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Title: Strengthening of σ phase in a Fe20Cr9Ni cast austenite stainless steel

The strengthening mechanism of σ phase in a Fe20Cr9Ni cast austenite stainless steel used for primary coolant pipes of nuclear power plants has been investigated. The yield and ultimate tensile strengths of aged specimens increased comparing with those of the unaged ones. It was found that the increase of strengths is due to the hard and brittle (σ + γ{sub 2}) structure which decomposed from α phase in the steel. Fracture surfaces of specimens after in situ tensile test showed that the inhibition of (σ + γ{sub 2}) structure on the dislocation movements was more significant than ferrite although cracks started predominately at σ/γ{sub 2} interfaces. The (σ + γ{sub 2}) structure behaves like a fiber reinforced composite material. - Highlights: • The strengthening mechanism of σ phase in a Fe20Cr9Ni CASS is investigated. • The yield and ultimate tensile strengths increase with increasing of σ phase. • The increase of strengths is due to hard and brittle (σ + γ{sub 2}) structure. • The (σ + γ{sub 2}) structure in CASS behaves like a fibre reinforced composite material. • The σ/γ{sub 2} and α/σ/γ{sub 2} boundaries hinder the movement of dislocation.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22288668
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 84; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITE; CALCIUM SULFIDES; COMPOSITE MATERIALS; CRACKS; DISLOCATIONS; FERRITES; FRACTURES; PRIMARY COOLANT CIRCUITS; REINFORCED MATERIALS; STAINLESS STEELS; TENSILE PROPERTIES