Method for 3D printing hot-rolled composite to prepare functional coating

Abstract

The application discloses a method for preparing a functional coating by 3D printing and hot rolling, and adopts an additive manufacturing technology to print two kinds of alloy powder with different materials into a heterogeneous alloy composite plate; the plate is heated to a roughing temperature, and at the roughing temperature, the heterogeneous alloy composite plate is rapidly subjected to multi-pass rough rolling and multi-pass finish rolling in sequence, the compression rate of each pass is 30%-50% during rough rolling, and the total compression rate of finish rolling is 20%-50%, so as to achieve the purposes of crushing grains, recrystallization and expanding the size of the plate, and ensure that the last pass of finish rolling is carried out as the finishing at the finish rolling temperature. The application realizes the preparation of the functional coating on the base plate by combining the additive manufacturing and the hot rolling, improves the microstructure of the composite plate, reduces the thickness of the upper layer of the composite plate, and forms the functional coating.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and more specifically to a method for preparing functional coatings by 3D printing hot-rolled composite. Background Technology

[0002] Metal coating technology can leverage the advantages of each component material, achieving optimal resource allocation, saving precious metal materials, and fulfilling performance requirements that cannot be met by a single metal. Taking stainless steel-steel composite plates for pressure vessels as an example, the base layer uses ordinary carbon steel (Q245R, Q345R, etc.) with excellent mechanical properties, while the coating uses stainless steel (304, 316L, etc.) with excellent corrosion resistance. Only a few millimeters of expensive stainless steel are needed, significantly reducing costs and almost completely preserving the various mechanical properties of the substrate. In addition, there are composite manufacturing processes using steel (e.g., 316) with titanium (e.g., TC4), steel (e.g., 304) with high-temperature alloys (e.g., IN625), and titanium (e.g., TB5) with high-temperature alloys (e.g., IN718), among others, combining substrates with functional material layers.

[0003] Traditional methods for preparing heterogeneous metal composite sheets mainly include: explosive bonding, explosive rolling bonding, rolling bonding, sintering bonding, casting-rolling bonding, reverse solidification, and electromagnetic continuous casting. However, among these methods: explosive bonding has drawbacks such as high noise, low yield, and space limitations; direct rolling has drawbacks such as complex processes, long processing cycles, and oxidation at the joint interface; sintering bonding has disadvantages such as high porosity, complex processes, high energy consumption, and narrow applicability; casting-rolling bonding suffers from problems such as easy formation of oxide layers and melt loss; reverse solidification has problems such as high operational difficulty, low yield, and poor dimensional accuracy; and electromagnetic continuous casting is still in the research stage.

[0004] Commonly used methods for preparing functional coatings include plasma spraying, chemical vapor deposition, physical vapor deposition, and combined physical-chemical vapor deposition techniques. However, coatings prepared by these methods all suffer from several critical defects: insufficient bonding strength between the functional layer and the substrate, and poor mechanical properties of the functional layer, making them unable to meet relatively demanding service conditions.

[0005] 3D printing can easily combine base metal and functional layer metal directly using element diffusion and metallurgical bonding. However, 3D printed products are cast metals, which suffer from problems such as coarse grains and metallurgical defects, resulting in relatively poor mechanical properties such as strength and plasticity. With appropriate hot rolling and heat treatment processes, composite materials with high-performance functional coatings can be easily obtained. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing functional coatings by 3D printing and hot rolling composite, which aims to produce functional coating composite boards with excellent performance through 3D printing and rolling.

[0007] To achieve the above objectives, this invention proposes a method for preparing functional coatings using 3D printing and hot rolling composite. First, a two-layer heterogeneous alloy functional composite sheet is prepared using a metal 3D printer, wherein the lower layer is a thicker base layer and the upper layer is a thinner coating. Then, a multi-pass hot rolling process is employed to refine the grains, regulate the microstructure, and optimize the mechanical properties of the sheet.

