Steel material for 3D printing and 3D printing method

Abstract

The invention relates to a steel material for 3D printing and a 3D printing method, in particular to the technical field of additive manufacturing, and the steel material for 3D printing comprises, by mass, 14-20% of Ni, 10-17% of Co, 4-12% of Mo, 0.5-2% of Ti, 0.05-0.3% of Al, less than 0.03% of C, less than or equal to 0.1% of Si, less than or equal to 0.1% of Mn and the balance Fe and inevitable impurities. According to the steel material for 3D printing provided by the invention, the components are reasonably designed, and a proper heat treatment process is used, so that an obtained 3D printing product can have good mechanical properties, the tensile strength is greater than or equal to 2316 MPa, and the yield strength is greater than or equal to 2187 MPa.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a steel material for 3D printing and a 3D printing method. Background Art

[0002] At present, the use of 3D printing technology to form complex components has many advantages: including the combination of multiple components through functional integration, lightweighting through topological optimization, direct forming of complex internal structures, and direct forming of final parts. Ultra-high-strength steel materials are mainly used to manufacture structural parts that withstand high stress and are often used in important fields such as aerospace and rail transportation. Therefore, the use of 3D printing to form ultra-high-strength steel structural parts can achieve lightweight design, shorten delivery cycles, reduce the number of components, and improve structural stability. It has broad application prospects and important market value.

[0003] The tensile strength of traditional ultra-high strength steel materials that have been industrially applied can reach about 2400-2600MPa, such as AerMet340, 18Ni350, 13Ni400 and other materials, and have certain plastic toughness. The existing 3D printing high-strength steel materials mainly include 18Ni300, S136, and H13, which have problems such as insufficient maximum strength, poor plastic toughness, easy thermal cracking and cracking of carbon-containing steel. Among them, 18Ni300 is a martensitic aging steel. After aging heat treatment, the strength can reach 2100MPa, but the elongation is about 4%, and the strength-plasticity product is only 8GPa%. S136 and H13 have medium and low carbon contents and are commonly used in the mold industry. After tempering heat treatment, the tensile strength is 1700-1900MPa, the elongation is 5-7%, the plastic toughness is poor, and when using 3D printing technology to form, it is easy to cause thermal cracks caused by low-melting point carbides, as well as macro cracking caused by stress accumulation and insufficient toughness.

[0004] For example, CN112404420A discloses a high-strength steel powder for 3D printing, a preparation method thereof, a 3D printing method and the obtained high-strength steel. The high-strength steel powder for 3D printing comprises, by mass percentage, 0.15%-0.3% C, 0.4%-0.6% V, 0.8%-1.2% Ti, 0.8%-1.5% Mo, 2.5%-4% Cr, 10%-12% Ni, 12%-15% Co, and the balance is Fe.

[0005] For example, CN112831721A discloses an additively manufactured ultra-high strength plastic steel material and a preparation method thereof, which is prepared from the following components in mass fractions: 0.20-0.58% C, 5.5-8.9% Ni, 0.35-2.8% Mn, 0.20-1.3% Si, 0.3-1.5% Cr, 0.50-0.60% Mo, 0.54-1.08% V, and the remainder is Fe. The additively manufactured ultra-high strength steel has a yield strength of ≥927MPa after tempering and a tensile strength of ≥1650MPa.

[0006] In summary, the strength of 3D printed products obtained from existing high-strength printing materials does not exceed 2200MPa. Therefore, it is necessary to develop ultra-high-strength steel materials that are suitable for 3D printing technology, not easy to crack, have a strength exceeding 2200MPa, and have certain plasticity and toughness. Summary of the invention

[0007] In view of the problems existing in the prior art, the object of the present invention is to provide a steel material for 3D printing and a 3D printing method to solve the defect of poor mechanical properties of existing 3D printed products.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a steel material for 3D printing, wherein the steel material for 3D printing comprises, by weight percentage:

[0010] Ni 14-20%, Co 10-17%, Mo 4-12%, Ti 0.5-2%, Al 0.05-0.3%, C<0.03%, Si≤0.1%, Mn≤0.1%, and the balance is Fe and unavoidable impurities.

[0011] The steel material for 3D printing provided by the present invention has good mechanical properties, a tensile strength of ≥2316MPa, and a yield strength of ≥2187MPa, by rationally designing the components.

[0012] As a preferred technical solution of the present invention, the steel material for 3D printing includes, by mass percentage:

[0013] Ni 14-17%, Co 12-17%, Mo 4-10%, Ti 0.7-1.6%, Al 0.18-0.3%, C<0.03%, Si≤0.01%, Mn≤0.01%, the balance is Fe and unavoidable impurities, the total mass percentage of Ni and Mo is ≤25%.

