15/16 Semester genap
Corrosion process and control
(TKK-2289)
Instructor: Rama Oktavian; Vivi Nurhadianty.
Email: [email protected]
Office Hr.: T. 11-12, Th. 08-10; 13-15, F. 08-10; 13-15
Corrosion types
Hydrogen damage
-
embrittlement is not the only way in which materials are damaged by
hydrogen. Steels are also damaged by hydrogen blistering at high
temperatures
-
three categories of hydrogen damage:
a. High temperature hydrogen attack
b. Hydrogen blistering
c. Hydrogen embrittlement
Corrosion types
Hydrogen damage
Corrosion types
Hydrogen damage
Corrosion types
Hydrogen damage
a. High temperature hydrogen attack
-
requires the presence of atomic hydrogen
-
At temperatures above 230◦C
-
hydrogen partial pressure above 100 psi (7 kg/cm2)
-
atomic hydrogen reacts with the carbon component in the steel to
form methane
Corrosion types
Hydrogen damage
b. Hydrogen blistering (hydrogen induced cracking)
-
caused by the atomic hydrogen diffusing into a steel and being
trapped at a non-metallic inclusion
-
a high pressure is localized at the inclusions or grain boundaries until
the bulging occurs, producing blisters or cracks
-
Stepwise cracking occurs when short blisters at varying depths within
the steel link together to form a series of steps
Corrosion types
Hydrogen damage
b. Hydrogen blistering (hydrogen induced cracking)
Corrosion types
Hydrogen damage
b. Hydrogen blistering (hydrogen induced cracking)
Condition for HIC to occur:
-
The presence of water phase
-
The presence of atomic hydrogen
-
An agent that retards the formation of molecular hydrogen at the
surface
-
Presence of grain boundaries or inclusions
-
Maintenance of an active surface
-
Discontinuity in metal, such as slag, inclusion and/or void
Corrosion types
Hydrogen damage
b. Hydrogen blistering (hydrogen induced cracking)
Source of hydrogen:
-
Surface treatment of metal
-
Hydrogen absorption from metal fabrication
Mechanism of hydrogen formation
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
-
Cathodic hydrogen is adsorbed on the surface as atomic hydrogen
(reduced)
-
The internal pressure produced by the gaseous hydrogen is much
lower than produced by cathodic hydrogen
-
occurs during the plastic deformation of alloys in contact with
hydrogen gas
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
Example:
-
In plating operations.
-
In pickling operations
-
In cleaning of high strength steels in chloride or fluoride solution
-
Manufacturing and fabrication processes
Materials that are most susceptible to hydrogen embrittlement:
Iron, titanium, zirconium, martensitic steels, high strength aluminum
alloys.
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
Example:
-
In plating operations.
-
In pickling operations
-
In cleaning of high strength steels in chloride or fluoride solution
-
Manufacturing and fabrication processes
Materials that are most susceptible to hydrogen embrittlement:
Iron, titanium, zirconium, martensitic steels, high strength aluminum
alloys.
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
Different between SCC and Hydrogen embrittlement
-
SCC begins at the surface, whereas hydrogen embrittlement begins
internally
-
The magnitude of corrosion is higher at the origin of SCC than
observed with hydrogen embrittlement
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
Different between SCC and Hydrogen embrittlement
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
 Important parameter : THE TEMPERATURE
T  200°C
Hydrogen embrittlement
T  200°C
Hydrogen attack
Corrosion types
Hydrogen damage
c. Hydrogen embrittlement
Example
FAILURE OF A
HYDROGEN
TRANSPORT
VESSEL IN 1980
Corrosion types
Hydrogen damage
FAILURE OF A
HYDROGEN
TRANSPORT VESSEL
IN 1983. HYDROGEN
CRACK INITIATED ON
INTERNAL
CORROSION PITS
Corrosion types
Hydrogen damage
Corrosion types
Hydrogen damage