Phosphorus free energy change associated with segregation to grain boundaries in submerged-arc welds

Conference · Fri Oct 01 04:00:00 EDT 1999

OSTI ID:679490

Mendes, C M ^[1]

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1. Magnox Electric plc, Berkeley (United Kingdom)

The segregation of phosphorus from the matrix to grain boundaries has been associated with increased brittleness in carbon-manganese submerged-arc weld metals, with the failure mode on the lower shelf and transition regime changing from cleavage to intergranular failure. The quantification of segregation and hence thermal embrittlement requires the knowledge of the energy decrease for an atom in the matrix moving to a grain boundary, {Delta}G. There is some evidence to suggest that the energy decrease depends on the level of alloying constituents and this paper considers a steel with a 1.46 wt% manganese and 0.08% carbon. The value of {Delta}G was calculated as a function of temperature by measuring grain boundary segregation after annealings at constant temperature in the range 763--873 K. The grain refined and columnar regions of the welds were analyzed separately. The phosphorus grain boundary monolayer coverages observed were smaller than those reported for a PWR steel.

• OSTI ID: 679490
• Report Number(s): CONF-960643--
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
36 MATERIALS SCIENCE
EMBRITTLEMENT
GRAIN BOUNDARIES
PHOSPHORUS
PHYSICAL RADIATION EFFECTS
PRESSURE VESSELS
PWR TYPE REACTORS
REACTOR MATERIALS
SEGREGATION
STEELS
WELDED JOINTS