Preparation method of stainless steel product

Abstract

The invention provides a preparation method of a stainless steel product, and relates to the technical field of additive manufacturing, the method comprises the following steps: stainless steel powder is placed in additive manufacturing equipment, a preparation plane is preset, and a plurality of scanning paths which are parallel to one another and have the same scanning interval are arranged in the preparation plane; selecting a first starting point and a second starting point in each scanning path, wherein a strip-shaped offset is formed between the first starting point and the second starting point; and on the basis of the first starting point and the second starting point, the laser is subjected to multiple times of interval scanning along the multiple scanning paths to form finished stainless steel. A multi-direction heat flow interference field is constructed by formulating a composite scanning strategy and introducing strip-shaped deviation, compared with a traditional scanning strategy, the problem that the flowing direction of a molten pool is single is avoided, the oscillation frequency of the molten pool is reduced, the probability of keyhole collapse is reduced by reducing heat accumulation, molten pool disturbance is caused through strip-shaped deviation, and equiaxed crystal formation is promoted; and therefore, the surface quality of the 316L stainless steel product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and particularly relates to a preparation method for stainless steel products. Background Art

[0002] The research and development of biomedical materials have always been one of the hotspots in the field of materials science. As a common biomedical material, stainless steel has good mechanical properties and corrosion resistance, and is widely used in medical devices, artificial joints, dental restorations and other fields. Among them, 316L stainless steel has become an important representative of biomedical stainless steel due to its good corrosion resistance and biocompatibility. In the biomedical field, the surface topography of materials has an important impact on cell adhesion, proliferation and differentiation.

[0003] Additive Manufacturing (AM) has been widely used in the fields of aerospace and biomedicine due to its advantages such as short processing cycle, high material utilization rate, and the ability to realize the integrated forming of complex structures. This technology can precisely control the microstructure and surface topography of materials, thereby optimizing the performance of biomedical materials.

[0004] Different from traditional subtractive manufacturing, the AM technology directly constructs three-dimensional entities by layer-by-layer stacking of materials. Among them, laser powder bed fusion, as a typical metal additive manufacturing technology, uses a high-energy laser beam to selectively melt the spread metal powder layer and forms a dense component by layer-by-layer stacking.

[0005] The existing methods for preparing 316L stainless steel products generally add stainless steel powder to an additive manufacturing device and perform sequential scanning preparation through a continuous strip scanning strategy. The surface quality of the 316L stainless steel product is controlled by controlling the scanning spacing (hatch spacing, h) between different columns. However, this method can only locally alleviate surface defects and still cannot obtain 316L stainless steel products with high surface quality. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method for stainless steel products, aiming to solve the technical problem that in the prior art, sequential scanning preparation through a continuous strip scanning strategy can only locally alleviate surface defects and still cannot obtain 316L stainless steel products with high surface quality.

[0007] To achieve the above purpose, the present invention provides a preparation method for stainless steel products, including the following steps:

[0008] Place the 316L stainless steel product powder in an additive manufacturing device, preset several preparation planes arranged from bottom to top, and set several scanning paths in each of the preparation planes. The several scanning paths are parallel to each other, and the scanning spacing between the several scanning paths is the same;

[0009] In each scanning path of the same preparation plane, select a first starting point and a second starting point. The connection lines of the first starting points in different scanning paths are parallel to the connection lines of the second starting points in different scanning paths, and a strip-shaped offset is formed between the first starting point and the second starting point;

[0010] Based on the first starting point and the second starting point, make the laser perform several intermittent scans along the several scanning paths to prepare a finished sub-layer in the preparation plane, and the finished sub-layers are sequentially prepared from bottom to top, thereby forming a 316L stainless steel product.

[0011] Further, the step of making the laser perform several intermittent scans along the several scanning paths based on the first starting point and the second starting point to prepare a finished sub-layer in the preparation plane includes:

[0012] Select the scanning paths located on both sides in the preparation plane as the starting path and the ending path;

[0013] Make the laser scan along the starting path from the first starting point in the starting path in the direction away from the second starting point until the termination scanning condition is met, stop scanning and move the laser position to the second starting point of the starting path;

[0014] Make the laser scan along the starting path from the second starting point in the starting path in the direction away from the first starting point until the termination scanning condition is met, stop scanning and move the laser position to the first starting point of the adjacent scanning path to complete the intermittent scan;

[0015] Perform the intermittent scan on each of the scanning paths and the ending path from the starting path to the ending path direction to form a finished sub-layer.

