Austenitic stainless steel and preparation method and application thereof

Abstract

The invention discloses austenitic stainless steel and a preparation method and application thereof, and relates to the technical field of metal additive manufacturing, and the preparation method comprises the steps that dried stainless steel alloy powder is printed into an austenitic stainless steel part; during printing, the laser power ranges from 180 W to 220 W, the scanning speed ranges from 870 mm / s to 970 mm / s, the scanning interval ranges from 0.09 mm to 0.11 mm, and the thickness of a powder layer ranges from 30 micrometers to 50 micrometers; and during printing, the layers are rotated by 67 degrees layer by layer. The high-strength and high-plasticity 316H stainless steel is prepared by optimizing process parameters such as laser power, scanning rate and scanning spacing by utilizing the characteristics of an additive manufacturing rapid cooling process, fine grain size, cellular substructure and the like, and the stainless steel has excellent strength and plasticity, and can be used for preparing the high-strength and high-plasticity 316H stainless steel. The method has important application value in the fields of complex fine structural components and high-strength and high-plasticity application.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, specifically to an austenitic stainless steel, its preparation method, and its applications. Background Technology

[0002] 316H austenitic stainless steel has advantages such as excellent corrosion resistance, good structural stability, high operating temperature (up to 700℃), good weldability, and excellent processing performance. It can serve in harsh environments such as high temperature and high pressure, corrosive atmosphere and physical radiation, and is widely used in high-temperature components of equipment in nuclear industry, aerospace, petroleum and chemical industry.

[0003] Additive manufacturing (AM) technology, an advanced manufacturing technology developed in recent decades, is based on the discrete-stacking principle. Through computer-aided design, material processing and forming technology, it directly stacks special materials layer by layer to manufacture physical objects based on digital models. It has the advantages of free forming of complex structures, excellent mechanical properties and high material utilization, and has become an important force driving the development of the manufacturing industry.

[0004] For existing 316H stainless steel, forged alloys are currently used to manufacture components. However, the comprehensive mechanical properties such as strength, ductility, and toughness cannot meet the high strength and high ductility requirements of complex and delicate structural components, and the manufacturing process needs to be improved. Summary of the Invention

[0005] Given the current shortcomings of 316H austenitic stainless steel in terms of strength and toughness, the present invention aims to provide an austenitic stainless steel, its preparation method, and its applications. This stainless steel possesses excellent strength and toughness, and has significant application value in complex and delicate structural components and high-strength and high-ductility applications.

[0006] This invention is achieved through the following technical solution:

[0007] In one aspect, this application provides a method for preparing austenitic stainless steel, wherein dried stainless steel alloy powder is printed into austenitic stainless steel molds. The laser power during printing is 180W~220W, the scanning speed is 870mm / s~970mm / s, the scanning spacing is 0.09mm~0.11mm, and the powder layer thickness is 30-50μm. During printing, the layers are rotated 67° one by one.

[0008] This invention utilizes the rapid cooling process characteristics, fine grain size, and cellular substructure of additive manufacturing to prepare high-strength and high-ductility 316H stainless steel by optimizing process parameters such as laser power, scanning rate, and scanning spacing. This stainless steel possesses excellent strength and ductility, making it valuable for applications in complex and delicate structural components and high-strength, high-ductility applications.

[0009] Through this manufacturing process, the austenitic stainless steel (316H stainless steel) of the present invention achieves a density of over 99.50%, and the room temperature yield strength of the austenitic stainless steel parallel to the printing direction reaches 490MPa~510MPa, the room temperature tensile strength reaches 535~560MPa, the elongation after fracture reaches 84%~91%, and the reduction of area reaches 65%~71%. The room temperature yield strength of the austenitic stainless steel perpendicular to the printing direction reaches 525~580MPa, the room temperature tensile strength reaches 630~675MPa, the elongation after fracture reaches 35%~60%, and the reduction of area reaches 55%~75%.

[0010] The austenitic stainless steel prepared by this invention through the manufacturing process has high strength and high ductility and toughness. Compared with the existing forged 316H stainless steel, both strength and ductility and toughness have been greatly improved. At the same time, the preparation process of this invention is simple, has a large process window, and has great application prospects.

