Oxidation of selected alloys during 25,000 h in superheated steam at 482 and 538/sup 0/C

Technical Report · Sat Mar 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/5491716· OSTI ID:5491716

Griess, J. C.; Maxwell, W. A.

The corrosion of several ferritic and austenitic materials in flowing superheated steam at 482 and 538/sup 0/C (900 and 1000/sup 0/F) were studied. Results obtained during the first 12,000 h of the test were presented previously. Results obtained during the first 25,000 h are summarized. The test specimens are mounted in a nonrecirculating loop that receives steam from the superheater circuit of a fossil-fired power plant. At both temperatures all materials exhibited parabolic oxidation kinetics during the first year and subsequently have oxidized at low constant rates. The ferritic steels containing 2 1/4 and 9% Cr have oxidized at about the same rates, averaging 4.2 and 8.6 ..mu..m/year (0.17 and 0.34 mils/year) at 482 and 538/sup 0/C, respectively, after the first year. Sandvik HT-9 (11.4% Cr) has corroded at slightly lower rates. Annealed and Cold-worked surfaces of these alloys have exhibited identical behavior. At 482/sup 0/C all materials have retained their corrosion products completely, but at 538/sup 0/C some began experiencing exfoliation after 12,000 h. Data suggest that a high silicon content in the alloy minimizes exfoliation. Cold-worked surfaces of alloy 800 are corroding at lower rates than annealed and pickled ones, but in both cases the rates are very low. Alloy 800 specimens that had been intergranularly corroded before exposure to steam are oxidizing at much higher rates, but intergranular penetration has not progressed. Type 304 stainless steel is corroding nonuniformly, but the attack rates are low at both temperatures. Alloy 617 is corroding at the lowest rate of any material in the loop; even after 25,000 h surface films are thin enough to show interference colors.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5491716
• Report Number(s): ORNL/TM-7114
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
ALUMINIUM ALLOYS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
CHROMIUM-NICKEL STEELS
COBALT ALLOYS
CORROSION
CORROSION RESISTANT ALLOYS
CORROSIVE EFFECTS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEATING
INCOLOY 800
INCOLOY ALLOYS
INCONEL 617
INCONEL ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
OXIDATION
STAINLESS STEEL-304
STAINLESS STEELS
STEAM
STEELS
SUPERHEATING
TEMPERATURE DEPENDENCE
TIME DEPENDENCE