Microstructure and Mechanical Properties of Inconel 625 Alloy Manufactured by Selective Laser Melting

The Inconel 625 alloy powder was prepared by the powder atomization method, and then the metallographic, tensile and impact specimens were directly formed with the alloy powder by the selective laser melting technology. The surface residual stresses, microstructures and mechanical properties of the specimens before and after annealing were studied. The results show that a small amount of micro cracks were observed at the surface of the specimen and few oxycarbide inclusion particles existed inside the specimen. The microstructure was uniformity and dense and consisted of the single austenite phase. The surface residual stress of the specimen before annealing was 398 MPa, which was higher than 242 MPa of the specimen after annealing at 1 140 ℃ for 2 h. The average yield strength, tensile strength, impact energy, percentage elongation and reduction of area were 743 MPa, 1 043 MPa, 139 J, 31.4% and 49.6% respectively. After annealing, the yield strength and tensile strength of the specimen decreased while the impact energy, percentage elongation and reduction of area improved. The tensile and impact fracture of the specimen before annealing showed a ductile fracture characteristic.