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CN-121972790-A - Stirring head for titanium alloy and fiber reinforced thermoplastic composite material and friction stir welding method

CN121972790ACN 121972790 ACN121972790 ACN 121972790ACN-121972790-A

Abstract

The invention belongs to the technical field of dissimilar material connection, and particularly relates to a stirring head for a titanium alloy and fiber reinforced thermoplastic composite material and a friction stir welding method. The stirring head is provided with a concave shaft shoulder, the stirring pin is provided with a thread groove, the conical surface is provided with a groove along the direction of a bus, and the axis of the stirring pin is not coincident with the axis of the main shaft. Before friction stir welding, ultrasonic treatment and alkali heat treatment are carried out on the titanium alloy plate, and a layer of silane film is thermoset. And after the titanium alloy plate is pretreated, friction stir lap welding is carried out by using a designed stirring head. The design of the stirring head and the pretreatment process improve the mechanical performance of the heterojunction.

Inventors

  • CHEN SIYANG
  • XU MENGJIA
  • CHEN YU
  • LIU HUA

Assignees

  • 东北大学

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. A stirring head for a titanium alloy and fiber reinforced thermoplastic composite material is characterized by comprising a main shaft and a stirring needle which are integrally formed, wherein the main shaft is a cylinder, the connecting part of the main shaft and the stirring needle is a shaft shoulder, the end face of the shaft shoulder is concave, the stirring needle is conical, a threaded groove is formed in the conical surface, the rotation direction of the threads is opposite to that of the main shaft, a groove is formed in the conical surface along the direction of a bus, and the axis of the stirring needle is not coincident with that of the main shaft, so that the eccentric effect of the stirring needle is realized.
  2. 2. The stirring head for the titanium alloy and fiber reinforced thermoplastic composite material according to claim 1, wherein the inward concave depth of the end face of the shaft shoulder is not more than 0.5mm, and the diameter of the shaft shoulder is 8-15 mm.
  3. 3. The stirring head for a titanium alloy and fiber reinforced thermoplastic composite material according to claim 1, wherein the diameter of the root of the stirring pin is 0.5-0.7 times the diameter of the shaft shoulder, and the diameter ratio of the root to the tip is 1.2-2:1.
  4. 4. The stirring head for the titanium alloy and fiber reinforced thermoplastic composite material, which is disclosed in claim 1, is characterized in that the thread pitch of the thread groove of the stirring pin is 0.1-0.3 times of the length of the stirring pin, three grooves are formed in the conical surface along the direction of a bus, the bottom surfaces of the grooves are parallel to the conical surface, and the depth of the grooves is 0.3-0.6 mm.
  5. 5. The stirring head for the titanium alloy and fiber reinforced thermoplastic composite material according to claim 1, wherein the eccentric distance between the axis of the stirring pin and the axis of the main shaft is 0.03-0.2 times the diameter of the root of the stirring pin.
  6. 6. The friction stir welding method of the stirring head for the titanium alloy and fiber reinforced thermoplastic composite material is characterized by comprising the steps of removing an oxide layer and oil stains on the surface of a titanium alloy plate, carrying out ultrasonic cleaning on the titanium alloy plate and the fiber reinforced thermoplastic composite material plate, then treating the titanium alloy plate in a hot alkaline solution to enable micro-nano holes to appear on the surface of the titanium alloy plate, spraying a silane solution on the welding surface of the titanium alloy plate, overlapping the welding surface of the titanium alloy plate with the fiber reinforced thermoplastic composite material plate after solidification, and carrying out friction stir welding treatment.
  7. 7. The friction stir welding method of a stirring head for a titanium alloy and fiber reinforced thermoplastic composite material according to claim 6, wherein the treatment in a hot alkaline solution is immersing a titanium alloy plate in a NaOH solution, and the temperature is kept at 30-40 ℃ for 24 hours.
  8. 8. The friction stir welding method for a stirring head of a titanium alloy and fiber reinforced thermoplastic composite material according to claim 6, wherein the preparation method of the silane solution is characterized by mixing silane, distilled water and ethanol in a mass ratio of 10:1:90, stirring at room temperature, and hydrolyzing the silane to obtain the silane solution; The silane comprises KH230, KH550 and NQ54, and after spraying a silane solution, the temperature is kept at 100-120 ℃ for 1h, and curing is carried out.
  9. 9. The friction stir welding method for the stirring head of the titanium alloy and fiber reinforced thermoplastic composite material, which is disclosed in claim 6, is characterized in that when friction stir lap welding is carried out, the upper plate is a titanium alloy plate, the lower plate is a fiber reinforced thermoplastic composite material plate, the included angle between the stirring head and the titanium alloy plate is 88-90 degrees, the thickness of the titanium alloy plate is 2-8 mm, the sum of the thicknesses of the upper plate and the lower plate is not more than 12mm, and the length of a stirring pin is 0.1-0.8 mm shorter than the thickness of the titanium alloy plate.
  10. 10. The friction stir welding method of the stirring head for the titanium alloy and fiber reinforced thermoplastic composite material, which is characterized in that when friction stir lap welding is carried out, the advancing speed of a main shaft is 5 mm/min-1000 mm/min, the rotating speed is not more than 6000r/min, and inert gas is continuously introduced in the welding process to protect the surface of a welding line from being oxidized.

