High-toughness maraging steel wire suitable for electric arc additive manufacturing as well as preparation method and application of high-toughness maraging steel wire

Abstract

The invention discloses a high-toughness maraging steel wire suitable for electric arc additive manufacturing and a preparation method and application of the high-toughness maraging steel wire, and belongs to the technical field of materials for electric arc additive manufacturing. The maraging steel alloy comprises the following components in percentage by mass: less than or equal to 0.02% of C, less than or equal to 0.5% of Si, less than or equal to 1% of Mn, 16.0-20.0% of Ni, 10.0-12.0% of Co, 3.0-6.0% of Mo, 0.5-1.8% of Ti, 0.05-0.20% of Al, less than or equal to 0.003% of P, less than or equal to 0.003% of S, less than or equal to 5ppm of H, less than or equal to 0.002% of N, less than or equal to 0.003% of O and the balance of Fe. According to the maraging steel wire with the high strength and toughness, a block component prepared through an electric arc additive manufacturing process is adopted, the stacking state tensile strength of the block component is larger than or equal to 1500 MPa, and meanwhile the ductility is 10% or above.

Description

Technical Field

[0001] The invention relates to a high-strength and tough martensitic aged steel wire suitable for arc additive manufacturing and a preparation method and application thereof, belonging to the technical field of materials for arc additive manufacturing. Background Art

[0002] Maraging steel is an ultra-low carbon, high-alloy, ultra-high-strength steel. It is widely used in aviation, aerospace, shipbuilding, weapons, rails, vehicles, molds and other fields because of its high strength, excellent load-bearing capacity and welding processability. With the development of large-scale engineering machinery and equipment and the integration of function and structure, the structure of maraging steel parts has become increasingly complex and diversified. However, traditional processing technologies such as casting, forging and welding can hardly meet the manufacturing needs of large and complex maraging steel parts. In recent years, the development of arc additive manufacturing technology has provided new processes and methods for manufacturing large and complex maraging steel parts. The arc additive manufacturing technology of maraging steel uses arc as the heat source and maraging steel wire as the filler metal. It accumulates layer by layer according to the preset additive path to achieve near-net forming of large and complex parts. Compared with traditional processing technology, arc additive manufacturing technology for maraging steel has high material utilization rate, short single-piece trial production cycle, and high yield rate; compared with laser and electron beam powder-based additive manufacturing technology, arc additive manufacturing technology has high material utilization rate, high forming efficiency, high density, large size of additive parts, low cost, and can achieve overall rapid forming of large and medium-complex maraging steel parts. Therefore, arc additive manufacturing technology for maraging steel has been applied to aerospace, marine machinery, weapons and equipment, and mold manufacturing. However, the arc additive manufacturing technology of maraging steel still has the following problems: First, there is a lack of maraging steel wire suitable for arc additive manufacturing. Currently, commercial ultra-high-strength steel welding wire is mainly used as a substitute, but the strength is relatively low; second, there is element segregation in the microstructure of arc additive manufacturing of maraging steel, resulting in unstable mechanical properties; finally, maraging steel requires a combination of solid solution + aging heat treatment to achieve a strengthening effect, but for large maraging steel parts, the risk of cracking is very likely to occur during the solid solution quenching stage. The above problems have seriously restricted the application and promotion of arc additive manufacturing technology of maraging steel.

[0003] Therefore, the development of maraging steel wire suitable for arc additive manufacturing has important engineering application value. Summary of the invention

[0004] The invention provides a high-strength and tough maraging steel wire suitable for arc additive manufacturing. The tensile strength of the maraging steel parts prepared by using the wire reaches above 1500MPa, and the elongation is maintained above 10%.

[0005] At the same time, the present invention provides a method for preparing high-strength and tough martensitic aged steel wire suitable for arc additive manufacturing. The martensitic aged steel wire component system and process designed by the present invention fully consider the multi-heat cycle characteristics of the arc additive manufacturing process, and reasonably utilize the heat treatment effect of the post-deposition layer on the deposited substrate, which easily induces austenite reverse transformation and Ni 3 The precipitation of intermetallic compounds such as (Ti, Mo) and Ni(Ti, Al) improves the microstructure of additive components and synergistically improves the strength and plasticity of additive components.

[0006] At the same time, the present invention provides an application of high-strength and tough martensitic aged steel wire suitable for arc additive manufacturing.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A high-strength and tough maraging steel wire suitable for arc additive manufacturing, the maraging steel wire comprising the following mass percentage composition: C: ≤0.02%, Si: ≤0.5%, Mn: ≤1.0%, Ni: 16.0-20.0%, Co: 10.0-12.0%, Mo: 3.0-6.0%, Ti: 0.5-1.8%, Al: 0.05-0.20%, P: ≤0.003%, S: ≤0.003%, H: ≤5ppm, N: ≤0.002%, O: ≤0.003%, and Fe as the balance.

