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Effect of Hydrogen On Mechanical
Behavior, strength and ductility properties
and related fracture mechanisms in a low
carbon and low alloy 2.25 Cr- I Mo
bainitic steel were studied. Entrance of
hydrogen into the microstructure was done
by cathodic charging in IN sulfuric acid
containing arsenic trioxide as a cathodic
poison. Immediately after cathodic
hydrogen charging, slow strain rate testing
(SSRT) at strain rates of 10.6 to l0-4s, as
well as ordinary tension test and sustained
load test were performed. Fractographic
investigation were performed using stereo
and scanning electron microscopes. The
process of hydrogen charging into the alloy
steel brings about reductions in strength
and ductility properties leading to a
completely brittle mechanical behavior.
The results of fractographic studies
showed that hydrogen induced cracking
was initiated at subsurface inclusion-
matrix interfaces, which initially
propagated by an inter-granular cracking
mechanism, and was followed by extensive
low energy quasi-cleavage mode at later
stages of crack growth. Crack growth
mechanisms under various testing
conditions are presented in a schematic
model and discussed.