Directed laser deposition of super duplex stainless steel: Microstructure, texture evolution, and mechanical properties.

Microstructure and texture evolution of directed-laser deposited super-duplex stainless-steel, in the as-received block, were characterized using light and electron microscopies and electron backscattered diffraction. Mechanical properties in different directions were studied. Local FCC-depleted and FCC-rich zones and extensive precipitation of oxides were detected at the matrix wherein the different types of reformed austenite were surrounded by the elongated coarse ferrite. A vertical gradient of austenite content, caused by overall change in cooling rate, generated a waning hardness distribution along the building direction. The texture of austenite across the different deposition layers was not as intense as that of the ferrite. A dominant ⫽ND fibre, embedding strong Cube , was calculated for ferrite on the layer away from the bottom while the Goss appeared in the layer near the building substrate due to the considerable epitaxially developed grains. The less intensified multi-component texture of austenite at the layer near the substrate changed to ⫽ND fibre adorned by Rotated-Goss and Goss components at the upper layers where an incomplete fibre with a major Rotated-Cube was also partially inherited from the parent phase. The inter-phase boundaries obeying Kurdjumov-Sachs orientation relationship were predominantly formed at all layers. A slight increase of Σ3 coincidence site lattice interfaces was observed in austenite across the build direction. The possible mechanical anisotropy was depressed due to complex and multi-component transformation texture of the austenite. The material showed brittleness corresponding to significantly high tensile strength and low impact toughness.