The influence of internal hydrogen on the mechanical behavior of the 42CrMo4 steel grade has been evaluated by means of internal pressure fracture tests performed on hydrogen precharged notched cylindrical specimens. The notched cylindrical specimens were precharged in a 1 M H2SO4 solution + 0.25 g/l As2O3 for 3 h and 1.2 mA/cm2. Thereupon, hydraulic fracture tests were done under different ramps of pressure: 208, 100, 52, 35 and 25 MPa/h, respectively. Hydrogen content introduced into the notched cylindrical specimens (∼1 ppm) was determined by thermal desorption analysis (TDA), using a LECO DH 603 hydrogen analyser. Hydrogen damage was observed as testing time increased until 2 h. The burst pressure is reduced around 28 % while the Notch Mouth Opening Displacement decreased around 50 %. Hydrogen embrittlement susceptibility is discussed through the hydrogen embrittlement micromechanisms.
