scholarly journals Correlation of mechanical property changes in neutron irradiated pressure vessel steels on the basis of spectral effects

1989 ◽  
Author(s):  
H.L. Heinisch
Keyword(s):  
Mechanical Property ◽  
Pressure Vessel ◽  
Pressure Vessel Steels ◽  
Property Changes

An Application of a Method for Correlating Mechanical Property Changes with Microstructural Changes in Ion-Irradiated Specimens

1996 ◽  
Vol 54 ◽  
pp. 1018-1019
Author(s):  
P. M. Rice ◽  
R. E. Stoller
Keyword(s):  
Mechanical Property ◽  
Pressure Vessel ◽  
Ion Irradiation ◽  
Dislocation Loops ◽  
White Line ◽  
Cross Sectional ◽  
Microstructural Changes ◽  
Sem Image ◽  
Property Changes ◽  
Defect Microstructure

A method for correlating mechanical property changes and microstructural changes as a function of depth in ion irradiated specimens has been applied to a series of model pressure vessel steels. The technique employs nanoindentation with very small indent depths, on cross sectional specimens, to measure changes in hardness with sub-micron spatial resolution. Conventional TEM imaging of the cross sectional specimens allows the investigation of the defect microstructure as a function of depth below the original irradiated surface. For ion irradiations (implantations) the dose varies as a function of depth in the specimen and can be calculated with reasonable accuracy using TRIM calculations. Thus changes in both hardness and defect microstructure can be measured and correlated, over a range of doses, from a single specimen.The technique has been applied to a set of model ferritic pressure vessel alloys to study the effect of various solutes on embrittlement. 2.5 MeV He ion irradiation was used to produce qualitatively similar microstructural features to those created in a nuclear reactor environment allowing the study to be carried out without the added complications associated with radioactive specimens. Figure la is an SEM image showing a set of nano-indents that starts on the left, beyond the end of range of the ions which is easily seen as the dark band. The indents eventually cross the thin oxide that marks the original irradiated surface (the white line) and enter the Fe electroplating seen here as the fine grained material at the bottom of the images. Figure lb is a higher magnification SEM image of the same indents showing the three-sided pyramid shaped indents reflective of the Berkovich diamond used in nanoindenting. Each of these residual indents is the result of a multipule indent process. The first indent is 50nm deep to acquire the sub-micron resolution hardness data, and the second is twice as deep (thus twice as wide) to clearly mark the position of the shallower indent before moving to the next position. Figure 2a is a bright-field TEM micrograph showing the defect microstructure of the entire irradiated region of an Fe + low N alloy, taken with g = {330} such that the dislocation loops appear dark. Figure 2b is a plot of the actual change in hardness, AH, as a function of depth below the original irradiated surface at the same scale, and for the same alloy shown in figure 2a.

Microstructural and Mechanical Property Changes in Model Fe-Cu Alloys

1994 ◽  
Vol 373 ◽  
Author(s):  
Philip M. Rice ◽  
Roger E. Stoller ◽  
Barry N. Lucas ◽  
Warren C. Oliver
Keyword(s):  
Mechanical Property ◽  
Ion Irradiation ◽  
Light Water Reactor ◽  
Hardening Model ◽  
Light Water ◽  
Single Defect ◽  
Cu Alloys ◽  
Pressure Vessel Steels ◽  
Dislocation Barrier ◽  
Property Changes

AbstractThis paper describes a technique developed to determine values for the dislocation barrier strength of the defects believed to be responsible for the embrittlement of light water reactor (LWR) pressure vessel steels. Microstructures consisting of a single defect type were introduced by ion irradiation or thermal annealing, and the defect distributions were determined by TEM. Hardness changes were measured using a nano indenter and the dislocation barrier strengths for the defects involved were computed based on a dispersed barrier hardening model.

Recent results on mechanical property changes obtained by light ion simulation

1984 ◽  
Vol 122 (1-3) ◽  
pp. 448
Author(s):  
H. Ullmaier ◽  
H. Schroeder ◽  
P. Jung
Keyword(s):  
Mechanical Property ◽  
Property Changes
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