[0011] In one specific embodiment, the stainless steel powder comprises the following components by mass percentage:

[0012] C: 0.04~0.10 wt.%, Si: ≤1.00 wt.%, Mn: ≤2.00 wt.%, Co: ≤0.2 wt.%, P: ≤0.035 wt.%, S: ≤0.020 wt.%, Cu: ≤0.2 wt.%, Mo: 2.00~3.00 wt.%, N: ≤0.10 wt.%, Ni: 10.0~14.0 wt.%, Cr: 16.0~18.0 wt.%, O: ≤0.03 wt.%, H: ≤0.03 wt.%, the balance is Fe and impurities.

[0013] In one specific embodiment, the particle size of the stainless steel alloy powder is 15μm~53μm.

[0014] In one specific embodiment, the sphericity of the stainless steel alloy powder is >0.95.

[0015] In one specific embodiment, the flowability of the stainless steel alloy powder is ≤20s / 50g.

[0016] In one specific embodiment, the loose packing density of the stainless steel alloy powder is ≥4.3 g / cm³. 3 .

[0017] In one specific embodiment, the tap density of the stainless steel alloy powder is ≥4.8 g / cm³. 3 .

[0018] In one specific embodiment, the void ratio of the stainless steel alloy powder is ≤0.3%.

[0019] In one specific embodiment, the amount of non-metallic inclusions in the stainless steel alloy powder is ≤5 particles / 100g.

[0020] In one specific embodiment, a vacuum dryer is used to dry the stainless steel alloy powder.

[0021] In one specific embodiment, the drying temperature is 80℃~120℃, and the holding time is 2h~4h.

[0022] Secondly, this application provides an austenitic stainless steel prepared by the above-described preparation method.

[0023] Thirdly, this application provides an application of the above-mentioned austenitic stainless steel, including its use in the manufacture of complex and fine-structured, high-strength, high-plasticity, and high-temperature resistant components.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] (1) This invention utilizes the characteristics of rapid cooling process in additive manufacturing, fine grain size, and cellular substructure to prepare high-strength and high-ductility 316H stainless steel by optimizing process parameters such as laser power, scanning rate, and scanning spacing. This stainless steel has excellent strength and ductility, and has important application value in complex and delicate structural components and high-strength and high-ductility applications.

[0026] (2) The austenitic stainless steel (316H stainless steel) of the present invention has a density of more than 99.50%, and the room temperature yield strength of the austenitic stainless steel parallel to the printing direction is 490MPa~510MPa, the room temperature tensile strength is 535~560 MPa; the elongation after fracture is 84%~91%, and the reduction of area is 65%~71%; the room temperature yield strength of the austenitic stainless steel perpendicular to the printing direction is 525~580 MPa, the room temperature tensile strength is 630~675 MPa; the elongation after fracture is 35%~60%, and the reduction of area is 55%~75%.

[0027] (3) The austenitic stainless steel prepared by the present invention through this manufacturing process has high strength and high plasticity and toughness. Compared with the existing forged 316H stainless steel, the strength and plasticity and toughness have been greatly improved. At the same time, the preparation process of the present invention is simple, has a large process window, and has great application prospects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0029] Figure 1 The morphology of 316H stainless steel powder obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 1 of the present invention;

[0030] Figure 2 The microstructure of polished 316H stainless steel obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 1 of the present invention.

[0031] Figure 3 The image shows a CT scan of 316H stainless steel obtained using a high-strength, high-plasticity 316H stainless steel additive manufacturing process as described in Example 1 of this invention.

[0032] Figure 4 The microstructure of 316H stainless steel in corrosion state perpendicular to the printing direction is obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 1 of the present invention.

[0033] Figure 5 The microstructure of 316H stainless steel with corrosion state parallel to the printing direction obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 1 of the present invention.

[0034] Figure 6 The image shows the engineering stress-strain curve of 316H stainless steel parallel to the printing direction, obtained by using a high-strength, high-plasticity 316H stainless steel additive manufacturing process method in Example 1 of this invention.

