Gradient structure alloy plate and reinforcing method, and preparation method thereof

Abstract

The present application relates to a kind of gradient structure alloy plate and reinforcing, preparation method, belong to alloy material field.The present application discloses by component alloying, embedding aluminizing, low-temperature thermal diffusion and local precipitation method of aging, with the process for enhancing the strength of plate material, and disclosed under the process made with gradient structure plate and the complete processing process of plate with gradient structure.The scheme disclosed in the present application can improve the tensile strength of nickel-copper alloy plate, wear resistance while keeping the plasticity basically unchanged.The plate disclosed in the present application has a surface aluminum-rich layer, a middle aluminum-poor precipitation hardening layer and a core original layer, the chemical composition, the organization features, the grain size, the precipitation phase quantity present gradient change in the thickness direction, can significantly improve the tensile strength while keeping the plasticity almost unchanged, greatly widen the use range of nickel-copper alloy.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials and relates to a gradient structure alloy plate, its reinforcement, and its preparation method. Background Technology

[0002] As common alloy materials, nickel-copper alloys typically possess high strength, high toughness, and excellent corrosion resistance. Among them, Monel alloy (Ni70Cu30) is one of the most widely used nickel-based corrosion-resistant alloys. This alloy exhibits excellent resistance to salts, acids, and alkalis, especially hydrofluoric acid and fluorides, thus playing an irreplaceable role in shipbuilding, oil refining, chemical engineering, and metallurgy. It is commonly used to manufacture pump shafts, valves, and pipe products.

[0003] With the development of industrial technology, traditional nickel-copper alloys, due to their low strength and wear resistance, are unsuitable for many applications requiring both high strength and high wear resistance. Because of the insufficient overall mechanical properties of traditional Monel alloys, many researchers have attempted to improve strength and wear resistance by introducing other alloying elements into the nickel-copper alloy matrix through solid solution strengthening, aging strengthening, and other methods. However, such methods typically reduce ductility and toughness while improving material strength and wear resistance, leading to poorer processing performance and service safety, posing potential safety hazards. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a gradient structure alloy plate and a reinforcement and preparation method, which improves the tensile strength of the plate while maintaining its plasticity by means of external infiltration, thermal diffusion and aging precipitation of the reinforcing metal.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A gradient structure alloy sheet has a gradient structure in which the particle size gradually decreases from the inside to the outside along the thickness direction of the sheet; the gradient structure is generated by the external infiltration of reinforcing metal, thermal diffusion and aging precipitation.

[0007] Optionally, the plate has a layered structure, with the core being a coarse-grained layer without aging precipitates and the edge being a fine-grained layer with aging precipitates. The microstructure changes in a gradient from the core to the edge.

[0008] Optionally, the gradient structure includes the gradient distribution of components, the gradient distribution of aged precipitates, and the gradient distribution of microstructure.

[0009] Optionally, Al can be used as the reinforcing metal.

[0010] Optionally, the plate material is a nickel-copper alloy, and the second phase reinforcement precipitated during aging is a precipitate formed by any two or three elements selected from aluminum, titanium, and scandium.

[0011] Optionally, the size of the precipitated phase is 10-1500 nm.

[0012] A method for reinforcing alloy plates includes the following steps:

[0013] Aluminizing: Aluminum powder and aluminizing agent are used to embed and aluminize the sheet material.

[0014] Thermal diffusion: The aluminized sheet material undergoes thermal diffusion treatment;

[0015] Cold rolling: Cold rolling is performed on sheet metal after "thermal diffusion".

[0016] Optionally, the cold-rolled sheet material may be subjected to aging treatment.

[0017] Optionally, the aging treatment temperature is 450-650℃, and the aging time is 5-24 hours.

[0018] Optionally, during the "aluminizing" process, aluminum powder accounts for 5% to 65%.

[0019] Optionally, the temperature for "thermal diffusion" is 200℃-450℃, and the holding time is 5-72 hours.