[0014] In a second aspect, the present invention provides a 3D printing method, comprising: using the steel material for 3D printing as described in the first aspect as a printing raw material for 3D printing, and then performing heat treatment to obtain a 3D printed product.

[0015] As a preferred technical solution of the present invention, the content of deposited retained austenite in the material obtained by 3D printing is greater than 20%, and the heat treatment includes a first heat treatment, a first cooling, a second heat treatment and a second cooling performed in sequence.

[0016] As a preferred technical solution of the present invention, the heating rate in the first heat treatment is 3-10°C / min.

[0017] Preferably, the holding temperature in the first heat treatment is 850-1050°C.

[0018] Preferably, the holding time in the first heat treatment is 0.5-1.5h.

[0019] As a preferred technical solution of the present invention, the heating rate in the second heat treatment is 3-10°C / min.

[0020] Preferably, the holding temperature in the second heat treatment is 460-510°C.

[0021] Preferably, the holding time in the second heat treatment is 4-10 hours.

[0022] As a preferred technical solution of the present invention, the first cooling method includes air cooling.

[0023] Preferably, the second cooling method includes air cooling.

[0024] As a preferred technical solution of the present invention, the content of deposited retained austenite in the material obtained by 3D printing is ≤20%, and the heat treatment includes a third heat treatment and a third cooling performed sequentially.

[0025] As a preferred technical solution of the present invention, the heating rate in the third heat treatment is 3-10°C / min.

[0026] Preferably, the holding temperature in the third heat treatment is 460-510°C.

[0027] Preferably, the holding time in the third heat treatment is 4-10 hours.

[0028] As a preferred technical solution of the present invention, the third cooling method includes air cooling.

[0029] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0030] (1) The present invention redesigns the material composition based on the process characteristics of 3D printing technology, and regulates the microstructure through the combination of composition and heat treatment, including grain size, residual / reversed austenite ratio and distribution, size and distribution of second phase particles, etc., so as to achieve ultra-high strength while maintaining a certain plasticity and toughness.

[0031] (2) The steel material provided by the present invention is ultra-high strength steel, specifically low-carbon / carbon-free steel, the carbon content of which is controlled below 0.03%, and no thermal cracks are generated during the forming process; carbon significantly improves the strength of steel in the form of solid solution and carbide, but it also reduces the plasticity and toughness of steel. In addition, when carbon-containing steel materials are formed by 3D printing technology, the low-melting-point carbides are easily torn by rapid cooling in the final stage of solidification to produce high tensile stress and form cracks. In addition, since carbon steel has lower toughness, when the deformation caused by thermal stress reaches a certain extent, macroscopic cracking will occur in the formed part. The microstructure is mainly composed of low-carbon / carbon-free martensite with good plasticity and toughness, as well as a small amount of residual austenite, and has good toughness. Macroscopic cracking is not easy to occur when forming large-sized components.

[0032] (3) The steel material provided by the present invention contains 14.0-20.0% nickel to avoid the generation of ferrite and pearlite during high-temperature cooling (3D printing solidification and heat treatment). At the same time, the nickel content does not exceed 20% to avoid the transformation of the microstructure to austenite and reduce the strength of the material.

[0033] (4) The steel material provided by the present invention contains 10.0-17.0% cobalt. Cobalt is mainly used to control (increase) the Ms point, that is, the temperature at which supercooled austenite begins to transform into martensite, to control the ratio of martensite / austenite. At the same time, it reduces the stacking fault energy, increases the work hardening stress, reduces the solubility of Mo, and maintains a certain density of dislocations to provide nucleation sites for the second phase particles.

[0034] (5) The steel material provided by the present invention contains a certain proportion of Mo, Ti, and Al. These elements form strengthening phase particles such as Ni3Mo, Ni3Ti, Ni3Al, and Fe2Mo during heat treatment, greatly improving the strength of the material.

[0035] (6) When the total content of Mo and Ni in the steel material provided by the present invention is too high, sufficient strength cannot be obtained. Therefore, in the present invention, the total mass percentage of Ni+Mo is controlled within 25%. DETAILED DESCRIPTION

[0036] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0037] This embodiment provides a steel material for 3D printing, and the steel material for 3D printing includes, by mass percentage:

[0038] Ni 14-20%, Co 10-17%, Mo 4-12%, Ti 0.5-2%, Al 0.05-0.3%, C<0.03%, Si≤0.1%, Mn≤0.1%, and the balance is Fe and unavoidable impurities.

