Laser cladding of IN713 LC superalloy with Amdry 997 powder: microstructural evolution

Abstract

In this research, Amdry 997 powder was applied by a laser cladding process to the IN713 Low Carbon (IN713 LC) nickel-based superalloy. To evaluate the microstructural behaviors of the clad zones, different variables (the laser speed, laser frequency, and pulse width) were used in the laser cladding process. The final aim of this study was to achieve a clad zone without obvious cracks and pores with a low dilution ratio. The results showed that the upper region of the cladding includes very small equiaxed dendrites. The middle region of the cladding includes columnar dendrites. Equiaxed and columnar grains can be formed at the interface region. With an increase in the heat input of the laser (increasing the pulse width and laser frequency or decreasing the laser speed), the solidification rate reduces and consequently, a longer solidification time exists. Hence, more elongated grains are formed at the interface region. The microstructure of coatings in the upper and middle regions includes γ-Ni, β-NiAl and γ′-Ni3Al phases and TaC carbide, whereas the microstructure of the coatings at the interface region includes γ and β-NiAl and γ′-Ni3Al phases and M (Mo, Ta)C carbide. The optimum laser parameters that result in a low dilution ratio (14%) and a dense clad zone without obvious crack and porosity are a laser speed of 140 mm min−1,laser frequency of 14 Hz, and pulse width of 9 ms.