[0020] Optionally, the product of the diffusion temperature and diffusion time for "thermal diffusion" is between 12,000 and 16,500, with the diffusion temperature in degrees Celsius and the diffusion time in hours.

[0021] Optionally, the number of pressing passes in "cold rolling" is 5-20, and the number of pressing passes is positively correlated with the aluminum content of the surface layer.

[0022] A method for preparing a gradient structure alloy plate includes the following steps:

[0023] Microalloying: Melting, with the addition of microalloying elements during the melting process;

[0024] Hot rolling; hot rolling of materials that have undergone "micro-alloying";

[0025] Aluminizing: Aluminum powder and aluminizing agent are used to embed and aluminize the sheet material.

[0026] Thermal diffusion: The aluminized sheet material undergoes thermal diffusion treatment;

[0027] Cold rolling: Cold rolling is performed on sheet metal after "thermal diffusion";

[0028] Aging treatment: The cold-rolled sheet material is subjected to aging treatment.

[0029] Optionally, during the "microalloying" process, Ti and / or Sc are added for microalloying.

[0030] Optionally, during the "microalloying" process, the mass percentage of microalloying elements is 0.01-5% wt.

[0031] Optionally, during the "microalloying" process, at least one remelting is performed to ensure uniform melt composition.

[0032] Optionally, during the "hot rolling" process, a protective gas is used, the heating temperature is 1050-1150℃, and the temperature is held for 10-60 minutes before hot rolling, with a hot rolling reduction of 10%-70%.

[0033] Optionally, the sheet material can be surface treated after hot rolling.

[0034] The beneficial effects of this invention are as follows:

[0035] In some embodiments of the present invention, based on a non-precipitation-strengthened NiCu alloy, precipitated alloying elements are introduced into the matrix. Through hot rolling and surface treatment, the diffusion capacity of subsequent Al elements is increased. Then, a powder embedding method is used to infiltrate a high concentration of Al elements within a range of about 50-100 μm on the surface of the plate. Then, a low-temperature diffusion heat treatment is performed to allow the high concentration of Al elements to diffuse from the surface to the core, with a maximum diffusion depth of 500-5000 micrometers. Subsequently, through cold rolling deformation, a large number of dislocations are introduced into the plate, which enhances the strengthening effect of subsequent aging treatment. Finally, an aluminum-rich layer on the surface, an aluminum-poor precipitated hardened layer in the middle, and an original layer in the core are obtained. The chemical composition, microstructure, grain size, and number of precipitated phases show a gradient change in the thickness direction. It can significantly improve tensile strength while maintaining almost unchanged plasticity, greatly expanding the application range of nickel-copper alloys.

[0036] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0038] Figure 1 This is a process flow diagram for some embodiments of the present invention. Detailed Implementation

[0039] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0040] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0041] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0042] Please see Figure 1 The above describes the alloy preparation process routes in some embodiments of the present invention. Three embodiments and comparative examples are given below.

[0043] Example 1

[0044] A gradient structure Ni68Cu30Ti2 alloy plate, the preparation method of which includes the following steps:

[0045] 1) Ti microalloying

[0046] The Ni68Cu30Ti2 composition was selected and smelted in a vacuum induction furnace. First, pure nickel, pure copper, or an intermediate alloy of both were added and completely melted. Then, trace element Ti was added, with a mass percentage of 2% wt, in the form of Ti particles. After complete melting, the mixture was held at this temperature for 20 minutes, and then cast using a water-cooled copper mold. The process was repeated twice to ensure uniform composition in the melt.

[0047] 2) Hot rolling

[0048] Argon protection, heating temperature 1050℃, holding for 30 minutes and then hot rolling, with a reduction of 50%;

[0049] 3) Surface treatment

[0050] After rinsing the hot-rolled sheet with deionized water, the surface of the hot-rolled sheet is then polished.

[0051] 4) Embedding and aluminizing

[0052] The surface-treated sheet was placed in a powder embedding agent. The aluminizing temperature was 550℃, the aluminizing time was 12h, the proportion of aluminum powder in the aluminizing was 25%, and ammonium chloride was used as the aluminizing agent.