[0035] Figure 7 The image shows the engineering stress-strain curve of 316H stainless steel perpendicular to the printing direction, obtained by using a high-strength, high-plasticity 316H stainless steel additive manufacturing process method as described in Example 1 of this invention.

[0036] Figure 8 The morphology of 316H stainless steel powder obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process in Example 2 of the present invention;

[0037] Figure 9 The microstructure of polished 316H stainless steel obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 2 of the present invention.

[0038] Figure 10 The image shows a CT scan of 316H stainless steel obtained using a high-strength, high-plasticity 316H stainless steel additive manufacturing process as described in Example 2 of this invention.

[0039] Figure 11 The microstructure of 316H stainless steel in corrosion state perpendicular to the printing direction is obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 2 of the present invention.

[0040] Figure 12 The microstructure of 316H stainless steel with corrosion state parallel to the printing direction obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 2 of the present invention.

[0041] Figure 13 The image shows the engineering stress-strain curve of 316H stainless steel parallel to the printing direction, obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 2 of this invention.

[0042] Figure 14 The image shows the engineering stress-strain curve of 316H stainless steel perpendicular to the printing direction, obtained by using a high-strength, high-plasticity 316H stainless steel additive manufacturing process method in Example 2 of this invention.

[0043] Figure 15 The morphology of 316H stainless steel powder obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 3 of the present invention;

[0044] Figure 16 The microstructure of polished 316H stainless steel obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 3 of the present invention.

[0045] Figure 17 The image shows a CT scan of 316H stainless steel obtained using a high-strength, high-plasticity 316H stainless steel additive manufacturing process as described in Example 3 of this invention.

[0046] Figure 18 The microstructure of 316H stainless steel in corrosion state perpendicular to the printing direction is obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 3 of the present invention.

[0047] Figure 19 The microstructure of 316H stainless steel with corrosion state parallel to the printing direction obtained by using a high-strength and high-plasticity 316H stainless steel additive manufacturing process method in Example 3 of the present invention.

[0048] Figure 20The image shows the engineering stress-strain curve of 316H stainless steel parallel to the printing direction, obtained by using a high-strength, high-plasticity 316H stainless steel additive manufacturing process method in Example 3 of this invention.

[0049] Figure 21 The image shows the engineering stress-strain curve of 316H stainless steel perpendicular to the printing direction, obtained by using a high-strength, high-plasticity 316H stainless steel additive manufacturing process method as described in Example 3 of this invention.

[0050] Figure 22 The image shows a CT scan of 316H stainless steel obtained using a high-strength, high-plasticity 316H stainless steel additive manufacturing process as described in Comparative Example 1 of this invention.

[0051] Figure 23 The image shows a CT scan of 316H stainless steel obtained using a high-strength, high-plasticity additive manufacturing process for 316H stainless steel as described in Comparative Example 2 of this invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0053] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0054] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0055] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0057] An embodiment of the present invention provides an additive manufacturing process for high-strength, high-ductility 316H stainless steel, comprising the following steps:

[0058] Step 1: Select 316H stainless steel powder with the following chemical composition as the additive manufacturing raw material: C: 0.04~0.10 wt.%, Si: ≤1.00 wt.%, Mn: ≤2.00 wt.%, Co: ≤0.2 wt.%, P: ≤0.035 wt.%, S: ≤0.020 wt.%, Cu: ≤0.2 wt.%, Mo: 2.00~3.00 wt.%, N: ≤0.10 wt.%, Ni: 10.0~14.0 wt.%, Cr: 16.0~18.0 wt.%, O: ≤0.03 wt.%, H: ≤0.03 wt.%, with the remainder being Fe and unavoidable trace impurities.

[0059] The requirements for 316H stainless steel powder are as follows: particle size: 15~53μm, sphericity >0.95, flowability ≤20s / 50g, loose powder density ≥4.3g / cm3, tapped powder density ≥4.8g / cm3, void ratio ≤0.3%, non-metallic inclusions ≤5 particles / 100g;

[0060] Step 2: Dry the powder using a vacuum dryer at 80℃ for 2 hours. The printing substrate is made of 316L stainless steel and requires no preheating.