[0009] C: The C element is an interstitial solid solution strengthening element, which can significantly improve the strength of alloy steel. However, the wire alloy system in the present invention is maraging steel. For maraging steel, the C element will cause the precipitation of large-sized TiC during arc additive manufacturing, significantly reducing plastic toughness, and the C element will make the processability of arc additive manufacturing worse. Therefore, in the present invention, the C element content is controlled to be less than 0.02%.

[0010] Si: Si element has good deoxidation ability in the arc additive manufacturing process, but the oxide formed by Si element deoxidation has a high melting point and a small size. In the arc additive manufacturing process, due to the fast solidification rate, Si oxide is difficult to float up, which easily causes slag inclusion and reduces strength and elongation. Therefore, the Si element content in the present invention is controlled to be less than 0.5%.

[0011] Mn: Mn also has good deoxidation ability in the arc additive manufacturing process; Mn is considered an impurity element in traditional maraging steel and is strictly controlled; however, from the Fe-Mn phase diagram, since its alloy can form lath martensite in a wide cooling rate range, the presence of Mn also contributes to alloy strengthening; in addition, Mn as an austenite-forming element can partially replace Ni and Co, although doing so will reduce the toughness of the alloy. Therefore, the Mn content in the present invention is controlled to be less than 1%.

[0012] Mo: Mo element has good substitution solid solution strengthening effect, and can inhibit the temper brittleness and overheating tendency caused by thermal cycle in the arc material addition process. For the martensitic aging steel wire alloy system of the present invention, Mo can be dissolved into the matrix to change the lattice constant of the matrix, reduce the mismatch between the precipitate phase and the matrix, promote the uniform dispersion and precipitation of the precipitate phase, and inhibit Ni 3 (Ti, Mo) and Ni (Ti, Al) precipitate phase coarsening. The alloying element that contributes to both strength and toughness in maraging steel is Mo. This is mainly because the Mo-rich phase precipitated at the beginning of aging contributes to the strength of the steel while also ensuring the toughness of the steel; at the same time, Mo also prevents the strengthening phase from precipitating in a grid-like manner along the original austenite grain boundaries, which also improves the fracture toughness of the steel; it is worth noting that too high Mo content will produce Mo-rich intermetallic compounds, which are not easy to dissolve even during high-temperature solution treatment, which will leave residual austenite in the organization and cause a decrease in toughness. Therefore, the Mo element content of the present invention is controlled at 3.0-6.0%.

[0013] Ni: Ni can inhibit the decomposition of screw dislocations in maraging steel to ensure the occurrence of cross slip, thereby improving the plasticity and toughness of the steel; Ni is also an austenite-forming element. Its presence expands the austenite phase region, making it easier for the steel to obtain single-phase austenite when heated, so as to obtain lath martensite with good plasticity when cooled; but at the same time, nickel will lower the Ms temperature and improve the stability of supercooled austenite, which is not conducive to the formation of full martensitic structure; nickel will also form a precipitation phase with strengthening elements, which will lead to a decrease in the nickel content in the matrix. Therefore, in order to ensure the toughness of the alloy, the nickel content should not be too low. Ni can form Ni 3 (Ti, Mo) and Ni (Ti, Al) precipitation phases produce significant precipitation strengthening effect. Therefore, the Ni element content in the present invention is controlled at 16.0-20.0%.

[0014] Co: Co element is dissolved in the Fe-Ni matrix of maraging steel, promoting the formation of Mo intermetallic compounds (such as Ni 3 Mo, Fe 2In addition, Co can also increase the Ms temperature, ensuring that the alloy obtains a full martensite structure after solid solution quenching. Therefore, the Co element content in the present invention is controlled to be 10.0-12.0%.

[0015] Ti: Ti element has a solid solution strengthening effect and can 3 It precipitates in the form of Ti or NiTi, producing a significant precipitation strengthening effect, and is the main strengthening element of maraging steel. The solute distribution coefficient of the Ti element is less than 1, and it is easy to segregate between the dendrites that solidify later during the arc additive manufacturing solidification process of maraging steel. The Ti element is a ferrite-forming element that can reduce the mechanical stability of austenite (the difficulty of austenite to martensite transformation under external force). Therefore, the present invention increases the Ti element content, on the one hand, it can promote the precipitation of Ni-Ti intermetallic compounds in the deposited metal during the arc additive manufacturing maraging steel multi-heat cycle process, and produce a strengthening effect; on the other hand, it increases the segregation content of titanium elements between dendrites during the arc additive manufacturing process, reduces the mechanical stability of the reversed austenite formed in the dendrite region during the arc additive manufacturing multi-heat cycle process, and is easy to undergo deformation-induced martensitic phase transformation under external force load, producing a phase transformation-induced plastic effect, while improving strength, it can ensure high elongation. However, too high a Ti content will reduce the fracture toughness of maraging steel. Therefore, the Ti content in the present invention is controlled at 0.5-1.8%.

