Hydrogen effect on the deformation evolution process in situ detected by nanoindentation continuous stiffness measurement

The extent of hydrogen effect on the mechanical property is dependent on the deformation stage. Hydrogen decreases the elastic modulus in the initial stage of plastic deformation, while the hydrogen effect becomes weaker with further plastic deformation, as shown in Fig.1. Strain-induced α′ martensite increases the elastic modulus greatly, as shown in Fig. 2. α′ martensite counteracts the hydrogen effect on elastic modulus.85