A method of additive manufacturing of a sandwich structured high strength steel with interlaminar orientation differences

Abstract

The application discloses an additive manufacturing method of sandwich structure high-strength steel with interlayer orientation difference, which utilizes an additive manufacturing technology, adopts a layer-by-layer accumulation mode, sequentially deposits materials with different strengths and toughnesses, and realizes preparation of a sandwich structure component with high strength, high toughness and high strength. Meanwhile, in the deposition process, the deposition direction of the deposited layer is adjusted, so that the stress direction of each deposited layer is optimal in the stretching process, the good strength-toughness matching of the component is further realized, and the strength-plasticity product is significantly increased.

Description

Technical Field

[0001] This invention relates to electric arc additive manufacturing technology for high-strength steel, and more specifically, to an additive manufacturing method for high-strength steel with a sandwich structure having interlayer orientation differences. Background Technology

[0002] High-strength steel, as a core material of modern industry, possesses irreplaceable strategic value in aerospace, rail transportation, resource exploration, and deep-sea engineering due to its excellent lightweight and economical synergy. This material system, which combines structural performance and energy efficiency, not only drives industrial technological innovation but also serves as a crucial support for national sustainable development strategies and the competitiveness of high-end equipment manufacturing. The field of materials science has long faced the well-known problem of the inverse relationship between strength and toughness, a classic contradiction that manifests differently in different grades of high-strength steel systems. Specifically, the 800MPa-grade advanced high-strength steel system, while improving material strength, is prone to toughness degradation, leading to significant work hardening and increased brittle fracture tendencies during component forming, severely restricting its engineering applications. While the 400MPa-grade traditional high-strength steel system possesses good ductility and forming stability, its yield strength cannot meet the high-load design requirements of modern heavy equipment for load-bearing components. This strength ceiling effect directly limits its application prospects in main load-bearing structures.

[0003] With the cross-integration of materials design and advanced manufacturing technologies, additive manufacturing is reshaping the forming patterns of high-strength steel materials. This revolutionary manufacturing technology has successfully constructed an integrated innovation platform encompassing materials, structure, and performance through a three-dimensional collaborative mechanism of digital modeling, directional material deposition, and microstructure control. Its unique layer-by-layer deposition forming principle not only breaks through the geometric constraints of traditional molds or processing equipment shapes, achieving near-net-shape forming of complex components, but also provides a novel solution to the dilemma of the "strength-toughness mismatch" in high-strength steel through precise control of deposition direction and multi-material gradient composite technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies. Addressing the key challenge of achieving a good balance between strength and toughness in high-strength steel components, this invention proposes an innovative solution—an additive manufacturing method for high-strength steel with a sandwich structure featuring interlayer orientation differences. Specifically, through additive manufacturing technology, high-strength steel of grades "800MPa—400MPa—800MPa" is deposited layer by layer to create a sandwich structure component with a "high strength—high toughness—high strength" profile. Simultaneously, during the deposition process, the deposition direction is adjusted to optimize the stress direction of each layer during tensile testing, further achieving a good balance between strength and toughness in the component and significantly increasing the strength-ductility product.

[0005] The technical objective of this invention is achieved through the following technical solution.

[0006] An additive manufacturing method for sandwich-structured high-strength steel with interlayer orientation difference, wherein the deposition directions of adjacent layers are different during the additive fabrication of the sandwich structure to form interlayer orientation difference.

[0007] In the above technical solution, the interlayer orientation difference is 30-60 degrees.

[0008] In the above technical solution, a high-strength-high-toughness-high-strength sandwich structure is selected, in which the two sides are high-strength steel of 800MPa grade with high strength, and the middle part is high-strength steel of 400MPa grade with good toughness.

[0009] In the above technical solution, the interlayer orientation difference is guaranteed to be 45°.

