Effect of solution and aging treatments on the mechanical properties, and fracture behavior of additively manufactured maraging steel

Abstract

Regarding the importance of annealing and solution treatments on the final microhardness of maraging steel, this study investigates the impact of different treatment times and temperatures on the microhardness of additively manufactured maraging steel. Annealing temperatures ranged from 815°C to 845°C, annealing times from 60 to 120 min, aging temperatures from 540°C to 580°C, and aging times from 90 to 180 min. The study examines the unique features of the fractured surface and the behavior of maraging steel after these treatments, as well as the critical limits of these treatments on the microstructure and fracture behavior. Results show that the oxygen diffusion rate in additively manufactured material is significantly higher than in bulk material, leading to considerable oxide formation, especially in porosities, after heat treatment. This phenomenon could contribute to porosity regrowth, resulting in abnormal dimple sizes in the fractography of additively manufactured maraging steel. An aging temperature of 580°C is critical, leading to severe necking under tensile load, resulting in low UTS, microhardness, and elongation, despite extreme softness and brittle fracture behavior. Aging temperature is identified as the most effective parameter on microhardness, with increasing temperatures reducing it. Annealing time and temperature have the opposite effect, with maximum microhardness at lower aging and higher annealing temperatures.