Residual stresses in roller-expanded steam generator tube transitions
- Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.
The residual stresses induced by roller expansion were studied in two overexpanded and two underexpanded Inconel Alloy 600, 3/4 inch O.D. tubes. Each pair were intended to be duplicates and were expanded using procedures similar to those applied in nuclear power plant installations wherein the steam generator tubing is expanded into a hole in the tube sheet. The stresses were measured using a combination of strain gage and stress relief and X-ray diffraction (XRD) with most being performed by XRD. Over 1,000 measurements were repeated at least three times on each tube sample. Both hoop and axial direction stresses were measured along transverses through the expanded zone of the tubes on the outside diameter (O.D.) and inside diameter (I.D.) surfaces. Also, subsurface measurements were performed on the inside diameters. The profiles of the XRD obtained residual stress distributions agreed reasonably well with previously published results, but the magnitudes were much higher. The profiles and magnitudes of the stresses, when compared with in-service and stress-corrosion tests, confirmed the correlation between cracking and residual stresses due to roller expansion. Comparison of the residual stress patterns in the overexpanded (340 MPa hoop and 245 MPa axial) and underexpanded (436 MPa hoop and 508 MPa axial) tubes confirmed the greater susceptibility of the latter for stress corrosion cracking.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (United States); Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.
- Sponsoring Organization:
- EPRI; Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 6503499
- Report Number(s):
- EPRI-TR-102355
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220200* -- Nuclear Reactor Technology-- Components & Accessories
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALLOY-NI76CR15FE8
ALLOYS
ALUMINIUM ADDITIONS
ALUMINIUM ALLOYS
BOILERS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COHERENT SCATTERING
CORROSION
CORROSION RESISTANT ALLOYS
CRACK PROPAGATION
DATA
DIFFRACTION
EXPANSION
EXPERIMENTAL DATA
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCONEL 600
INCONEL ALLOYS
INFORMATION
IRON ALLOYS
MATERIALS
MEASURING INSTRUMENTS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIMONIC
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
NUMERICAL DATA
POWER PLANTS
PRESSURE DEPENDENCE
RESIDUAL STRESSES
SCATTERING
STEAM GENERATORS
STRAIN GAGES
STRESS CORROSION
STRESSES
THERMAL POWER PLANTS
TITANIU
TITANIUM ADDITIONS
TUBES
VAPOR GENERATORS
VERY HIGH PRESSURE
X-RAY DIFFRACTION