Abstract: Bonding technology has been widely used in the connection of components in the aerospace field, and the use of surface treatment technology can effectively enhance the interface bonding strength. Among various surface treatment technologies, laser surface treatment technology has been widely concerned because of its flexibility and high efficiency. In this paper, five different textures of 90 °, 0 ° groove, circular array, honeycomb and mesh are processed on the surface of TC4 alloy by nanosecond laser. The influence of texture morphology with different depth and width on the bonding strength of TC4 interface is analyzed. The mapping relationship between texture morphology and shear strength is established, and the failure mechanism of different texture morphology is discussed. The results show that the micro-texture with appropriate depth makes the bonding interface form a strong mechanical interlocking nail structure. When the depth is 10 μm, the shear strength of the 90 ° groove is 8.7% higher than that of the untextured surface. With the increase of the width, the contact area increases, the interlocking structure between the binder and the substrate surface increases, and the surface energy increases, which is conducive to the formation of a good interface bonding morphology. When the width is 800 μm, the shear strength is increased by 18.2%. The different texture shapes are beneficial to reduce the interface stress concentration, deflect the crack and inhibit the crack propagation. The shear strength of mesh, honeycomb, circular array and 0° groove is increased by 20.7%, 16.3%, 14% and 5.6%, respectively. The above studies have clarified the enhancement mechanism and influence law of TC4 surface texture morphology on bonding strength, which provides process guidance and theoretical basis for improving the practical application of TC4 in aerospace field.

Key words: laser micro-texture, texture morphology, interfacial bonding strength, fracture failure, mechanical interlock