Corrosion behavior of coated 2 1/4 Cr-1 Mo and carbon steels in a simulated high p/sub S/sub 2// waste heat recovery system environment of a coal gasifier. [Al and/or Cr coatings applied by pack-diffusion process]

Technical Report · Sat Mar 01 04:00:00 EST 1986

OSTI ID:5932267

Baxter, D J

Corrosion tests have been conducted on coated 2-1/4Cr-1Mo and A106 carbon steels in a gaseous environment typical of that expected in a downstream waste-heat recovery system of a coal gasifier. The environment contained controlled oxygen and sulfur partial pressures, and the tests were run in a rig designed to expose specimens under simulated heat-exchanger conditions. Uncoated steel substrates exhibited breakaway corrosion behavior. Incoloy 800 also exhibited breakaway corrosion behavior. Coatings containing the stable oxide-forming elements Al and/or Cr were applied by pack-diffusion processes by several commercial vendors. Coatings containing Al contained numerous internal oxide particles and cracks while chromizing occasionally resulted in coatings containing voids. Results indicate that a minimum Cr concentration of approximately 20 to 22 wt % is required to suppress rapid corrosive degradation in the most aggressive environment used in the investigation. A minimum Al concentration could not be as closely defined, but would appear to lie in the range of 14 to 20 wt %. A minimum total concentration of combined additions of Al and Cr could not be defined. The presence of cracks in the aluminized materials promotes internal oxidation. Two Ni-base weld metals were used to simulate joining or repair operations of prior aluminized steel substrates. Both Inconel 625 and Inconel 72 exhibited breakaway corrosion behavior, the former at an unacceptable rate and the latter at a rate on the borderline of acceptability. The corrosion behavior of all coated and coated/welded materials is described and the results used to formulate a provisional specification for the procurement of coatings for eventual commercial application. 11 refs., 15 figs., 5 tabs.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5932267
• Report Number(s): ANL/FE-86-1; ON: DE86009344
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CARBON STEELS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
COAL GASIFICATION
COATINGS
CORROSION
DATA
ELEMENTS
EXPERIMENTAL DATA
GASIFICATION
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCOLOY 800
INCOLOY ALLOYS
INCONEL 625
INCONEL ALLOYS
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS
MATERIALS TESTING
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
NONMETALS
NUMERICAL DATA
OXYGEN
SIMULATION
STEEL-ASTM-A106
STEELS
SULFUR
TANTALUM ALLOYS
TESTING
THERMOCHEMICAL PROCESSES
WELDED JOINTS