Ferrite morphology and variations in ferrite content in austenitic stainless steel welds
Four distinct ferrite morphologies have been identified in Type 308 stainless steel multipass welds: vermicular, lacy, acicular, and globular. The first three ferrite types are related to transformations following solidfication and the fourth is related to the shape instability of the residual ferrite. An earlier study showed that most of the ferrite observed in austenitic stainless steel welds containing a duplex structure may be identified as residual primary ferrite resulting from incomplete delta ..-->.. ..gamma.. transformation during solidification and/or residual ferrite after Widmanstatten austenite precipitation in primary ferrite. These modes of ferrite formation can be used to explain observed ferrite morphologies in austenitic stainless steel welds. Variations in ferrite content within the weld were also related to weld metal composition, ferrite morphology, and dissolution of ferrite resulting from thermal cycles during subsequent weld passes. An investigation of the Type 308 stainless steel filler metal solidified over cooling rates ranging from 7 to 1600/sup 0/C/s (44.6 to 2912/sup 0/F/s) showed that the cooling rate of the weld metal within the freezing range of the alloy affects the amount of ferrite in the microstructure very little. However, the scale of the solidification substructure associated with various solidification rates may influence the ferrite dissolution kinetics.
- Research Organization:
- Oak Ridge National Lab., TN
- OSTI ID:
- 6599765
- Journal Information:
- Weld. J. (Miami); (United States), Journal Name: Weld. J. (Miami); (United States)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FERRITES
MORPHOLOGY
TRANSFORMATIONS
STAINLESS STEEL-308
WELDED JOINTS
EXPERIMENTAL DATA
HEAT TREATMENTS
MICROSTRUCTURE
VERY HIGH TEMPERATURE
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CRYSTAL STRUCTURE
DATA
FERRIMAGNETIC MATERIALS
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
IRON COMPOUNDS
JOINTS
MAGNETIC MATERIALS
MATERIALS
NICKEL ALLOYS
NUMERICAL DATA
OXYGEN COMPOUNDS
STAINLESS STEELS
STEELS
TRANSITION ELEMENT COMPOUNDS
360101* - Metals & Alloys- Preparation & Fabrication