[0010] In the above technical solution, the deposition direction of the first layer of 800MPa high-strength steel is 0°, the deposition direction of the second layer of 400MPa high-strength steel is 45°, and the deposition direction of the third layer of 800MPa high-strength steel is 0°.

[0011] In the above technical solution, the deposition direction of the first layer of 800MPa high-strength steel is 45°, the deposition direction of the second layer of 400MPa high-strength steel is 0°, and the deposition direction of the third layer of 800MPa high-strength steel is 45°.

[0012] In the above technical solution, the composition of the 800MPa grade high-strength steel welding wire is 0.08%C, 1.00%Mn, 0.30%Si, 0.28%Al, 0.80%Mg, 0.35%Cr, 0.40%Mo, 3.00%Ni, 1.50%Cu, with the balance being Fe (mass percentage). It is a metal-cored welding wire with a filler ratio of 15% and a wire diameter of 1.20mm.

[0013] In the above technical solution, the composition of the 400MPa grade high-strength steel welding wire is 0.07%C, 1.98%Mn, 0.84%Si, 0.015%Cr, 0.009%Ni, with the balance being Fe (mass percentage). It is a solid core welding wire with a diameter of 1.20mm.

[0014] In the above technical solutions, when additive manufacturing of 800MPa grade high-strength steel, the arc current is 180A, the wire feed speed is 1cm / min, and the welding speed is 1.5mm / s; when additive manufacturing of 400MPa grade high-strength steel, the arc current is 190A, the wire feed speed is 1.8cm / min, and the welding speed is 1.8mm / s.

[0015] In the above technical solution, during additive manufacturing, the arc voltage is automatically matched by the Transtig 5000 welding machine.

[0016] In the above technical solutions, the protective gas used during additive manufacturing is 99.99% Ar, and the flow rate of the protective gas is 20.00-25.00 L / min.

[0017] Compared with existing technologies, the additive manufacturing method proposed in this invention possesses precise process control capabilities and cost-effectiveness advantages, achieving efficient forming of layered heterogeneous components by reducing post-heat treatment and machining processes. This technology supports flexible configuration of material composition and process parameters for each deposition layer, demonstrating significant adaptability in the manufacturing of complex metal components. The sandwich-structured high-strength steel design with interlayer orientation differences provided by this invention first combines the excellent properties of both 800MPa and 400MPa high-strength steel, and further optimizes the properties of each layer during stretching through deposition direction design, thereby achieving a synergistic effect of "strength and toughness." This results in the fabrication of high-strength steel structural components with a strength-ductility product exceeding 14.5 GPa·%, demonstrating practical necessity and promising application prospects. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the deposition strategy for the sandwich structure high-strength steel additive component with interlayer orientation difference prepared by the present invention.

[0019] Figure 2 This is a schematic diagram of the deposition direction of the high-strength steel additive component with interlayer orientation difference sandwich structure prepared by the present invention.

[0020] Figure 3 This is a schematic diagram of additive manufacturing of a sandwich-structured high-strength steel tensile member with interlayer orientation difference prepared according to an embodiment of the present invention.

[0021] Figure 4 This is a comparison diagram of the tensile properties of a sandwich-structured high-strength steel structural component with interlayer orientation difference prepared according to an embodiment of the present invention and a single-material additive component. Detailed Implementation

[0022] The following description, in conjunction with the accompanying drawings and embodiments, illustrates the purpose of this invention. The objective is to provide an additive manufacturing method for high-strength components with a strength-ductility product ≥ 14.5 GPa·% by designing sandwich-structured high-strength steel additive components with interlayer orientation differences, thereby achieving a synergistic effect of strength and toughness in high-strength steel.

[0023] The substrate used in the additive manufacturing experiment was Q235 steel, with dimensions of 300×150×15mm. Its composition was ≤0.20C, ≤1.70Mn, ≤0.50Si, with the balance being Fe. Before the experiment, the oxide film and oil stains on the surface of the Q235 steel substrate were removed using a polishing machine to ensure that the substrate exhibited a metallic luster.