[0016] Al: Al can be in the form of NiAl or Ni 3 Al precipitates in the form of Al, producing precipitation strengthening. At the same time, Al can deoxidize and reduce inclusions. However, when the Al content is too high, a large amount of oxide inclusions will be formed, reducing strength and toughness. Moreover, when the Al content is too high, the arc additive manufacturing process of maraging steel will be reduced and crack sensitivity will be increased. Therefore, the Al content in the present invention is controlled at 0.05-0.20%.

[0017] Impurity elements such as H, O, N, P and S: H increases the sensitivity to hydrogen embrittlement; O forms oxide inclusions that seriously affect strength and toughness; N reacts with Ti in steel to generate TiN, reducing toughness; P and S reduce toughness. Therefore, the content of the above impurity elements needs to be strictly controlled during the design of maraging steel alloy composition and smelting process. In the present invention, the content of H is controlled to be less than 0.0005%, the content of O is controlled to be less than 0.003%, the content of N is controlled to be less than 0.002%, and the contents of P and S are both controlled to be less than 0.003%.

[0018] A method for preparing a maraging steel wire suitable for arc additive manufacturing, the maraging steel wire comprising the following preparation steps:

[0019] (1) Vacuum melting: The maraging steel alloy is initially melted in a vacuum melting furnace and cast to obtain a primary melt ingot;

[0020] (2) Electrode preparation: Forging the initial melt ingot to prepare the electrode sample;

[0021] (3) electroslag remelting: the electrode sample is subjected to secondary smelting by electroslag remelting, and a final ingot is obtained by casting;

[0022] (4) high temperature forging: subjecting the secondary smelting ingot to high temperature forging to prepare a rod;

[0023] (5) high temperature rolling: high temperature rolling the bar to prepare wire rod;

[0024] (6) Annealing: Annealing the wire rod;

[0025] (7) Wire drawing: Drawing the annealed wire rod to make wire;

[0026] (8) Cleaning and winding: Clean, dry and wind the wire after drawing.

[0027] Since the drawing formability of martensitic steel wire and the processability of arc additive manufacturing as well as the mechanical properties of additive parts are very sensitive to impurities such as H, O, N, P, and S, it is necessary to strictly control the content of impurity elements in the wire raw materials. The present invention adopts a dual smelting method of vacuum smelting and electroslag remelting to purify the martensitic aging steel wire alloy ingot.

[0028] Preferably, the vacuum degree of vacuum smelting in step (1) is 0-20 Pa, the heating temperature of the initial melt ingot is 1000-1200° C., and the holding time is 6-8 h.

[0029] Preferably, in step (2), the electrode is prepared by keeping the initial melt ingot at 1000-1200° C. for 2-4 hours and forging it, and the final forging temperature is not less than 850° C. Since ultra-high strength steel has poor plastic deformation ability, in order to avoid surface cracks during deformation and oxide scale inclusions, higher initial and final forging temperatures are used before electrode forging.

[0030] Preferably, in step (3), the electroslag remelting has an electroslag rate of 1.5 to 2.0 kg / min, a voltage of 25 to 40 V, and a current of 1.8 to 3.0 kA.

[0031] Since ultra-high strength steel has poor plastic deformation ability, in order to avoid surface cracks during deformation and the formation of oxide scale inclusions, preferably, in step (4), high temperature forging is performed, the secondary smelting ingot is heated to 1100-1200°C, the holding time is 2-4h, and then forging is performed, the final forging temperature is not less than 950°C, and then air cooling is performed.

[0032] In order to avoid the occurrence of surface and internal cracks in the wire rod due to the rolling temperature being too low, thereby reducing the wire drawing yield and wire quality, a higher rolling temperature and a longer holding time are used during rolling. Preferably, in step (5), the forged bar is kept at 1100-1200°C for 1-3h, and is rolled into a wire rod through multiple hot rolling passes.

[0033] In order to reduce the hardness of the wire rod and improve its plastic deformation capacity, preferably, in step (6), the wire rod is kept at 1100-1200° C. for 1-2 h and then air-cooled.

[0034] In order to reduce the hardness of the wire rod and improve its plastic deformation capacity, it is preferred that online annealing is performed during the drawing process in step (7), the annealing temperature is 1000-1150° C., and the annealing time is about 1 hour.

[0035] Since pickling is used to remove the oxide scale on the surface of the wire rod, it may cause hydrogen embrittlement of the ultra-high strength steel and affect the wire drawing forming ability and yield rate. Preferably, in step (7), the wire rod is mechanically descaled before drawing, washed with water and dried, and then subjected to film treatment, and then dried at 80-100°C before drawing.

[0036] To avoid hydrogen embrittlement fracture, preferably, alkali washing and water washing are performed in sequence in step (8).

[0037] A high-strength and tough maraging steel wire suitable for arc additive manufacturing is used in maraging steel parts.