[0008] Specifically, the following steps are included:

[0009] Step 1: Using additive manufacturing technology, two alloy powders, A and B, of different materials, are printed into a heterogeneous alloy composite plate. The selection of alloy powders A and B must satisfy the rolling temperature range T of alloy powder A. A The rolling temperature range T of alloy powder B B There is an intersection between them, let the intersection be T. A ∩T B ;

[0010] Step 2: Confirm the rolling temperature of the dissimilar alloy composite sheet, where the rolling temperature T = T A ∩T B Rolling temperature T k Select the upper limit value T of the rolling temperature T. 上 ±3℃, i.e., T A ∩T B The upper limit is ±3℃, and the final rolling temperature T z Select the lower limit value of the rolling temperature T. 下 +5~10℃, i.e., T A ∩T B The lower limit is +5 to 10℃;

[0011] Step 3: Heat the dissimilar alloy composite plate to the initial rolling temperature T. k At this rolling temperature T k The heterogeneous alloy composite sheet is subjected to rapid multi-pass rough rolling and multi-pass finish rolling. The reduction rate of each pass during rough rolling is 30% to 50%, and the total reduction rate during finish rolling is 20% to 50%, in order to achieve the purpose of grain breaking, recrystallization, and enlarging the sheet size, and to ensure the final rolling temperature T. z The final rolling pass is then performed as the final rolling.

[0012] Furthermore, in step 1, additive manufacturing technology is used to print two alloy powders A and B of different materials into heterogeneous alloy composite plates of different materials in the order of base layer and coating layer. Alloy powder A can be used as the base layer or as the coating layer.

[0013] Furthermore, in step 3, the multi-pass roughing is preferably performed in 2 to 4 passes.

[0014] Furthermore, in step 3, the multi-pass finishing rolling is preferably performed in 3 to 9 passes.

[0015] Compared with the prior art, the significant advantages of the present invention are as follows: (1) The present invention combines additive manufacturing and hot rolling to prepare heterogeneous alloy functional composite plates. The composite plates printed by additive manufacturing have a tight bond between the upper and lower layers, few defects, no inclusions, and a simple process. (2) The present invention, combined with a suitable hot rolling process, can effectively break and recrystallize the coarse grains in the composite plate to generate small, uniformly distributed equiaxed grains, thereby improving the microstructure of the composite plate and optimizing its mechanical properties. (3) At the same time, the hot rolling process also expands the area of ​​the plate, effectively eliminating the limitations of metal 3D printing equipment on the size of the workpiece. (4) The method of preparing functional composite plates of the present invention can meet the requirements of one or more special properties such as corrosion resistance, wear resistance, high temperature resistance, impact resistance, pressure resistance, and thermal deformation resistance.

[0016] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the inventive subject matter of this disclosure.

[0017] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0018] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0019] Figure 1 This is a schematic diagram of the microstructure of the functional sheet material prepared by 3D printing and hot rolling composite before hot rolling, according to the present invention. In the figure: 1 represents the base layer, and 2 represents the coating.

[0020] Figure 2 This is a schematic diagram of the microstructure evolution during the hot rolling process of preparing functional sheet materials by 3D printing hot rolling composite according to the present invention. Detailed Implementation

[0021] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0022] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0023] According to the disclosure of this invention, a method for preparing functional coatings using 3D printing hot-rolled composite materials is provided. This method involves preparing a two-layer heterogeneous alloy composite plate using 3D printing technology. The materials of the base layer and the functional layer in the composite plate, namely alloy powder A and alloy powder B, can be composites of steel and steel, steel and titanium, steel and high-temperature alloys, titanium and high-temperature alloys, etc., and are not limited to the four material combinations listed above. However, the selection of alloy powder A and alloy powder B must satisfy the rolling temperature T of alloy powder A. A The rolling temperature T of alloy powder B B Since there is overlap between the two types of alloy powders, the selection range of the two alloy powders has been defined in this invention. That is, two alloy powders whose rolling temperature ranges do not overlap are not applicable to this invention. For example, the melting point of aluminum alloy is about 660°C, which is much lower than the final rolling temperature of titanium alloy. Therefore, there is no overlap in the rolling temperature of titanium alloy and aluminum alloy powders, and they are not applicable to this invention.