[0024] The 800MPa grade high-strength steel welding wire used had a composition of 0.08C, 1.00Mn, 0.30Si, 0.28Al, 0.80Mg, 0.35Cr, 0.40Mo, 3.00Ni, 1.50Cu, with the balance being Fe (mass percentage). It was a metal-cored welding wire with a filler content of 15% and a diameter of 1.20mm. The 400MPa grade high-strength steel welding wire used had a composition of 0.07C, 1.98Mn, 0.84Si, 0.015Cr, 0.009Ni, with the balance being Fe (mass percentage). It was a solid-core welding wire with a diameter of 1.20mm. Before the experiment, both types of welding wire were installed in two separate wire feeders, and the program was input into a 6-axis ABB IRB 4600 robot, ready for additive manufacturing.

[0025] The additive manufacturing process employs a non-consumable electrode inert gas shielded arc additive manufacturing mode, using a Transtig 5000 welding machine. Orthogonal experiments were used to match the optimal process parameters for both soft and hard welding wires, ensuring a deposition height of approximately 1.98–2.00 mm and a deposition width of approximately 9.50–10 mm. For additive manufacturing of 800 MPa grade high-strength steel (i.e., deposition of 800 MPa grade high-strength steel), the arc current was determined to be 180 A, the wire feed speed 1 cm / min, and the welding speed 1.5 mm / s; for additive manufacturing of 400 MPa grade high-strength steel (i.e., deposition of 400 MPa grade high-strength steel), the arc current was determined to be 190 A, the wire feed speed 1.8 cm / min, and the welding speed 1.8 mm / s. The arc voltage was automatically matched by the Transtig 5000 welding machine. During additive manufacturing, the shielding gas used was 99.99% Ar, with a flow rate of 20.00–25.00 L / min. Each layer of deposition follows a linear additive manufacturing path, with the interpass temperature controlled at approximately 100℃ (±10℃). After each layer of additive manufacturing is completed, the surface is polished with a grinding wheel to remove weld slag, giving the deposited layer a metallic luster. The robotic arm is then raised by 2mm to deposit another material until the additive manufacturing process is finished.

[0026] A "high-strength-high-toughness-high-strength" sandwich structure was designed, with the two outer layers consisting of high-strength 800MPa grade steel and the middle layer consisting of high-toughness 400MPa grade steel. To reduce the wetting effect of the substrate on the first layer of 800MPa grade high-strength steel, a "2+1+1" deposition pattern was adopted. This involves depositing two layers of 800MPa grade high-strength steel (as the bottom layer), followed by the deposition of 400MPa grade high-strength steel, and finally, the top layer of 800MPa grade high-strength steel. A schematic diagram of the deposition strategy is shown below. Figure 1 As shown.

[0027] Two types of sandwich-structured high-strength steel additive components were deposited while maintaining an interlayer orientation difference of 45°. The deposition directions were 0° and 45°. The 0° direction was aligned with the x-axis (i.e., the deposition direction was aligned with the subsequent stretching direction), and the 45° direction formed a 45° angle with the x-axis (i.e., the deposition direction was at a 45° angle with the subsequent stretching direction). In Example 1, high-strength steel was deposited along the 0° direction, and high-toughness steel was deposited along the 45° direction; in Example 2, high-strength steel was deposited along the 45° direction, and high-toughness steel was deposited along the 0° direction. A schematic diagram of the deposition directions is shown below. Figure 2 As shown, the upper part is deposited at 0° and the lower part is deposited at 45°.

[0028] After additive manufacturing is completed, tensile test specimens are processed. For example... Figure 3 As shown, the left side corresponds to Example 1, and the right side corresponds to Example 2, where a is 6mm, b is 10mm, and c is 32mm. The height of the stretched part is set to 6mm to ensure that it contains three layers: "high strength-high toughness-high strength". Furthermore, the length and width of the parallel section, the transition arc, and the dimensions of the clamping end of the stretched part conform to standard ASTM E8M-09. During the stretching process, the stretching direction is consistent with the 0° deposition direction.