[0053] 5) Diffusion heat treatment

[0054] The heat treatment temperature is 450℃, and the holding time is 12 hours.

[0055] 6) Cold rolling

[0056] Cold rolling is performed at room temperature with a reduction of 50%.

[0057] 7) Timeliness processing

[0058] Aging temperature 550℃, aging time 6 hours.

[0059] After the above treatment, a gradient structure Ni68Cu30Ti2 plate was obtained. Its composition was optimized based on the traditional Monel alloy (Monel 400) to give it higher strength, higher wear resistance and similar plasticity. Its specific properties are listed in Table 1.

[0060] Example 2

[0061] A gradient structure Ni69Cu30Sc1 alloy plate, the preparation method of which includes the following steps:

[0062] 1) Sc microalloying

[0063] The composition Ni69Cu30Sc1 was selected and smelted in a vacuum induction furnace. First, pure nickel, pure copper, or an intermediate alloy of the two were added and completely melted. Then, trace element Sc was added, with a mass ratio of 1% wt, in the form of metallic Sc ​​blocks. After complete melting, the mixture was held at the temperature for 20 minutes, and then cast using a water-cooled copper mold. The process was repeated twice to ensure uniform composition in the melt.

[0064] 2) Hot rolling

[0065] Argon protection, heating temperature 1150℃, holding for 20 minutes and then hot rolling, with a reduction of 50%;

[0066] 3) Surface treatment

[0067] After rinsing the hot-rolled sheet with deionized water, the surface of the hot-rolled sheet is then polished.

[0068] 4) Embedding and aluminizing

[0069] The surface-treated sheet was placed in a powder embedding agent. The aluminizing temperature was 650℃, the aluminizing time was 8 hours, the proportion of aluminum powder in the aluminizing was 25%, and ammonium chloride was used as the aluminizing agent.

[0070] 5) Diffusion heat treatment

[0071] The heat treatment temperature is 450℃, and the holding time is 12 hours.

[0072] 6) Cold rolling

[0073] Cold rolling is performed at room temperature with a reduction of 50%.

[0074] 7) Timeliness processing

[0075] Aging temperature 580℃, aging time 6 hours.

[0076] After the above treatment, a gradient structure Ni69Cu30Sc1 plate was obtained. Its composition was optimized based on the traditional Monel alloy (Monel 400). Compared with the gradient structure plate after Ti microalloying, it has higher strength and higher wear resistance, but its plasticity is reduced. Its specific properties are listed in Table 1.

[0077] Example 3

[0078] A gradient structure Ni68Cu30Ti1Sc1 alloy plate, the preparation method of which includes the following steps:

[0079] 1) Ti and Sc microalloying

[0080] The composition Ni68Cu30TiSc1 was selected and smelted in a vacuum induction furnace. First, pure nickel, pure copper, or an intermediate alloy of both were added and completely melted. Then, trace elements Ti and Sc were added, with a mass ratio of 2% wt, in the form of Ti particles and metallic Sc ​​blocks. After complete melting, the mixture was held at this temperature for 20 minutes, and then cast using a water-cooled copper mold. The process was repeated twice to ensure uniform composition in the melt.

[0081] 2) Hot rolling

[0082] Argon protection, heating temperature 1150℃, holding for 20 minutes and then hot rolling, with a reduction of 50%;

[0083] 3) Surface treatment

[0084] After rinsing the hot-rolled sheet with deionized water, the surface of the hot-rolled sheet is then polished.

[0085] 4) Embedding and aluminizing

[0086] The surface-treated sheet was placed in a powder embedding agent. The aluminizing temperature was 650℃, the aluminizing time was 10h, the proportion of aluminum powder in the aluminizing was 25%, and ammonium chloride was used as the aluminizing agent.

[0087] 5) Diffusion heat treatment

[0088] The heat treatment temperature is 500℃, and the holding time is 12 hours.

[0089] 6) Cold rolling

[0090] Cold rolling is performed at room temperature with a reduction of 50%.

