 0.05 0.005 0.005 0.01 Comparative Example 2 4 18 0.2 10 1.1 0.02 0.08 0.05 0.005 0.005 0.01 Comparative Example 3 4 18 0.1 7 1.1 0.02 0.08 0.05 0.005 0.005 0.01 Comparative Example 4 4 18 0.1 10 2.1 0.02 0.08 0.05 0.005 0.005 0.01

[0025] Examples 4-5 and Comparative Examples 5-7

[0026] A selective laser melting preparation method for alloy steel comprises the following steps:

[0027] The alloy powder with the formula as in Example 3 was subjected to selective laser melting to form a blank, which was cooled to room temperature in a nitrogen atmosphere and then heat treated to obtain alloy steel; wherein the parameters of the selective laser melting and the heat treatment parameters are shown in Table 2.

[0028] Table 2 Parameters of laser melting and heat treatment of each group of selected areas

[0029]

[0030]

[0031] The alloy steels obtained in Examples 1-5 and Comparative Examples 1-9 were tested for performance. The results are shown in Tables 3 and Figure 1-6 shown.

[0032] Figure 1 These are photos of the alloy steels prepared in Examples 1-5, wherein ae are Examples 1-5 respectively.

[0033] Figure 2-6 The photographs of the alloy steels prepared in Comparative Examples 1, 3, 5, 7 and 9 are shown in sequence.

[0034] Table 3 Test results

[0035]

[0036] From Table 3 and Figure 1-6 It can be seen that the alloy steel prepared by the method of the present invention has good density and no cracks compared with comparative examples 1-9;

[0037] It can be seen from the comparison between Example 3 and Comparative Examples 1-4 that when the content of Mo, Ni, Al, Co, and Ti is too low or too high, the density, tensile strength, yield strength, and Vickers hardness of the alloy steel will be greatly reduced, affecting its mechanical properties;

[0038] It can be seen from the comparison between Example 3 and Comparative Examples 5-8 that when the laser melting parameters and heat treatment parameters of the selected area are not properly selected, the density, tensile strength, yield strength and Vickers hardness of the alloy steel will also decrease, affecting the mechanical properties;

[0039] It can be seen from Example 3 and Comparative Example 9 that after only one solution treatment and one aging treatment, the mechanical properties and density of the alloy steel are relatively low, and the existing process requires multiple solution + aging treatments, which takes a long time.

[0040] It can be seen from the present invention that the alloy steel can have good crack resistance, density and mechanical properties by selecting suitable alloy components and screening suitable selective laser melting parameters and heat treatment parameters.

[0041] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An alloy powder for selective laser melting, characterized in that: The raw materials include, by weight percentage: C≤0.03%, Si≤0.10%, Mn≤0.10%, P≤0.01%, S≤0.01%, O≤0.08%, Mo 3-6%, Ni 15-21%, Al 0.02-0.18%, Co 8-15.75%, Ti 0.7-1.95%, and the balance is Fe.

2. The alloy powder for selective laser melting according to claim 1, characterized in that: The raw materials include, by weight percentage: C≤0.03%, Si≤0.10%, Mn≤0.10%, P≤0.01%, S≤0.01%, O≤0.08%, Mo 3.5-4.5%, Ni 17-19%, Al 0.05-0.15%, Co 9-11%, Ti 1.0-1.2%, and the balance is Fe.

3. The alloy powder for selective laser melting according to claim 1 or 2, characterized in that: The raw materials include, by weight percentage, C 0.02%, Si 0.08%, Mn 0.05%, P 0.005%, S 0.005%, O 0.01%, Mo 4%, Ni 18%, Al 0.1%, Co 10%, Ti 1.1%, and the balance is Fe.

4. A method for preparing alloy steel by selective laser melting, characterized in that: The method comprises the following steps: performing selective laser melting on the alloy powder as claimed in any one of claims 1 to 3 to prepare a blank, cooling the blank to room temperature in an inert atmosphere, and then performing heat treatment to obtain alloy steel.

5. The method for preparing alloy steel by selective laser melting according to claim 4, characterized in that: The parameters of selective laser melting are: scanning layer thickness of 30-50 μm, scanning speed of 800-1000 mm / s, laser power of 270-310 W, scanning spacing of 0.08-0.11 mm, and inter-layer rotation angle of 16-18°.

6. The method for preparing alloy steel by selective laser melting according to claim 4 or 5, characterized in that: The parameters of selective laser melting are: scanning layer thickness of 30-40 μm, scanning speed of 850-950 mm / s, laser power of 290-310 W, scanning spacing of 0.09-0.10 mm, and inter-layer rotation angle of 16-18°.

7. The method for preparing alloy steel by selective laser melting according to any one of claims 4 to 6, characterized in that: Heat treatment parameters are: temperature 460-500°C, time 4-8h.

8. The method for preparing alloy steel by selective laser melting according to any one of claims 4 to 7, characterized in that: Heat treatment parameters are: temperature 460-480°C, time 4-6h.

9. An alloy steel, characterized in that: The alloy steel is prepared by the selective laser melting preparation method of alloy steel according to any one of claims 4 to 8.

10. Use of the alloy steel as claimed in claim 9 in aerospace and automobile manufacturing.

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