Deciphering Hydrogen Embrittlement Mechanisms in Ti6Al4V Alloy: Role of Solute Hydrogen and Hydride Phase

Abstract

Ti6Al4V (Ti64) is a versatile material, finding applications in a wide range of industries due to its unique properties. However, hydrogen embrittlement (HE) poses a challenge in hydrogen-rich environments, leading to a notable reduction in strength and ductility. This study investigates the complex interplay of solute hydrogen (SH) and hydride phase (HP) formation in Ti64 by employing two different current densities during the charging process. Nanoindentation measurements reveal distinct micro-mechanical behavior in base metal, SH, and HP, providing crucial insights into HE mechanisms affecting macro-mechanical behavior. The fractography and microstructural analysis elucidate the role of SH and HP in hydrogen-assisted cracking behaviors. The presence of SH heightens intergranular cracking tendencies. In contrast, the increased volume of HP provides sites for crack initiation and propagation, resulting in a two-layer brittle fracture pattern. The current study contributes to a comprehensive understanding of HE in Ti6Al4V, essential for developing hydrogen-resistant materials.

Simultaneous Enhancement of Strength and Sulfide Stress Cracking Resistance of Hot-Rolled Pressure Vessel Steel Q345 via a Quenching and Tempering Treatment

“…Usually, steel that has a higher strength or hardness presents worse SSC resistance [12][13][14][15]. However, for this experimental steel, the Q&T counterparts gave a higher YS and UTS while showing better SSC resistance.…”

“…There is, thus, a resulting strong desire to improve the strength and SSC resistance of the pressure vessel steel Q345 as used in harsh, wet H 2 S environments. However, the strength of the steel significantly determines its SSC susceptibility, and the strength increases usually simultaneously with decreasing the SSC resistance for the steel [12][13][14][15]. Increasing the strength will put higher requirements on the SSC resistance, and it has long been difficult to strike a good balance between strength and SSC resistance in steels.…”