[0016] Furthermore, the termination scanning condition is that the moving distance of the laser position is greater than 0.08 mm or the distance between the laser position and the edge of the preparation plane is less than 0.04 mm.

[0017] Furthermore, the scanning spacing is 0.06 mm to 0.12 mm, and the strip-shaped offset is -0.08 mm to +0.08 mm.

[0018] Furthermore, the scanning pitch is 0.09 mm.

[0019] Furthermore, in two adjacent preparation planes, the included angle between the scanning paths of the two layers is 67°.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting the first starting point and the second starting point, a scanning path with the strip offset is formed, dispersing the thermal stress of the molten pool, reducing the problem of uneven overlap of the molten pool caused by continuous scanning, and reducing the formation of surface porosity and cracks; During the scanning process, by performing the reset, the molten pool is allowed to cool during scanning, avoiding local deformation caused by heat accumulation, improving the surface finish. At the same time of resetting, by controlling the reset time, the complete solidification of the molten pool can be avoided, maintaining the interlayer bonding force; Different preparation planes are distinguished, combined with the scanning pitch and the strip offset, ensuring a more uniform distribution of laser energy, reducing the lack of fusion defect, and improving the density of the 316L stainless steel product; Compared with the traditional continuous strip scanning method that only considers the scanning pitch, by formulating a composite scanning strategy, the heat accumulation caused by the laser scanning sequentially in a fixed direction without cooling is avoided, thereby avoiding the generation of microcracks and warping deformation caused by thermal stress. After introducing the strip offset, a multi-directional heat flow interference field is constructed, avoiding the problem of single molten pool flow direction, reducing the frequency of molten pool oscillation, and at the same time, by reducing heat accumulation, reducing the probability of keyhole collapse. At the same time, the continuous growth of epitaxial columnar crystals induced by a single heat flow direction can be avoided. By causing molten pool disturbance through the strip offset, the formation of equiaxed crystals is promoted, thereby improving the surface quality of the 316L stainless steel product. Description of the Drawings

[0021] Figure 1 It is a flowchart of the preparation method of the stainless steel product in the embodiment of the present invention;

[0022] Figure 2 It is a schematic diagram of the scanning strategy in the embodiment of the present invention. Among them, a is a schematic diagram of the traditional continuous strip scanning strategy, and b is a schematic diagram of the composite scanning strategy;

[0023] Figure 3 It is a result diagram of density detection in the embodiment of the present invention. Among them, a is a relationship diagram between the scanning pitch and the density, b is a relationship diagram between the strip offset and the density, and c is a density distribution diagram between the conditional pitch and the density;

[0024] Figure 4 It is a result diagram of surface roughness detection in the embodiment of the present invention. Among them, a is a measurement schematic diagram of line roughness and surface roughness, b is a measurement result diagram of line roughness, c is a measurement result diagram of Ssk and Sku, and d is a measurement result diagram of surface roughness;

[0025] Figure 5 The roughness machining diagram drawn based on Figure 4 the data, where a is the line roughness Ra machining diagram, b is the line roughness Rz machining diagram, c is the surface roughness Sa machining diagram, and d is the surface roughness Sz machining diagram;

[0026] Figure 6 The surface topography diagram in the horizontal direction under different scanning spacings with a +0.08 mm strip offset in the embodiment of the present invention, where a is the OM diagram under a 0.06 mm scanning spacing, b is the three-dimensional depth-of-field diagram under a 0.06 mm scanning spacing, c is the SEM diagram under a 0.06 mm scanning spacing, d is the OM diagram under a 0.09 mm scanning spacing, e is the three-dimensional depth-of-field diagram under a 0.09 mm scanning spacing, f is the SEM diagram under a 0.09 mm scanning spacing, g is the OM diagram under a 0.12 mm scanning spacing, h is the three-dimensional depth-of-field diagram under a 0.12 mm scanning spacing, and i is the SEM diagram under a 0.12 mm scanning spacing;

[0027] Figure 7 The surface SEM topography diagram in the horizontal direction with different strip offsets under a 0.09 mm scanning spacing in the embodiment of the present invention, where a is the SEM diagram with a +0.08 mm strip offset, b is the SEM diagram with a 0.00 mm strip offset, and c is the SEM diagram with a -0.08 mm strip offset;

