Aluminum steel dissimilar part and preparation method thereof

Abstract

The invention relates to an aluminum steel dissimilar part and a preparation method thereof, and relates to the technical field of metal processing. According to the main technical scheme, an aluminum component of a set structure is deposited on a steel component through a friction extrusion deposition method, so that aluminum-steel interface connection is achieved, and an aluminum-steel dissimilar part is obtained; wherein the aluminum component is made of aluminum or aluminum alloy. According to the method, the aluminum-steel dissimilar part is prepared mainly through the friction extrusion deposition additive manufacturing process, a traditional aluminum-steel interface hard and brittle intermetallic compound layer is converted into a tough amorphous layer, and the problems that an existing aluminum-steel dissimilar part is low in interface tensile strength and prone to cracking are solved.

Description

Technical Field

[0001] The invention relates to the technical field of metal processing, and in particular to an aluminum-steel heterogeneous part and a preparation method thereof. Background Art

[0002] Aluminum-steel dissimilar parts have both functional and economic advantages and have been widely used in aerospace, vehicles, polar ships, etc. Due to the huge differences between aluminum and steel in properties such as melting point, thermal conductivity, ductility, density, etc., it is very difficult to connect aluminum components and steel components.

[0003] In the prior art, the processes for connecting aluminum components to steel components are mainly as follows: (1) using fusion welding or fusion additive process; (2) using solid-state friction stir welding process by controlling welding temperature and high-temperature dwell time; (3) using mechanical connection process without active heat input.

[0004] However, the above prior art has the following technical problems:

[0005] (1) When aluminum components and steel components are directly connected by fusion welding or fusion additive process, the molten aluminum components will react quickly after contact with the steel components, and a layer of brittle intermetallic compounds will be generated at the aluminum-steel interface, resulting in low interfacial tensile strength of the prepared aluminum-steel dissimilar parts. This process is mostly used for functional parts that do not have strict requirements on interface tensile and shear resistance, or for components that do not have strict requirements on joint size, and is generally not used as a key load-bearing structural part.

[0006] (2) Although the solid-state friction stir welding process has achieved remarkable results in reducing the size of intermetallic compounds at the interface by controlling the welding temperature and high-temperature residence time, the process controllability is low, the welding quality is unstable, the tools are easily worn, and the interface tensile strength of the prepared aluminum-steel dissimilar parts cannot fully meet the increasingly stringent service requirements, and the size and shape are greatly restricted.

[0007] (3) For the mechanical connection process, although the process is simple and there is no active heat input, it can effectively avoid the formation of brittle metal compounds at the interface and weaken the mechanical properties of the joint. However, there are problems such as insufficient joint flatness, poor sealing, stress concentration, and large structural volume.

[0008] In summary, a new type of aluminum-steel dissimilar parts preparation technology is urgently needed to transform the traditional hard and brittle intermetallic compound layer at the aluminum-steel interface into a strong and tough amorphous layer, so as to solve the problems of low tensile strength and easy cracking at the interface of existing aluminum-steel dissimilar parts. Summary of the invention

[0009] In view of this, the present invention provides an aluminum-steel dissimilar part and a preparation method thereof. The main purpose is to adopt a friction extrusion deposition additive manufacturing process to prepare the aluminum-steel dissimilar part, transform the traditional aluminum-steel interface hard and brittle intermetallic compound layer into a strong and tough amorphous layer, and solve the problems of low tensile strength and easy cracking of the interface of existing aluminum-steel dissimilar parts.

[0010] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0011] On the one hand, an embodiment of the present invention provides a method for preparing an aluminum-steel dissimilar part, wherein an aluminum component with a set structure is deposited on a steel component by a friction extrusion deposition method to achieve a stable aluminum-steel interface connection to obtain an aluminum-steel dissimilar part; wherein the material of the aluminum component is aluminum or aluminum alloy.

[0012] Preferably, the preparation method comprises the following steps:

[0013] Pretreatment step: surface pretreatment of steel components;

[0014] Friction extrusion deposition step: The softened raw material is extruded by a friction extrusion deposition device, and deposited on the surface of the steel component according to a set trajectory to form a first deposition layer; then, deposition is performed layer by layer to deposit an aluminum component with a set structure on the steel component to obtain an aluminum-steel heterogeneous part.

[0015] Preferably, the pretreatment step includes: polishing, cleaning and drying the surface of the steel component; wherein the polishing treatment is selected from any one of mechanical polishing, electrolytic polishing and chemical polishing, preferably mechanical polishing;

[0016] Preferably, after the pretreatment, the surface roughness of the steel component is lower than Ra3.2.

[0017] Preferably, a transition layer is formed at the connection interface between the first deposition layer and the steel component; wherein the transition layer is a nano-amorphous transition layer with a thickness of ≤600nm; preferably, atoms in the nano-amorphous transition layer are arranged in a long-range disordered state.

