Impact of hydrogen on the high cycle fatigue behaviour of Inconel 718 in asymmetric push-pull mode at room temperature

The influence of hydrogen on the high cycle fatigue (HCF) behaviour of Inconel 718 has been studied at room temperature in asymmetric push-pull mode using an ultrasonic HCF test rig. Fatigue tests have been carried out in gaseous hydrogen (GH2) and in Ar at a pressure of 30 MPa. Oscillating stresses with amplitudes (S_a) up to 450 MPa and mean stresses (S_m) up to 600 MPa have been applied. For a given S_a and S_m, the lifetime in Ar is generally longer than in GH2, which is explained by a hydrogen-induced embrittlement of the material. For a constant S_a of 218 MPa, the lifetime in Ar and in GH2 is very similar for high S_m, but the difference in lifetime increases as the mean stress decreases. An approach is presented to describe the number of cycles to failure N_f as a function of S_a and S_m. Microstructural analysis has been performed on the specimens tested at S_a = 218 MPa and two values of S_m (300 MPa and 600 MPa). SEM analyses of the fracture surfaces of these samples indicate embrittlement of the material when tested in hydrogen atmosphere.

BRUCHHAUSEN Matthias;  FISCHER Burkhard;  RUIZ MORENO Ana Maria;  GONZALEZ SANCHEZ Sergio;  HAEHNER Peter;  SOLLER Sebastian; 

2014-10-07

ELSEVIER SCI LTD

JRC90314

0142-1123,   

http://www.sciencedirect.com/science/article/pii/S0142112314002333#,    https://publications.jrc.ec.europa.eu/repository/handle/JRC90314,   

10.1016/j.ijfatigue.2014.09.005,