[0091] 7) Timeliness processing

[0092] Aging temperature 580℃, aging time 6 hours.

[0093] After the above treatment, a gradient structure Ni68Cu30TiSc1 plate was obtained. Its composition was optimized based on the traditional Monel alloy (Monel 400). Compared with the gradient structure plate after Ti microalloying, it has higher strength, higher wear resistance, and its plasticity remains basically unchanged. Its specific properties are listed in Table 1.

[0094] Comparative Example 1 (using conventional Monel alloy composition, without the addition of microalloying elements Ti and Sc)

[0095] A gradient structure Ni70Cu30 alloy plate, the preparation method of which includes the following steps:

[0096] 1) Smelting

[0097] The composition is Ni70Cu30. It is smelted in a vacuum induction furnace by first adding pure nickel, pure copper, or an intermediate alloy of both and melting them completely. After complete melting, the mixture is held at this temperature for 20 minutes, and then cast using a water-cooled copper mold. The process is repeated twice to ensure uniform composition in the melt.

[0098] 2) Hot rolling

[0099] Argon protection, heating temperature 1050℃, holding for 30 minutes and then hot rolling, with a reduction of 50%;

[0100] 3) Surface treatment

[0101] After rinsing the hot-rolled sheet with deionized water, the surface of the hot-rolled sheet is then polished.

[0102] 4) Embedding and aluminizing

[0103] The surface-treated sheet was placed in a powder embedding agent. The aluminizing temperature was 550℃, the aluminizing time was 12h, the proportion of aluminum powder in the aluminizing was 25%, and ammonium chloride was used as the aluminizing agent.

[0104] 5) Diffusion heat treatment

[0105] The heat treatment temperature is 450℃, and the holding time is 12 hours.

[0106] 6) Cold rolling

[0107] Cold rolling is performed at room temperature with a reduction of 50%.

[0108] 7) Timeliness processing

[0109] Aging temperature 550℃, aging time 6 hours.

[0110] Compared with Examples 1, 2 and 3, Comparative Example 1 did not undergo Ti and Sc microalloying. After the above treatment, its performance was significantly worse. Its specific performance is listed in Table 1.

[0111] Comparative Example 2 (without embedding and aluminizing)

[0112] A gradient structure Ni68Cu30Ti2 alloy plate, the preparation method of which includes the following steps:

[0113] 1) Ti microalloying

[0114] The Ni68Cu30Ti2 composition was selected and smelted in a vacuum induction furnace. First, pure nickel, pure copper, or an intermediate alloy of both were added and completely melted. Then, trace element Ti was added, with a mass percentage of 2% wt, in the form of Ti particles. After complete melting, the mixture was held at this temperature for 20 minutes, and then cast using a water-cooled copper mold. The process was repeated twice to ensure uniform composition in the melt.

[0115] 2) Hot rolling

[0116] Argon protection, heating temperature 1050℃, holding for 30 minutes and then hot rolling, with a reduction of 50%;

[0117] 3) Surface treatment

[0118] After rinsing the hot-rolled sheet with deionized water, the surface of the hot-rolled sheet is then polished.

[0119] 4) Diffusion heat treatment

[0120] The heat treatment temperature is 450℃, and the holding time is 12 hours.

[0121] 5) Cold rolling

[0122] Cold rolling is performed at room temperature with a reduction of 50%.

[0123] 6) Timeliness processing

[0124] Aging temperature 550℃, aging time 6 hours.

[0125] After the above treatment, a gradient structure Ni68Cu30Ti2 plate was obtained. Compared with Example 1, Comparative Example 2 did not undergo embedding aluminizing. After the above treatment, the performance was higher than that of the traditional Monel alloy composition plate (Comparative Example 1), but lower than that of the plate after embedding aluminizing (Example 1). This shows that embedding aluminizing is an important step in the process. This is because the main purpose of embedding aluminizing is to produce nano-precipitates with microalloying elements, thereby greatly improving the performance of the material.