[0018] Preferably, the friction extrusion deposition device comprises:

[0019] A rotary extrusion die is provided with an extrusion port at the bottom thereof, wherein the extrusion port is communicated with the interior of the rotary extrusion die and is used for extruding the softened raw material.

[0020] Preferably, the bottom of the rotary extrusion die is connected with one or more protrusions;

[0021] Preferably, the height of the protrusion is less than 3.0 mm;

[0022] Preferably, in the friction extrusion deposition step: when depositing the first deposition layer, the distance between the bottom of the rotary extrusion die and the surface of the steel component is greater than the height of the protrusion, so as to ensure that the protrusion will not be inserted into the steel plate to avoid the formation of a large amount of intermetallic compounds; preferably, the distance between the protrusion and the surface of the steel component is 0.01-1.50 mm, preferably 0.1-0.60 mm, so that an amorphous transition layer is formed at the connection interface between the first deposition layer and the steel component during friction extrusion deposition;

[0023] Preferably, in the friction extrusion deposition step: after depositing the first deposition layer, the interlayer spacing between the deposition layers is ≤ the height of the protrusion, so as to ensure that the protrusion can achieve mechanical stirring between the aluminum or aluminum alloy deposition layers, thereby improving the material strength of the aluminum component.

[0024] Preferably, the friction extrusion deposition device further comprises:

[0025] A feeding cavity, the feeding cavity is used to feed the raw material into the rotary extrusion die;

[0026] A feeding mechanism, the feeding mechanism is used to apply an axial thrust to the raw material in the feeding cavity, so as to gradually push the raw material from the feeding cavity to the inner bottom surface of the rotary extrusion die, and friction cutting occurs, and the softened material is extruded from the extrusion port;

[0027] Preferably, the feeding cavity is a hollow cavity with two ends open;

[0028] The top of the rotary extrusion die is open;

[0029] One end of the feeding cavity extends from the opening of the rotary extrusion die into the rotary extrusion die; the feeding mechanism extends from the other end of the feeding cavity into the feeding cavity to apply thrust to the raw material.

[0030] Preferably, in the friction extrusion deposition step:

[0031] The raw material is fed into a feeding chamber of a friction extrusion deposition device; the raw material is fed into a rotary extrusion deposition mold under the action of a feeding mechanism; wherein, in the rotary extrusion deposition mold, friction and cutting occur between the raw material and the inner bottom surface of the rotary extrusion deposition mold, resulting in local softening; wherein, the softened material is pushed axially under the action of the feeding mechanism, extruded from an extrusion port of the rotary extrusion deposition mold, and deposited layer by layer on the steel component according to a set trajectory.

[0032] Preferably, the rotation speed of the rotary extrusion deposition mold is ≥50 rpm, preferably 150-1000 rpm;

[0033] Preferably, in the friction extrusion deposition step, the following conditions must be met:

[0034] SV1 = V2wha;

[0035] Among them, S is the cross-sectional area of ​​the deposited raw material; V1 is the axial advancement speed of the raw material; V2 is the lateral movement speed of the rotary extrusion deposition mold; w is the width of a single additive layer; h is the thickness of a single additive layer; a is a fixed coefficient, and the value range is 1-3.

[0036] On the other hand, an embodiment of the present invention provides an aluminum-steel dissimilar part, wherein the aluminum-steel dissimilar part is composed of an aluminum component and a steel component; wherein the material of the aluminum component is aluminum or an aluminum alloy; wherein a nano-amorphous transition layer is formed at the connection interface between the aluminum component and the steel component;

[0037] Preferably, the aluminum-steel heterogeneous parts are prepared by any of the above-mentioned methods for preparing aluminum-steel heterogeneous parts;

[0038] Preferably, in the aluminum-steel dissimilar parts: the interface bonding strength between the steel component and the aluminum component is greater than 150 MPa.

[0039] Compared with the prior art, the aluminum-steel heterogeneous component and the preparation method thereof of the present invention have at least the following beneficial effects:

[0040] On the one hand, an embodiment of the present invention provides a method for preparing an aluminum-steel dissimilar part, and for the first time proposes to use a friction extrusion deposition method to deposit an aluminum component of a set structure on a steel component to obtain an aluminum-steel dissimilar part; wherein the material of the aluminum component is aluminum or an aluminum alloy. Here, by using a friction extrusion deposition additive manufacturing process, a rotating extrusion deposition mold is used to drive high-speed and instantaneous friction between aluminum and steel, so that a nano-amorphous transition layer can be introduced at the aluminum-steel interface to avoid the formation of a hard and brittle intermetallic compound layer at the aluminum-steel interface, so that the aluminum-steel connection interface has high hardness and high strength, and at the same time has good plasticity, which significantly improves the tensile strength of the aluminum-steel interface.

[0041] Furthermore, the present invention optimizes the design of the rotary extrusion deposition mold (adding a protruding structure design at the bottom), controls the distance of the protruding end relative to the surface of the steel component, and the roughness of the surface of the steel component to be deposited, so that the aluminum-steel dissimilar parts are connected by forming a nano-amorphous transition layer at the connection interface, and ultimately the aluminum-steel bonding strength is greater than 150MPa.

