TY - JOUR
T1 - Effect of hydrogen on the mechanical properties of alloy 945X (UNS N09945) and influence of microstructural features
AU - Demetriou, V.
AU - Robson, J. D.
AU - Preuss, M.
AU - Morana, R.
PY - 2017/1/27
Y1 - 2017/1/27
N2 - This study investigated the hydrogen embrittlement sensitivity of the precipitation hardened (PH) alloy 945X in three different metallurgical states. The three variants examined (obtained by different heat treatments) were the standard oil and gas industry condition, and two alternative microstructures with variations in fraction and morphology of γ', γ″ and δ phases. For each metallurgical state, mechanical tests were carried out on both uncharged and hydrogen pre-charged specimens in order to evaluate the deleterious influence of hydrogen on mechanical properties. Material characterisation and post-test fractography was performed to understand the link between microstructural features, fracture behaviour, and susceptibility to hydrogen embrittlement. Fractographic analysis showed that, in the presence of hydrogen, intergranular fracture occurred for all the heat treatments, regardless the presence of δ-phase at grain boundaries. There was no simple correlation between the volume fraction of δ-phase and susceptibility to hydrogen assisted embrittlement. Rather, it was demonstrated that the morphology and distribution of δ-phase along grain boundaries plays a key role and the other precipitate phases also have an influence through their influence on the ease of strain localization.
AB - This study investigated the hydrogen embrittlement sensitivity of the precipitation hardened (PH) alloy 945X in three different metallurgical states. The three variants examined (obtained by different heat treatments) were the standard oil and gas industry condition, and two alternative microstructures with variations in fraction and morphology of γ', γ″ and δ phases. For each metallurgical state, mechanical tests were carried out on both uncharged and hydrogen pre-charged specimens in order to evaluate the deleterious influence of hydrogen on mechanical properties. Material characterisation and post-test fractography was performed to understand the link between microstructural features, fracture behaviour, and susceptibility to hydrogen embrittlement. Fractographic analysis showed that, in the presence of hydrogen, intergranular fracture occurred for all the heat treatments, regardless the presence of δ-phase at grain boundaries. There was no simple correlation between the volume fraction of δ-phase and susceptibility to hydrogen assisted embrittlement. Rather, it was demonstrated that the morphology and distribution of δ-phase along grain boundaries plays a key role and the other precipitate phases also have an influence through their influence on the ease of strain localization.
KW - Alloy 945X
KW - Hydrogen Embrittlement
KW - Precipitation hardening
KW - Slip bands
KW - Tensile properties
KW - δ phase
UR - http://www.scopus.com/inward/record.url?scp=85007198730&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2016.12.088
DO - 10.1016/j.msea.2016.12.088
M3 - Article
AN - SCOPUS:85007198730
VL - 684
SP - 423
EP - 434
JO - Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing
SN - 0921-5093
ER -