The hydrogen embrittlement sensitivity of duplex stainless steel with different phase fractions evaluated by in-situ mechanical testing

Abstract

The influence of the austenite (γ) phase fraction on the hydrogen embrittlement of duplex stainless steel is investigated. Heat treatments are performed to create two duplex stainless steel specimens, containing 50% and 44% of austenite, respectively. Mechanical testing with and without hydrogen charging reveals that significant embrittlement occurs regardless of the austenite fraction. A higher austenite fraction results in a reduced ductility loss under the presence of hydrogen. Samples with a higher ferrite fraction are embrittled more due to their higher hydrogen diffusivity. In-situ tensile tests, interrupted at the ultimate tensile strength, show hydrogen-assisted cracks on the specimen surface both in austenite and ferrite and across the α/γ interface.

Change in Hydrogen Trapping Characteristics and Influence on Hydrogen Embrittlement Sensitivity in a Medium-Carbon, High-Strength Steel: The Effects of Heat Treatments

“…However, the strength and ductility of this class of steel are reduced due to the process of hydrogen degradation known as hydrogen embrittlement (HE) [5][6][7]. As the strength of the steel increases, the hydrogen embrittlement sensitivity becomes more pronounced [8][9][10][11][12]; therefore, the strength level of high-strength bolts has so far been limited to about >1000 MPa [13,14]. In a hydrogen-rich environment, once hydrogen enters the steel, it diffuses through the steel's microstructure, but some of it is trapped in a "trap site", which can reduce the overall rate of the hydrogen diffusion.…”