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Properties and Structure of CPF8 and CPF8M Centrifugally Cast Pipe

Technical Report ·
DOI:https://doi.org/10.2172/711242· OSTI ID:711242
 [1];  [1];  [1]
  1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
The chemical contents, microstructures, tensile properties from room temperature to 649°C, and short-term creep-rupture properties at 538 and 649°C of two CPF8 and two CPF8M cast pipes were investigated. All test specimens had circumferentially oriented tensile axes. One casting of each type had relatively low ferrite content, and one had relatively high ferrite content. The 0.2% yield strength was higher for higher ferrite castings for the entire test temperature range. The ultimate tensile strength was higher for higher ferrite castings only at low temperatures. At 538 and especially 649°C ultimate tensile strength values were not significantly different for the low- and high-ferrite castings. Some of the ultimate tensile strengths were below the minimum values suggested for wrought materials of equivalent compositions. The measured creep-rupture strengths for the cast steels frequently were lower than the suggested minimum values of the wrought counter-parts, types 304 and 316 stainless steel. The creep-rupture ductility of CPF8 material tends to decrease with increasing rupture time at both 538 and 649°C. Fracture at 649°C follows substructural boundaries and is associated with sigma phase formed from the original ferrite phase. The results suggest that separate analyses of the properties of wrought and cast austenitic steels for design are warranted, particularly for elevated-temperature service.
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
W-7405-ENG-26;
OSTI ID:
711242
Report Number(s):
ORNL/TM--7142
Country of Publication:
United States
Language:
English