[0061] Step 3: Using the 316H powder obtained in Step 2, prepare 316H stainless steel according to the following printing parameters: laser power: 200W, scanning speed: 870mm / s, scanning interval: 0.09mm, powder layer thickness: 30μm, and printing strategy: rotating 67° between layers.

[0062] This invention utilizes the rapid cooling process characteristics, fine grain size, and cellular substructure of additive manufacturing to prepare high-strength and high-ductility 316H stainless steel by optimizing process parameters such as laser power, scanning rate, and scanning spacing. This stainless steel possesses excellent strength and ductility, making it valuable for applications in complex and delicate structural components and high-strength, high-ductility applications. Through this manufacturing process, the austenitic stainless steel (316H stainless steel) of this invention achieves a density of over 99.50%. The room temperature yield strength of the austenitic stainless steel parallel to the printing direction reaches 490 MPa~510 MPa, and the room temperature tensile strength reaches 535~560 MPa; the elongation after fracture reaches 84%~91%, and the reduction of area reaches 65%~71%. The room temperature yield strength of the austenitic stainless steel perpendicular to the printing direction reaches 525~580 MPa, and the room temperature tensile strength reaches 630~675 MPa; the elongation after fracture reaches 35%~60%, and the reduction of area reaches 55%~75%. The austenitic stainless steel prepared by this manufacturing process has high strength and high ductility and toughness. Compared with the existing forged 316H stainless steel, both strength and ductility and toughness have been greatly improved. At the same time, the preparation process of this invention is simple, has a large process window, and has great application prospects.

[0063] Example 1

[0064] This embodiment provides a method for preparing high-strength, high-ductility 316H stainless steel, the specific steps of which are as follows:

[0065] S1. 316H stainless steel powder with the following chemical composition is selected as the additive manufacturing raw material: C: 0.053 wt.%, Si: 0.35 wt.%, Mn: 1.54 wt.%, Co: 0.03 wt.%, P: 0.014 wt.%, S: 0.005 wt.%, Cu: 0.1 wt.%, Mo: 2.51 wt.%, N: 0.061 wt.%, Ni: 11.8 wt.%, Cr: 16.9 wt.%, O: 0.025 wt.%, H: 0.0005 wt.%, with the remainder being Fe and unavoidable trace impurities.

[0066] The requirements for 316H stainless steel powder are as follows: particle size: 15~53μm, sphericity: 0.96, flowability: 20s / 50g, and loose powder density: 4.3g / cm³. 3 The tap density of the powder is 4.8 g / cm³. 3 The hollow rate is 0.3%, and the non-metallic inclusions are 5 particles / 100g.

[0067] S2. Use a vacuum dryer to dry the above powder at a temperature of 80℃ for 2 hours. The printing substrate is made of 316L stainless steel and is not preheated.

[0068] S3. Using the 316H powder obtained in step S2, prepare 316H stainless steel according to the following printing parameters: laser power: 200W, scanning speed: 870mm / s, scanning interval: 0.09mm, powder layer thickness: 30μm, and printing strategy: rotating 67° between layers.

[0069] See Figure 1 The high-strength and high-plasticity 316H stainless steel powder obtained in step S1 was characterized and found to be free of inclusions and possess excellent sphericity.

[0070] See Figure 2 The high-strength, high-ductility 316H stainless steel prepared in step S3 was polished, and a metallographic photograph of its polished state was obtained. As shown in Figure 2, the high-strength, high-ductility 316H stainless steel obtained using the printing parameters in step S3 has a density of 99.66%, which is high.

[0071] See Figure 3 The high-strength, high-ductility 316H stainless steel prepared in step S3 was subjected to industrial CT inspection to obtain the results of internal defect detection. According to... Figure 3 It can be seen that no defects were found at a resolution of 6.116μm, indicating excellent density.

