Crack tip oxidation of a superalloy in molten nitrate salt

Journal Article · Fri Apr 01 04:00:00 EST 1983 · Scr. Metall.; (United States)

DOI:https://doi.org/10.1016/0036-9748(83)90347-2· OSTI ID:5319325

Goods, S H

Alloy 800 has been proposed for use in the receiver tube panel arrays of advanced solar central receiver (SCR) designs. In this application the alloy will be exposed to a molten mixture of sodium and potassium nitrate salts at temperatures ranging up to approximately 600/sup 0/C While these salts are routinely used in a variety of applications including metal heat treating and process heat transfer, common industrial experience has been limited to maximum temperatures of 400/sup 0/C - 450/sup 0/C. There is, therefore, considerable interest in the compatibility of these salts with containment alloys at the higher temperatures associated with SCR designs. Additionally, the containment alloy may be subject to thermally induced fatigue damage resulting from intermittent cloud cover and diurnal cycling. Previous work has found that slower near-threshold fatigue crack growth rates (FCGR) in Alloy 800 result when it is tested in molten nitrate salt at 600/sup 0/C (relative to air). This reduction in FCGR was attributed to an environmentally induced increase in oxidation resulting in oxide-induced crack closure. The purpose of the present work was to examine the influence of a typical nitrate salt composition on crack tip oxidation in Alloy 800 in order to determine if in fact the proposed corrosion phenomena could explain the fatigue crack growth characteristics of the alloy.

• Research Organization: Sandia National Laboratories, Livermore, CA 94550
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5319325
• Journal Information: Scr. Metall.; (United States), Journal Name: Scr. Metall.; (United States) Vol. 17:4; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140702* -- Solar Thermal Power Systems-- Central Receiver
141000 -- Solar Collectors & Concentrators
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALKALI METAL COMPOUNDS
ALLOYS
CENTRAL RECEIVERS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COMMINUTION
CORROSIVE EFFECTS
CRACK PROPAGATION
DISPERSIONS
FATIGUE
FRACTURING
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCOLOY 800
INCOLOY ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MECHANICAL PROPERTIES
MIXTURES
MOLTEN SALTS
NICKEL ALLOYS
NITRATES
NITROGEN COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM NITRATES
SALTS
SODIUM COMPOUNDS
SODIUM NITRATES
SOLAR RECEIVERS
TEMPERATURE GRADIENTS
TESTING
THERMAL FRACTURING
USES