[0038] Maraging steel parts include large and complex maraging steel parts, which include ground-level rocket engine casings, tank armored vehicle main structures, and aircraft wing hinges.

[0039] The large complex maraging steel parts in the present invention are generally considered large if they are meter-sized, 1 meter or more.

[0040] A maraging steel component is prepared by a high-strength and tough maraging steel wire obtained by the preparation method of the invention. The preparation method comprises the following steps: current of 150-250A, voltage of 15-35V, wire feeding speed of 0.3-10m / min, material addition speed of 10-20cm / min, and interlayer temperature of 160-190°C.

[0041] The tensile strength of maraging steel parts reaches over 1500MPa and the elongation remains above 10%.

[0042] The invention discloses a high-strength and tough maraging steel wire suitable for arc additive manufacturing. Preferably, the maraging steel parts are additively manufactured according to the following process parameters: current 150-250A, voltage 15-35V, wire feeding speed 0.3-10m / min, additive speed 10-20cm / min, and interlayer temperature 160-190°C.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] (1) The composition design of the maraging steel wire prepared by the present invention is scientific and reasonable, reducing the content of Mo and increasing the content of Ti. The increase in the content of Ti can promote the precipitation of Ni during the multi-heat cycle of arc additive manufacturing maraging steel. 3 (Ti, Mo) and Ni (Ti, Al) intermetallic compounds can produce precipitation strengthening effect; on the other hand, it can increase the segregation content of Ti element in the post-solidification dendrites during arc additive manufacturing, reduce the mechanical stability of the reverse transformed austenite formed in the dendrite region during the multiple thermal cycles of additive manufacturing, and easily cause deformation-induced martensitic phase transformation under the action of external force load, resulting in phase transformation-induced plasticity effect, which can ensure high elongation while improving strength.

[0045] (2) The tensile strength of the maraging steel wire arc additively manufactured deposit prepared by the present invention can reach more than 1500 MPa, and the elongation can be maintained at more than 10%.

[0046] (3) In the prior art, welding wire is usually prepared by vacuum melting, electroslag remelting, forging, hot rolling and wire drawing; this is a common preparation method for cylindrical metal materials, such as welding wire, steel bars, nails, etc. However, the post-processing of each link is very important, especially for metal materials with relatively high strength. High-strength materials are prone to cracking, and each link needs to be heated to the austenite phase field temperature for homogenization and softening treatment. Therefore, whether it is melting, forging, or rolling, softening treatment is required, especially the key drawing and wire making link, which requires process stress relief treatment, because the drawing deformation of high-strength steel materials will produce internal stress, resulting in wire failure.

[0047] (4) Existing high-strength steel is generally a forging, which is difficult to manufacture for large and complex structural parts. The present invention is used for additive manufacturing, which can realize the overall additive manufacturing of large and complex metal components, and can achieve a strength of 1500MPa without post-heat treatment.

[0048] (5) The present invention proposes the composition design and manufacturing of wire materials. Compared with wire materials, the existing metal powders have a relatively simple powder preparation process. During the preparation of wire materials, especially the rolling and drawing processes, the cracking and wire forming rate of high-strength materials need to be considered. The wire materials obtained by the present invention do not crack, and the wire forming rate is greater than 99%.

[0049] (6) The wire material designed in the present invention has a very high strength component. Therefore, in the wire preparation process, an austenite phase field temperature homogenization annealing treatment step is added to each link, especially a stress relief annealing treatment is performed during the wire drawing process to ensure the wire drawing rate and the wire coiling performance.

[0050] (7) The wire composition designed in the present invention has taken into account the layer-by-layer deposition characteristics of the arc additive manufacturing process. The post-deposited metal has a heat treatment effect on the deposited metal, resulting in austenite reversal in the interdendritic region where the three elements Ni, Mo, and Ti are segregated, and Ni in the dendrite trunk region 3 (Ti, Mo), Ni (Ti, Al) and other intermetallic compounds are precipitated, so the subsequent additive process is consistent with the wire composition design. Traditionally, this type of material needs high-temperature solid solution + medium-temperature aging treatment to achieve this strength level. However, the wire material and the corresponding arc additive process in this article can achieve 1500MPa strength and 10% elongation without heat treatment.