[0042] In addition, when using the friction extrusion deposition additive process to prepare aluminum-steel heterogeneous parts, the high-speed rotating extrusion deposition mold and the raw material are rubbed and extruded to perform a local active softening treatment process, so that the local area remains in a hot plastic state, the fluidity of the deposited material is improved, and the material is extruded through the mold opening and deposited to the target position. The deposition process is controllable and the quality is stable, which can achieve continuous and large-scale production and improve production efficiency. In addition, the friction extrusion deposition additive manufacturing process effectively solves the problem of tool wear during solid-state stir friction welding, increases the service life of the rotating extrusion mold, and reduces production costs. Here, by setting the deposition path, aluminum-steel heterogeneous parts of different shapes can be manufactured quickly and at low cost to meet personalized customization needs and are not limited in size, achieving the purpose of economical and reasonable printing production.

[0043] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic diagram of depositing a first deposition layer on a steel component by a friction extrusion deposition method according to an embodiment of the present invention;

[0045] Figure 2 is a schematic diagram of depositing an aluminum component on a steel component by a friction extrusion deposition method according to an embodiment of the present invention;

[0046] Figure 3 is a schematic diagram of an aluminum-steel interface of an aluminum-steel dissimilar part prepared in an embodiment of the present invention;

[0047] Figure 4 This is a physical picture of an aluminum-steel heterogeneous part prepared in Example 1 of the present invention;

[0048] Figure 5 This is a cross-sectional microstructure morphology diagram of the aluminum-steel dissimilar component in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0050] The embodiment of the present invention provides a method for preparing an aluminum-steel dissimilar part, which uses a friction extrusion deposition method to deposit an aluminum component with a set structure on a steel component and achieve a stable aluminum-steel interface connection to obtain a high-strength aluminum-steel dissimilar part; the method mainly includes the following steps:

[0051] Pretreatment step: treating the surface of the steel component, including: polishing, cleaning and drying the surface of the steel component; wherein the polishing treatment is any one of mechanical polishing, electrolytic polishing and chemical polishing, preferably mechanical polishing; wherein the surface roughness of the steel component needs to be lower than Ra3.2, and it is fixed by a fixing component.

[0052] Friction extrusion deposition step: The softened raw material is extruded by a friction extrusion deposition device, and deposited on the steel component according to a set trajectory to obtain a first deposition layer; then deposited layer by layer to deposit an aluminum component with a set structure on the steel component and achieve a stable aluminum-steel interface connection to obtain a high-strength aluminum-steel dissimilar part.

[0053] Among them, Figure 1 and Figure 2 The friction extrusion deposition device comprises: a rotary extrusion die 41, a feeding cavity 42 and a feeding mechanism 43. One end of the rotary extrusion die 41 is the first end (i.e., the lower end), and an extrusion port is provided at the first end (bottom 412) of the rotary extrusion die 41, wherein the extrusion port is connected to the interior of the rotary extrusion die 41 for extruding the softened raw material. The feeding cavity 42 is used to feed the raw material into the rotary extrusion die 41. The feeding mechanism 43 is used to apply an axial thrust to the raw material in the feeding cavity 42, so as to gradually push the raw material from the feeding cavity 42 to the inner bottom surface 413 of the rotary extrusion die 41. The feeding cavity 42 is a hollow cavity with two open ends; the top of the rotary extrusion die 41 is open; wherein the second end of the rotary extrusion die 41 is arranged opposite to the first end. Among them, one end (i.e., the lower end) of the feeding cavity 42 extends into the rotating extrusion mold 41 from the opening of the rotating extrusion mold 41; the feeding mechanism 43 extends into the feeding cavity 42 from the other end (i.e., the upper end) of the feeding cavity 42 to apply thrust to the raw material.

[0054] Among them, the friction extrusion deposition steps are mainly as follows:

[0055] like Figure 1 and Figure 2As shown, the raw material 3 (aluminum rod or aluminum alloy rod) is fed into the feeding cavity 42, and is fed to the high-speed rotating rotary extrusion deposition mold 41 under the action of the feeding mechanism 43. The rotation speed of the rotary extrusion deposition mold 41 is greater than or equal to 50rpm, preferably 150-1000rpm, so that the raw material 3 and the inner bottom surface of the rotary extrusion deposition mold 41 are rubbed and cut. The cutting force causes the material to deform and break so that it can be quickly heated and plasticized; at the same time, friction increases heat generation, and the heat generated by friction keeps the raw material in a thermoplastic state, improves the fluidity of the material, and causes the raw material near the rotary extrusion deposition mold 41 to reach a viscoplastic rheological state due to friction and deformation heat, and the softened material is pushed axially under the action of the feeding mechanism. According to the relationship between the volume of the consumed rod material and the volume of the additive deposition, the axial advancement speed and the lateral movement speed are defined to meet the following conditions: SV1 = V2wha; where S is the cross-sectional area of ​​the deposited raw material; V1 is the axial advancement speed of the raw material; V2 is the lateral movement speed of the rotary extrusion deposition mold; w is the width of a single additive layer; h is the thickness of a single additive layer; a is a fixed coefficient ranging from 1 to 3. Here, the formula SV1 = V2wha is only a preferred solution of the present invention to better achieve continuous additive.

