Tensile Failure of Stainless-Steel Notched Bars Under Hydrogen Charging

The influence of hydrogen embrittlement on the tensile failure of 316L stainless-steel notched bars is phenomenologically modeled in this paper. Tensile tests of notched samples suffering hydrogen embrittlement show that hydrogen damage consists in multicracking in the area surrounding the notch, but the macromechanical behavior of the specimens remains ductile. This suggests two different ways for modeling the damage in order to explain its effect on the tensile failure load. The Notch Extension Model (NEM) considers that damage intensity around the notch is high enough to cancel out the mechanical resistance of this multicracked zone, so it assumes that the hydrogen effect is equivalent to a geometric enlargement of the notch. In the Notch Cracking Model (NCM), it is assumed that high intensity damage is concentrated at the notch root and causes this area to behave as a macroscopic crack that extends the original notch. Experimental values from tests and calculated values from models indicate that the notch extension model describes well the influence of hydrogen on the tensile notch behavior of 316 L stainless steel.