Effect of processing parameters on the microhardness, shear, and tensile properties of layer-cladded Inconel 718

Abstract

Inconel 718 alloy (IN718) is a popular choice for aerospace hot-end components due to its exceptional mechanical properties. This study investigates the impact of processing parameters (i.e., laser power, powder feeding rate, and scanning speed) on the microhardness, bond strength, and tensile strength of layer-cladded IN718. The results show that IN718 coatings have high microhardness (277.15 HV0.1), strong metallurgical bonding strength (33.97 kN), substantial yield strength (794.09 MPa), impressive ultimate tensile strength (1171.81 MPa), and notable elongation at failure (8.24 %) under laser power is 1.2 kW, powder feeding rate is 250 mg/s, and scanning speed is 4.5 mm/s. In particular, decreased laser energy input enhances microhardness, yield strength, and ultimate tensile strength but reduces bonding strength and elongation. This is attributed to improved Nb element segregation, the reduction of the Laves phase, and grain refinement. However, inadequate energy input leads to cracks and unmelted powder, negatively affecting metallurgical bonding strength. The shear and tensile fracture mechanism of the IN718 coatings is a typical ductile fracture with a microvoid accumulation fracture. The study can facilitate the fabrication of the IN718 coatings with the excellent mechanical properties and the applications in the engineering field.