Texture Preference and Variant Analysis of Martensite Formation in Laser Powder Bed Fusion

In laser powder bed fusionLaser powder bed fusion (L-PBF) (L-PBF) of maraging steelMaraging steel, oscillating thermal cycles inherent to additive manufacturing (AMAdditive manufacturing (AM)) revert the melt pool to its parent phase repeatedly and create sharp lath transformation morphologies. Investigating the influence of parent textureTexture and solute distribution, this study delves into the variant formation during fcc-γ austenite to bct-α′ martensitic transformation, especially under prolonged aging. Results indicate columnar prior austenite grains in as-built samples, which undergo refinement after direct aging and adopt an equiaxed morphology after annealing. By contrast, overaged specimens show austenite reversionAustenite reversion which starts at cellular boundaries that have disintegrated over time due to chemical diffusion. The austenite grain formation remarkably mirrors the preceding melt pool patterns. Furthermore, certain reverted austenite grains displayed limited orientation selection, such as a columnar grain that did not manifest any of the six possible c ( \(\overline{1}\) 11) variants. Future studies will discover the mechanisms dictating selection during austenite reversionAustenite reversion.