Influence of processing parameters and heat treatment on the mechanical properties of 18Ni300 manufactured by laser based directed energy deposition

Laser based direct energy deposition is an additive manufacturing method that can produce or repair fully dense components. Maraging steels are well known for its superior strength and toughness with low carbon content. Here, 18Ni300 maraging components were fabricated by laser based directed energy deposition under argon atmosphere. The influence of processing parameters on the forming quality was studied based on orthogonal experiment and the results showed that the macroscopic forming generally performed well and the density of forming parts was positively correlated with laser energy density. The effects of different heat treatments on microstructure evolution and mechanical properties were explored after an hour of solid solution treatment in 830 °C and aging treatments for 1 h, 4 h, 7 h, 10 h respectively. It was found that with the extension of aging time, the directional dendritic columnar crystals transformed into lath martensites and the number of stomas decreased considerably. Meanwhile, the microhardness and tensile properties of the forming parts were promoted greatly after the heat treatments.