[0028] Figure 8 The surface metallographic micrograph in the building direction under different scanning spacings in the embodiment of the present invention, where a is the surface metallographic micrograph under a 0.06 mm scanning spacing, b is the surface metallographic micrograph under a 0.09 mm scanning spacing, and c is the surface metallographic micrograph under a 0.12 mm scanning spacing;

[0029] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0030] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] Please refer to Figure 1 and Figure 2 , an embodiment of the present invention provides a method for preparing a stainless steel product, comprising the following steps:

[0034] S10: Place the 316L stainless steel product powder in an additive manufacturing device, preset a plurality of preparation planes arranged from bottom to top, and set a plurality of scanning paths in each of the preparation planes. The plurality of scanning paths are parallel to each other, and the scanning spacing between the plurality of scanning paths is the same;

[0035] In this embodiment, a 10*10*10mm 3 cubic specimen is prepared by using a HANS M100 type device. The basic process parameter combination of this device is: laser power (P) = 115W, scanning speed (v) = 600mm / s, powder spreading layer thickness (t) = 30μm, interlayer rotation angle = 67°, scanning line length (L) = 8mm. Preferably, the scanning spacing is 0.06mm to 0.12mm.

[0036] S20: In each scanning path of the same preparation plane, select a first starting point and a second starting point. The connection line of the first starting points in different scanning paths is parallel to the connection line of the second starting points in different scanning paths, and a strip-shaped offset is formed between the first starting point and the second starting point;

[0037] Preferably, the strip-shaped offset is -0.08mm to +0.08mm. It can be understood that the strip-shaped offset refers to the distance between the first starting point and the second starting point in the same scanning path.

[0038] The step S20 includes:

[0039] S210: Select the scanning paths located on both sides in the preparation plane as the starting path and the ending path;

[0040] The starting path and the ending path refer to in this preparation plane, the laser starts scanning from the starting path, and after completing the scanning of the ending path, the preparation work of this preparation plane is completed.

[0041] S220: Make the laser scan along the starting path from the first starting point in the starting path in the direction away from the second starting point of the first starting point until the termination scanning condition is met, stop scanning and move the laser point to the second starting point of the starting path;

[0042] The termination scanning condition is that the moving distance of the laser point is greater than 0.08 mm or the distance between the laser point and the edge of the preparation plane is less than 0.04 mm. It can be understood that the scanning path is a straight line, and both ends of it are close to the side of the preparation plane. When the distance between the laser point and the edge of the preparation plane is less than 0.04 mm or when the laser point scans more than 0.08 mm, it represents that the laser has completed one scan.

[0043] S230: Make the laser scan along the starting path from the second starting point in the starting path in the direction away from the first starting point of the second starting point until the termination scanning condition is met, stop scanning and move the laser point to the first starting point of the adjacent scanning path to complete the interval scanning;

[0044] After the laser completes the scan from the first starting point to the second starting point direction of the starting path and the scan from the second starting point to the first starting point direction, the scan of the starting path is completed. It should be noted that the termination scanning conditions in different steps are the same and will not be elaborated further. And the scanning process from when the laser moves to the first starting point of the starting path to when the laser moves to the first starting point of the scanning path adjacent to the starting path is one interval scan. Preferably, when the laser completes the determination of the termination scanning condition, the time for stopping scanning and moving to the next position (the second starting point of the same scanning path or the first starting point of the adjacent scanning path) is 0.5 s to 1 s.

[0045] S240: Perform the interval scan on each of the scanning paths and the termination path from the starting path to the termination path direction to form a finished product sublayer;

[0046] It can be understood that the scanning process for the scanning paths and the termination path is the same as that of the starting path and will not be elaborated here. The formation process of the finished product sublayer is completed through several interval scans. It should be noted that after the scan of the termination path of the preparation plane is completed, the laser point moves to the starting path of the next preparation plane.

[0047] S30: Based on the first starting point and the second starting point, make the laser perform multiple spaced scans along a plurality of the scanning paths to prepare a finished sub-layer in the preparation plane, and the finished sub-layers are sequentially prepared from bottom to top to form a 316L stainless steel product.