[0126] Comparative Example 3 (without diffusion heat treatment)

[0127] A gradient structure Ni68Cu30Ti2 alloy plate, the preparation method of which includes the following steps:

[0128] 1) Ti microalloying

[0129] The Ni68Cu30Ti2 composition was selected and smelted in a vacuum induction furnace. First, pure nickel, pure copper, or an intermediate alloy of both were added and completely melted. Then, trace element Ti was added, with a mass percentage of 2% wt, in the form of Ti particles. After complete melting, the mixture was held at this temperature for 20 minutes, and then cast using a water-cooled copper mold. The process was repeated twice to ensure uniform composition in the melt.

[0130] 2) Hot rolling

[0131] Argon protection, heating temperature 1050℃, holding for 30 minutes and then hot rolling, with a reduction of 50%;

[0132] 3) Surface treatment

[0133] After rinsing the hot-rolled sheet with deionized water, the surface of the hot-rolled sheet is then polished.

[0134] 4) Embedding and aluminizing

[0135] The surface-treated sheet was placed in a powder embedding agent. The aluminizing temperature was 550℃, the aluminizing time was 12h, the proportion of aluminum powder in the aluminizing was 25%, and ammonium chloride was used as the aluminizing agent.

[0136] 5) Cold rolling

[0137] Cold rolling is performed at room temperature with a reduction of 50%.

[0138] 6) Timeliness processing

[0139] Aging temperature 550℃, aging time 6 hours.

[0140] After the above treatment, a gradient structure Ni68Cu30Ti2 plate was obtained. Compared with Example 1, Comparative Example 3 did not undergo diffusion heat treatment, resulting in a thinner aluminized layer. The aluminum element did not diffuse into the core of the plate, resulting in an indistinct gradient structure. The number of nano-precipitates formed was small and their size was large, resulting in lower performance than Example 1. This shows that diffusion heat treatment is an important step in this process.

[0141] Table 1 Mechanical Properties

[0142]

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a gradient structure alloy plate, characterized in that, Includes the following steps: Microalloying: Melting, and adding Ti and / or Sc during the melting process for microalloying; the mass percentage of microalloying elements is 0.01-5%wt; at least one remelting is performed during the process to make the melt composition uniform; Hot rolling: The micro-alloyed material is hot rolled using a protective gas. The heating temperature is 1050~1150℃, and the temperature is held for 10-60 minutes before hot rolling. The hot rolling reduction is 10%~70%. After hot rolling, the plate is surface treated. Aluminizing: Aluminum powder and aluminizing agent are used to embed and aluminize the sheet material, with the aluminum powder accounting for 5% to 65%; Thermal diffusion: The aluminized sheet is subjected to thermal diffusion treatment at a temperature of 200℃-450℃ for 5-72 hours. The product of diffusion temperature and diffusion time is between 12000 and 16500. The unit of diffusion temperature is degrees Celsius and the unit of diffusion time is hours. Cold rolling: Cold rolling is performed on the sheet material after heat diffusion, with 5-20 passes. The number of passes is positively correlated with the aluminum content of the surface layer. Aging treatment: The cold-rolled sheet is subjected to aging treatment at a temperature of 450-650℃ for 5-24 hours to finally obtain a gradient structure alloy sheet. The gradient structure alloy sheet exhibits a gradient structure with grain size gradually decreasing from the inside to the outside along the thickness direction of the sheet. This gradient structure is caused by the external infiltration, thermal diffusion, and aging precipitation of the reinforcing metal. The sheet has a layered structure, with a coarse-grained layer without aging precipitates in the core and a fine-grained layer with aging precipitates in the edge. The microstructure changes gradient from the core to the edge. The gradient structure includes the gradient distribution of composition, the gradient distribution of aging precipitates, and the gradient distribution of microstructure. Al is used as the reinforcing metal. The sheet is a nickel-copper alloy, and the second phase reinforcement precipitated during aging is a precipitate formed by any two or three elements selected from aluminum, titanium, and scandium. The size of the precipitate is 10-1500 nm.

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