Mechanical rotary semi-solid welding method of aluminum alloy and its composite materials in atmospheric environment

Abstract

The invention relates to a mechanical rotation semi-solid welding method for an aluminum alloy and a composite material thereof in an atmospheric environment, which comprises the following steps of: clamping the aluminum alloy and a composite material weldment thereof on a fixture, putting intermediate temperature solders such as Zn-Al and the like on two surfaces to be welded, heating the weldment at the temperature of between 400 and 480 DEG C, and applying pressure of 0.1 to 2MPa to make the solder in an intermediate layer positioned in a semi-solid state; starting a rotating device, rotating at a speed of 65 to 1,500r / min for 10 to 300 seconds, and keeping the temperature constant in the rotating process; raising the temperature at a certain heating rate after rotation is stopped, andpreserving heat at the predetermined temperature of between 480 and 520 DEG C for 1 to 5 minutes to make the solder dissolve parent metal with certain thickness; and applying pressure of 0.1 to 1MPa,starting the rotating device again, rotating for the second time at a speed of 65 to 600r / min for 3 to 60 seconds, stopping rotation, preserving heat for 1 to 30 minutes, and cooling with a furnace. By the method, the aluminum alloy and the composite material thereof can be efficiently and economically connected at high quality.

Description

technical field [0001] The invention relates to a welding method for aluminum alloy and aluminum matrix composite material. Background technique [0002] Aluminum matrix composites stand out for their outstanding advantages such as low cost, easy preparation, good wear resistance, strong designability of performance and functions, etc., and become the mainstream of research on metal matrix composites. It has broad application prospects in thermal and wear-resistant parts, and is considered to be one of the most promising composite materials in the 21st century. However, if aluminum-based composite materials are to be further popularized and applied in aerospace, weaponry and civilian products, it is necessary to solve the problem of secondary processing technology, especially the connection technology of some complex components is far behind the research of other technologies. Therefore, it is very necessary to deeply study the scientific problems in the welding of aluminum...

AI Technical Summary

Problems solved by technology

[0007] (1) Physical compatibility problem: Part of the solid SiC and other reinforcing phases in the liquid molten pool seriously affect the heat transfer and mass transfer process in the molten pool, making the molten pool exhibit high viscosity and poor flow. The sensitivity to defects such as fusion and incomplete penetration is high; it is difficult to mix the aluminum-based composite material and the filling material in the molten pool evenly, and the dilution rate is low, and the molding is difficult; at the same time, the segregation of the reinforcing phase when the liquid metal solidifies destroys it. The original distribution characteristics deteriorate the performance of the joint; in addition, due to the large difference in the linear expansion coefficient between the reinforcing phase and the matrix, a large internal stress will remain in the joint during the heating and cooling process of welding, requiring further heat treatment

[0008] (2) Chemical compatibility problem: Some reinforcing phases (such as SiC) and the matrix Al are thermodynamically unstable in a large temperature range, and harmful interfacial reactions are inevitable at the high temperature of fusion welding

[0012] (2) The melting points of the aluminum alloy matrix and the reinforcing phase (such as SiC) are very different, and the reinforcing body does not melt at the brazing temperature, resulting in poor fluidity of the solder. Wetting and spreading are seriously hindered; adding some alloy elements and increasing the brazing temperature can be improved to some extent, but too high a temperature can easily cause overburning and erosion of the base metal, which brings great difficulties to the brazing process

[0020] While instantaneous liquid phase welding has more advantages, it also has some disadvantages: (1) The segregation of the reinforcing phase has become the main problem of TLP welding of this material

(2) The instantaneous liquid phase welding temperature generally exceeds 550°C, and the base metal will soften to varying degrees

However, at present, a large number of welding work of aluminum matrix composite materials is still carried out in the laboratory, and the TLP welding process with more practical application significance still needs to make further efforts

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