Kinetics and mechanisms of hydrogen attack in 2. 25Cr-1Mo steel

Technical Report · Mon Aug 01 04:00:00 EDT 1988

OSTI ID:6705325

Chao, B L; Odette, G R; Lucas, G E

It is the purpose of this study to understand the kinetics and mechanisms of the hydrogen attack process in a 2.25Cr-1Mo steel which is a candidate for the pressure vessel material for the coal liquefaction process. An SA387-G22-C2 2.25Cr-1Mo steel together with its heat affected zone and weld sections were used as the material for studying the kinetics and mechanisms of HA. These materials were exposed to 490 to 585/degree/C and 16.2 to 20.7MPa hydrogen pressure for up to 9000 hours. The same materials were exposed to thermal control conditions (490 to 585/degree/C and 0.35MPa helium) so that the difference in volume swelling and mechanical property change is defined as the net effect due to hydrogen alone. Tensile, Charpy impact, and creep/creep rupture properties were evaluated as a function of hydrogen damage. X-ray diffraction and transmission/analytical electron microscopy (TEM/AEM) techniques were used to study the carbide species and their chemical compositions. A two-stage replication/TEM technique was used to study the distribution and growth of methane cavities. Based on the concept of pre-existing cavities and a constrained cavity growth mechanism, a mathematical model is developed and calibrated with experimentally measured parameters. This model is used to predict the material response to temperatures and hydrogen pressures not tested in this study. 125 refs., 74 figs., 36 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA); California Univ., Santa Barbara (USA). Dept. of Chemical and Nuclear Engineering
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6705325
• Report Number(s): ORNL/Sub-82-22276/01; ON: DE89001381
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010405 -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALKANES
ALLOYS
CARBIDES
CARBON COMPOUNDS
CAVITIES
CHARPY TEST
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
COAL LIQUEFACTION
CONTAINERS
CREEP
CRYSTAL STRUCTURE
DESTRUCTIVE TESTING
ELEMENTS
EQUATIONS
GRAIN BOUNDARIES
HEAT AFFECTED ZONE
HYDROCARBONS
HYDROGEN
IMPACT TESTS
IRON ALLOYS
IRON BASE ALLOYS
KINETICS
LIQUEFACTION
MATERIALS TESTING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MECHANICAL TESTS
METHANE
MICROSCOPY
MICROSTRUCTURE
NONMETALS
ORGANIC COMPOUNDS
PRESSURE EFFECTS
PRESSURE VESSELS
STEELS
SWELLING
TENSILE PROPERTIES
TESTING
THERMAL DEGRADATION
THERMOCHEMICAL PROCESSES
ZONES