[0039] In the present invention, the exemplary preparation process of the steel material for 3D printing is as follows: the ingredients are prepared according to the formula, and then smelted. After the smelting is qualified, the raw materials commonly used in 3D printing in the field are atomized and powdered or formed into wires for 3D printing. The parameters involved in the preparation process are selected according to the conventional design in the field to ensure that the element content limit of the present invention is met.

[0040] In the present invention, the mass percentage of Ni in the steel material for 3D printing is 14-20%, for example, it can be 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5% or 20%, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0041] In the present invention, the Co content in the steel material for 3D printing is 10-17% by mass, for example, it can be 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5% or 17%, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0042] In the present invention, the Mo content in the steel material for 3D printing is 4-12% by mass, for example, it can be 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12%, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0043] In the present invention, the mass percentage of Ti in the steel material for 3D printing is 0.5-2%, for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8% or 2%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0044] In the present invention, the mass percentage of Al in the steel material for 3D printing is 0.05-0.3%, for example, it can be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25% or 0.3%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0045] In the present invention, the C content in the steel material for 3D printing is less than 0.03% by mass percentage, for example, it can be 0.025%, 0.02%, 0.015%, 0.01%, 0.005%, 0.004%, 0.003%, 0.002% or 0.001%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0046] In the present invention, the Si content in the steel material for 3D printing is ≤0.1% by mass percentage, for example, it can be 0.1%, 0.08%, 0.06%, 0.04%, 0.02%, 0.01% or 0.001%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0047] In the present invention, the Mn content in the steel material for 3D printing is ≤0.1% by mass percentage, for example, it can be 0.1%, 0.08%, 0.06%, 0.04%, 0.02%, 0.01% or 0.001%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0048] Furthermore, the steel material for 3D printing includes, by mass percentage:

[0049] Ni 14-17%, Co 12-17%, Mo 4-10%, Ti 0.7-1.6%, Al 0.18-0.3%, C<0.03%, Si≤0.01%, Mn≤0.01%, the balance is Fe and unavoidable impurities, the total mass percentage of Ni and Mo is ≤25%.

[0050] Furthermore, the present invention provides a 3D printing method, which comprises: using the steel material for 3D printing as a printing raw material to perform 3D printing, and then performing heat treatment to obtain a 3D printed product.

[0051] In the present invention, the 3D printing method can be a commonly used printing method in the art, such as powder bed fusion. When a powdered printing material is used, the particle size of the powder is in the range of 10-100 μm. When a wire is used, the diameter of the wire is 0.5-1.5 mm. The specific printing control parameters can be designed and selected according to the conventional printing process in the art. The exemplary printing process is as follows:

[0052] Use a scraper or roller to evenly spread the powder with a particle size range of 10-100μm on the substrate (the substrate material can be 304 stainless steel). Control the laser beam to scan the single-layer scanning area obtained after slicing according to the CAD file. Move the forming cylinder down by one forming layer thickness, then repeat the powder spreading process and control the laser beam to scan the next layer of scanning area. Repeat the above process until the part is formed.

[0053] In the present invention, the particle size range of the powder used in the printing process is an aggregate of particles with a particle size within a certain range, for example, an aggregate of all particles within a particle size range of 20-63 μm, or an aggregate of all particles within a particle size range of 15-53 μm, or an aggregate of all particles within a particle size range of 25-90 μm, or an aggregate of all particles within a particle size range of 10-70 μm, etc.

[0054] Wherein, when the content of deposited retained austenite in the material obtained by 3D printing is greater than 20%, the heat treatment includes a first heat treatment, a first cooling, a second heat treatment and a second cooling performed in sequence.

[0055] Among them, the heating rate in the first heat treatment is 3-10℃ / min, for example, it can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0056] Among them, the insulation temperature in the first heat treatment is 850-1050℃, for example, it can be 850℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, 1020℃, 1040℃ or 1050℃, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0057] Among them, the holding time in the first heat treatment is 0.5-1.5h, for example, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h or 1.5h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0058] Wherein, the first cooling method includes air cooling.

[0059] Among them, the heating rate in the second heat treatment is 3-10℃ / min, for example, it can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0060] Among them, the insulation temperature in the second heat treatment is 460-510℃, for example, it can be 460℃, 465℃, 470℃, 475℃, 480℃, 485℃, 490℃, 495℃, 500℃, 505℃ or 510℃, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0061] Among them, the holding time in the second heat treatment is 4-10h, for example, it can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0062] Wherein, the second cooling method includes air cooling.