[0024] The morphology of the upper and lower layers of coarse grains in the cast state is as follows: Figure 1 As shown, the composite sheet at this stage has relatively coarse grains, which cannot meet the high performance requirements of engineering. Therefore, a hot rolling process is used to heat-process the composite sheet. Through multiple rolling passes, the coarse cast grains after 3D printing are broken and recrystallized to generate fine equiaxed grains, such as... Figure 2 As shown, this improves the overall mechanical properties of the composite board.

[0025] To facilitate better understanding, the present invention will be further illustrated below with specific examples. In these examples, a series of paired dissimilar alloy powders are selected, such as: Q235 and 316 stainless steel (steel and steel), 316 and TC4 (steel and titanium), 316 and IN625 alloy (steel and high-temperature alloy), TC4 and IN625 alloy (titanium and high-temperature alloy), and TC4 and IN718 alloy (titanium and high-temperature alloy), etc., for hot-rolled composite preparation of functional coatings. However, the types of alloy powders are not limited to the alloy compositions listed in the examples, and the content of the present invention includes, but is not limited to, the material combinations shown in the examples.

[0026] Example 1

[0027] Taking Q235 and 316 stainless steel (steel and steel) as an example, heterojunction powders are used. Q235 possesses excellent comprehensive mechanical properties, while 316 stainless steel exhibits superior corrosion resistance and high-temperature resistance. Composite plates composed of Q235 (base layer) and 316 stainless steel (coating) combine excellent mechanical properties, corrosion resistance, and high-temperature resistance, making them highly valuable in engineering applications. The rolling temperature range for Q235 is 910–1213℃, and for 316 stainless steel, it is 900–1230℃. The intersection of the rolling temperature ranges of the two alloys, T = T0. A ∩T B =910~1213℃. In this embodiment, 1213±3℃ is selected as the initial rolling temperature and 915~920℃ is selected as the final rolling temperature.

[0028] (1) Using metal 3D printing equipment, Q235 alloy powder is preferentially laid out for additive manufacturing to prepare a surface of 100*100mm. 2 Once the substrate thickness reaches the expected 10mm, 316 alloy powder is used to continue printing on the substrate until the composite material thickness reaches the expected 5mm, at which point the preparation process ends.

[0029] (2) The Q235 / 316 composite sheet prepared by 3D printing was heated to 1213±3℃, and then subjected to a continuous rolling process, consisting of two rough rolling passes and four finishing rolling passes. The first rough rolling pass was rolled to a thickness of 9.75mm with a compression rate of 35%; the second rough rolling pass was rolled to a thickness of 6.83mm with a compression rate of approximately 30%. The rough rolling process widened the sheet to 120mm, and then the width was fixed by finishing rolling. A total of four finishing rolling passes were used to roll the 6.83mm sheet to a thickness of 5mm, with a total compression rate of 26.8%. Among these, the time interval and temperature between each pass of rough rolling and finishing rolling were precisely controlled to ensure that the fourth finishing rolling pass was performed at 915~920℃ as the final rolling.

[0030] (3) The final dimensions of the rolled plate are 250*120*5mm. 3The base layer is approximately 3.35 mm thick, and the coating is approximately 1.65 mm thick.

[0031] The specific process parameters for this implementation can also be adapted to different alloy types.