Description

Stirring head for titanium alloy and fiber reinforced thermoplastic composite material and friction stir welding method Technical Field The invention belongs to the technical field of dissimilar material connection, and particularly relates to a stirring head for a titanium alloy and fiber reinforced thermoplastic composite material and a friction stir welding method. Background The fiber reinforced thermoplastic composite material consists of fibers, a thermoplastic material matrix and an interfacial phase of the fibers and the thermoplastic material matrix, and has excellent specific strength, corrosion resistance and other excellent properties, so that the fiber reinforced thermoplastic composite material is widely applied to the fields of aerospace, automobile engineering and the like. Titanium alloys have excellent fracture toughness and low weight, and are attracting attention in the aerospace industry. At present, the joint of titanium alloy and fiber reinforced thermoplastic composite material is widely applied to aviation equipment so as to achieve the aim of realizing the light weight of the equipment. But the significant difference in thermo-physical properties presents a significant challenge for the joining of two materials. The connection modes commonly used at present comprise gluing, laser welding, ultrasonic welding, mechanical connection and the like. However, the bonding method has problems of low joint strength, poor performance reproducibility, and the like. The cost of laser welding is high. And the mechanical connection can introduce defects at the joint, so that stress concentration is caused, and meanwhile, extra weight is added, so that strict requirements on materials in the aerospace field are difficult to meet. Friction Stir Welding (FSW) is a new welding technique that has been rapidly developed in the industry because of its significant advantages such as high joint quality, small welding distortion, and environmental protection. Friction stir welding for metal and fiber reinforced thermoplastic composites has been widely studied. However, the joint of the metal and the fiber reinforced thermoplastic composite material obtained by welding by using the friction stir welding method has the problems of poor weld morphology, low strength and the like, and the problems are not solved at present. There is a large margin for friction stir welding studies of this portion of titanium alloys and composites. It is therefore important to find a welding tool and a welding method to achieve a high strength connection at the joint of titanium alloy and fiber reinforced thermoplastic composite. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a friction stir welding method and a special stirring head so as to realize a high-strength solid phase welding method of a titanium alloy and fiber reinforced thermoplastic composite material. The stirring head structure is designed to optimize the surface morphology of the welding line, avoid the defects of pores and the like in the joint, and simultaneously realize mechanical interlocking and chemical combination of interfaces by designing a pretreatment process so as to obtain the high-strength dissimilar material connecting joint. The special stirring head for the titanium alloy and fiber reinforced thermoplastic composite material comprises a main shaft and a stirring needle which are integrally formed, wherein the main shaft is a cylinder, the connecting part of the main shaft and the stirring needle is a shaft shoulder, the end face of the shaft shoulder is concave, the stirring needle is conical, a threaded groove is formed in the conical surface, the rotation direction of the threads is opposite to that of the main shaft, a groove is formed in the conical surface along the direction of a bus, and the axis of the stirring needle is not coincident with that of the main shaft, so that the eccentric effect of the stirring needle is realized. The material of the stirring head is tungsten-rhenium alloy. The concave depth of the shaft shoulder end surface of the stirring head is not more than 0.5mm, the diameter of the shaft shoulder is 8 mm-15 mm. The diameter of the root of the stirring pin is 0.5-0.7 times of the diameter of the shaft shoulder, and the diameter ratio of the root to the tip is 1.2-2:1. The screw pitch of the screw groove of the stirring pin is 0.1-0.3 times of the length of the stirring pin, three grooves are formed in the conical surface along the direction of a bus, the bottom surfaces of the grooves are parallel to the conical surface, and the depth of the grooves is 0.3-0.6 mm. The eccentric distance between the axis of the stirring pin and the axis of the main shaft is 0.03-0.2 times of the diameter of the root of the stirring pin. Removing an oxide layer and oil stains on the surface of a titanium alloy plate, cleaning the titanium alloy plate and the fiber reinforced thermoplastic compos