[0048] In this embodiment, in two adjacent preparation planes, the included angle between two scanning paths is 67°. It should be noted that because the directions of the scanning paths in different preparation planes are different, during the process of selecting the first starting point and the second starting point, there may be a situation where the connection line between some scanning paths and the first starting point and / or the connection line of the second starting point do not intersect. Therefore, in the same preparation plane, it is judged whether the connection line between each scanning path and the first starting point and / or the connection line of the second starting point intersects. If a certain scanning path intersects the connection line of the first starting point or the second starting point, then along the scanning path, the scanning is completed from the intersection point to the side direction of the preparation plane. If a certain scanning path does not intersect both the first starting point and the second starting point, then the intersection point of the scanning path and the side of the preparation plane is selected as the judgment point, the scanning direction is determined based on the positional relationship between the scanning path and the strip offset, and the third starting point is selected from two judgment points, and the scanning is completed based on the third starting point and the scanning direction.

[0049] By setting the angles of the scanning paths in two adjacent preparation planes, the anisotropy is broken, the interlayer molten pools are distributed in a staggered manner, the defects in the vertical direction (such as columnar crystal growth) are reduced, the mechanical properties and isotropy of the 316L stainless steel product are improved. At the same time, through the staggered scanning paths, the extension path of the crack along a single direction can be blocked, and the fracture toughness of the material is improved.

[0050] The prepared 316L stainless steel product is combined with different specimens (316L stainless steel products prepared based on the same composite scanning strategy with different scanning spacings and strip offsets) for quality inspection and comparison:

[0051] Density detection: After separating the 316L stainless steel product from the substrate by wire electrical discharge machining, perform 40 kHz ethanol ultrasonic cleaning (15 min) and drying in sequence, and measure the density by the Archimedes drainage method. Please refer to Figure 3, when the scanning pitch h is 0.09 mm, the average relative density is relatively high, reaching 99.01±0.32% (n = 5); compared with h = 0.06 mm (93.46±1.02%) and h = 0.12 mm (96.83±0.75%), it is increased by 5.55% and 2.18% respectively. And when the scanning pitch is 0.09 mm and the strip offset is +0.08 mm, the relative density reaches the peak value of 99.53. Since under the condition of certain laser power, scanning speed and layer thickness, the appropriate scanning pitch matches a better energy density, and under the action of the strip offset, the overlap rate of the melt tracks is optimized to 32±4%, reaching a better process parameter window.

[0052] Surface roughness detection: Please refer to Figure 4 , use a KEYENCE VHX-7000 ultra-depth-of-field microscope (equipped with a focus change probe, vertical resolution 0.1 μm) to perform three-dimensional roughness analysis on the surface of the product to be measured. Select areas with different areas in the X / Y construction directions to measure the roughness values. The evaluation parameters related to roughness are shown in Table 1 (line roughness evaluation parameters) and Table 2 (surface roughness evaluation parameters). Among them, Ra and Sa reflect the average undulation of the two-dimensional and three-dimensional surfaces and are the core indicators for evaluating processing accuracy. Rz characterizes the extreme defects on the surface (such as deep valleys or sharp peaks), and surface local defects (such as molten pool spatter or lack of fusion) can be identified through Sz, and Sz is the most sensitive to process parameter changes (for example, the average value of Sz is 454.41 μm when h = 0.07 mm, and 162.58 μm when h = 0.12 mm). For RzJIS, it has the same trend as Rz but lower values, and its versatility is lower than that of Rz. Sku is close to 3 in most cases and has low sensitivity to changes only under extreme processes, and is suitable for detecting abnormal surface height distributions. And Ssk is mostly negative (valley-dominated) when the scanning pitch is 0.07 mm and close to 0 in other cases, with insufficient discrimination. It is used only when it is necessary to judge whether the surface is biased towards peaks / valleys. Therefore, Ssk and Sku have limited significance for conventional process optimization. Rp, Sp, Rv, and Sv are the vertical distances from the deepest valley in the three-dimensional surface to the reference plane, and they are greatly affected by the setting of the reference plane:

[0053] Table 1

[0054]

[0055] Table 2

[0056] Parameter Symbol Definition Arithmetic mean height Sa It represents the average value of the absolute values of the height differences of each point with respect to the average plane of the surface. Maximum height Sz It is defined as the sum of the maximum peak height and the maximum valley depth in the defined area. Root mean square height Sq It is defined as the root mean square of the heights of each point in the defined area, which is equivalent to the standard deviation of the heights. Skewness (degree of deviation) Ssk A parameter indicating the tendency of the roughness shape (concavity and convexity) Kurtosis (sharpness) Sku A parameter indicating the sharpness of the roughness shape Maximum peak height Sp Maximum peak height Maximum valley depth Sv It is defined as the absolute value of the height of the lowest point in the defined area.