[0032]

Example 2

[0033] Taking 316 stainless steel and TC4 (steel and titanium) as examples, heterojunction powders demonstrate that 316 stainless steel possesses high mechanical properties along with good corrosion resistance and high-temperature resistance; while TC4, compared to 316 stainless steel, exhibits even superior mechanical properties and corrosion resistance. Composite plates composed of 316 stainless steel (base layer) and TC4 (coating) combine excellent mechanical properties, corrosion resistance, and high-temperature resistance, enabling them to withstand harsher environments, such as corrosion-resistant components in the ocean. This has significant application value in the marine engineering field. The rolling temperature range for 316 stainless steel is 900–1230℃, while the rolling temperature range for TC4 titanium alloy is 700–1050℃. The intersection of the rolling temperature ranges of the two alloys, T = T0. A ∩T B =900~1050℃. In this embodiment, 1050±3℃ is selected as the initial rolling temperature and 905~910℃ as the final rolling temperature.

[0034] (1) Using metal 3D printing equipment, 316 stainless steel alloy powder was preferentially laid out for additive manufacturing to prepare a surface of 80*40mm. 2 Once the substrate thickness reaches the expected 8mm, TC4 titanium alloy powder is used to continue printing on the substrate until the composite material thickness reaches the expected 4mm, at which point the preparation process ends.

[0035] (2) The 316 / TC4 composite sheet prepared by 3D printing was heated to 1050±3℃, and then subjected to a continuous rolling process, consisting of two roughing passes and four finishing passes. The first roughing pass compressed the sheet to a thickness of 7.80mm with a compression rate of 35%; the second roughing pass compressed the sheet to a thickness of 5.46mm with a compression rate of approximately 30%. The roughing process widened the sheet to 60mm, and then the width was fixed by finishing. A total of four finishing passes were used to roll the 5.46mm sheet to a thickness of 4mm, with a total compression rate of 26.7%. The time interval and temperature between each pass of the roughing and finishing processes were precisely controlled to ensure that the fourth finishing pass was performed at 905~910℃ as the final rolling temperature.

[0036] (3) The final dimensions of the rolled plate are 160*60*4mm. 3 The base layer is approximately 2.74 mm thick, and the overlay is approximately 1.26 mm thick.

[0037] The specific process parameters for this implementation can also be adapted to different alloy types.

[0038]

Example 3

[0039] Taking 316 stainless steel and IN625 (steel and high-temperature alloy) as examples, heterogeneous alloy powders are used. 316 stainless steel possesses high mechanical properties along with good corrosion resistance and high-temperature resistance; while IN625 exhibits superior high-temperature resistance compared to 316 stainless steel. Composite plates composed of 316 stainless steel (base layer) and IN625 (coating) combine excellent mechanical properties, corrosion resistance, and high-temperature resistance, enabling them to withstand harsher environments, such as corrosion-resistant components in the ocean. This has significant application value in marine engineering. The rolling temperature range for 316 stainless steel is 900–1230℃, while the rolling temperature range for IN625 high-temperature alloy is 930–1200℃. The intersection of the rolling temperature ranges of the two alloys, T = T0. A ∩T B =930~1200℃. In this embodiment, 1200±3℃ is selected as the initial rolling temperature and 935~940℃ as the final rolling temperature.

[0040] (1) Using metal 3D printing equipment, 316 stainless steel alloy powder was preferentially laid out for additive manufacturing to prepare a surface of 300*100mm. 2 Once the substrate thickness reaches the expected 10mm, IN625 high-temperature alloy powder is used to continue printing on the substrate until the composite material thickness reaches the expected 4mm, at which point the preparation process ends.

[0041] (2) The 316 / IN625 composite sheet prepared by 3D printing was heated to 1200±3℃, and then subjected to a continuous rolling process, consisting of two roughing passes and four finishing passes. The first roughing pass compressed the sheet to a thickness of 9.10mm with a compression rate of 35%; the second roughing pass compressed the sheet to a thickness of 6.37mm with a compression rate of approximately 30%. The roughing process widened the sheet to 120mm, and then the width was fixed by finishing. A total of four finishing passes were used to roll the 6.37mm sheet to a thickness of 5mm, with a total compression rate of 21.5%. The time interval and temperature between each pass of the roughing and finishing processes were precisely controlled to ensure that the fourth finishing pass was performed at 935~940℃ as the final rolling temperature.

