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Corrosion
4.2 Corrosion characteristics of powder
and gas-actuated fasteners
Hilti galvanized carbon steel
fasteners
DX fasteners are galvanized with a zinc plating
thickness of approx. 5 to 15 microns.
The lifetime of this form of corrosion protection
depends on the environmental-conditions
and therefore on the rate of corrosion
of the zinc layer. Most commonly observed
Application provisions to observe potential
risk of failure due to Hydrogen embrittlement
All Hilti powder and gas-actuated fasteners
are manufactured from a high-strength
material and, accordingly, are exposed to
the risk of corrosion-induced hydrogen
embrittlement.
Hydrogen embrittlement
• Brittleness due to dissolution of hydrogen
in the metal lattice
• Inter-crystalline (between the grains)
• Tensile stress
• Associated with hardened high-strength
steel
Example of incorrect application
Zinc-plated powder-actuated fastener used
in corrosive industrial environment
material degradation can be traced back to
homogeneous corrosion, characterized by a
more or less homogeneous surface reduction.
The life expectancy of galvanized fasteners
and nails in wet atmospheres is therefore
very short.
When zinc-plated fasteners are used in wet
or corrosive surroundings, the zinc plating is
attacked and the fastener can corrode.
Cracks will form in the fastener and it may
suddenly fail even under a very low static
load. This phenomenon, resulting in a high
risk to the structure, is unpredictable and not
controllable.
Stress cracks
1.30 11 / 2007