Aging heat treatment of additively manufactured maraging steels in nitrogen containing atmospheres

Abstract

Additive Manufacturing (AM) is a manufacturing method that pushes the limits of imagination and eliminates the question of whether complex industrial products can be produced that cannot be obtained with traditional manufacturing methods. In this study, microstructure and mechanical properties of maraging steels produced by DMLS method and aged in different times (6 and 9 h) and atmospheres (Air, N2 and N2/H2) were investigated. When the SEM images were examined, it was observed that the molten pool boundaries did not disappear completely but became blurred with increasing temperature. Coaxial cellular structures and bands are seen in all samples. XRD results show martensite and gamma phases for all atmospheres. In addition, ℇ-Fe3N phase was detected at N2-490-9 h. In the hardness test, the sample with the highest hardness value is found in Air-490-6 h. Increasing aging time decreases hardness. In the tensile test results, the strength values of all samples were quite close to each other, the sample with the lowest strength is N2-490-6. In terms of wear, the sample with the worst abrasion resistance is Air-490-6. Increasing aging time also has a negative effect on wear resistance. In the corrosion results, the nitrogen atmosphere gave more positive results than the air atmosphere. According to the Archimedes test results, it can be said that the density values of the samples are very close to the values in the literature, and it can be said that they are produced successfully by the additive manufacturing method.