[0056] A plurality of protrusions 411 are arranged at the bottom of the rotary extrusion deposition mold 41, and the shapes of the end faces of the protrusions 411 include but are not limited to: plane, pointed, threaded, hemispherical, etc. The protrusions 411 are conducive to driving the deposition material to rub against the surface of the steel component at high speed and instantaneously, promoting the plastic flow of the deposition material during processing, reducing the distortion of the forming interface and the cold lap defects, obtaining a deposition layer with continuous thickness, and forming a nano-amorphous transition layer at the aluminum-steel connection interface to achieve connection.

[0057] The rotating extrusion deposition mold moves along the planned processing path. During the processing, the protrusion 411 (the lower end surface of the protrusion) of the rotating extrusion deposition mold 41 does not contact the steel component 1, and the distance is 0.01-1.50mm, preferably 0.1-0.60mm. The height of the protrusion 411 can be appropriately adjusted according to the change in the thickness of the deposition layer.

[0058] The material in the viscoplastic rheological state is extruded from the mouth of the rotating extrusion deposition die and deposited on the surface of steel components of various structural forms such as plates, profiles or pipes; in order to achieve a deposition height that meets the use requirements, after the first deposition layer is formed on the surface of the steel component, the rotating deposition die moves along a predetermined path, and deposits layer by layer to obtain an aluminum component of the required structural height. At this time, the interlayer spacing is less than or equal to the height of the protrusion 411, and the protrusion 411 plays the role of interlayer stirring, driving the flow of interlayer materials, promoting the effect of interlayer bonding, and realizing the improvement of the strength of the aluminum component.

[0059] Here, the preparation method of the above-mentioned aluminum-steel heterogeneous parts is described as follows:

[0060] (1) The sealing of dissimilar metal components prepared by the traditional dissimilar metal connection process is insufficient, the interface contains coarse intermetallic compounds, and the interface bonding strength is low, the joint cracking and other problems directly affect the performance of the joint. Different from the prior art, the present invention uses the friction extrusion deposition additive manufacturing process, through the rotating extrusion deposition mold, to drive the aluminum alloy and steel to rub at high speed and instantaneously, which can introduce a nano-amorphous transition layer at the aluminum-steel interface, avoid the formation of a hard and brittle intermetallic compound layer, and significantly improve the tensile strength of the aluminum-steel interface.

[0061] (2) The traditional aluminum-steel connection process has poor controllability, unstable quality, and high production costs, and cannot meet the dual requirements of economy and practicality of dissimilar metal components. Different from the prior art, the present invention adopts a friction extrusion deposition additive process to prepare aluminum-steel components. The high-speed rotating extrusion deposition mold rubs against the raw materials to perform a local active softening treatment process, so that the local area remains in a hot plastic state, improves the fluidity of the deposited material, and is extruded through the mold opening to deposit at the target position. The deposition process is controllable and the quality is stable. Continuous and large-scale production can be achieved, which improves production efficiency and reduces production costs. Here, the friction extrusion deposition additive manufacturing process adopted by the present invention can quickly and inexpensively manufacture aluminum-steel components of different shapes through deposition path setting, meet personalized customization needs and are not limited in size, and achieve economical and reasonable printing production purposes.

[0062] The present invention is further described below by specific experimental examples:

[0063] Example 1

[0064] This embodiment adopts a friction extrusion deposition method to prepare an aluminum-steel heterogeneous part, which mainly includes the following steps:

[0065] Step 1): The surface of a steel plate (i.e., a steel component) with a length of 300 mm, a width of 100 mm, and a thickness of 6 mm to be deposited is mechanically polished, cleaned, and dried to reduce the surface roughness to Ra0.05, and the fixing work is completed by fixing components.

[0066] Step 2): Figure 1 As shown, a protrusion 411 with a height of 2 mm is added to the bottom 412 of the rotary extrusion deposition mold 41. At the same time, the distance d between the protrusion of the rotary extrusion deposition mold 41 (the lower end surface of the protrusion) and the surface of the steel plate (i.e., the steel component 1) is set to 0.6 mm (at this time, the interlayer spacing, i.e., the height of the bottom 412 of the rotary extrusion mold 41 from the steel plate is 2.6 mm).