[0063] Wherein, when the content of deposited retained austenite in the material obtained by 3D printing is ≤20%, the heat treatment includes a third heat treatment and a third cooling performed sequentially.

[0064] Among them, the heating rate in the third heat treatment is 3-10℃ / min, for example, it can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0065] Among them, the insulation temperature in the third heat treatment is 460-510℃, for example, it can be 460℃, 465℃, 470℃, 475℃, 480℃, 485℃, 490℃, 495℃, 500℃, 505℃ or 510℃, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0066] Among them, the holding time in the third heat treatment is 4-10h, for example, it can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0067] Wherein, the third cooling method includes air cooling.

[0068] Further, in order to illustrate the high strength performance that can be achieved by the products printed by the steel material for 3D printing provided by the present invention, actual examples are used for illustration, as follows:

[0069] The 3D printing technology used in the following example is laser powder bed fusion manufacturing, the particle size range of the powder is 15-53μm, the laser power is 250W, the scanning speed is 1000mm / s, the scanning spacing is 0.08mm, the powder layer thickness is 30μm, and the density is more than 99.5%, and there is no unfused defect inside. The oxygen content of the forming chamber is controlled below 500ppm during the fusion manufacturing process, and the substrate heating temperature can be set to 100℃.

[0070] Example 1

[0071] This embodiment provides a steel material for 3D printing, which includes, by weight percentage:

[0072] Ni 17%, Co 17%, Mo 8%, Ti 0.7%, Al 0.3%, C 0.02%, Si 0.01%, Mn 0.01%, and the balance is Fe and inevitable impurities.

[0073] The 3D printing process is as follows:

[0074] Using the steel material for 3D printing as the printing raw material for 3D printing, and then performing heat treatment to obtain a 3D printed product;

[0075] The content of deposited residual austenite in the material obtained by 3D printing is greater than 20%, and the heat treatment includes a first heat treatment, a first cooling, a second heat treatment and a second cooling performed in sequence; the heating rate in the first heat treatment is 7°C / min; the holding temperature in the first heat treatment is 900°C; the holding time in the first heat treatment is 1.2h; the heating rate in the second heat treatment is 7°C / min; the holding temperature in the second heat treatment is 500°C; the holding time in the second heat treatment is 8h; the first cooling method includes air cooling; the second cooling method includes air cooling;

[0076] Example 2

[0077] This embodiment provides a steel material for 3D printing, which includes, by weight percentage:

[0078] Ni 14%, Co 12%, Mo 10%, Ti 1.6%, Al 0.18%, C 0.01%, Si 0.008%, Mn 0.008%, and the balance is Fe and inevitable impurities.

[0079] The 3D printing process is as follows:

[0080] Using the steel material for 3D printing as the printing raw material for 3D printing, and then performing heat treatment to obtain a 3D printed product;

[0081] The content of deposited residual austenite in the material obtained by 3D printing is ≤20%, and the heat treatment includes a third heat treatment and a third cooling performed in sequence; the heating rate in the third heat treatment is 6°C / min; the holding temperature in the third heat treatment is 480°C; the holding time in the third heat treatment is 6h; and the third cooling method is air cooling.

[0082] Example 3

[0083] This embodiment provides a steel material for 3D printing, which includes, by weight percentage:

[0084] Ni 20%, Co 11%, Mo 4%, Ti 0.5%, Al 0.05%, C 0.025%, Si 0.1%, Mn 0.09%, and the balance is Fe and inevitable impurities.

[0085] The 3D printing process is as follows:

[0086] Using the steel material for 3D printing as the printing raw material for 3D printing, and then performing heat treatment to obtain a 3D printed product;

[0087] The content of deposited residual austenite in the material obtained by 3D printing is ≤20%, and the heat treatment includes a third heat treatment and a third cooling performed in sequence; the heating rate in the third heat treatment is 10°C / min; the holding temperature in the third heat treatment is 460°C; the holding time in the third heat treatment is 10h; and the third cooling method is air cooling.

[0088] Example 4

[0089] This embodiment provides a steel material for 3D printing, which includes, by weight percentage:

[0090] Ni 18%, Co 10%, Mo 6%, Ti 0.8%, Al 0.1%, C 0.02%, Si 0.08%, Mn 0.1%, and the balance is Fe and inevitable impurities.

[0091] The 3D printing process is as follows:

[0092] Using the steel material for 3D printing as the printing raw material for 3D printing, and then performing heat treatment to obtain a 3D printed product;

[0093] The content of deposited residual austenite in the material obtained by 3D printing is ≤20%, and the heat treatment includes a third heat treatment and a third cooling performed in sequence; the heating rate in the third heat treatment is 3°C / min; the holding temperature in the third heat treatment is 510°C; the holding time in the third heat treatment is 4h; and the third cooling method is air cooling.

