Surface additive manufacturing of Ni-based superalloy/H13 steel system by laser depositing: Microstructure, microhardness and flexural response

The Ni-based superalloy was deposited on the AISI H13 tool steel by laser depositing as a surface additive manufacturing method. The microstructure and microhardness were analysed from the top surface of deposited layer to base metal. And the composition and constituent phases of Ni-based deposited layer were characterized. Furthermore, considering the anisotropy along three orthogonal directions of the system (Ni-based superalloy/H13 steel), the three-points bending test combined with fracture analysis was performed to evaluate the flexural behavior of the system. The results suggest that laser deposited Ni-based superalloy layer has interdendritic eutectic structures and the finely intermixed dendrites with directionality. Corresponding to the order of the deposited layer, transition zone, heat affected zone and the base metal, the average microhardness decreases gradually, which shows a gradient distribution. Moreover, the flexural response of the system is influenced by the type of applied load which determines the stress state of the deposited layer. The flexural capacity of the system can be maximized when the deposited layer is subjected to pure compressive stress. And the flexural ductility of the system is weakened when the tensile stress exists in the deposited layer.