[0067] Step 3): Figure 1 As shown, the cross-sectional area is 40mm 2The 5083 aluminum alloy bar is used as the raw material 3 and fed into the non-rotating feeding chamber 42. Under the action of the feeding mechanism 43, the raw material 3 is fed to the high-speed rotating rotary extrusion deposition mold 41, and high-speed friction occurs between the raw material 3 and the inner bottom surface 413 of the rotary extrusion deposition mold 41, so that the raw material near the rotary extrusion deposition mold 41 reaches a viscoplastic rheological state due to friction and deformation heat. The softened material is pushed axially by the feeding mechanism, extruded from the extrusion port and deposited on the surface of the steel plate to form the first deposition layer 21. Among them, the process parameters for depositing the first deposition layer 21 are set as follows: the rotation speed of the rotary extrusion deposition mold, the axial advancement speed V1 of the raw material and the lateral movement speed V2 of the rotary extrusion deposition mold are 150rpm, 45mm / min and 20mm / min respectively. The additive layer width is expected to be 25mm, and the selected additive parameters satisfy SV1=V2wha, (a=1.38). Among them, if Figure 1 As shown, for the first deposition layer, the thickness h of a single additive layer is 2.6 mm.

[0068] Step 4): Figure 2 As shown, in order to achieve a deposition height that meets the use requirements, the material in the viscoplastic rheological state is deposited continuously layer by layer. At this time, the rotation speed of the rotary extrusion deposition mold, the axial propulsion speed V1 of the raw material, and the lateral movement speed V2 of the rotary extrusion deposition mold are adjusted to 200rpm, 40mm / min, and 25mm / min, respectively, and the selected additive parameters satisfy SV1=V2wha, (a=1.70). Among them, the interlayer spacing of the finally prepared deposition layer 2 is reduced to 1.5mm (here, the thickness h of the single additive layer of other layers except the first deposition layer is 1.5mm). Deposition layer 2 forms an aluminum component. Finally, aluminum-steel heterogeneous parts are obtained.

[0069] The connection interface of the aluminum-steel dissimilar parts prepared in this embodiment is as follows Figure 3 As shown in the figure, due to the selected aluminum-steel interface additive parameters and the distance between the protrusion and the steel plate surface (0.6mm), the raw material is subjected to friction and deformation heat to reach a viscoplastic rheological state and is extruded from the extrusion hole and deposited on the steel plate surface. The protrusion drives the extruded material to rub against the steel plate surface at high speed and instantaneously, and introduces a nano-amorphous transition layer at the aluminum-steel interface, thereby avoiding the formation of a hard and brittle intermetallic compound layer. The thickness of the nano-amorphous transition layer is less than 600nm. Large-scale complex three-dimensional components are obtained by layer-by-layer deposition. The protrusion drives the flow of interlayer materials and promotes the dense bonding between layers.

[0070] Figure 4 This is a physical picture of an aluminum-steel heterogeneous part prepared in Example 1 of the present invention. It can be seen that the aluminum-steel heterogeneous part can be successfully prepared by adopting the scheme of the present invention. Figure 5This is a cross-sectional microstructure morphology diagram of the aluminum-steel dissimilar component in Example 1 of the present invention. It can be seen that the aluminum component has good interlayer bonding and no groove or hole defects.

[0071] The samples of the aluminum-steel dissimilar parts prepared in this embodiment were subjected to tensile tests, as follows: The tensile test was performed perpendicular to the aluminum-steel interface and it was found that the sample fracture occurred in the aluminum alloy rather than at the aluminum-steel interface, and the tensile strength reached 280 MPa.

[0072] Example 2

[0073] This embodiment adopts the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part, and the main difference from the embodiment 1 is:

[0074] In step 1): the surface roughness of the steel plate is reduced to Ra1.6.

[0075] In step 2), the height of the protrusion is 1.9 mm. At the same time, the distance between the protrusion of the rotary extrusion deposition die (the lower end surface of the protrusion) and the surface of the steel plate is set to 0.1 mm (at this time, the interlayer spacing, i.e., the height between the bottom of the rotary extrusion die and the steel plate is 2.0 mm). The raw material is replaced with 7075 aluminum alloy rod.

[0076] In step 3), the rotation speed of the rotary extrusion deposition mold, the axial advancement speed V1 of the raw material, and the lateral movement speed V2 of the rotary extrusion deposition mold are 800 rpm, 35 mm / min, and 20 mm / min, respectively, and the selected additive parameters satisfy SV1=V2wha, (a=1.4). Figure 1 As shown, for the first deposition layer, the thickness h of a single additive layer is 2.0 mm.

[0077] In step 4): the spacing of continuously deposited additive layers is adjusted to 1.0 mm (here, the thickness of a single additive layer other than the first deposited layer is 1 mm), the rotation speed of the rotary extrusion deposition mold, the axial advancement speed V1 of the raw material and the lateral movement speed V2 of the rotary extrusion deposition mold are adjusted to 600 rpm, 30 mm / min and 20 mm / min respectively, and the selected additive parameters satisfy SV1=V2wha, (a=2.4).

[0078] The other steps and parameters are the same as those in Example 1.