[0094] Comparative Example 1

[0095] The only difference from Example 1 is that the mass percentage of Co in the steel material is 8.5%.

[0096] Comparative Example 2

[0097] The only difference from Example 1 is that the total mass percentage of Ni and Mo is 28%, that is, the Ni content is increased, and the nickel content is 20% at this time.

[0098] Comparative Example 3

[0099] The only difference from Example 1 is that the total mass percentage of Ni and Mo is 29%, that is, the Mo content is increased, and the Mo content is 12% at this time.

[0100] Comparative Example 4

[0101] The only difference from Example 1 is that no heat treatment is performed.

[0102] Comparative Example 5

[0103] The only difference from Example 1 is that the heat treatment is replaced by heating to 700° C. at a heating rate of 8° C. / min, keeping the temperature for 2 h, and air cooling.

[0104] The 3D printed products obtained in the embodiment and the comparative example were subjected to mechanical property tests, wherein the room temperature tensile properties (strength and elongation) were tested in accordance with GB / T 228.1-2021. The test results are detailed in Table 1.

[0105] Table 1

[0106] Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 2650 2450 3.8 Example 2 2543 2498 4.9 Example 3 2460 2357 7.7 Example 4 2316 2187 9.6 Comparative Example 1 2545 2234 1.5 Comparative Example 2 1760 1070 13.5 Comparative Example 3 1900 806 11.5 Comparative Example 4 1423 923 15.2 Comparative Example 5 1970 1200 8.6

[0107] As shown in Table 1, in the solution provided by the present invention, by controlling the content of Co, high strength is ensured while achieving good plastic toughness. In addition, by controlling the ratio and total amount of Ni and Mo elements (both are austenite stabilizing elements), the ratio of retained austenite is controlled to improve material strength. By suitable heat treatment temperature and holding time, the size and distribution of the second phase strengthening particles are controlled so that they are evenly distributed in the substrate with a small size, and the plastic toughness of the material is not reduced while the strength is improved.

[0108] It is stated that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0109] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0110] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0111] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A steel material for 3D printing, characterized in that: The steel material used for 3D printing includes, by weight percentage: Ni 14-20%, Co 10-17%, Mo 4-12%, Ti 0.5-2%, Al 0.05-0.3%, C<0.03%, Si≤0.1%, Mn≤0.1%, and the balance is Fe and unavoidable impurities.

2. The steel material for 3D printing according to claim 1, characterized in that: The steel material used for 3D printing includes, by mass percentage: Ni 14-17%, Co 12-17%, Mo 4-10%, Ti 0.7-1.6%, Al 0.18-0.3%, C<0.03%, Si≤0.01%, Mn≤0.01%, the balance is Fe and unavoidable impurities, the total mass percentage of Ni and Mo is ≤25%.

3. A 3D printing method, characterized in that: The 3D printing method comprises: using the steel material for 3D printing as claimed in claim 1 or 2 as a printing raw material to perform 3D printing, and then performing heat treatment to obtain a 3D printed product.

4. The 3D printing method according to claim 3, characterized in that: The content of deposited retained austenite in the material obtained by 3D printing is greater than 20%, and the heat treatment includes a first heat treatment, a first cooling, a second heat treatment and a second cooling performed in sequence.

5. The 3D printing method according to claim 4, characterized in that: The heating rate in the first heat treatment is 3-10°C / min; The holding temperature in the first heat treatment is 850-1050°C; The holding time in the first heat treatment is 0.5-1.5h.

6. The 3D printing method according to claim 4, characterized in that: The heating rate in the second heat treatment is 3-10°C / min; The holding temperature in the second heat treatment is 460-510°C; The holding time in the second heat treatment is 4-10 hours.

7. The 3D printing method according to claim 4, characterized in that: The first cooling method includes air cooling; The second cooling method includes air cooling.

8. The 3D printing method according to claim 3, characterized in that: The content of deposited retained austenite in the material obtained by 3D printing is ≤20%, and the heat treatment includes a third heat treatment and a third cooling performed in sequence.

9. The 3D printing method according to claim 8, characterized in that: The heating rate in the third heat treatment is 3-10°C / min; The holding temperature in the third heat treatment is 460-510°C; The holding time in the third heat treatment is 4-10 hours.

10. The 3D printing method according to claim 8, characterized in that: The third cooling method includes air cooling.