A.H. Wang

Fractural behavior in the transitional region of laser-clad Al–Fe bronze on Al–Si alloy under tensile loading

Abstract The laser-clad Al–Fe bronze coating on a eutectic Al–Si alloy produced by a 2-kW CO 2 laser displays a special transitional region. The Cambridge S250MK3-type SEM equipped with a tensile stage was employed to test the bond strength and then to investigate the fracture behavior in this special transitional region. The bond strength was mainly influenced by scanning velocity, that is, an increase of scanning velocity from 6 to 14 mm s −1 resulted in a linear increase of the bond strength but the scanning velocity over 14 mm s −1 caused a sharp drop. Dynamic observations of the fractural process showed that the cracking initiated in the needle-like structure layer (i.e. CuAl 2 -rich layer) and the propagation of cracks prefer in CuAl 2 -rich layer to in the others. The reason of the influence of scanning velocity on the bond strength has been explained finally.

Cracking behavior in the transitional region of laser-clad coatings on Al–Si alloy under multiple impact loading

Abstract An experiment was designed to investigate the cracking behavior in the transitional region of laser-clad iron–base alloy and bronze coatings on an Al–Si alloy under multiple impact loading. The concept of transitional crack ratio (TCR) was introduced to evaluate the crack resistance of the transitional region to multiple impact loading (simply called impact resistance). The results showed that the microstructure of the transitional regions and the impact resistances of both types of coating were significantly influenced by laser cladding process parameters (substrate temperature for the iron–base alloy and scanning velocity for the bronze). The laser-clad iron–base alloy coatings with the highest impact resistance were obtained at substrate temperatures between 275 and 320 °C, while the equivalent laser-clad bronze coatings were produced using the scanning velocities in the range 10–12 mm s −1 . The study also included analysis of the cracking mechanism in the transitional regions of the two kinds of coating.