CN112025073B - Method for improving mechanical property of laminated armor aluminum alloy friction stir welding joint - Google Patents

Method for improving mechanical property of laminated armor aluminum alloy friction stir welding joint Download PDF

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CN112025073B
CN112025073B CN201910476791.8A CN201910476791A CN112025073B CN 112025073 B CN112025073 B CN 112025073B CN 201910476791 A CN201910476791 A CN 201910476791A CN 112025073 B CN112025073 B CN 112025073B
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aluminum alloy
powder
groove
welding
friction stir
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CN112025073A (en
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周琦
时孝东
孙智鸣
孙宏宇
马新蕊
雷济旭
金鸣
高健
洪浩源
胡宇鹏
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Nanjing University of Science and Technology
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Nanjing University of Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
    • B23K20/24—Preliminary treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
    • B23K20/12—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding
    • B23K20/122—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding using a non-consumable tool, e.g. friction stir welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
    • B23K20/12—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding
    • B23K20/122—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding using a non-consumable tool, e.g. friction stir welding
    • B23K20/128—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding using a non-consumable tool, e.g. friction stir welding making use of additional material

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)

Abstract

The invention discloses a method for improving the mechanical property of a friction stir welding joint of laminated armor aluminum alloy. The method comprises the steps of groove machining, drilling and powder filling, clamping and preheating and welding. The method provided by the invention can simply and quickly weld the laminated armor aluminum alloy friction stir welding joint sample, and obviously improve the mechanical property of the laminated armor aluminum alloy friction stir welding joint. The method ensures that the filled reinforcing phase powder is not easy to extrude out of the welding seam, can ensure that the powder implanting hole is positioned at any position in the thickness direction of the welding seam, and can ensure that the reinforcing phase powder is distributed in the whole welding seam.