[0079] Among them, the first layer spacing of the aluminum-steel interface selected in this embodiment meets the process margin requirement, and the aluminum-steel dissimilar parts prepared in this embodiment form a nano-amorphous transition layer at the aluminum-steel interface.

[0080] In addition, through tensile testing, the tensile strength of the aluminum-steel dissimilar parts prepared in this embodiment along the height direction of the additive is up to 230 MPa.

[0081] Example 3

[0082] This embodiment adopts the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part, and the main difference from the embodiment 1 is:

[0083] In step 1): the surface roughness of the steel plate is reduced to Ra3.2;

[0084] In step 2), the height of the protrusion is 0.5 mm. At the same time, the distance between the lower end surface of the protrusion of the rotary extrusion deposition mold and the surface of the steel plate is set to 1.5 mm (at this time, the interlayer spacing, i.e., the height between the bottom of the rotary extrusion mold 41 and the steel plate is 2.0 mm).

[0085] In step 3), the raw material is replaced with 6061 aluminum alloy. The rotation speed of the rotary extrusion deposition mold, the axial advancement speed V1 of the raw material, and the lateral movement speed V2 of the rotary extrusion deposition mold are 1000 rpm, 50 mm / min, and 30 mm / min, respectively. The selected additive parameters satisfy SV1=V2wha, (a=1.33). Figure 1 As shown, for the first deposition layer, the thickness h of a single additive layer is 2.0 mm.

[0086] In step 4): the spacing between continuously deposited additive layers is adjusted to 0.5 mm (here, the thickness of a single additive layer other than the first deposited layer is 0.5 mm). At this time, the rotation speed, axial advancement speed V1 and lateral movement speed V2 of the rotary extrusion deposition mold are adjusted to 1000 rpm, 30 mm / min and 45 mm / min respectively. The selected additive parameters satisfy SV1=V2wha, (a=2.13).

[0087] The other steps and parameters are the same as those in Example 1.

[0088] Among them, the first layer spacing of the aluminum-steel interface selected in this embodiment meets the process margin requirement, and the aluminum-steel dissimilar parts prepared in this embodiment form a nano transition layer at the aluminum-steel interface.

[0089] In addition, through tensile testing, the tensile strength of the aluminum-steel dissimilar parts prepared in this embodiment along the height direction of the additive is up to 180 MPa.

[0090] Example 4

[0091] This embodiment adopts the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part, and the main difference from the embodiment 1 is:

[0092] In step 2): the distance between the lower end surface of the protrusion of the rotary extrusion deposition mold and the surface of the steel plate is set to 0.01 mm.

[0093] In step 3): the rotation speed of the rotary extrusion die is 100 rpm.

[0094] Among them, the first layer spacing of the aluminum-steel interface selected in this embodiment meets the process margin requirement, and the aluminum-steel dissimilar parts prepared in this embodiment form a nano transition layer at the aluminum-steel interface.

[0095] The other steps and parameters are the same as those in Example 1.

[0096] In addition, according to the tensile test, the tensile strength of the aluminum-steel dissimilar parts prepared in this embodiment along the height direction of the additive material is 270MPa. However, due to the small distance between the lower end surface of the protrusion and the surface of the steel plate, it is easily affected by the surface parallelism of the plate surface and the influence of the operating equipment (such as the error of the deposition tool), and the operation is difficult.

[0097] Example 5

[0098] This embodiment adopts the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part, and the main difference from the embodiment 1 is:

[0099] In step 3): the rotation speed of the rotary extrusion die is 50 rpm.

[0100] Among them, the first layer spacing of the aluminum-steel interface selected in this embodiment meets the process margin requirement, and the aluminum-steel dissimilar parts prepared in this embodiment form a nano transition layer at the aluminum-steel interface.

[0101] The other steps and parameters are the same as those in Example 1.

[0102] In addition, after tensile testing, the tensile strength of the aluminum-steel dissimilar parts prepared in this embodiment along the height direction of the additive is up to 270 MPa. However, due to the low rotation speed of the rotary extrusion die, there is a risk of insufficient heat generation, and the molding quality will deteriorate.

[0103] Comparative Example 1

[0104] Comparative Example 1 uses a friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 1 and Example 1 are:

[0105] In step 1), the surface of the steel plate is mechanically polished, cleaned, and dried to reduce the surface roughness to Ra6.3.

[0106] The other steps are the same as those in Example 1.

[0107] Here, due to the large surface roughness of the steel plate, an effective nano-amorphous transition layer cannot be formed. Along the height direction of the additive, some tensile specimens break at the aluminum-steel interface, and the tensile strength is lower than 140 MPa.

[0108] Comparative Example 2

[0109] Comparative Example 2 uses the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 2 and Example 1 are:

[0110] In step 2), the height of the protrusion added to the lower end surface of the rotary extrusion deposition mold is 5 mm.

[0111] The other steps are the same as those in Example 1.

