Microstructure and microdeformation effects on IGSCC of Alloy 600 steam generator tubing
Microdeformation characteristics in Alloy 600 tubing have been examined after various tensile deformations. Microstructure developed during processing was found to control subsequent microdeformation behavior. Grain boundary carbides were the most effective source of dislocations, activating at lower macro-strains and continuing to operate at higher macrostrains than other sources. Ledges within grain boundaries, twin boundaries and matrix carbides also acted as dislocation sources. Most dislocation activity at low strains was confined to planar arrays. A conceptual model is presented to account for the effects of interfacial and matrix microstructure on microdeformation and primary-side SCC of Alloy 600 tubing. Microstructure is linked to IGSCC resistance through its influence on microdeformation behavior and the resultant crack-tip stress rate. Dislocation source activity at grain interfaces is proposed to be a critical aspect controlling IGSCC susceptibility. Effective sources such as grain boundary carbides promote crack blunting, decrease the crack-tip stress state and increase resistance to cracking.
- OSTI ID:
- 6976941
- Report Number(s):
- CONF-870314-
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
BOILERS
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CORROSION
CORROSION RESISTANCE
CORROSIVE EFFECTS
CRACKS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
FRACTURE MECHANICS
HEAT EXCHANGERS
INCONEL 600
INCONEL ALLOYS
INTERGRANULAR CORROSION
IRON ALLOYS
LINE DEFECTS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
STEAM GENERATORS
STRESS CORROSION
STRUCTURAL CHEMICAL ANALYSIS
TENSILE PROPERTIES
TUBES
VAPOR GENERATORS