[0072] See Figure 4 and Figure 5The surfaces of the high-strength, high-ductility 316H stainless steel prepared in step S3 were polished and etched in both the parallel and perpendicular printing directions to obtain its microstructure. The microstructure in the perpendicular printing direction showed a cross-distributed stripe feature parallel to the laser scanning direction, while the microstructure in the parallel printing direction showed a fish-scale morphology.

[0073] See Figure 6 and Figure 7 The high-strength, high-ductility 316H stainless steel specimens prepared in step S3 were subjected to room temperature tensile tests in the parallel and perpendicular printing directions. The test results are as follows: Figure 6 , Figure 7 As shown in Table 1, the high-strength, high-ductility 316H stainless steel prepared using this embodiment has a density of over 99.50%. The room temperature yield strength of the specimens parallel to the printing direction reaches 490–510 MPa, and the room temperature tensile strength reaches 535–560 MPa; the elongation after fracture reaches 84%–91%, and the reduction of area reaches 65%–71%. The room temperature yield strength of the specimens perpendicular to the printing direction reaches 525–580 MPa, and the room temperature tensile strength reaches 630–675 MPa; the elongation after fracture reaches 35%–60%, and the reduction of area reaches 55%–75%.

[0074] This embodiment optimizes process parameters such as laser power, scanning rate, and scanning spacing to prepare high-strength and high-ductility 316H stainless steel with excellent strength and ductility.

[0075] Example 2

[0076] This embodiment provides a method for preparing high-strength, high-ductility 316H stainless steel. The difference from Embodiment 1 is that the laser power in step S3 of this embodiment is controlled at 180W. Other processes are the same as in Embodiment 1.

[0077] The specific steps are as follows:

[0078] S1. 316H stainless steel powder with the following chemical composition is selected as the additive manufacturing raw material: C: 0.053 wt.%, Si: 0.35 wt.%, Mn: 1.54 wt.%, Co: 0.03 wt.%, P: 0.014 wt.%, S: 0.005 wt.%, Cu: 0.1 wt.%, Mo: 2.51 wt.%, N: 0.061 wt.%, Ni: 11.8 wt.%, Cr: 16.9 wt.%, O: 0.025 wt.%, H: 0.0005 wt.%, with the remainder being Fe and unavoidable trace impurities.

[0079] The requirements for 316H stainless steel powder are as follows: particle size: 15~53μm, sphericity: 0.96, flowability: 20s / 50g, and loose powder density: 4.3g / cm³. 3 The tap density of the powder is 4.8 g / cm³. 3 The hollow rate is 0.3%, and the non-metallic inclusions are 5 particles / 100g.

[0080] S2. Use a vacuum dryer to dry the above powder at a temperature of 80℃ for 2 hours. The printing substrate is made of 316L stainless steel and is not preheated.

[0081] S3. Using the 316H powder obtained in step S2, prepare 316H stainless steel according to the following printing parameters: laser power: 180W, scanning speed: 870mm / s, scanning interval: 0.09mm, powder layer thickness: 30μm, and printing strategy: rotating 67° between layers.

[0082] See Figure 8 The high-strength and high-plasticity 316H stainless steel powder obtained in step S1 was characterized and found to be free of inclusions and possess excellent sphericity.

[0083] See Figure 9 The high-strength, high-ductility 316H stainless steel prepared in step S3 was polished to obtain a metallographic photograph of its polished state. According to... Figure 9 It can be seen that the high-strength, high-plasticity 316H stainless steel obtained using the printing parameters in step S3 has a density of 99.95%, which is high.

[0084] See Figure 10 The high-strength, high-ductility 316H stainless steel prepared in step S3 was subjected to industrial CT inspection to obtain the results of internal defect detection. According to... Figure 10 It can be seen that the density is 99.999% at a resolution of 6.116μm, which is excellent.

[0085] See Figure 11 and Figure 12 The surfaces of the high-strength, high-ductility 316H stainless steel prepared in step S3 were polished and etched in both the parallel and perpendicular printing directions to obtain its microstructure. The microstructure in the perpendicular printing direction showed a cross-distributed stripe feature parallel to the laser scanning direction, while the microstructure in the parallel printing direction showed a fish-scale morphology.