[0057] Please refer to Figure 5 , based on Figure 4For the data results, representative arithmetic mean height and maximum height are extracted to plot the machining diagrams of roughness Ra, Rz, Sa, and Sz. It can be found that when the scanning spacing decreases from 0.12 mm to 0.06 mm, Ra increases from 13.57 μm to 80.73 μm, and Sa increases from 13.9 μm to 96.7 μm, which is directly related to the change in the thermodynamic behavior of the molten pool. A smaller spacing increases the overlap rate of adjacent weld beads, resulting in a decrease in the cooling rate of the molten pool, restricted Marangoni flow of the liquid metal, and the formation of irregular fluctuations before solidification. At the same time, a large amount of heat accumulation will make the molten pool unstable, generating defects such as pores, leading to an increase in roughness.

[0058] Under a small scanning spacing, the influence of strip offset on roughness is greater. For example, when the scanning spacing is 0.06 mm, the specimens with a -0.04 mm negative offset have the maximum values of both Ra and Sa. Compared with the specimens with a +0.08 mm positive offset, Ra increases from 57.48 μm to 96.71 μm, with an increase rate of 168%. The Sz value of the 0 mm offset reaches 599.24 μm, with an increase rate of 203% compared with the -0.04 mm negative offset. The strip offset affects the surface continuity by regulating the spatial distribution of the scanning path. The path gap introduced by a large positive offset may lead to local lack of fusion defects, increasing the maximum profile valley depth Rv of the specimen. The negative offset and the process with a small spacing are prone to trigger the keyhole effect, and the internal vapor recoil pressure of the molten pool causes deep hole defects in the specimen.

[0059] Surface topography detection: Please refer to Figure 6 and Figure 7 Under a small scanning spacing, the weld beads overlap with each other and there are irregular protrusions, and there are a large number of protrusions and depressions on the surface. At a scanning spacing of 0.09 mm, the weld beads overlap well with each other, and their 3D topography is relatively flat. Tiny particles and unfused powder can be observed on the surface of all specimens. At a scanning spacing of 0.12 mm, it is obvious that there are grooves between the weld beads, the width of the weld beads changes irregularly, and the weld bead trajectory is discontinuous. There are large gaps between the weld beads and unfused areas. When the offset is +0.08 mm, there are partial lack of fusion areas in the offset area. Due to the impact of the laser twice in the offset area, the splashing of powder particles results in voids between the weld beads. In the offset area with an offset of -0.08 mm, although the heat of laser remelting results in fewer unmelted particles on the surface, under the action of surface tension, there are local protrusions in the weld beads in the offset area, reducing the overall surface roughness. Therefore, with appropriate strip offset, the surface roughness is good, the molten pool overlaps sufficiently, and there are no large voids or protrusion areas.

[0060] Microstructure: Please refer to Figure 8, the main reason for the "fish scale" morphology of the molten pool is the action of the Gaussian laser heat source, and the scanned molten pool boundary shows an arc shape. Near-circular pores and irregular holes can also be observed in the middle of the molten pool, and these defects are the main reasons for the low density. Among them, the smaller near-circular pores are formed because there is a small amount of gas in the powder and it has not completely escaped from the molten pool; the irregular holes are mainly caused by the keyhole effect. Because the laser beam used in SLM has the characteristic of high energy density, a recoil pressure will be generated during the forming process to form a preliminary keyhole. In most cases, the keyhole is stable and will not induce the formation of internal holes. However, due to the extremely complex thermodynamics, hydrodynamics and the complex liquid, solid, gas transition process during the SLM process, it is difficult for the keyhole to always remain stable. If the keyhole collapses, part of the metal vapor does not completely escape from the molten pool and is trapped in the molten pool. As the molten pool solidifies, irregular holes will be formed at the position where the metal vapor is trapped. Due to the action of the temperature gradient and pressure, the holes tend to form near the lower part of the molten pool.

[0061] In the building direction, the depth of the melt track in the picture was measured using Image J software, and it was found that the measured depth of the melt track at different scanning spacings was about 110μm. This is because during the SLM forming process, the Marangoni effect caused by surface tension is the main driving force for the flow of the molten pool, and the cooling time between the melt tracks of all specimens was controlled to be the same in the process. Therefore, the surface tension gradient of the melt track remained consistent in the building direction, and the forming depth difference was small.

