HYDROGEN EMBRITTLEMENT AND LOW TEMPERATURE EFFECTS ON CARBON STEELS

This paper presents an experimental study on the mechanical characteristics of carbon steels used for pipeline applications. The considered materials are: X65 micro-alloyed and F22 low-alloyed steel. C(T) specimens are extracted directly from the pipes, and fatigue crack growth tests are carried out considering three parameters affecting crack growth rates in mechanical components: absence or presence of hydrogen, low temperature and test frequency. This work is dedicated to the description of the setup used in the experimental tests and to the discussion of obtained results. Experimental results show an evident effect of the hydrogen presence on the fatigue crack growth. Fracture surface examination confirms the results of mechanical testing.