Evaluation of advanced austenitic alloys relative to alloy design criteria for steam service
The results are summarized for a task within a six-year activity to evaluate advanced austenitic alloys for heat recovery systems. Commercial, near-commercial, and development alloys were evaluated relative to criteria for metallurgical stability, fabricability, weldability, mechanical properties, and corrosion in fireside and steamside environments. Alloys that were given special attention in the study were 800HT{reg sign}, NF709{reg sign}, HR3C{reg sign}, and a group of 20/25% chromium-30% nickel-iron alloys identified as HT- UPS (high-temperature, ultrafine-precipitation strengthened) alloys. Excellent metallurgical stability and creep strength were observed in the NF709 and HR3C steels that contained niobium and nitrogen. One group of HT-UPS alloys was strengthened by solution treating to temperatures above 1150{degrees}C and subsequent cold or warm working. Test data to beyond 35,000 h were collected. The ability to clad some of the alloys for improved fireside corrosion resistance was demonstrated. Weldability of the alloys was a concern. Hot cracking and heat-affected-zone (HAZ) liquation cracking were potential problems in the HR3C stainless steel and HT-UPS alloys, and the use of dissimilar metal filler wire was required. By the reduction of phosphorous content and selection of either a nickel-base filler metal or alloy 556 filler metal, weldments were produced with minimum HAZ cracking. The major issues related to the development of the advanced alloys were identified and methods to resolve the issues suggested. 56 refs., 19 figs., 8 tabs.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5436731
- Report Number(s):
- ORNL-6629/P2; ON: DE91017800
- Country of Publication:
- United States
- Language:
- English
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Evaluation of HAZ liquation cracking susceptibility and HAZ softening behavior in modified 800H
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Related Subjects
36 MATERIALS SCIENCE
AUSTENITIC STEELS
CORROSION RESISTANCE
MECHANICAL PROPERTIES
CHROMIUM ALLOYS
IRON ALLOYS
NICKEL ALLOYS
ANNEALING
BOILERS
CARBIDES
CARBONITRIDES
CRACKS
CREEP
FILLER METALS
FOSSIL-FUEL POWER PLANTS
HEAT AFFECTED ZONE
METALLURGICAL EFFECTS
MICROSTRUCTURE
PHOSPHORUS
SUPERHEATERS
TENSILE PROPERTIES
WELDABILITY
ALLOYS
CARBON COMPOUNDS
CRYSTAL STRUCTURE
ELEMENTS
HEAT TREATMENTS
IRON BASE ALLOYS
NITROGEN COMPOUNDS
NONMETALS
POWER PLANTS
STEELS
THERMAL POWER PLANTS
ZONES
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360105 - Metals & Alloys- Corrosion & Erosion
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