[0086] See Figure 13 and Figure 14 The high-strength, high-ductility 316H stainless steel specimens prepared in step S3 were subjected to room temperature tensile tests in the parallel and perpendicular printing directions. The test results are as follows: Figure 13 , Figure 14As shown in Table 1, the high-strength, high-ductility 316H stainless steel prepared using this embodiment has a density of over 99.50%. The room temperature yield strength of the specimens parallel to the printing direction reaches 490–510 MPa, and the room temperature tensile strength reaches 535–560 MPa; the elongation after fracture reaches 84%–91%, and the reduction of area reaches 65%–71%. The room temperature yield strength of the specimens perpendicular to the printing direction reaches 525–580 MPa, and the room temperature tensile strength reaches 630–675 MPa; the elongation after fracture reaches 35%–60%, and the reduction of area reaches 55%–75%.

[0087] This embodiment optimizes process parameters such as laser power, scanning rate, and scanning spacing to prepare high-strength and high-ductility 316H stainless steel with excellent strength and ductility.

[0088] Example 3

[0089] This embodiment provides a method for preparing high-strength, high-ductility 316H stainless steel. The difference from Embodiment 1 is that the laser power in step S3 of this embodiment is controlled at 220W. Other processes are the same as in Embodiment 1.

[0090] The specific steps are as follows:

[0091] S1. 316H stainless steel powder with the following chemical composition is selected as the additive manufacturing raw material: C: 0.053 wt.%, Si: 0.35 wt.%, Mn: 1.54 wt.%, Co: 0.03 wt.%, P: 0.014 wt.%, S: 0.005 wt.%, Cu: 0.1 wt.%, Mo: 2.51 wt.%, N: 0.061 wt.%, Ni: 11.8 wt.%, Cr: 16.9 wt.%, O: 0.025 wt.%, H: 0.0005 wt.%, with the remainder being Fe and unavoidable trace impurities.

[0092] The requirements for 316H stainless steel powder are as follows: particle size: 15~53μm, sphericity: 0.96, flowability: 20s / 50g, and loose powder density: 4.3g / cm³. 3 The tap density of the powder is 4.8 g / cm³. 3 The hollow rate is 0.3%, and the non-metallic inclusions are 5 particles / 100g.

[0093] S2. Use a vacuum dryer to dry the above powder at a temperature of 80℃ for 2 hours. The printing substrate is made of 316L stainless steel and is not preheated.

[0094] S3. Using the 316H powder obtained in step S2, prepare 316H stainless steel according to the following printing parameters: laser power: 220W, scanning speed: 870mm / s, scanning interval: 0.09mm, powder layer thickness: 30μm, and printing strategy: rotating 67° between layers.

[0095] See Figure 15 The high-strength and high-plasticity 316H stainless steel powder obtained in step S1 was characterized and found to be free of inclusions and possess excellent sphericity.

[0096] See Figure 16 The high-strength, high-ductility 316H stainless steel prepared in step S3 was polished to obtain a metallographic photograph of its polished state. According to... Figure 16 It can be seen that the high-strength, high-plasticity 316H stainless steel obtained using the printing parameters in step S3 has a density of 99.98%, which is high.

[0097] See Figure 17 The high-strength, high-ductility 316H stainless steel prepared in step S3 was subjected to industrial CT inspection to obtain the results of internal defect detection. According to... Figure 17 It can be seen that the density is 99.999% at a resolution of 6.116μm, which is excellent.

[0098] See Figure 18 and Figure 19 The surfaces of the high-strength, high-ductility 316H stainless steel prepared in step S3 were polished and etched in both the parallel and perpendicular printing directions to obtain its microstructure. The microstructure in the perpendicular printing direction showed a cross-distributed stripe feature parallel to the laser scanning direction, while the microstructure in the parallel printing direction showed a fish-scale morphology.

