Anisotropy in Young's modulus of thick – walled 316LSi Wire Arc Additive Manufacturing (WAAM) deposits

Abstract

This study investigates elastic anisotropy in thick-walled 316LSi stainless steel deposits fabricated by Wire Arc Additive Manufacturing (WAAM). Four deposition conditions were evaluated by varying heat input (10 and 15 kJ/in.) and interpass temperature (121 and 399 °C), while maintaining a consistent alternating parallel toolpath strategy with 45% bead overlap. Optical metallography revealed that this tool path promoted cyclic partial remelting and produced a distinct periodic, wavy columnar grain morphology. Electron Backscatter Diffraction (EBSD) indicated corresponding crystallographic texture tendencies, with <100> alignment along the deposition direction (X-axis) and <111> alignment along the transverse direction (Y-axis). Since <111> is the stiffest and <100> is the most compliant crystallographic direction in FCC 316L/316LSi, these texture tendencies provide a mechanistic basis for the observed macroscopic elastic anisotropy. Room-temperature tensile testing showed a consistent orientation-dependent elastic response across all four processing conditions, with E Y > E X , while the Z-oriented specimens tested for the HH and HL conditions exhibited intermediate modulus values. Temperature-dependent resonant frequency and damping analysis (RFDA) measurements of the HL condition independently reproduced the E Y > E Z > E X directional stiffness hierarchy from 23 °C to 400 °C. The lowest Young’s modulus values were consistently measured along the deposition direction (X-axis: 146 to 150 GPa), while the highest values were observed along the transverse direction (Y-axis: 187 to 197 GPa). Overall, the observed elastic anisotropy was primarily associated with the toolpath-induced microstructure and crystallographic texture, while variations in heat input and interpass temperature had comparatively little influence within the processing window studied.

The authors' abstract, as published at the source. Materials Science and Engineering A, 2026 · DOI ↗