[0051] The invention discloses a high-strength and tough martensitic aged steel wire suitable for arc additive manufacturing, belonging to the technical fields of materials for arc additive manufacturing, metallurgy and additive manufacturing. The martensitic aged steel wire component system designed by the invention fully considers the multi-heat cycle characteristics of the arc additive manufacturing process, and reasonably utilizes the heat treatment effect of the post-deposition layer on the deposited substrate, which easily induces austenite reverse transformation and Ni in the substrate. 3 (Ti, Mo), Ni (Ti, Al) and other intermetallic compounds are precipitated to improve the microstructure of the additive component and synergistically improve the strength and plasticity of the additive component. The block component prepared by the arc additive manufacturing process using the high-strength and tough martensitic aged steel wire of the present invention has a stacked tensile strength of ≥1500MPa and an elongation of more than 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart for preparing maraging steel wire;

[0053] Figure 2 Tensile property curves of maraging steel parts manufactured by arc additive manufacturing;

[0054] Figure 3 Typical microstructure of maraging steel parts manufactured by arc additive manufacturing;

[0055] Figure 4 Element distribution of a maraging steel component manufactured using arc additive manufacturing. DETAILED DESCRIPTION

[0056] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0057] Example 1

[0058] A high-strength and tough maraging steel wire suitable for arc additive manufacturing. The maraging steel alloy includes the following components in percentage by mass: C: 0.02%, Si: 0.5%, Mn: 1%, Ni: 18.0%, Co: 11.0%, Mo: 4.0%, Ti: 1.0%, Al: 0.10%, P: 0.003%, S: 0.003%, H: 5ppm, N: 0.002%, O: 0.003%, and Fe is the balance.

[0059] A method for preparing a maraging steel wire suitable for arc additive manufacturing comprises the following steps:

[0060] (1) Vacuum Melting: The maraging steel alloy is initially melted in a vacuum melting furnace with a vacuum degree of 14 Pa, and the initial melt ingot is cast. The heating temperature of the initial melt ingot is 1100°C and the holding time is 7 hours.

[0061] (2) Electrode preparation: The primary melt ingot was kept at 1100° C. for 3 h, and forged to prepare an electrode sample, with a final forging temperature of 850° C., followed by air cooling.

[0062] (3) Electroslag remelting: The electrode sample was remelted for a second time by electroslag remelting at an electroslag speed of 1.8 kg / min, a voltage of 30 V, and a current of 2.5 kA to obtain a final ingot.

[0063] (4) High temperature forging: The secondary smelting ingot is heated to 1150°C and kept at this temperature for 3 hours, and then forged to prepare a rod, with a final forging temperature of 950°C.

[0064] (5) High temperature rolling: The bar is kept at 1100°C for 2 hours and subjected to multiple hot rolling passes to be rolled into a Φ6.5 wire rod.

[0065] (6) Annealing treatment: keep the wire rod at 1150℃ for 1h and then air cool it.

[0066] (7) Wire drawing: The softened wire rod is mechanically descaled, washed and dried, and then subjected to film treatment. It is then drawn after drying at 80°C. The drawing diameter changes from Φ6.2→Φ5.2→Φ4.8→Φ4.4→online annealing (annealing temperature is 1000°C, annealing time is 1h) + alkali washing→Φ3.8→Φ3.4→Φ2.0→Φ1.6→Φ1.2.

[0067] (8) Cleaning and winding: After drawing, the wire is alkali-washed, water-washed, dried, and wound.

[0068] A high-strength and tough maraging steel wire suitable for arc additive manufacturing is used in maraging steel parts.

[0069] The maraging steel parts include large and complex maraging steel parts, which include ground-level rocket engine casings, tank armored vehicle main structures, and aircraft wing hinges.

[0070] A maraging steel component is prepared by the high-strength and tough maraging steel wire obtained by the preparation method described in this embodiment. The preparation method is: current 200A, voltage 25V, wire feeding speed 5m / min, additive speed 15cm / min, and interlayer temperature 180°C.

[0071] The preparation process of maraging steel wire is as follows Figure 1 shown.

[0072] The prepared martensitic aged steel wire was subjected to arc additive manufacturing forming experiments using a MOTAMAN MH6 arc welding robot, a DX100 robot control cabinet, a Fronius MagicWave 3000 welding power source, a plasma control cabinet, and a plasma additive gun body. The substrate was made of ordinary low-quality steel with a thickness of 12 mm, a current of 200 A, a voltage of 25 V, a wire feeding speed of 5 m / min, an additive speed of 15 cm / min, and an interlayer temperature of 180 ° C. Tensile specimens were taken along the length of the welding gun. The specimens were standard tensile specimens and tensile properties were tested. The mechanical properties were as follows: Figure 2 As shown. Figure 2 As shown, the tensile strength of the maraging steel wire arc additively manufactured deposit prepared in this embodiment is above 1500 MPa, while the elongation is maintained above 10%.