[0029] The test results are as follows Figure 4 As shown, Example 1 (Design Part 1) has a tensile strength of 943 MPa, an elongation of 18.3%, and a strength-ductility product of 17.3 GPa·%, which represents an improvement of 66% and 32% respectively compared to additive components made of single-material high-strength steel and high-toughness steel. Example 2 (Design Part 2) has a tensile strength of 813 MPa, an elongation of 17.8%, and a strength-ductility product of 14.5 GPa·%, which represents an improvement of 39% and 11% respectively compared to additive components made of single-material high-strength steel and high-toughness steel. Furthermore, impact tests were conducted on both designs, with impact energy of 111 J and 108 J respectively, approximately 10 times higher than high-strength steel (11 J), but only 20.5% lower than high-toughness steel (136 J).

[0030] By adjusting the process parameters according to the present invention, additive manufacturing can be achieved, and sandwich-structured high-strength steel additive components can be prepared. The present invention has been described above as exemplary. It should be noted that any simple modifications, alterations, or other equivalent substitutions that can be made by those skilled in the art without creative effort, without departing from the core of the present invention, fall within the protection scope of the present invention.

Claims

1. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation differences, characterized in that, In the additive fabrication of sandwich structures, the deposition directions of adjacent layers are different to form an interlayer orientation difference; the interlayer orientation difference is 30-60 degrees.

2. The additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to claim 1, characterized in that, A high-strength-high-toughness-high-strength sandwich structure is selected, with the two sides made of high-strength 800MPa grade steel and the middle part made of high-toughness 400MPa grade steel; ensuring that the interlayer orientation difference is 45°.

3. The additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to claim 2, characterized in that, The deposition direction of the first layer of 800MPa high-strength steel is 0°, the deposition direction of the second layer of 400MPa high-strength steel is 45°, and the deposition direction of the third layer of 800MPa high-strength steel is 0°.

4. The additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to claim 2, characterized in that, The deposition direction of the first layer of 800MPa high-strength steel is 45°, the deposition direction of the second layer of 400MPa high-strength steel is 0°, and the deposition direction of the third layer of 800MPa high-strength steel is 45°.

5. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to any one of claims 2-4, characterized in that, The composition of the 800MPa grade high-strength steel welding wire is 0.08% C, 1.00% Mn, 0.30% Si, 0.28% Al, 0.80% Mg, 0.35% Cr, 0.40% Mo, 3.00% Ni, 1.50% Cu, with the balance being Fe (by mass percentage). It is a metal-cored welding wire with a filler content of 15% and a wire diameter of 1.20 mm.

6. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to any one of claims 2-4, characterized in that, The composition of the 400MPa grade high-strength steel welding wire is 0.07% C, 1.98% Mn, 0.84% ​​Si, 0.015% Cr, 0.009% Ni, with the balance being Fe (mass percentage). It is a solid core welding wire with a diameter of 1.20 mm.

7. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to any one of claims 2-4, characterized in that, When additively producing 800MPa grade high-strength steel, the arc current is 180A, the wire feed speed is 1cm / min, and the welding speed is 1.5mm / s.

8. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to any one of claims 2-4, characterized in that, When additively producing 400MPa grade high-strength steel, the arc current is 190A, the wire feed speed is 1.8cm / min, and the welding speed is 1.8mm / s.

9. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to any one of claims 2-4, characterized in that, During additive manufacturing, the arc voltage is automatically matched by the welding machine.

10. An additive manufacturing method for a sandwich-structured high-strength steel with interlayer orientation difference according to any one of claims 2-4, characterized in that, During additive manufacturing, the protective gas used is 99.99% Ar, and the flow rate of the protective gas is 20.00-25.00 L / min.

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