[0099] See Figure 20 and Figure 21 The high-strength, high-ductility 316H stainless steel specimens prepared in step S3 were subjected to room temperature tensile tests in the parallel and perpendicular printing directions. The test results are as follows: Figure 20 , Figure 21 As shown in Table 1, the high-strength, high-ductility 316H stainless steel prepared using this embodiment has a density of over 99.50%. The room temperature yield strength of the specimens parallel to the printing direction reaches 490–510 MPa, and the room temperature tensile strength reaches 535–560 MPa; the elongation after fracture reaches 84%–91%, and the reduction of area reaches 65%–71%. The room temperature yield strength of the specimens perpendicular to the printing direction reaches 525–580 MPa, and the room temperature tensile strength reaches 630–675 MPa; the elongation after fracture reaches 35%–60%, and the reduction of area reaches 55%–75%.

[0100] This embodiment optimizes process parameters such as laser power, scanning rate, and scanning spacing to prepare high-strength and high-ductility 316H stainless steel with excellent strength and ductility.

[0101] Comparative Example 1

[0102] This comparative example provides a method for preparing 316H stainless steel. The difference from Example 1 is that the laser power in step S3 of this example is controlled at 150W. Other processes are the same as in Example 1.

[0103] The specific steps are as follows:

[0104] S1. 316H stainless steel powder with the following chemical composition is selected as the additive manufacturing raw material: C: 0.053 wt.%, Si: 0.35 wt.%, Mn: 1.54 wt.%, Co: 0.03 wt.%, P: 0.014 wt.%, S: 0.005 wt.%, Cu: 0.1 wt.%, Mo: 2.51 wt.%, N: 0.061 wt.%, Ni: 11.8 wt.%, Cr: 16.9 wt.%, O: 0.025 wt.%, H: 0.0005 wt.%, with the remainder being Fe and unavoidable trace impurities.

[0105] The requirements for 316H stainless steel powder are as follows: particle size: 15~53μm, sphericity: 0.96, flowability: 20s / 50g, and loose powder density: 4.3g / cm³. 3 The tap density of the powder is 4.8 g / cm³. 3 The hollow rate is 0.3%, and the non-metallic inclusions are 5 particles / 100g.

[0106] S2. Use a vacuum dryer to dry the above powder at a temperature of 80℃ for 2 hours. The printing substrate is made of 316L stainless steel and is not preheated.

[0107] S3. Using the 316H powder obtained in step S2, prepare 316H stainless steel according to the following printing parameters: laser power: 150W, scanning speed: 870mm / s, scanning interval: 0.09mm, powder layer thickness: 30μm, and printing strategy: rotating 67° between layers.

[0108] See Figure 22 The high-strength, high-ductility 316H stainless steel prepared in step S3 was subjected to industrial CT inspection to obtain the results of internal defect detection. According to... Figure 22 It can be seen that the density is 99.05% at a resolution of 6.116μm, which is relatively poor.

[0109] Comparative Example 2

[0110] This comparative example provides a method for preparing 316H stainless steel. The difference from Example 1 is that the scanning speed in step S3 of this example is controlled at 990 mm / s. Other processes are the same as in Example 1.

[0111] The specific steps are as follows:

[0112] S1. 316H stainless steel powder with the following chemical composition is selected as the additive manufacturing raw material: C: 0.053 wt.%, Si: 0.35 wt.%, Mn: 1.54 wt.%, Co: 0.03 wt.%, P: 0.014 wt.%, S: 0.005 wt.%, Cu: 0.1 wt.%, Mo: 2.51 wt.%, N: 0.061 wt.%, Ni: 11.8 wt.%, Cr: 16.9 wt.%, O: 0.025 wt.%, H: 0.0005 wt.%, with the remainder being Fe and unavoidable trace impurities.

[0113] The requirements for 316H stainless steel powder are as follows: particle size: 15~53μm, sphericity: 0.96, flowability: 20s / 50g, and loose powder density: 4.3g / cm³. 3 The tap density of the powder is 4.8 g / cm³. 3 The hollow rate is 0.3%, and the non-metallic inclusions are 5 particles / 100g.

[0114] S2. Use a vacuum dryer to dry the above powder at a temperature of 80℃ for 2 hours. The printing substrate is made of 316L stainless steel and is not preheated.

