Creep and the corrosion characteristics of Incoloy Alloy 800 in molten nitrate salts

Technical Report · Sun Mar 01 04:00:00 EST 1981

DOI:https://doi.org/10.2172/6579692· OSTI ID:6579692

Goods, S H

Incoloy Alloy 800 (I800) has been proposed for use in the receiver tube panel arrays in a number of advanced solar central receiver (SCR) concepts. Because of their high heat capacity and high thermal energy density, several designs require the use of molten sodium and potassium nitrate salt mixture to act as the cooling or heat transfer fluid. The effects of deformation on the corrosion resistance of Incoloy Alloy 800 in sodium nitrate and potassium nitrate salt mixtures have been studied. Hollow tube specimens filled with the salt mixture (60%-NaNO/sub 3/-40% KNO/sub 3/) were tested in constant load tension creep at elevated temperatures (550/sup 0/ less than or equal to T less than or equal to 670/sup 0/C). Depending on the temperature and initial stress, fracture times (and therefore salt exposure times) ranged between 300 and 1000 hours. While the fracture strain of specimens tested to failure was only slightly reduced when exposed to the salt environment, metallographic observations of polished cross-sections revealed severe surface oxidation. In order to characterize the effect of total imposed strain on oxide morphology a number of creep tests were terminated prior to fracture. Increasing deformation resulted in a more extensively damaged surface oxide as well as a more rapid rate of corrosion. EDX analysis revealed that the oxide was multiphase, with a near surface iron rich oxide above a chromium-rich oxide layer. Below 630/sup 0/C the oxide-metal interface was well defined (although irregular). Above 630/sup 0/C the interface was more diffuse with fine oxide intrusions growing into the base metal and small particles of the alloy visible in the oxide near the base metal interface.

• Research Organization: Sandia National Labs., Livermore, CA (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6579692
• Report Number(s): SAND81-8665
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
141000* -- Solar Collectors & Concentrators
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALKALI METAL COMPOUNDS
ALLOYS
CENTRAL RECEIVERS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CONCENTRATING COLLECTORS
CORROSION
CORROSION RESISTANCE
CORROSIVE EFFECTS
CREEP
CSP
Concentrating Solar Power
DATA
DEFORMATION
DISPERSIONS
EQUIPMENT
EXPERIMENTAL DATA
FAILURES
FLUIDS
GRAPHS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TRANSFER FLUIDS
HIGH TEMPERATURE
INCOLOY 800
INCOLOY ALLOYS
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
MIXTURES
MOLTEN SALTS
NICKEL ALLOYS
NITRATES
NITROGEN COMPOUNDS
NUMERICAL DATA
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM NITRATES
SALTS
SODIUM COMPOUNDS
SODIUM NITRATES
SOLAR COLLECTORS
SOLAR EQUIPMENT
SOLAR RECEIVERS
STRAINS
TESTING
TOWER FOCUS COLLECTORS