Hydrogen Embrittlement Behavior And Mechanisms Of Ti-6al-4v Alloy Based On Small Punch Test

Ti-6Al-4V (TC4) alloy is widely used in the field of marine and aviation, and its severe service environment is easy to induce hydrogen embrittlement (HE) which can cause the degradation of mechanical properties and a sudden catastrophic fracture for the material. To investigate the HE behavior and mechanisms, mechanical properties of the TC4 alloy after different electrochemical hydrogen charging (EHC) time were measured by small punch test (SPT) first. Then, hydrogen distribution and the phase transition of the TC4 alloy with different EHC time were discussed by the atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The strength and elongation obtained from SPT fitting data show obvious deterioration with the increase of EHC time while the macroscopic fracture morphology of the TC4 alloy exhibits a transformation from ductile mode to brittle mode. At the same time, the generation of hydride after EHC is proved a main contributor to the HE of the TC4 alloy. The results in this paper provide an effective and convenient method to assess the HE behavior of TC4 alloy in service.