Forms of Metallic Corrosion
47
Over the years, many alloy–environment combinations have been discovered that have led to SCC. Practically all alloys used for engineering purposes are subject to SCC. However, all alloys are not susceptible to SCC in all
environments. Table 3.4 provides a list of alloy–environment combinations
that exhibit stress corrosion cracking. However, note that this list is not allTabLE 3.4
Alloy–Environment Combinations Causing Stress Corrosion Cracking
Alloy
Environment
Aluminum alloys
Air with water
Potable waters
Seawater, NaCl solutions
NaCl-H 2 O 2 solutions
Carbon steels
Caustic NaOH solutions
HCN solutions
Calcium, ammonium, and sodium nitrate solutions
Acidified H 2 S solutions
Anhydrous liquid ammonia
Carbonate/bicarbonate CO/CO 2 solutions
Seawater
Copper alloys
Ammoniacal solutions
Amines
Nitrates
Nickel alloys
Caustic alkaline solutions
High-temperature chloride solutions
High-purity steam
Hydrofluoric acid
Acidic fluoride solutions
Stainless Steels
Austenitic
Hot acid chloride solutions
NaCl-H 2 O 2 solutions
NaOH-H 2 S solutions
Seawater
Concentrated caustic solutions
Neutral halides, Br - , I - , F -
Austenitic (sensitized) Polythionic acids
Sulfurous acid
Pressurized hot water containing 2 ppm dissolved
oxygen
Ferric
H 2 S, NH 4 Cl, NH 4 NO 3 , hypochlorite solutions
Martensitic
Caustic NaOH solutions
Titanium alloys
Red-fuming nitric acid
Hot salts, molten salts
N 2 O 4
Methanol/halide
Source: From Reference 3.