Description

Method for improving mechanical property of laminated armor aluminum alloy friction stir welding joint
Technical Field
The invention relates to the field of friction stir welding, in particular to a method for improving the mechanical property of a friction stir welding joint of laminated armor aluminum alloy.
Background
The laminated structural plate is prepared by using at least two or more materials and achieving interfacial bonding through various processing methods. The friction stir welding process is similar to forging, the texture of a weld nucleus area is refined, the strength of a welded joint is also higher, but the dimensional characteristics of a stirring needle determine the uneven heat input of the welded joint along the plate thickness direction, and the texture and the mechanical property of the welded joint along the plate thickness direction are different.
The mechanical property along the thickness direction of the welded joint shows that the tensile strength of the first layer of the laminated armor aluminum alloy is weakest, and in order to improve the tensile strength of the layer and further improve the overall mechanical property of the welded joint, a mode of opening a hole at a weld groove is adopted, and the hole is firstly plantedAdding metal elements and then carrying out friction stir welding. The method for improving the strength of the welding joint by powder-implanted friction stir welding has fine grain strengthening and solid solution strengthening. The metal powder filled into the powder planting hole is TiB2The reinforcing phase powder is an aluminum alloy reinforcer and can obviously improve the hardness of the surface of the aluminum alloy weld joint of the laminated armor.
The proper powder planting hole size is a precondition for obtaining a good welding seam, and a long-strip-shaped groove is directly processed by predecessors when powder planting welding is carried out, the groove is positioned on a welding seam central line, the groove size is smaller than 4mm (depth) multiplied by 5mm (width), but in actual welding, because the stirring head has an extrusion effect on metal powder in front of the groove, a large amount of metal powder is extruded out of the groove. Although the groove is small in size and a weld with a well-formed surface can be obtained by increasing the amount of pressing, the possibility of loose tissue at the groove still exists.
Disclosure of Invention
The invention aims to provide a method for improving the mechanical property of a laminated armor aluminum alloy friction stir welding joint, which mainly aims at solving the problem of uneven mechanical property of the laminated armor aluminum alloy friction stir welding joint in the thickness direction.
In order to realize the problems, the technical scheme adopted by the invention is as follows:
a method for improving the mechanical property of a friction stir welding joint of laminated armor aluminum alloy,
the groove machining method comprises the following steps:
1) processing a special groove on a laminated aluminum alloy plate for welding by using an edge milling machine, wherein the processed groove is divided into a convex groove and a concave groove, and the angle range is as follows: 30-45 degrees, and the width of the groove is not more than the diameter of the root part of the stirring pin. The bevel angles at the two sides of the welding seam are consistent and can be superposed. The height of the upper groove is equal to that of the lower groove.
The drilling and powder filling method comprises the following steps:
1) a powder implanting hole size design experiment is carried out by selecting Cu powder as a marking material so as to determine the size range of a well formed welding seam. The determined processing size range of the powder implanting hole is as follows: the hole depth is 1 mm-2 mm, and the hole diameter is 1 mm-2 mm; the hole depth is 3mm, and the hole diameter is 1.5 mm-2 mm; when the hole depth is 4mm, the hole diameter is 2.5 mm.
2) And drilling a hole on the bevel face of the laminated armor aluminum alloy, wherein the powder filling holes are positioned on the upper bevel face of the convex groove and the lower bevel face of the concave groove and are perpendicular to the bevel face.
3) And processing powder implanting holes on the bevel face along the welding advancing direction. The distance between the processed powder implanting hole and the surface of the welding seam can be adjusted at will and can be distributed in the thickness direction of the whole welding seam.
4) And (3) polishing by using a stainless steel wire brush, removing an oxide film at the splicing part of the laminated armor aluminum alloy, and cleaning the splicing surface by using alcohol. Using a spoon to make TiB whose grain size is less than 30 micrometers2The reinforcing phase powder fills the powder implanting holes and compacts the powder to prevent the powder from shaking off before welding.
The clamping preheating method comprises the following steps:
1) clamping and fixing the powder-filled laminated armored aluminum alloy on a workbench
2) Two poles of the resistor are respectively connected with the plate, and then the plate is preheated to 150-200 ℃ from the groove contact surface.
The welding method comprises the following steps:
1) selecting a stirring head with the size specification corresponding to the thickness of the laminated armored aluminum alloy plate.
2) And starting a welding machine and welding the laminated armor aluminum alloy plate by adopting proper welding parameters.
The mechanical properties of the invention are tensile strength and impact absorption power.
Compared with the prior art, the invention has the following advantages:
1. the method provided by the invention can simply and rapidly weld the laminated armor aluminum alloy friction stir welding joint sample, remarkably improve the mechanical property of the laminated armor aluminum alloy friction stir welding joint, and facilitate subsequent continuous deep research;
2. the method provided by the invention ensures that the filled reinforcing phase powder is not easy to extrude out of the welding seam;
3. the method provided by the invention can enable the powder implanting hole to be positioned at any position in the thickness direction of the welding seam, and can enable the reinforcing phase powder to be distributed in the whole welding seam;
4. the equipment in the method provided by the invention is common and easy to obtain, the laminated armor aluminum alloy friction stir welding joint sample can be simply and quickly welded, and the mechanical property of the laminated armor aluminum alloy friction stir welding joint is obviously improved.
Drawings
FIG. 1 is a top view of grooves and boreholes machined in the method provided by the present invention.
Fig. 2 is a schematic diagram of welding the powder filling plate by using a welding machine in the method provided by the invention.
Fig. 3 is a diagram of a real object of a weldment according to embodiment 2 of the present invention.
Detailed Description
The method for improving the mechanical property of the friction stir welding joint of the laminated armor aluminum alloy is further described in detail by combining the attached drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are all used in a non-precise ratio for the purpose of facilitating and distinctly aiding in the description of the embodiments of the invention. A
The invention aims to provide a method for improving the mechanical property of a laminated armor aluminum alloy friction stir welding joint, aiming at the problem of uneven mechanical property of the laminated armor aluminum alloy friction stir welding joint in the thickness direction.