[0062] In the horizontal direction, the width of the molten pool is determined by the laser spot size and energy density. The width of the melt track of the specimen with a small scanning spacing is significantly larger than that of the specimen with a large scanning spacing. This is because the reduction of the scanning spacing increases the energy density and improves the overlap rate between the melt tracks. The previously heated part of the molten pool will remelt, resulting in an increase in the width of the melt track horizontally.

[0063] By setting the first starting point and the second starting point, a scanning path with the strip offset is formed, which disperses the thermal stress of the molten pool, reduces the problem of uneven overlap of the molten pool caused by continuous scanning, and reduces the formation of surface porosity and cracks; during the scanning process, by performing the reset, the molten pool is allowed to cool during scanning, avoiding local deformation caused by heat accumulation, and improving the surface finish. At the same time of the reset, by controlling the reset time, the complete solidification of the molten pool can be avoided, and the interlayer bonding force can be maintained; different preparation planes are distinguished and combined with the scanning spacing and the strip offset to ensure a more uniform distribution of laser energy, reduce the lack of fusion defect, and improve the density of the finished product; compared with the traditional continuous strip scanning method that only considers the scanning spacing, by formulating a strategy that conforms to the scanning, the heat accumulation caused by the laser scanning sequentially in a fixed direction without cooling is avoided, thereby avoiding the generation of microcracks and warping deformation caused by thermal stress. After introducing the strip offset, a multi-directional heat flow interference field is constructed, avoiding the problem of single flow direction of the molten pool, reducing the frequency of molten pool oscillation, and by reducing heat accumulation, reducing the probability of keyhole collapse. At the same time, the continuous growth of epitaxial columnar crystals induced by a single heat flow direction can be avoided. By causing the molten pool disturbance through the strip offset, the formation of equiaxed crystals is promoted.

[0064] In the description of this specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0065] The above-described embodiments merely represent several implementation manners of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A method for preparing a stainless steel product, characterized in that, It includes the following steps: Place the 316L stainless steel product powder in an additive manufacturing device, preset a number of preparation planes arranged from bottom to top, and set a number of scanning paths in each of the preparation planes. The a number of scanning paths are parallel to each other, and the scanning spacing between the a number of scanning paths is the same; In each scanning path of the same preparation plane, select a first starting point and a second starting point. The connection lines of the first starting points in different scanning paths are parallel to the connection lines of the second starting points in different scanning paths, and a strip-shaped offset is formed between the first starting point and the second starting point; Based on the first starting point and the second starting point, make the laser perform a number of intermittent scans along a number of the scanning paths to prepare a finished sub-layer in the preparation plane, and the finished sub-layers are sequentially prepared from bottom to top to form a 316L stainless steel product.

2. The preparation method of the stainless steel product according to claim 1, characterized in that, The step of making the laser perform a number of intermittent scans along a number of the scanning paths based on the first starting point and the second starting point to prepare a finished sub-layer in the preparation plane includes: Select the scanning paths located on both sides in the preparation plane as the starting path and the ending path; Make the laser scan along the starting path from the first starting point in the starting path in the direction away from the second starting point until the termination scanning condition is met, stop scanning and move the laser point position to the second starting point of the starting path; Make the laser scan along the starting path from the second starting point in the starting path in the direction away from the first starting point until the termination scanning condition is met, stop scanning and move the laser point position to the first starting point of the adjacent scanning path to complete the intermittent scan; From the starting path to the ending path direction, perform the intermittent scan on each of the scanning paths and the ending path to form a finished sub-layer.

3. The preparation method of the stainless steel product according to claim 2, characterized in that, The termination scanning condition is that the moving distance of the laser point position is greater than 0.08 mm or the distance between the laser point position and the edge of the preparation plane is less than 0.04 mm.

4. The preparation method of the stainless steel product according to claim 1, characterized in that, The scanning spacing is 0.06 mm to 0.12 mm, and the strip-shaped offset is -0.08 mm to +0.08 mm.

5. The preparation method of the stainless steel product according to claim 4, characterized in that, The scanning spacing is 0.09 mm.

6. The preparation method of the stainless steel product according to claim 2, characterized in that, In two adjacent preparation planes, the included angle between the two scanning paths is 67°.

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