Time-Temperature-Sensitization diagrams have been established for a low-carbon version of alloy 625 (UNS N06625). Sensitization in terms of a 50 μm (2 mils) intergranular penetration criterion starts after about 3 h aging time at 750°C (soft annealed condition) or after less than 1 h aging time at 800°C (solution annealed condition) when tested according to ASTM-G 28 method A. Grain boundary precipitation of carbides occurs during aging of both the soft annealed and the solution annealed material, but the soft annealed material exhibits a more pronounced general precipitation of Ni3(Nb,Mo) phase giving rise to more distinct loss of ductility. Sensitization of alloy 625 may be retarded by lowering its iron content.

Subject
Materials, Precipitation (solids), Microstructure, Nickel based alloys, Nickel chromium molybdenum alloys, Corrosion losses, Sensitization, Brinell hardness, Annealing, Grain boundary, Alloys, Aging, Ductility
Keywords:
Alloy 625, Uns N06625, solution annealing, soft annealing, aging, sensitization, precipitation, hardness
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1996
Association for Materials Protection and Performance (AMPP)
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