TY - JOUR
T1 - Strain visualization of DED 316 steel via Digital image correlation and Fourier Transform analysis
T2 - effects of hydrogen and heat treatment
AU - Liu, Qingyang
AU - Yan, Yan
AU - Farhat, Hanan
AU - Wang, Dongze
AU - Barnoush, Afrooz
AU - Liu, Zhaoyang
AU - Ponraj, Janarthanan
AU - Pasha, Mujaheed
AU - Aissa, Brahim
N1 - Publisher Copyright:
© 2025 The Author(s)
PY - 2025/11
Y1 - 2025/11
N2 - This study investigates the influence of heat treatment at different temperatures (600, 800, and 1200 °C) on the microstructure, dislocation stability, and element segregation of 316L stainless steel fabricated by direct energy deposition. To understand how these changes affect hydrogen embrittlement resistance and the mechanical properties of the samples, tensile testing and digital image correlation (DIC) were employed to examine the strain/instability evolution under combined conditions after heat treatment and hydrogen charging. Results show that dislocation densities decreased after heat treatment, which in turn increased the hydrogen embrittlement resistance of samples with emergence of recrystallization and twin grains. DIC revealed that heat-treated samples exhibited more strain hotspots, which initiated and developed more extensively compared to as-received (AR) samples. In comparison, AR samples showed fewer sites of strain accumulation, leading to wider crack propagation and earlier failure. Hydrogen-charged specimens exhibited narrower strain ranges and more localized strain distributions, indicating a shift toward brittle fracture behavior. In contrast, hydrogen-free samples exhibited higher mean magnitude values and spatial variation across the range of spatial frequencies, as confirmed by two-dimensional Fourier Transform analysis. The methods and analyses in this paper provide a new perspective on evaluating hydrogen embrittlement via demystifying strain/instability evolution.
AB - This study investigates the influence of heat treatment at different temperatures (600, 800, and 1200 °C) on the microstructure, dislocation stability, and element segregation of 316L stainless steel fabricated by direct energy deposition. To understand how these changes affect hydrogen embrittlement resistance and the mechanical properties of the samples, tensile testing and digital image correlation (DIC) were employed to examine the strain/instability evolution under combined conditions after heat treatment and hydrogen charging. Results show that dislocation densities decreased after heat treatment, which in turn increased the hydrogen embrittlement resistance of samples with emergence of recrystallization and twin grains. DIC revealed that heat-treated samples exhibited more strain hotspots, which initiated and developed more extensively compared to as-received (AR) samples. In comparison, AR samples showed fewer sites of strain accumulation, leading to wider crack propagation and earlier failure. Hydrogen-charged specimens exhibited narrower strain ranges and more localized strain distributions, indicating a shift toward brittle fracture behavior. In contrast, hydrogen-free samples exhibited higher mean magnitude values and spatial variation across the range of spatial frequencies, as confirmed by two-dimensional Fourier Transform analysis. The methods and analyses in this paper provide a new perspective on evaluating hydrogen embrittlement via demystifying strain/instability evolution.
KW - Directed energy deposition
KW - Fourier transform
KW - Heat treatment
KW - Hydrogen embrittlement
KW - Strain/instability evolution
UR - https://www.scopus.com/pages/publications/105018176487
U2 - 10.1016/j.matdes.2025.114894
DO - 10.1016/j.matdes.2025.114894
M3 - Article
AN - SCOPUS:105018176487
SN - 0264-1275
VL - 259
JO - Materials and Design
JF - Materials and Design
M1 - 114894
ER -