(The role of grain boundary chemistry and structure in the environmentally-assisted intergranular cracking of nickel-base alloys)

Technical Report · Mon Jan 01 00:00:00 EST 1990

DOI:https://doi.org/10.2172/6452413· OSTI ID:6452413

An experimental research program is proposed with the objective of determining the role of the chemistry and structure of grain boundaries in the environmentally-assisted intergranular cracking (EAIC) of nickel-base alloys. Recent work conducted under our current grant has shown that several (previously unreported) microstructural features may control grain boundary cracking. These include the occurrence of IG cracking in carbon-depleted Ni-16Cr-9Fe (alloy 600) and carbon-free Ni-30Cr-9Fe (alloy 690), the formation of strong grain boundary orientation textures following thermal mechanical processing, and the dependence of oxide film composition on C and Cr content. The proposed program focuses on (1) the role of carbon in solution and as carbides on the IG creep-controlled cracking in 360{degree}C water, (2) determination of the role of grain boundary orientation on IG cracking in 360{degree}C water and creep in 360{degree}C Ar, and (3) the role of the film character (composition and structure) in the correlation of creep, repassivation rate, and IGSCC susceptibility in Ni-(16--30)Cr-Fe alloys. Experiments will be conducted on laboratory and commercial heats of Ni-16Cr-9Fe (alloy 600), Ni-30Cr-9Fe (alloy 690) and to a limited extent, alloy X-750 (Ni-16Cr-9Fe-Al-Ti-Nb). The program is designed to systematically isolate each of the aforementioned features, and to determine their influence on IG cracking in high temperature water with the objective of controlling IG cracking through the control of grain boundary chemistry and structure. 12 figs., 7 tabs.

• Research Organization: Michigan Univ., Ann Arbor, MI (USA). Dept. of Nuclear Engineering
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG02-85ER45184
• OSTI ID: 6452413
• Report Number(s): DOE/ER/45184-8; ON: DE91004588
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM ALLOYS
CRACKS
GRAIN BOUNDARIES
CHEMISTRY
IRON ALLOYS
NICKEL BASE ALLOYS
CREEP
GRAIN SIZE
HEAT TREATMENTS
HYDROGEN EMBRITTLEMENT
INTERGRANULAR CORROSION
MICROSTRUCTURE
PROGRESS REPORT
STRAIN RATE
WATER
ALLOYS
CHEMICAL REACTIONS
CORROSION
CRYSTAL STRUCTURE
DOCUMENT TYPES
EMBRITTLEMENT
HYDROGEN COMPOUNDS
MECHANICAL PROPERTIES
NICKEL ALLOYS
OXYGEN COMPOUNDS
SIZE
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies