Additive manufacturing light alloy steel, preparation and application

Abstract

The invention relates to the field of light alloy steel, and provides additive manufacturing light alloy steel, preparation and application, and the atomic percentage expression of the light alloy steel is Fe Mn Al < f > Ni < d > Mg < Ce >, wherein M is one or more of Cr, Mo, V, Ti and Cu, b is equal to 5-35 at%, f is equal to 20-40 at%, d is equal to 8-20 at%, e is equal to 1-7 at%, and g is equal to 0-5 at%. The preparation method comprises the steps that S1, alloy steel element blocks or powder are prepared according to the proportion and smelted into alloy blocks; s2, the alloy block is machined, and powder for additive manufacturing is prepared; and S3, the powder for additive manufacturing is put into an additive manufacturing device, printing parameters are selected, and layer-by-layer printing forming is conducted. The aluminum content in the printing light alloy steel is greatly increased, the formability is good, cracks and microcracks are eliminated, the strength is high, and the printing light alloy steel has good printing performance and excellent mechanical performance.

Description

Technical Field

[0001] The present invention relates to the field of lightweight alloy steel, and in particular to additively manufactured lightweight alloy steel, its preparation and application. Background Art

[0002] The development of advanced automotive steels with high specific strength and ductility has become an important issue for improving safety standards and environmental protection. In order to achieve lightweight effects and high strength, Mn and Al have been used extensively in the development of lightweight steels. There is a problem of difficulty in forming due to cracking in the preparation of lightweight steel by additive manufacturing. Due to the large difference in the melting points of iron and aluminum, a large amount of aluminum added to the alloy leads to a serious tendency to crack during the high thermal gradient process in the additive manufacturing process, making it difficult to form. The upper limit of aluminum in lightweight steel aluminum alloys reported for additive manufacturing is about 9%. If this upper limit is exceeded, the steel aluminum alloy in additive manufacturing is prone to cracking and cannot be formed.

[0003] In order to further reduce the density of steel-aluminum alloys, improve their formability and increase their strength, it is urgent to develop a new lightweight alloy steel with a higher aluminum content and high temperature stability. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for additively manufacturing lightweight alloy steel, preparation and application. The prepared lightweight alloy steel with high aluminum content has good printing and forming properties.

[0005] The present invention adopts the following technical solution:

[0006] In one aspect, the present invention provides an additively manufactured lightweight alloy steel, the atomic percentage expression of Fe a Mn b Al f Ni d M g C e ; Wherein, M is one or more of Cr, Mo, V, Ti, and Cu, b = 5-35at%, f = 20-40at%, d = 8-20at%, e = 1-7at%, g = 0-5at%, and a+b+f+d+e+g = 100at%.

[0007] Any possible implementation as described above further provides an implementation, wherein the atomic percentage expression of the additively manufactured lightweight alloy steel is Fe 40 Mn 26 Al 20 Ni9C5.

[0008] As any possible implementation described above, an implementation is further provided, wherein the additively manufactured lightweight alloy steel has a dual-phase structure of a face-centered cubic phase and a B2 phase.

[0009] As any possible implementation described above, an implementation is further provided, wherein the strength of the additively manufactured lightweight alloy steel is ≥1 GPa, and the elongation is ≥8.5%.

[0010] On the other hand, the present invention also provides a method for preparing the above-mentioned additively manufactured lightweight alloy steel, comprising:

[0011] S1. Allocate blocks or powders of various alloy steel elements in proportion and melt them into alloy blocks;

[0012] S2, processing the alloy block obtained in step S1 to obtain powder for additive manufacturing;

[0013] S3, placing the additive manufacturing powder obtained in step S2 into an additive manufacturing device, selecting printing parameters, and printing and forming layer by layer to obtain the additive manufacturing light alloy steel.

[0014] Any possible implementation as described above further provides an implementation, in which in step S1, the atomic percentage of the alloy steel is Mn:Al:Ni::M:C=(5-35):(20-40):(8-20):(0-5):(1-7) at%.

[0015] Any possible implementation as described above further provides an implementation, in step S2, when printing adopts laser melting LPBF, the particle size of the additive manufacturing powder is 13 to 53 μm; when printing adopts coaxial powder feeding process LDED, the particle size of the additive manufacturing powder is 54 to 105 μm.

[0016] Any possible implementation as described above further provides an implementation, in which in step S2, the powder for additive manufacturing is prepared by using gas atomization VIGA, a rotary motor or an electrode induction gas atomization process EIGA.

[0017] Any possible implementation as described above, further provides an implementation, in step S3, the printing parameters are: ① selective laser melting process: laser power 110-275W, scanning speed 650-1250mm / s, layer thickness of each layer 30-60μm, pass spacing Hatch 80-150μm, each layer angle 67°; ② laser direct deposition process: laser power 450-650W, scanning speed 5-10mm / s, spot diameter 1-2mm, powder feeding rate 8-10g / min, protective gas 5-8L / min, powder feeding gas 10-20L / min.

[0018] On the other hand, the present invention also provides an application of the above-mentioned additively manufactured lightweight alloy steel, wherein the additively manufactured lightweight alloy steel is used to prepare lightweight steel parts for automobiles.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention solves the problem of cracking and failure to form alloy steel with high aluminum content (≥10). By optimizing and improving the element composition of alloy steel, the aluminum content is greatly increased, the density of alloy steel is reduced, and the molding is crack-free.

[0021] 2. The prepared alloy steel has a (FCC+B2) dual-phase structure and has high strength and high elongation.

[0022] 3. The prepared alloy steel has a strength of more than 1 GPa and an elongation of more than 8.5%.

[0023] 4. It has broad application prospects in the field of automotive steel technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a schematic flow chart of a method for preparing lightweight alloy steel by additive manufacturing according to an embodiment of the present invention.

[0025] Figure 2 Shown is a physical picture of the additively manufactured lightweight alloy steel printed in the embodiment.

[0026] Figure 3 The low aluminum content lightweight steel without nickel content and FeMn in the embodiment are shown. 26 Al 20 Ni 10 Comparison chart of mechanical properties of C5 lightweight steel.

[0027] Figure 4 The low aluminum content lightweight steel without nickel content and the FeMnAl 20 Ni 10 Phase analysis results of C.

[0028] Figure 5 Shown is a simulated phase diagram of a light alloy steel with an aluminum content of 20% in the embodiment. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention will be described in detail below in conjunction with specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0030] The embodiment of the present invention is an additively manufactured lightweight alloy steel, the atomic percentage expression is Fe a Mn bAl f Ni d M g C e ; Wherein, M is one or more of Cr, Mo, V, Ti, and Cu, b = 5-35at%, f = 20-40at%, d = 8-20at%, e = 1-7at%, g = 0-5at%, and a+b+f+d+e+g = 100at%.

[0031] In a specific embodiment, the atomic percentage expression of the additively manufactured lightweight alloy steel is:

[0032] Fe 40 Mn 26 Al 20 Ni9C5.

[0033] In a specific embodiment, the additively manufactured lightweight alloy steel is a dual-phase structure of a face-centered cubic phase and a B2 phase. Single-phase FCC has high plasticity but low strength. Single-phase BCC has high strength but no plasticity and cannot be applied. The dual-phase structure of the present invention has the characteristics of both high strength and high elongation.

[0034] The additively manufactured lightweight alloy steel has a strength of ≥1 GPa and an elongation of ≥8.5%.

[0035] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing the above-mentioned light alloy steel by additive manufacturing, comprising:

[0036] S1. Allocate blocks or powders of various alloy steel elements in proportion and melt them into alloy blocks;

[0037] S2, crushing the alloy block obtained in step S1 to prepare powder for additive manufacturing;

[0038] S3, placing the additive manufacturing powder obtained in step S2 into an additive manufacturing device, selecting printing parameters, and printing and forming layer by layer to obtain the additive manufacturing light alloy steel.

[0039] In a specific embodiment, in step S1, the atomic percentage of the alloy steel is: Mn:Al:Ni::M:C=(5-35):(20-40):(8-20):(0-5):(1-7) at%, and the rest is Fe.

[0040] In a specific embodiment, in step S2, when printing adopts laser melting LPBF, the particle size of the additive manufacturing powder is 13-53 μm; when printing adopts coaxial powder feeding process LDED, the particle size of the additive manufacturing powder is 54-105 μm.

[0041] In a specific embodiment, in step S2, the powder for additive manufacturing is prepared by gas atomization VIGA, rotary motor or electrode induction gas atomization process EIGA.

[0042] In a specific embodiment, in step S3, the printing parameters are: laser power 150-275W, scanning speed 650-1250mm / s, layer thickness of each layer 30-60μm, pass spacing Hatch of 80-150μm, and rotation angle of each layer 67°.

[0043] Example 1

[0044] In this embodiment, the atomic percentage expression of additive manufacturing lightweight alloy steel is Fe 40 Mn 26 Al 20 Ni9C5.

[0045] Preparation method:

[0046] Elements such as iron, manganese, aluminum, carbon, and nickel are melted into alloys in proportion, and prepared into powders suitable for additive manufacturing through gas atomization, rotating motors, electrode induction gas atomization, etc. Taking selective laser melting as an example, 15-53 micron powder is required. The coaxial powder feeding process requires 54-105 micron powder. It depends on the process requirements. Put the powder into the additive manufacturing equipment, adjust the printing process, and select the appropriate printing parameters. Taking a certain brand of printer as an example, the laser power is 200W, the scanning speed is 800mm / s, the layer thickness is 30 microns, the pass spacing Hatch is about 120 microns, and the angle of each layer is 67°.

[0047] Example 2

[0048] In the embodiment, the atomic percentage expression of the additively manufactured lightweight alloy steel is FeMnAl 30 Ni 10 C3.

[0049] Preparation method:

[0050] Elements such as iron, manganese, aluminum, carbon, and nickel are melted into alloys in proportion, and prepared into powders suitable for additive manufacturing through gas atomization, rotating motors, electrode induction gas atomization, etc. Taking selective laser melting as an example, 15-53 micron powder is required. The coaxial powder feeding process requires 54-105 micron powder. It depends on the process requirements. Put the powder into the additive manufacturing equipment, adjust the printing process, and select the appropriate printing parameters. Taking a certain brand of printer as an example, the laser power is 150W, the scanning speed is 1000mm / s, the layer thickness is 30 microns, the pass spacing Hatch is about 150 microns, and the angle of each layer is 67°.

[0051] Example 3

[0052] In the embodiment, the atomic percentage expression of the additively manufactured lightweight alloy steel is FeMnAl 38 Ni 15 C5.

[0053] Preparation method:

[0054] Elements such as iron, manganese, aluminum, carbon, and nickel are melted into alloys in proportion, and prepared into powders suitable for additive manufacturing through gas atomization, rotating motors, electrode induction gas atomization, etc. Taking selective laser melting as an example, 15-53 micron powder is required. The coaxial powder feeding process requires 54-105 micron powder. It depends on the process requirements. Put the powder into the additive manufacturing equipment, adjust the printing process, and select the appropriate printing parameters. Taking a certain brand of printer as an example, the laser power is 115W, the scanning speed is 720mm / s, the layer thickness is 30 microns, the pass spacing Hatch is about 80 microns, and the angle of each layer is 67°.

[0055] In the light alloy steel of the present invention, iron, manganese, aluminum, carbon and nickel are essential elements. To further control the performance, M element (one or more of Cr, Mo, V, Ti and Cu) may be added, with the total content not exceeding 5% at%.

[0056] Example 4

[0057] In the embodiment, the atomic percentage expression of the additively manufactured lightweight alloy steel is FeMnAl 22 Ni 11 (TiCu)5C6.