[0073] Figure 3 Microstructure of maraging steel parts manufactured by arc additive manufacturing, including: Figure 3 (a) and Figure 3 (b) are the metallographic solidification organization diagrams of the longitudinal section and cross section of the component, respectively. It is obvious from the figure that the solidification organization of this component is composed of cellular dendrites and columnar dendrites. Figure 3 (c) is the SEM image of the component. The white area with a rough surface is the cellular / columnar martensite area, and the black area with a smooth surface is the interdendritic austenite. Figure 3(d) is the EBSD phase diagram of the component, which further confirms that the cellular / columnar dendrite area is martensite (blue area) and the interdendritic area is austenite (red area). The above microstructure information shows that during the arc additive manufacturing of maraging steel, the molten pool metal solidifies according to the cellular / columnar mode, resulting in the segregation of Ni, Mo, and Ti elements between the post-solidified dendrites (the distribution coefficients of these solute elements are all less than 1, and the solute elements have high solubility in the liquid phase). The microstructure produced by this solidification mode is particularly conducive to the segregation of solute elements in specific locations (between dendrites), resulting in the performance of these areas being different from that of the dendrite trunk. Under the high heat input and multi-heat cycle conditions of arc additive manufacturing, austenite reverse transformation occurs, resulting in plasticization and toughening effects.

[0074] Figure 4 The element point scan and surface scan clearly show the segregation of Ni, Mo and Ti elements. The point scan further quantifies the Ti element content between dendrites to be 0.37% and the content in the dendrite trunk to be 1.25%.

[0075] Example 2

[0076] A high-strength and tough maraging steel wire suitable for arc additive manufacturing. The maraging steel alloy includes the following components in percentage by mass: C: 0.01%, Si: 0.4%, Mn: 0.5%, Ni: 16.0%, Co: 10.0%, Mo: 3.0%, Ti: 0.5%, Al: 0.05%, P: 0.002%, S: 0.003%, H: 4ppm, N: 0.001%, O: 0.001%, and Fe is the balance.

[0077] A method for preparing a maraging steel wire suitable for arc additive manufacturing comprises the following steps:

[0078] (1) Vacuum Melting: The maraging steel alloy is initially melted in a vacuum melting furnace with a vacuum degree of 0.5 Pa, and the initial melt ingot is cast. The heating temperature of the initial melt ingot is 1000°C and the holding time is 6 hours.

[0079] (2) Electrode preparation: The primary melt ingot was kept at 1000° C. for 2 h, and forged to prepare an electrode sample, with a final forging temperature of 880° C., followed by air cooling.

[0080] (3) Electroslag remelting: The electrode sample was remelted for a second time by electroslag remelting at an electroslag speed of 1.5 kg / min, a voltage of 25 V, and a current of 1.8 kA to obtain the final ingot.

[0081] (4) High temperature forging: The secondary smelting ingot is heated to 1100°C and kept at this temperature for 2 hours, and then forged to prepare a rod, with the final forging temperature being 990°C.

[0082] (5) High temperature rolling: The bar is kept at 1200°C for 1 hour and subjected to multiple hot rolling passes to be rolled into a Φ6.0 wire rod.

[0083] (6) Annealing treatment: keep the wire rod at 1100℃ for 2h and then air cool it.

[0084] (7) Wire drawing: The softened wire rod is mechanically descaled, washed and dried, and then subjected to film treatment. It is then drawn after drying at 100°C. The drawing diameter changes from Φ5.8→Φ5.0→Φ4.6→Φ4.2→online annealing (annealing temperature is 1150°C, annealing time is 1h) + alkali washing→Φ3.6→Φ3.2→Φ1.8→Φ1.4→Φ1.0.

[0085] (8) Cleaning and winding: After drawing, the wire is alkali-washed, water-washed, dried, and wound.

[0086] A high-strength and tough maraging steel wire suitable for arc additive manufacturing is used in maraging steel parts.

[0087] The maraging steel parts include large and complex maraging steel parts, which include ground-level rocket engine casings, tank armored vehicle main structures, and aircraft wing hinges.

[0088] A maraging steel component is prepared by the high-strength and tough maraging steel wire obtained by the preparation method described in this embodiment. The preparation method is: current 150A, voltage 15V, wire feeding speed 0.3m / min, additive speed 10cm / min, and interlayer temperature 160°C.

[0089] The tensile strength of the arc additively manufactured deposit of the maraging steel wire prepared in this embodiment reaches 1580 MPa, and the elongation is 12%.

[0090] Example 3

[0091] A high-strength and tough maraging steel wire suitable for arc additive manufacturing. The maraging steel alloy includes the following components in percentage by mass: C: 0.015%, Si: 0.3%, Mn: 0.6%, Ni: 20.0%, Co: 12.0%, Mo: 6.0%, Ti: 1.8%, Al: 0.20%, P: 0.003%, S: 0.001%, H: 3ppm, N: 0.002%, O: 0.002%, and Fe is the balance.

[0092] A method for preparing a maraging steel wire suitable for arc additive manufacturing comprises the following steps:

[0093] (1) Vacuum Melting: The maraging steel alloy is initially melted in a vacuum melting furnace with a vacuum degree of 20 Pa, and the initial melt ingot is cast. The heating temperature of the initial melt ingot is 1200°C and the holding time is 8 hours.

[0094] (2) Electrode preparation: The primary melt ingot was kept at 1200° C. for 4 h, and forged to prepare an electrode sample, with a final forging temperature of 860° C., followed by air cooling.