In order to realize the problems, a special groove is firstly processed on the laminated aluminum alloy plate for welding by an edge milling machine, the processed groove is divided into a convex groove and a concave groove, and the angle range is as follows: 30-45 degrees, and the width of the groove is not more than the diameter of the root part of the stirring pin. The bevel angles at the two sides of the welding seam are consistent and can be superposed. The height of the upper groove is equal to that of the lower groove. Then, powder implanting holes are processed at the position of each layer of the lamination, and the processing size of the powder implanting holes is as follows: the hole depth is 1-2mm, and the hole diameter is 1-2 mm; the hole depth is 3mm, and the hole diameter is 1.5 mm-2 mm; when the hole depth is 4mm, the hole diameter is 2.5 mm. And then polishing by using a stainless steel wire brush, removing an oxide film at the splicing part of the laminated armor aluminum alloy, and cleaning the splicing surface by using alcohol. Then, the product is processedUsing a medicine spoon to mix TiB2The reinforcing phase powder is filled into the powder embedding holes, and the powder is compacted to prevent shaking off before welding. Then clamping and fixing the laminated armor aluminum alloy filled with the powder on a workbench, respectively connecting two electrodes of a resistor with plates, and preheating the plates to 150-200 ℃ from the groove contact surface. And finally, selecting a stirring head with the size and specification corresponding to the thickness of the laminated armor aluminum alloy plate, starting a welding machine and welding the laminated armor aluminum alloy plate by adopting proper welding parameters.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Example 1
Two 7B52 laminated armor aluminum alloy plates with the thickness of 12mm are welded in a butt joint mode by adopting a friction stir welding method, the diameter of a shaft shoulder is 24mm, the diameter of the root of a stirring pin is 12mm, and the length of the stirring pin is 12 mm. When the welding speed is 150mm/min, the rotating speed of the stirring head is 600r/min, and the preheating temperature is 150 ℃, the tensile strength obtained after welding is 350MPa, and the impact absorption work is 15.1J.
By adopting the method, a groove with an angle of 30 degrees is processed on the 7B52 laminated armor aluminum alloy with the thickness of 12mm used for welding, two rows of powder implanting holes 1 with the hole depth of 3mm and the hole diameter of 2mm are processed at the positions of the first layer and the second layer of the lamination along the advancing direction of welding, and TiB with the particle size of 20 mu m is filled2Powder is added, then two plates are respectively connected by resistors, preheating is carried out from the groove contact surface to 150 ℃, finally, the diameter of a shaft shoulder is 24mm, the diameter of the root part of a stirring pin is 12mm, the length of the stirring pin is 12mm, the welding speed is 150mm/min, the plate is welded by the rotation speed of the stirring pin being 600r/min, the tensile strength obtained after welding is 373MPa, the impact absorption power is 18.0J, and the tensile strength and the impact absorption power of the joint are obviously improved.
Example 2
Two 7B52 laminated armor aluminum alloy plates with the thickness of 16mm are welded in a butt joint mode by adopting a friction stir welding method, the diameter of a shaft shoulder is 32mm, the diameter of the root of a stirring pin is 16mm, and the length of the stirring pin is 16 mm. When the welding speed is 200mm/min, the rotating speed of the stirring head is 500r/min, and the preheating temperature is 150 ℃, the tensile strength obtained after welding is 375MPa, and the impact absorption work is 13.8J.
By adopting the method, a groove with an angle of 45 degrees is processed on the 7B52 laminated armor aluminum alloy with the thickness of 16mm used for welding, when a row of holes with the depth of 4mm are processed at the position of the first laminated layer along the advancing direction of welding, powder implanting holes with the hole diameter of 2.5mm are processed, and TiB with the grain diameter of 20 mu m is filled2And powder is added, then two plates are respectively connected by resistors, the preheating is carried out from the groove contact surface to 150 ℃, finally, the plate is welded by a stirring head with the diameter of a shaft shoulder being 32mm, the diameter of the root part of the stirring needle being 16mm and the length being 16mm, the welding speed is 200mm/min, the rotation speed of the stirring head is 500r/min, the tensile strength obtained after welding is 389MPa, and the impact absorption power is 16.8J, so that the tensile strength and the impact absorption power of the joint are obviously improved.
Example 3
Two 7B52 laminated armor aluminum alloy plates with the thickness of 20mm are welded in a butt joint mode by adopting a friction stir welding method, the diameter of a shaft shoulder is 36mm, the diameter of the root of a stirring pin is 20mm, and the length of the stirring pin is 20 mm. When the welding speed is 50mm/min, the rotating speed of the stirring head is 500r/min, and the preheating temperature is 150 ℃, the tensile strength obtained after welding is 347MPa, and the impact absorption work is 11.5J.
By adopting the method, a groove with an angle of 45 degrees is processed on the 7B52 laminated armor aluminum alloy with the thickness of 20mm used for welding, a row of powder implanting holes with the depth of 3mm and the aperture of 2mm are processed at the position of the first laminated layer along the advancing direction of welding, and TiB with the particle size of 10 mu m is filled2Powder is added, then two plates are respectively connected by resistors, preheating is carried out from the groove contact surface to 150 ℃, finally, the diameter of a shaft shoulder is 36mm, the diameter of the root of a stirring needle is 20mm, the length of the stirring head is 20mm, the welding speed is 50mm/min, the plates are welded by the stirring head at the rotating speed of 500r/min, the tensile strength obtained after welding is 361MPa, the impact absorption power is 13.9J, and the tensile strength and the impact absorption power of the joint are obviously improved.
As shown in FIG. 3, the present invention is a method for reinforcing a base material by adding aluminum to the base materialPhase TiB2The powder is used for improving the mechanical property of the laminated armor aluminum alloy friction stir welding joint. The method comprises the following steps of firstly processing a groove on a plate, and processing prefabricated holes on the upper surface of the left groove and the lower surface of the right groove of the groove. The prefabricated holes can be positioned on any layer or layers of the laminated layer or even distributed on the whole welding line by adjusting the height of the prefabricated holes from the upper surface of the plate. Then TiB2And adding the powder into the prefabricated holes of the welding seams, clamping and fixing the plate on the workbench. And finally, preheating the plate and formally welding. Compared with the prior art, the reinforcing phase powder added in the welding line can be added at any position in the height direction of the welding line, and the overflow phenomenon is completely avoided, so that the mechanical property of the laminated armor aluminum alloy friction stir welding joint can be remarkably improved.

