Characterization of rapidly solidified Type 304 stainless steel powder

Technical Report · Tue Apr 01 04:00:00 EST 1986

OSTI ID:5164725

Wright, R N; Flinn, J E; Korth, G E

The microstructure, morphology, size distribution and surface characteristics of rapidly solidified Type 304 stainless steel powders produced by centrifugal atomization and vacuum gas atomization have been characterized. Both powders are generally spherical with average particle sizes of 40 and 80 ..mu..m for the CA and VGA powders respectively. The CA powder forms an iron oxide layer about 2.5 nm thick and the VGA powder forms an iron-chromium oxide layer about 8.0 nm thick. The CA powder contains a significant amount of helium which is entrained during processing, and the retained helium is stable with respect to outgassing up to the melting point of the powder. Both CA and VGA powders contain a metastable bcc phase which is retained at room temperature. The volume fraction of bcc phase increases with decreasing particle size in the CA powder. The volume fraction of bcc does not depend strongly on the particle size in the VGA powder, but there is a trend for larger volume fraction of bcc with increasing particle size. Solidification as primary austenite is favored in the larger CA particles which contain potent catalytic sites for heterogeneous nucleation of the solid, and therefore solidify with relatively shallow undercooling. Small CA particles which are unlikely to contain potent nucleation sites solidify with deep undercooling as primary ferrite. Slower cooling rates associated with the VGA process favor solidification as primary austenite.

• Research Organization: EG and G Idaho, Inc., Idaho Falls (USA)
• DOE Contract Number: AC07-76ID01570
• OSTI ID: 5164725
• Report Number(s): EGG-SCM-7133; ON: DE87000470
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ATOMIZATION
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
COOLING
CORROSION RESISTANT ALLOYS
CRYSTAL STRUCTURE
ELEMENTS
FLUIDS
GASES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HELIUM
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
METALLURGY
MICROSTRUCTURE
NICKEL ALLOYS
NONMETALS
NUCLEATION
PARTICLE SIZE
PHASE STUDIES
PHASE TRANSFORMATIONS
POWDER METALLURGY
POWDERS
RARE GASES
SIZE
SOLIDIFICATION
SPLAT COOLING
STAINLESS STEEL-304
STAINLESS STEELS
STEELS
SURFACE PROPERTIES