[0095] (3) Electroslag remelting: The electrode sample was remelted for a second time by electroslag remelting at an electroslag speed of 2.0 kg / min, a voltage of 40 V, and a current of 3.0 kA to obtain a final ingot.

[0096] (4) High temperature forging: The secondary smelting ingot is heated to 1200°C and kept at this temperature for 4 hours, and then forged to prepare a rod, with the final forging temperature being 970°C.

[0097] (5) High temperature rolling: The bar is kept at 1150°C for 3 hours and subjected to multiple hot rolling passes to be rolled into a Φ6.2 wire rod.

[0098] (6) Annealing treatment: keep the wire rod at 1200℃ for 2h and then air cool it.

[0099] (7) Wire drawing: The softened wire rod is mechanically descaled, washed and dried, and then subjected to film treatment. It is then drawn after drying at 90°C. The drawing diameter changes from Φ6.0 to Φ4.8 to Φ4.4 to Φ4.0 to online annealing (annealing temperature is 1150°C, annealing time is 1h) + alkali washing to Φ3.4 to Φ3.0 to Φ1.6 to Φ1.2 to Φ0.8.

[0100] (8) Cleaning and winding: After drawing, the wire is alkali-washed, water-washed, dried, and wound.

[0101] A high-strength and tough maraging steel wire suitable for arc additive manufacturing is used in maraging steel parts.

[0102] The maraging steel parts include large and complex maraging steel parts, which include ground-level rocket engine casings, tank armored vehicle main structures, and aircraft wing hinges.

[0103] A maraging steel component is prepared by the high-strength and tough maraging steel wire obtained by the preparation method described in this embodiment. The preparation method is: current 250A, voltage 35V, wire feeding speed 10m / min, additive speed 20cm / min, and interlayer temperature 190°C.

[0104] The arc additive manufacturing deposit of the maraging steel wire prepared in this embodiment has an additive tensile strength of 1625 MPa and an elongation of 11%.

[0105] Example 4

[0106] A high-strength and tough maraging steel wire suitable for arc additive manufacturing. The maraging steel alloy includes the following components in percentage by mass: C: 0.02%, Si: 0.2%, Mn: 0.9%, Ni: 17.0%, Co: 10.5%, Mo: 5.0%, Ti: 1.6%, Al: 0.09%, P: 0.001%, S: 0.001%, H: 3ppm, N: 0.002%, O: 0.003%, and Fe is the balance.

[0107] A method for preparing a maraging steel wire suitable for arc additive manufacturing comprises the following steps:

[0108] (1) Vacuum Melting: The maraging steel alloy is initially melted in a vacuum melting furnace with a vacuum degree of 10 Pa, and the initial melt ingot is cast. The initial melt ingot is heated to 1050°C and kept at this temperature for 8 hours.

[0109] (2) Electrode preparation: The initial melt ingot was kept at 1150° C. for 3 h, and forged to prepare an electrode sample, with a final forging temperature of 850° C., followed by air cooling.

[0110] (3) Electroslag remelting: The electrode sample was remelted for a second time by electroslag remelting at an electroslag speed of 1.6 kg / min, a voltage of 30 V, and a current of 2.5 kA to obtain a final ingot.

[0111] (4) High temperature forging: The secondary smelting ingot is heated to 1180°C and kept at this temperature for 3 hours, and then forged to prepare a rod, with a final forging temperature of 960°C.

[0112] (5) High temperature rolling: The bar is kept at 1100°C for 1 hour and subjected to multiple hot rolling passes to be rolled into a Φ6.4 wire rod.

[0113] (6) Annealing treatment: keep the wire rod at 1200℃ for 1.5h and then air cool.

[0114] (7) Wire drawing: The softened wire rod is mechanically descaled, washed and dried, and then subjected to film treatment. It is then drawn after drying at 85°C. The drawing diameter changes from Φ6.1→Φ4.9→Φ4.5→Φ4.1→online annealing (annealing temperature is 1100°C, annealing time is 1h) + alkali washing→Φ3.5→Φ3.1→Φ1.7→Φ1.3→Φ0.9.

[0115] (8) Cleaning and winding: After drawing, the wire is alkali-washed, water-washed, dried, and wound.

[0116] A high-strength and tough maraging steel wire suitable for arc additive manufacturing is used in maraging steel parts.

[0117] The maraging steel parts include large and complex maraging steel parts, which include ground-level rocket engine casings, tank armored vehicle main structures, and aircraft wing hinges.

[0118] A maraging steel component is prepared by the high-strength and tough maraging steel wire obtained by the preparation method described in this embodiment. The preparation method is: current 180A, voltage 30V, wire feeding speed 2m / min, additive speed 18cm / min, and interlayer temperature 170°C.