[0058] Preparation method:

[0059] Elements such as iron, manganese, aluminum, carbon, nickel, titanium, and copper are melted into alloys in proportion, and prepared into powders suitable for additive manufacturing through gas atomization, rotary motors, electrode induction gas atomization, etc. Taking the coaxial powder feeding process as an example, 54-105 micron powders are screened. The powder is placed in the additive manufacturing equipment, the printing process is adjusted, and the appropriate printing parameters are selected. Taking a certain brand of printer as an example, the laser power is 650W, the scanning speed is 6mm / s, the spot diameter is 1.6mm, the powder feeding rate is 9.24g / min, the protective gas is 6L / min, and the powder feeding gas is 15L / min.

[0060] Example 5

[0061] In the embodiment, the atomic percentage expression of the additively manufactured lightweight alloy steel is FeMnAl 22 Ni 11 (CrTiCu)4C6.

[0062] Preparation method:

[0063] Elements such as iron, manganese, aluminum, carbon, nickel, chromium, titanium, and copper are melted into alloys in proportion, and prepared into powders suitable for additive manufacturing through gas atomization, rotary motors, electrode induction gas atomization, etc. Taking the coaxial powder feeding process as an example, 54-105 micron powders are screened. The powder is placed in the additive manufacturing equipment, the printing process is adjusted, and the appropriate printing parameters are selected. Taking a certain brand of printer as an example, the laser power is 650W, the scanning speed is 6mm / s, the spot diameter is 1.6mm, the powder feeding rate is 9.24g / min, the protective gas is 6L / min, and the powder feeding gas is 15L / min.

[0064] Example 6

[0065] In the embodiment, the atomic percentage expression of the additively manufactured lightweight alloy steel is FeMnAl 22 Ni 11 Cr5C6.

[0066] Preparation method:

[0067] Elements such as iron, manganese, aluminum, carbon, nickel, and chromium are melted into alloys in proportion, and prepared into powders suitable for additive manufacturing through gas atomization, rotary motors, electrode induction gas atomization, etc. Taking the coaxial powder feeding process as an example, 54-105 micron powders are screened. The powder is placed in the additive manufacturing equipment, the printing process is adjusted, and the appropriate printing parameters are selected. Taking a certain brand of printer as an example, the laser power is 650W, the scanning speed is 6mm / s, the spot diameter is 1.6mm, the powder feeding rate is 9.24g / min, the protective gas is 6L / min, and the powder feeding gas is 15L / min.

[0068] In the above-mentioned several embodiments, the additively manufactured lightweight alloy steel has an average strength of ≥1 GPa and an elongation of ≥8.5%.

[0069] The present invention uses composition gradient printing to test whether the material will crack after the nickel element is added. Figure 2 The printed material of FeMnAlNiC alloy with gradually increasing Ni content from left to right. The left side is FeMnAl20C lightweight steel without nickel, which has a serious tendency to crack when printed. The nickel content gradually increases to the right. As the Ni content is added to 5%, the macro cracks of the material disappear, but the micro cracks still exist. When the Ni content is increased to 8%, the micro cracks of the material disappear.

[0070] like Figure 3 As shown, nickel-free low aluminum content lightweight steel is the same as FeMn 26 Al 20 Ni 10 Compared with C lightweight steel, the strength of the lightweight alloy steel regulated by the present invention is greatly improved, and the ductility is slightly reduced.

[0071] Figure 4The FeMnAl2O3 steel is a lightweight steel with a low aluminum content and does not contain nickel. 20 Ni 10 The phase analysis results of C show that after adding Ni, the structure is transformed into a dual-phase structure of matrix FCC and B2 composite.

[0072] Figure 5 The simulated phase diagram of the light alloy steel with an aluminum content of 20% in the embodiment is shown. When the nickel content is less than 7.62, the first precipitated phase is a disordered body-centered cubic BCC. However, the growth rate of the body-centered cubic phase is much lower than that of the matrix face-centered cubic FCC structure, so it can only exist in the form of a crystal nucleus, so X-rays cannot detect it. When the nickel content is 7.62-27.13, the first precipitated phase is B2. At this time, due to the increase in entropy brought by the nickel element, the growth rate of the B2 phase is increased, so the B2 phase can nucleate and grow. The first precipitated B2 phase acts as a nucleation site for the matrix FCC, which promotes nucleation and refines grains, inhibiting cracking. In addition, the B2 phase consumes a large amount of aluminum, reducing the tendency of eutectic cracking caused by aluminum enrichment. When the nickel content is further increased (>27.13), carbides such as M23C6 precipitate and enrich at the grain boundaries, resulting in a significant increase in thermal stress during printing, reduced material printability, and reduced elongation of the material.