[0042] (3) The final dimensions of the rolled plate are 700*120*5mm. 3 The base layer is approximately 3.38 mm thick, and the secondary layer is approximately 1.62 mm thick.

[0043] The specific process parameters for this implementation can also be adapted to different alloy types.

[0044]

Example 4

[0045] Taking TC4 titanium alloy and IN625 (titanium and high-temperature alloy) as examples, heterogeneous alloy powders are used. TC4 possesses both high mechanical properties and good corrosion resistance, while IN625 exhibits superior high-temperature resistance compared to TC4 titanium alloy. Composite plates composed of TC4 (base layer) and IN625 (coating) combine excellent mechanical properties, corrosion resistance, and high-temperature resistance, enabling them to withstand harsher environments, such as corrosion-resistant components in the ocean. This has significant application value in marine engineering. The rolling temperature range of TC4 titanium alloy is 700–1050℃, and that of IN625 high-temperature alloy is 930–1200℃. The intersection of the rolling temperature ranges of the two alloys, T = T0. A ∩T B =930~1050℃. In this embodiment, 1050±3℃ is selected as the initial rolling temperature and 935~940℃ is selected as the final rolling temperature.

[0046] (1) Using metal 3D printing equipment, TC4 titanium alloy powder was preferentially laid out for additive manufacturing to prepare a surface of 200*80mm. 2 Once the substrate thickness reaches the expected 8mm, IN625 high-temperature alloy powder is used to continue printing on the substrate until the composite material thickness reaches the expected 4mm, at which point the preparation process ends.

[0047] (2) The TC4 / IN625 composite sheet prepared by 3D printing was heated to 1050±3℃, and then subjected to a continuous rolling process, consisting of two roughing passes and four finishing passes. The first roughing pass compressed the sheet to a thickness of 7.80mm with a compression rate of 35%; the second roughing pass compressed the sheet to a thickness of 5.46mm with a compression rate of approximately 30%. The roughing process widened the sheet to 100mm, and then the width was fixed by finishing. A total of four finishing passes were used to roll the 5.46mm sheet to a thickness of 4mm, with a total compression rate of 26.7%. The time interval and temperature between each pass of the roughing and finishing processes were precisely controlled to ensure that the fourth finishing pass was performed at 935~940℃ as the final rolling temperature.

[0048] (3) The final dimensions of the rolled plate are 480*100*4mm. 3 The base layer is approximately 2.72 mm thick, and the overlay is approximately 1.28 mm thick.

[0049] The specific process parameters for this implementation can also be adapted to different alloy types.

[0050] Example 5

[0051] Taking TC4 titanium alloy and IN718 (titanium and high-temperature alloy) as examples, heterogeneous alloy powders are used. TC4 possesses both high mechanical properties and good corrosion resistance, while IN625 exhibits superior high-temperature resistance compared to TC4 titanium alloy. Composite plates composed of TC4 (base layer) and IN625 (coating) combine excellent mechanical properties, corrosion resistance, and high-temperature resistance, enabling them to withstand harsher environments, such as corrosion-resistant components in the ocean. This has significant application value in marine engineering. The rolling temperature range of TC4 titanium alloy is 700–1050℃, while that of IN718 high-temperature alloy is 930–1200℃. The intersection of the rolling temperature ranges of the two alloys, T = T... A ∩T B =930~1050℃. In this embodiment, 1050±3℃ is selected as the initial rolling temperature and 935~940℃ is selected as the final rolling temperature.

[0052] (1) Using metal 3D printing equipment, TC4 titanium alloy powder was preferentially laid out for additive manufacturing to prepare a surface of 100*100mm. 2 Once the substrate thickness reaches the expected 8mm, IN718 high-temperature alloy powder is used to continue printing on the substrate until the composite material thickness reaches the expected 2mm, at which point the preparation process ends.

