Hydrogen Effect on Fatigue Behavior of a Quenched&tempered Steel

The investigated material is a quenched&tempered steel for hydrogen applications. Understanding of hydrogen embrittlement and its effect on the mechanical characteristics of steel becomes fundamental. It is, in fact, well known that the atomic hydrogen can cause embrittlement and degradation of the mechanical characteristics of the steels. Fracture mechanics parameters are usually considered to define the embrittlement effect of hydrogen. In the present work AISI 4130 is experimentally investigated. Several specimens were hydrogen charged by an electrochemical method, that allows to obtain a controlled amount of hydrogen into the specimens. Toughness and fatigue crack growth tests have been carried out on uncharged and hydrogen charged CT specimens. The effect of hydrogen is evident: the propagation curves are shifted and the toughness values are reduced.