[0073] The light alloy steel designed by the present invention increases the entropy value of the alloy system by adding the alloy element nickel. At the same time, the mixing enthalpy of nickel and aluminum is negative, and the B2 phase is directly precipitated from the liquid phase during solidification. Due to high temperature stability, the B2 phase acts as a nucleation site to change the original solidification behavior of the alloy, achieve rapid solidification, and consume aluminum to inhibit cracking behavior, solving the printing problem of light steel with high aluminum content; the combined product has a dual-phase structure (FCC+B2) and has high temperature stability.

[0074] Although several embodiments of the present invention have been given herein, those skilled in the art should understand that the embodiments of the present invention may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. An additively manufactured lightweight alloy steel, characterized in that: The atomic percentage expression of the additively manufactured lightweight alloy steel is Fe a Mn b Al f Ni d M g C e ; Wherein, M is one or more of Cr, Mo, V, Ti, and Cu, b = 5-35at%, f = 20-40at%, d = 8-20at%, e = 1-7at%, g = 0-5at%, and a+b+f+d+e+g = 100at%.

2. The additively manufactured lightweight alloy steel according to claim 1, characterized in that: The atomic percentage expression of the additively manufactured lightweight alloy steel is Fe 40 Mn 26 Al 20 Ni9C5.

3. The additively manufactured lightweight alloy steel according to claim 1, characterized in that: The additively manufactured light alloy steel has a dual-phase structure of a face-centered cubic phase and a B2 phase.

4. The additively manufactured lightweight alloy steel according to claim 1, characterized in that: The additively manufactured lightweight alloy steel has a strength of ≥1 GPa and an elongation of ≥8.5%.

5. A method for preparing light alloy steel by additive manufacturing according to any one of claims 1 to 4, characterized in that: The method comprises: S1. Allocate blocks or powders of various alloy steel elements in proportion and melt them into alloy blocks; S2, crushing the alloy block obtained in step S1 to prepare powder for additive manufacturing; S3, placing the additive manufacturing powder obtained in step S2 into an additive manufacturing device, selecting printing parameters, and printing and forming layer by layer to obtain the additive manufacturing light alloy steel.

6. The method for preparing light alloy steel by additive manufacturing according to claim 5, characterized in that: In step S1, the atomic percentage of the alloy steel is Mn:Al:Ni::M:C=(5-35):(20-40):(8-20):(0-5):(1-7) at%, and the rest is Fe.

7. The method for preparing light alloy steel by additive manufacturing according to claim 5, characterized in that: In step S2, when the printing adopts the laser melting LPBF, the particle size of the additive manufacturing powder is 13-53 μm; when the printing adopts the laser direct deposition process LDED, the particle size of the additive manufacturing powder is 54-105 μm.

8. The method for preparing light alloy steel by additive manufacturing according to claim 5, characterized in that: In step S2, in step S2, the powder for additive manufacturing is prepared by using gas atomization VIGA, rotary motor or electrode induction gas atomization process EIGA.

9. The method for preparing light alloy steel by additive manufacturing according to claim 5, characterized in that: In step S3, the printing parameters are: laser power 150-275 W, scanning speed 650-1250 mm / s, layer thickness of 30-60 μm, pass spacing Hatch of 80-150 μm, and rotation angle of 67° for each layer.

10. An application of additive manufacturing of lightweight alloy steel as claimed in any one of claims 1 to 4, characterized in that: The additively manufactured lightweight alloy steel is used to prepare lightweight steel parts for automobiles.

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