[0112] In Comparative Example 2, since the height of the protrusions is too high, the deposition spacing is set too large, resulting in the material extruded from the opening of the mold being too cold during deposition, and a continuous deposition layer cannot be formed, resulting in defects such as grooves and tunnels.

[0113] Comparative Example 3

[0114] Comparative Example 3 uses the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 3 and Example 1 are:

[0115] In step 2), the distance between the lower end surface of the protrusion of the rotary extrusion deposition mold and the surface of the steel plate is set to 1.6 mm.

[0116] The other steps are the same as those in Example 1.

[0117] In Comparative Example 3, since the distance between the lower end surface of the protrusion and the steel plate is too large, it cannot effectively drive the high-speed and instantaneous friction between the aluminum alloy and the steel, and thus a sufficient and effective nano-amorphous transition layer cannot be formed at the aluminum-steel interface. Along the height direction of the additive, the tensile part breaks at the aluminum-steel interface, and the tensile strength is less than 80 MPa.

[0118] Comparative Example 4

[0119] Comparative Example 4 uses the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 4 and Example 1 are:

[0120] In step 2): the lower end of the protrusion of the rotary extrusion deposition mold is set to be inserted into the steel plate by 0.1 mm.

[0121] The other steps are the same as those in Example 1.

[0122] In Comparative Example 4, since the protrusions are inserted into the steel plate, under the combined effects of heat and severe plastic deformation, the steel particles react with the deposited aluminum matrix to form hard and brittle intermetallic compounds at the interface. Along the height direction of the additive, the tensile part breaks at the aluminum-steel interface, and the tensile strength is less than 60 MPa.

[0123] Comparative Example 5

[0124] Comparative Example 5 uses the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 5 and Example 1 are:

[0125] In step 3): the rotation speed of the rotary extrusion deposition mold is 40 rpm.

[0126] The other steps are the same as those in Example 1.

[0127] Here, in Comparative Example 5, when depositing the first deposition layer, a nano-amorphous transition layer is formed at the aluminum-steel interface. However, since the rotation speed of the rotary extrusion deposition mold is too low, the heat generation is insufficient, the material fluidity is poor, and intra-layer defects are prone to occur, resulting in low elongation of the aluminum-steel tensile part.

[0128] Comparative Example 6

[0129] Comparative Example 6 uses the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 6 and Example 1 are:

[0130] In step 3: the axial advancement speed V1 of the raw material and the lateral movement speed V2 of the rotating extrusion deposition mold are 90 mm / min and 15 mm / min respectively.

[0131] The other steps are the same as those in Example 1.

[0132] Compared with Example 1, since the additive parameters selected in Example 6 do not satisfy SV1=V2wha, (a=1-3), the material can maintain basic molding, but too much material is fed, the deposition layer is spread too wide, and the edges cannot form an effective bond, resulting in partial waste of material.

[0133] Comparative Example 7

[0134] Comparative Example 7 uses the friction extrusion deposition method to prepare an aluminum-steel heterogeneous part. The main differences between Comparative Example 7 and Example 1 are:

[0135] In step 4): the interlayer spacing between the deposited layers is set to 2.5 mm (the interlayer spacing, ie, the height from the bottom of the rotary extrusion die 41 to the aluminum alloy layer is 2.5 mm).

[0136] The other steps are the same as those in Example 1.

[0137] Here, since the protrusions of comparative example 7 do not perform interlayer stirring and drive the flow of interlayer materials, the effect of promoting interlayer bonding is achieved. Along the height direction of the additive, the tensile part breaks on the aluminum side, and the tensile strength is less than 100 MPa.

[0138] In summary, by comparing the above embodiments and comparative examples, it can be known that according to the large-sized aluminum-steel dissimilar parts prepared by the friction extrusion deposition additive method of the present invention, along the additive height direction, the tensile parts break on the aluminum side, and the bonding strength is greater than 150MPa. Furthermore, the present invention pre-treats the steel plate, and through reasonable rotary extrusion deposition mold design and deposition spacing control, the protrusion drives the softened aluminum alloy and steel to rub at high speed and instantaneously, which can introduce a nano-amorphous transition layer at the aluminum-steel interface, avoid the formation of a hard and brittle intermetallic compound layer, and significantly improve the tensile strength of the aluminum-steel interface. Subsequently, large-sized complex aluminum-steel dissimilar parts are obtained by layer-by-layer deposition.

[0139] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing aluminum-steel heterogeneous parts, characterized in that: An aluminum component with a set structure is deposited on a steel component by a friction extrusion deposition method to achieve aluminum-steel interface connection and obtain an aluminum-steel heterogeneous component; wherein the aluminum component is made of aluminum or aluminum alloy.

2. The method for preparing aluminum-steel heterogeneous parts according to claim 1, characterized in that: The preparation method comprises the following steps: Pretreatment step: surface pretreatment of steel components; Friction extrusion deposition step: using a friction extrusion deposition device to extrude the softened raw material and deposit it on the surface of the steel component according to a set trajectory to form a first deposition layer; Then, aluminum components with a set structure are deposited on the steel components layer by layer to obtain aluminum-steel heterogeneous parts.