[0119] The arc additive manufacturing deposit of the maraging steel wire prepared in this embodiment has an additive tensile strength of 1532 MPa and an elongation of 12%.

[0120] Comparative Example 1

[0121] The only difference between this comparative example and Example 1 is that the interlayer temperature is not controlled. The interlayer temperature of this comparative example is 140°C, that is, the continuous additive strategy, resulting in the internal structure of the final additive component being a pure martensite structure without precipitation strengthening phase. Under this condition, the tensile strength of the additive component is 1000 MPa and the elongation is 8%, which is consistent with the level of forgings.

[0122] In Example 1, the interlayer temperature is controlled at 180°C, and during the additive process, austenite inversion and intermetallic compound precipitation occur inside the deposited metal, resulting in a tensile strength of 1500 MPa for the final additive component, and the elongation remains above 10%.

[0123] In this embodiment, in the additive process, the wire is first melted into a liquid state and then solidified into high-temperature austenite. Afterwards, when cooled to the martensitic transformation temperature (Ms), an austenite to martensite phase transformation occurs. The Ms of the wire system designed in the present invention is 220-230°C. If the interlayer temperature is too high, the martensitic phase transformation does not occur, resulting in low strength. If the interlayer temperature is too low, the austenite reverse transformation is insufficient, resulting in low elongation.

[0124] It should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Therefore, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0125] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-strength and tough maraging steel wire suitable for arc additive manufacturing, characterized in that: The maraging steel alloy includes the following components in mass percentage, C: ≤0.02%, Si: ≤0.5%, Mn: ≤1%, Ni: 16.0-20.0%, Co: 10.0-12.0%, Mo: 3.0-6.0%, Ti: 0.5-1.8%, Al: 0.05-0.20%, P: ≤0.003%, S: ≤0.003%, H: ≤5ppm, N: ≤0.002%, O: ≤0.003%, and Fe is the balance.

2. The method for preparing high-strength and tough maraging steel wire suitable for arc additive manufacturing according to claim 1, characterized in that: The method comprises the following preparation steps: S01, vacuum melting: using a vacuum melting furnace to perform initial melting of the maraging steel alloy, the heating temperature of the initial melting is 1000-1200°C, the holding time is 6-8h, and the initial melting ingot is cast; S02, electrode preparation: forging the initial melt ingot, before forging, the initial melt ingot is kept at 1000-1200°C for 2-4 hours, and then forged, the final forging temperature is not less than 850°C, and the electrode sample is prepared; S03, electroslag remelting: the electrode sample is subjected to secondary smelting by electroslag remelting, the electroslag remelting speed is 1.5-2.0 kg / min, the voltage is 25-40 V, the current is 1.8-3.0 kA, and the final ingot is cast; S04, high temperature forging: the final ingot is subjected to high temperature forging. Before forging, the final ingot is heated to a temperature of 1100-1200°C for 2-4 hours of holding time, and then forged. The final forging temperature is not less than 950°C to prepare a bar; S05, high temperature rolling: the bar is kept at 1100-1200℃ for 1-3h, and then rolled into wire rod through multiple hot rolling passes; S06, annealing treatment: annealing the wire rod; the annealing process is: keeping at 1100-1200°C for 1-2h, and then air cooling; S07, wire drawing: drawing the wire rod after annealing, and online annealing is performed during the drawing process, and the annealing temperature is 1000-1150°C; S08, cleaning and winding: cleaning, drying and winding the wire after drawing.

3. The preparation method according to claim 2, characterized in that: In S01, the vacuum degree of vacuum smelting is 0~20Pa.

4. The preparation method according to claim 2, characterized in that: In S07, the wire rod is mechanically descaled before drawing, and then treated with a film after washing and drying, and then drawn after drying at 80-100°C.

5. The preparation method according to claim 2, characterized in that: In S08, the cleaning is performed by sequentially performing alkaline cleaning and water cleaning.

6. Use of the high-strength and tough maraging steel wire suitable for arc additive manufacturing according to claim 1 in maraging steel parts.

7. The use according to claim 6, characterized in that: The maraging steel parts include large and complex maraging steel parts, which include ground-level rocket engine casings, tank armored vehicle main structures, and aircraft wing hinges.

8. The use according to claim 6, characterized in that: The preparation method of maraging steel parts is as follows: current 150-250A, voltage 15-35V, wire feeding speed 0.3-10m / min, additive speed 10-20cm / min, interlayer temperature 160℃-190℃.

9. A maraging steel component, characterized in that: The high-strength and tough martensitic aged steel wire is prepared by the preparation method according to any one of claims 2 to 5, and the preparation method is: current 150-250A, voltage 15-35V, wire feeding speed 0.3-10m / min, additive speed 10-20cm / min, interlayer temperature 160°C-190°C.

10. The maraging steel component according to claim 9, characterized in that: The tensile strength of maraging steel parts reaches over 1500MPa and the elongation remains above 10%.

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