[0053] (2) The TC4 / IN718 composite sheet prepared by 3D printing was heated to 1050±3℃, and then subjected to a continuous rolling process, consisting of two roughing passes and four finishing passes. The first roughing pass compressed the sheet to a thickness of 6.50mm with a compression rate of 35%; the second roughing pass compressed the sheet to a thickness of 4.55mm with a compression rate of approximately 30%. The roughing process widened the sheet to 120mm, and then the width was fixed by finishing, with a total of four finishing passes to roll the 4.55mm sheet to 3mm, resulting in a total compression rate of 34.1%. The time interval and temperature between each pass of the roughing and finishing processes were precisely controlled to ensure that the fourth finishing pass was performed at 935~940℃ as the final rolling temperature.

[0054] (3) The final dimensions of the rolled plate are 277*120*3mm. 3 The base layer is approximately 2.48 mm thick, and the overlay is approximately 0.52 mm thick.

[0055] The specific process parameters for this implementation can also be adapted to different alloy types.

[0056] In the additive manufacturing process, the formation of columnar crystals and coarse primary grains stems from the thermodynamic dynamics of the metallurgical process. The extraordinary metallurgical conditions and cyclic deposition within the tiny molten pool during additive manufacturing lead to insufficient cooling of temperature and composition, and the reduction of non-spontaneous nucleation particles is the core issue. This invention utilizes the above method and hot rolling process to break and recrystallize the columnar crystals and coarse primary grains in additive manufacturing, generating fine equiaxed grains, thereby achieving precise control over the microstructure of additively manufactured composite materials.

[0057] Table 1 compares the grain size and mechanical properties of the composite plates before and after hot rolling in each embodiment.

[0058] Table 1 Comparison of grain size and mechanical properties of various composite plates before and after hot rolling

[0059]

[0060] Since the relationship between the strength and grain size of alloy materials follows the Hall-Petch relationship, the finer the grain, the higher the strength of the alloy; moreover, only by refining the grain can the strength and plasticity of the material be improved simultaneously. In the foregoing embodiments of this invention, the hot rolling process can effectively refine the grain, improve the microstructure, and enhance the material properties. Heat treatment (aging, solution treatment, etc.) on the hot-rolled alloy sheet (functional coating) can eliminate residual internal stress, microcracks, and other defects from the rolling process.

[0061] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for preparing functional coatings using 3D printing hot-rolled composite, characterized in that, Specifically, the following steps are included: Step 1: Using additive manufacturing technology, two alloy powders, A and B, of different materials, are printed into a heterogeneous alloy composite plate. The selection of alloy powders A and B must satisfy the rolling temperature range T of alloy powder A. A The rolling temperature range T of alloy powder B B There is an intersection between them, let the intersection be T. A ∩T B ; Step 2: Confirm the rolling temperature of the dissimilar alloy composite sheet, where the rolling temperature T = T A ∩T B Rolling temperature T k Select the upper limit value of rolling temperature T. 上 ±3℃, final rolling temperature T z Select the lower limit value of rolling temperature T. 下 +5~10℃; Step 3: Heat the dissimilar alloy composite plate to the initial rolling temperature T. k At this initial rolling temperature, the dissimilar alloy composite plate is rapidly subjected to multiple passes of rough rolling and multiple passes of finish rolling. The reduction rate per pass during rough rolling is 30%~50%, and the total reduction rate during finish rolling is 20%~50%, while ensuring that the final rolling temperature T is maintained. z The final rolling pass is then performed as the final rolling.

2. The method as described in claim 1, characterized in that, In step 1, additive manufacturing technology is used to print two alloy powders A and B of different materials into heterogeneous alloy composite plates with different materials, according to the order of base layer and coating.

3. The method as described in claim 1, characterized in that, In step 3, the multi-pass roughing is 2 to 4 passes.

4. The method as described in claim 1, characterized in that, In step 3, the multi-pass finishing rolling process consists of 3 to 9 passes.

5. The method as described in claim 1, characterized in that, In step 3, the multi-pass finishing rolling process consists of 4 to 6 passes.

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