[0115] S3. Using the 316H powder obtained in step S2, prepare 316H stainless steel according to the following printing parameters: laser power: 200W, scanning speed: 860mm / s, scanning interval: 0.09mm, powder layer thickness: 30μm, and printing strategy: rotating 67° between layers.

[0116] See Figure 23 The high-strength, high-ductility 316H stainless steel prepared in step S3 was subjected to industrial CT inspection to obtain the results of internal defect detection. According to... Figure 23 It can be seen that the density is 99.47% at a resolution of 6.116μm, which is relatively poor.

[0117] The 316H stainless steel specimens prepared by the preparation methods of Examples 1-3 and Comparative Examples 1-2 were subjected to room temperature tensile tests in the parallel and perpendicular printing directions. The test results are shown in Table 1.

[0118] Table 1

[0119]

[0120] According to the room temperature tensile test results in Table 1, when the process range is not within the implementation process range of this patent, i.e., Comparative Example 1 and Comparative Example 2, the room temperature yield strength of the samples in the parallel printing direction is 423~486 MPa, and the room temperature tensile strength reaches 547~615 MPa; the elongation after fracture reaches 23.5%~52.5%, and the reduction of area reaches 20.0%~63.0%; the room temperature yield strength of the samples in the perpendicular printing direction reaches 460~557 MPa, and the room temperature tensile strength reaches 563~662 MPa; the elongation after fracture reaches 24.5%~40.0%, and the reduction of area reaches 23.0%~53.0%. These results are far lower than those of this patent.

[0121] The room temperature yield strength of austenitic stainless steel parallel to the printing direction reaches 490 MPa~510 MPa, and the room temperature tensile strength reaches 535~560 MPa; the elongation after fracture reaches 84%~91%, and the reduction of area reaches 65%~71%; the room temperature yield strength of austenitic stainless steel perpendicular to the printing direction reaches 525~580 MPa, and the room temperature tensile strength reaches 630~675 MPa; the elongation after fracture reaches 35%~60%, and the reduction of area reaches 55%~75%.

[0122] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this application.

Claims

1. A method for preparing austenitic stainless steel, characterized in that, The dried stainless steel alloy powder is printed into austenitic stainless steel molds; the laser power during printing is 180W~220W, the scanning speed is 870mm / s~970mm / s, the scanning spacing is 0.09mm~0.11mm, and the powder layer thickness is 30-50μm; the layers are rotated 67° between printing.

2. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The stainless steel powder comprises the following components by mass percentage: C: 0.04~0.10 wt.%, Si: ≤1.00 wt.%, Mn: ≤2.00 wt.%, Co: ≤0.2 wt.%, P: ≤0.035 wt.%, S: ≤0.020 wt.%, Cu: ≤0.2 wt.%, Mo: 2.00~3.00 wt.%, N: ≤0.10 wt.%, Ni: 10.0~14.0 wt.%, Cr: 16.0~18.0 wt.%, O: ≤0.03 wt.%, H: ≤0.03 wt.%, balance being Fe and impurities.

3. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The particle size of the stainless steel alloy powder is 15μm~53μm.

4. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The sphericity of the stainless steel alloy powder is >0.

95.

5. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The fluidity of the stainless steel alloy powder is ≤20s / 50g.

6. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The loose packing density of the stainless steel alloy powder is ≥4.3 g / cm³. 3 .

7. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The tap density of the stainless steel alloy powder is ≥4.8 g / cm³. 3 .

8. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The void ratio of the stainless steel alloy powder is ≤0.3%.

9. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The non-metallic inclusion content of the stainless steel alloy powder is ≤5 particles / 100g.

10. The method for preparing austenitic stainless steel according to claim 1, characterized in that, The stainless steel alloy powder was dried using a vacuum dryer.

11. The method for preparing austenitic stainless steel according to claim 10, characterized in that, The drying temperature is 80℃~120℃, and the holding time is 2h~4h.

12. An austenitic stainless steel, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 11.

13. An application of the austenitic stainless steel according to claim 12, characterized in that, This includes components used to prepare complex and intricate structures, high-strength and high-plasticity materials, and high-temperature resistant parts.

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