Aluminium base composite material ultra sonic electrical resistance welding method

Abstract

An ultrasonic-resistance welding method for the Al-based composition includes grinding the surfaces of Al-based compositions, ultrasonic cleaning, putting the flux between two surfaces to be welded, heating by electric resistance, decreasing the thickness of liquid film between two surfaces, ultrasonic vibrating, pressing and natural cooling.

Description

Technical field: [0001] The invention relates to a welding process of a metal matrix composite material, in particular to an ultrasonic-resistance welding process of an aluminum matrix composite material. Background technique: [0002] Metal matrix composites have the characteristics of specific strength, high specific stiffness, wear resistance, creep resistance, small thermal expansion coefficient, and good high temperature performance. They have been widely used in aerospace and defense fields, such as missiles, tanks, armored vehicles, etc. Wide range of applications, such as automotive engine pistons, connecting rod brakes and bicycle parts, etc. Since composite materials are composed of metal and non-metal materials with very different components, structures and properties, usually the physical and chemical compatibility between them is poor, so special and complicated processes are required in the manufacturing process. , which brings great difficulties to the subseq...

AI Technical Summary

Problems solved by technology

These welding wires and welding processes are very successful in welding aluminum alloys, but when they are applied to the welding of aluminum matrix composites, they face the following urgent problems: On the one hand, from the perspective of physical compatibility, aluminum matrix composites There is a large difference between the melting point of the material matrix and the reinforcing phase, and there is a large amount of unmelted reinforcing phase in the molten pool, which makes its fluidity worse, which will lead to defects such as pores, incomplete penetration and incomplete fusion; in addition, solidification in the molten pool During the process, the particles of the unmelted reinforcement phase concentrate and segregate at the solidification front, destroying the original distribution characteristics and deteriorating the performance. More importantly, in terms of chemical compatibility, the high temperature generated by fusion welding makes the relationship between the matrix and the reinforcement phase The following interface reactions are prone to occur: or , resulting in burning loss of the reinforced phase, and the reaction product Al 4 C 3 It is a brittle phase that seriously reduces the mechanical properties and crack resistance of the weld. It can react with water to release CH in an aqueous environment. 4 Gas, causing joint low stress failure

[0008] (2) Improper control of the welding process will lead to the melting of the matrix, and the enhanced phase segregation in the diffusion zone; no enhanced phase layer remains in the brazing seam structure, which cannot maintain the original special structure and special properties of the base metal

This is not suitable for occasions where joints have special performance requirements, such as joints that need to maintain good anti-damping characteristics and dimensional stability, etc.

[0009] (3) The melting points of the aluminum alloy matrix and the reinforcement phase are very different. At the brazing temperature, the matrix part melts, but the reinforcement does not melt, resulting in stickiness of the brazing filler metal, poor fluidity, and wetting of the brazing filler metal on the base metal. Spreading is seriously hindered by the presence of solid reinforcement phase, adding some alloying elements and increasing the brazing temperature can be improved to some extent, but the temperature is too high and it is easy to cause overburning and erosion of the base metal, which brings a negative impact on the brazing process. come very difficult

[0013] (2) In the absence of an intermediate layer, there is a phenomenon of direct contact between the reinforcement phase and the reinforcement phase on the contact surface of the aluminum matrix composite material, and it is difficult to realize the diffusion connection between the reinforcement phases under the diffusion welding condition

However, the joint is still prone to non-reinforced phase regions, and the quality of the joint is not stable enough

[0015] (4) In addition, this method has disadvantages such as long welding cycle, expensive equipment, high cost, and limited size and shape of weldments, which limits its wide application

[0018] (2) The instantaneous liquid phase welding temperature generally exceeds 550°C. At this temperature, the base metal will soften to varying degrees, which is a challenge for the composite material matrix

However, due to the great pressure exerted by friction welding, the energy consumption is large, the deformation of the test piece is large, and the joint form is relatively simple.

When using soft soldering, the temperature can be very low, but the joint strength is also low

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