3. The method for preparing aluminum-steel heterogeneous parts according to claim 2, characterized in that: The pretreatment step includes: polishing, cleaning and drying the surface of the steel component; wherein the polishing is selected from any one of mechanical polishing, electrolytic polishing and chemical polishing, preferably mechanical polishing; and / or After the pretreatment step, the surface roughness of the steel component is lower than Ra3.

2.

4. The method for preparing aluminum-steel heterogeneous parts according to claim 2 or 3, characterized in that: A transition layer is formed at the connection interface between the first deposition layer and the steel component; wherein the transition layer is a nano-amorphous transition layer with a thickness of ≤600nm; preferably, atoms in the nano-amorphous transition layer are arranged in a long-range disordered state.

5. The method for preparing aluminum-steel heterogeneous parts according to any one of claims 2 to 4, characterized in that: The friction extrusion deposition device comprises: A rotary extrusion die is provided with an extrusion port at the bottom thereof, wherein the extrusion port is communicated with the interior of the rotary extrusion die and is used for extruding the softened raw material.

6. The method for preparing aluminum-steel heterogeneous parts according to claim 5, characterized in that: The bottom of the rotary extrusion die is connected with one or more protrusions; Preferably, the height of the protrusion is less than 3.0 mm; Preferably, in the friction extrusion deposition step: when depositing the first deposition layer, the distance between the bottom of the rotary extrusion die and the surface of the steel component is greater than the height of the protrusion, so as to ensure that the protrusion will not be inserted into the steel plate to avoid the formation of a large amount of intermetallic compounds; preferably, the distance between the protrusion and the surface of the steel component is 0.01-1.50 mm, preferably 0.1-0.60 mm, so that an amorphous transition layer is formed at the connection interface between the first deposition layer and the steel component during friction extrusion deposition; Preferably, in the friction extrusion deposition step: after depositing the first deposition layer, the interlayer spacing between the deposition layers is ≤ the height of the protrusion, so as to ensure that the protrusion can achieve mechanical stirring between the aluminum or aluminum alloy deposition layers, thereby improving the material strength of the aluminum component.

7. The method for preparing aluminum-steel heterogeneous parts according to claim 5 or 6, characterized in that: The friction extrusion deposition device also includes: A feeding cavity, the feeding cavity is used to feed the raw material into the rotary extrusion die; A feeding mechanism, the feeding mechanism is used to apply an axial thrust to the raw material in the feeding cavity, so as to gradually push the raw material from the feeding cavity to the inner bottom surface of the rotary extrusion die, and friction cutting occurs, and the softened material is extruded from the extrusion port; Preferably, the feeding cavity is a hollow cavity with two ends open; The top of the rotary extrusion die is open; One end of the feeding cavity extends from the opening of the rotary extrusion die into the rotary extrusion die; the feeding mechanism extends from the other end of the feeding cavity into the feeding cavity to apply thrust to the raw material.

8. The method for preparing aluminum-steel heterogeneous parts according to any one of claims 2 to 7, characterized in that: In the friction extrusion deposition step: The raw material is fed into a feeding chamber of a friction extrusion deposition device; the raw material is fed into a rotary extrusion deposition mold under the action of a feeding mechanism; wherein, in the rotary extrusion deposition mold, friction occurs between the raw material and an inner bottom surface of the rotary extrusion deposition mold, resulting in local softening; wherein, the softened material is pushed axially under the action of the feeding mechanism, extruded from an extrusion port of the rotary extrusion deposition mold, and deposited layer by layer on a steel component according to a set trajectory.

9. The method for preparing aluminum-steel heterogeneous parts according to claim 8, characterized in that: The rotation speed of the rotary extrusion deposition mold is ≥50 rpm, preferably 150-1000 rpm; Preferably, in the friction extrusion deposition step, the following conditions must be met: SV1 = V2wha; Among them, S is the cross-sectional area of ​​the deposited raw material; V1 is the axial advancement speed of the raw material; V2 is the lateral movement speed of the rotary extrusion deposition mold; w is the width of a single additive layer; h is the thickness of a single additive layer; a is a fixed coefficient, and the value range is 1-3.

10. An aluminum-steel heterogeneous part, characterized in that: The aluminum-steel heterogeneous component is composed of an aluminum component and a steel component; wherein the material of the aluminum component is aluminum or aluminum alloy; wherein a nano-amorphous transition layer is formed at the connection interface between the aluminum component and the steel component; Preferably, the aluminum-steel heterogeneous parts are prepared by the method for preparing aluminum-steel heterogeneous parts according to any one of claims 1 to 9; Preferably, in the aluminum-steel dissimilar parts: the interface bonding strength between the steel component and the aluminum component is greater than 150 MPa.

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