Claims (6)

1. The method for improving the mechanical property of the friction stir welding joint of the laminated armor aluminum alloy is characterized by comprising four parts of groove machining, drilling and powder filling, clamping and preheating and welding, and comprises the following specific steps:
1) processing a groove on the laminated aluminum alloy plate for welding by using an edge milling machine;
2) selecting drilling equipment to process powder implanting holes on the grooves of the laminated armored aluminum alloy plates;
3) polishing by using a stainless steel wire brush, removing an oxide film at the splicing position of the laminated armor aluminum alloy, cleaning the splicing surface by using alcohol, filling metal powder into the processed powder planting hole, and compacting the powder;
4) clamping and fixing the powder-filled laminated armor aluminum alloy on a workbench, preheating the plate to 150-200 ℃ from the groove contact surface, selecting a stirring head with the size and the specification corresponding to the thickness of the laminated armor aluminum alloy plate, and starting a welding machine to weld the plate; the concrete steps in step 1) are that the processed groove is divided into a convex groove and a concave groove, and the angle range is as follows: 30-45 degrees, the width of the groove is not more than the diameter of the root part of the stirring pin, the angles of the grooves on two sides of the welding line are consistent and can be superposed, and the height of the upper groove is equal to that of the lower groove; in the step 2), the powder filling holes are positioned on the upper bevel face of the convex groove and the lower bevel face of the concave groove and are perpendicular to the bevel faces.
2. The method for improving the mechanical property of the friction stir welded joint of the laminated armor aluminum alloy according to claim 1, wherein in the step 2), the proper machining size range of the powder implanting hole is as follows: the hole depth is 1 mm-2 mm, and the hole diameter is 1 mm-2 mm; the hole depth is 3mm, and the hole diameter is 1.5 mm-2 mm; when the hole depth is 4mm, the hole diameter is 2.5 mm.
3. The method for improving the mechanical property of the friction stir welded joint of the laminated armor aluminum alloy according to claim 1, wherein in the step 2), the distance between the powder implanting holes processed on the welded plate and the upper surface of the weld joint can be adjusted at will and can be distributed in the thickness direction of the whole weld joint.
4. The method for improving the mechanical property of the friction stir welded joint of the laminated armor aluminum alloy according to claim 1, wherein in the step 3), the metal powder filled into the powder implanting hole is TiB2Reinforcing phase powder.
5. The method for improving the mechanical property of the friction stir welded joint of the laminated armor aluminum alloy according to claim 1, wherein in the step 3), the metal powder particle size filled in the powder implanting hole is small and should not exceed 30 μm.
6. The method for improving the mechanical property of the friction stir welded joint of the laminated armor aluminum alloy according to claim 1, wherein in the step 4), the preheating mode is resistance heating, and the electrodes are respectively connected with the two plates, so that the plates are preheated to a specified temperature from the groove contact surface.
CN201910476791.8A 2019-06-03 2019-06-03 Method for improving mechanical property of laminated armor aluminum alloy friction stir welding joint Active CN112025073B (en)

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JP2005125344A (en) * 2003-10-22 2005-05-19 Denso Corp Friction welded structure and its method
JP5151036B2 (en) * 2006-02-07 2013-02-27 株式会社日立製作所 Friction stir welding method
CN101058879A (en) * 2007-03-12 2007-10-24 兰州理工大学 Method of preparing thin crystal composite layer on magnesium alloy surface
CN104999175B (en) * 2015-08-05 2017-11-21 南昌航空大学 A kind of polytetrafluoroethylene (PTFE) that adds improves the method that mixing yoghurt prepares composite uniformity
CN106735851B (en) * 2016-12-26 2019-02-15 南京航空航天大学 Method for agitating friction connection 5mm thick steel plate
CN108817651A (en) * 2018-09-06 2018-11-16 合肥工业大学 A kind of aluminium alloy plate welding method
CN109623133B (en) * 2019-01-03 2020-11-24 南昌航空大学 Bolt-enhanced friction stir spot welding method suitable for titanium-aluminum heterogeneous material

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