Environmental Engineering Reference
In-Depth Information
8
Hydrogen Damage
8.1 INTRODUCTION
Hydrogen damage refers to the degradation of physical and mechanical properties
of metals resulting from the action of hydrogen, which may be initially present
inside the metal or accumulated through absorption. Most often the damage is
associated with residual or applied tensile stress. The damage may manifest itself
in several ways:
1.
Loss of ductility and/or tensile strength
2.
Internal damage due to defect formation
3.
Sustained propagation of defects at stresses well below those required for
mechanical fracture, and
4.
Macroscopic damage, such as internal flaking, blistering, fissuring, and
cracking
The term
hydrogen embrittlement
has long been in use to describe some of
these forms, but the generic term
hydrogen damage
should be preferred as many
of the damages do not conform to the classical features of embrittlement, namely,
the reduced load bearing capacity or fracture below the yield strength.
Hydrogen damage has been encountered in many metals and alloys of engi-
neering interest. The first report on hydrogen embrittlement of steels appeared
in 1873 [1]. The high-strength steels are particularly vulnerable, and there have
been many incidents of failure of oil drilling and other equipment made of high-
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