Delta-ferrite transformations in a type 316 weld metal

Technical Report · Wed Feb 01 04:00:00 EST 1978

OSTI ID:6495004

Lai, J K; Haigh, J R

The effects of stress relief heat treatments on the microstructure of a 316 weld metal are described for temperatures in the range 538 to 800/sup 0/C. In the as-welded condition, the weld deposit contains delta-ferrite and austenite and during stress relief the delta-ferrite transforms predominantly to carbides and austenite at 538 to 650/sup 0/C and to chi-phase at 800/sup 0/C. These observaions are related to creep crack growth data at 5380C and 600/sup 0/C and provide an explanation for the significantly improved ductility caused by heat treating at 800/sup 0/C. Weld metal heat treated at 800/sup 0/C for 10 h appears to be stabilised against any likely microstructural causes of embrittlement in long term service at up to 650/sup 0/C and may be treated for design purposes in the same way as parent steels. Therefore the more difficult solution heat treatments at 1050/sup 0/C used in the past are not necessary.

• Research Organization: Central Electricity Research Labs., Leatherhead (UK)
• OSTI ID: 6495004
• Report Number(s): CEGB/RD/B/N-159/77
• Country of Publication: United States
• Language: English

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ALLOYS
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CREEP
CRYSTAL STRUCTURE
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
PHASE TRANSFORMATIONS
REACTOR COMPONENTS
STAINLESS STEEL-316
STAINLESS STEELS
STEELS
TEMPERATURE DEPENDENCE
VERY HIGH TEMPERATURE
WELDED JOINTS