Hot corrosion degradation of metals and alloys - a unified theory. Final scientific report, 1 June 1976-30 September 1978

Technical Report · Fri Jun 01 04:00:00 EDT 1979

DOI:https://doi.org/10.2172/5572795· OSTI ID:5572795

Giggins, C S; Pettit, F S

The hot corrosion attack of metals and alloys has been examined over an extensive range of experimental conditions in order to develop a hot corrosion theory. Experiments have been performed at temperatures from 700 to 1000 C in air and in gases containing oxygen and SO 3. Sodium sulfate was the principal deposit used to induce attack and the effects of NaCl and carbon in the Na2SO4 was also studied. Nickel- and cobalt-base alloys containing various amounts of chromium, aluminum, molybdenum and tungsten constituted the principal materials studied. The hot corrosion attack of alloys has been found to consist of an initiation stage and a propagation stage. The factors which determine the length of the initiation stage and the type of propagation mode are shown to be; alloy composition, fabrication condition, gas composition and velocity, salt composition, salt deposition rate, condition of salt, temperature, temperature cycles, erosion and specimen geometry. The hot corrosion propagation modes are described and shown to consist of fluxing processes and processes involving the oxidation of phases formed in alloys as a result of reaction with components in the deposit (e.g. sulfides, chlorides). The effects produced by a number of different elements (e.g. Cr, Al, Mo, W) on the hot corrosion of alloys is examined. It is shown that by using the unified theory for hot corrosion, previous inconsistencies are resolved.

• Research Organization: Pratt and Whitney Aircraft, Middletown, CT (USA). Materials Engineering and Research Lab.
• OSTI ID: 5572795
• Report Number(s): AD-A-072645
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
AIR
ALKALI METAL COMPOUNDS
ALLOYS
ALUMINIUM
CARBON
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CHROMIUM
CHROMIUM ALLOYS
COBALT ALLOYS
CORROSION
CORROSION RESISTANT ALLOYS
CRYOGENIC FLUIDS
ELEMENTS
FLUIDS
GAS TURBINES
GASES
HALIDES
HALOGEN COMPOUNDS
MACHINERY
METALS
MOLYBDENUM
NICKEL ALLOYS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
REFRACTORY METALS
SODIUM CHLORIDES
SODIUM COMPOUNDS
SODIUM SULFATES
SULFATES
SULFUR COMPOUNDS
SULFUR OXIDES
TRANSITION ELEMENTS
TUNGSTEN
TURBINES
TURBOMACHINERY
VERY HIGH TEMPERATURE