Mechanical and microstructural characterisation of bulk Inconel 625 produced by direct laser deposition

Direct laser deposition (DLD) is an advanced additive manufacturing (AM) technology with growing industrial importance. In the present study, the mechanical and microstructural characterisation of a bulk produced by DLD depositing a nickel superalloy (type Inconel 625) on 42CrMo4 structural steel was performed. Optimized processing parameters (laser power, scanning speed and feed rate) were used for deposition and remained constant during bulk production. The bulk showed structural integrity, with no cracking or unmelted particles. Successive layers were deposited on a pre-heated substrate to reduce the cooling rate and minimize both the formation of metastable phases in the heat-affected zone and the dimensions of the deleterious phases in bulk. The bulk microstructure mainly consists of a coarse columnar/dendritic structure, and the longitudinal section microstructure revealed the layer-by-layer deposition pattern. Microstructural and mechanical characterisation demonstrated that a sound bulk was formed, with mechanical properties similar to wrought Inconel 625. These results contribute to the recognition of DLD as a suitable technique for the repair and remanufacturing of industrial components. •Bulk production using Inconel 625 (M625) type powders by Direct Laser Deposition (DLD) technique.•Strong metallurgical bonding of the bulk to the substrate and between all successive layers.•Mechanical properties of M625 bulk deposited by DLD, similar to wrought Inconel 625.•Fracture surface fracture analysis produced by tensile tests.•Microstructural analysis evidencing epitaxial grain growth of columnar dendritic microstructure.