Solidification and aging behavior of Types 308 and 308CRE stainless steel welds
Controlled Residual Element (CRE) additions of Ti, P, and B to type 308 stainless steel filler metal were previously shown to improve the elevated-temperature creep-rupture properties of welds. The solidification and aging behavior of types 308 and 308CRE stainless steel welds were examined in an effort to identify the mechanism responsible for the improved mechanical properties. Analysis of the as-welded microstructure and thermal analysis of the solidification behavior did not reveal any major differences that could be responsible for the creep-rupture improvement. However, extensive aging studies at 550 to 850/sup 0/C for times up to 10,000 h revealed significant differences. The transformation of ferrite in the as-welded duplex structure to sigma phase was not retarded by CRE additions. However, the extensive precipitation of M/sub 23/C/sub 6/ at the austenite-ferrite interfaces in the aged type 308 stainless steel welds was replaced by more homogeneous precipitation of titanium-rich carbides, nitrides, and sulfides in aged type 308CRE stainless steel. The results are summarized in the form of time-temperature-transformation diagrams. It is proposed that the elimination of a continuous network of carbides is responsible for the improved elevated-temperature properties. The different type of precipitate formed may also play a role.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6599381
- Report Number(s):
- ORNL/TM-9086; ON: DE84016552
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101* -- Metals & Alloys-- Preparation & Fabrication
AGING
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CREEP
CRYSTAL STRUCTURE
FABRICATION
FAILURES
FILLER METALS
HIGH TEMPERATURE
IRON ALLOYS
IRON BASE ALLOYS
JOINING
JOINTS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
PHASE TRANSFORMATIONS
RUPTURES
SOLIDIFICATION
STAINLESS STEEL-308
STAINLESS STEELS
STEELS
TITANIUM ADDITIONS
TITANIUM ALLOYS
VERY HIGH TEMPERATURE
WELDED JOINTS
WELDING