Grain Boundary Structure Control for Intergranular Stress-Corrosion Resistance

1991 ◽  
Vol 238 ◽  
Author(s):  
G. Palumbo ◽  
P. J. King ◽  
P. C. Lichtenberger ◽  
K. T. Aust ◽  
U. Erb
Keyword(s):  
Grain Boundary ◽  
Stress Corrosion ◽  
Geometric Model ◽  
Boundary Structure ◽  
Polycrystalline Materials ◽  
Intergranular Stress Corrosion ◽  
Structure Control ◽  
Grain Boundary Structure ◽  
Stress Corrosion Resistance ◽  
Intergranular Stress Corrosion Cracking

ABSTRACTA geometric model for intergranular stress corrosion cracking (IGSCC) is presented and used to evaluate the influence of grain boundary structure on the IGSCC resistance of polycrystalline materials. Preliminary observations regarding the structure of intergranular fracture paths in Alloy 600 C-ring specimens exposed to high temperature caustic media are noted to be consistent with the general predictions of the proposed geometric model and demonstrate that significant enhancement to bulk IGSCC resistance may be achieved through material processing considerations which result in (1) moderate increases in the frequency of structurally ‘special’ grain boundaries (i.e., interfaces close to low Σ CSL's) and (2) refinement in grain size.

Linking Grain Boundary Structure and Composition to Intergranular Stress Corrosion Cracking of Austenitic Stainless Steels

2004 ◽  
Vol 819 ◽  
Author(s):  
S. M. Bruemmer
Keyword(s):  
Grain Boundary ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Potential ◽  
Boundary Structure ◽  
Intergranular Stress Corrosion ◽  
Grain Boundary Structure ◽  
Intergranular Stress Corrosion Cracking

AbstractGrain boundary structure and composition is assessed in austenitic stainless steels along with its influence on intergranular stress corrosion cracking (IGSCC) in high-temperature water. Brief examples are presented illustrating effects of grain boundary character and segregation on behavior in specific light-water-reactor environments. Although grain boundary engineering can produce an increased fraction of “special” boundaries in austenitic stainless alloys, practical benefits depend on the boundary orientation distribution. It is critical to recognize that only ∑3s appear to be more resistant to SCC and the behavior of other low ∑ boundaries is uncertain. Grain boundary composition can have a dominant effect on IGSCC under certain conditions, but altered interfacial chemistry is not required for cracking. In high-potential oxidizing environments, IGSCC susceptibility is a direct function of the boundary Cr concentration. Non- equilibrium thermal segregation of Cr and Mo is often present in mill-annealed stainless steels and may influence cracking susceptibility. This initial grain boundary composition alters subsequent radiation-induced segregation and delays irradiation-assisted SCC susceptibility to higher doses. Other alloying elements and impurities in 300-series stainless steels have been seen to enrich grain boundaries, but few have any significant impact on IGSCC susceptibility. One exception is Si that strongly segregates during irradiation. Recent results suggest that Si may accelerate crack propagation in both low- and high-potential water environments. Critical research is still needed to isolate individual grain boundary characteristics and quantitatively link them to IGSCC.

Grain boundary design and control for intergranular stress-corrosion resistance

1991 ◽  
Vol 25 (8) ◽  
pp. 1775-1780 ◽  
Author(s):  
G. Palumbo ◽  
P.J. King ◽  
K.T. Aust ◽  
U. Erb ◽  
P.C. Lichtenberger
Keyword(s):  
Corrosion Resistance ◽  
Grain Boundary ◽  
Stress Corrosion ◽  
Intergranular Stress Corrosion ◽  
Stress Corrosion Resistance ◽  
And Control

Cation Coordination At Σ Grain Boundaries in TiO2 and SrTiO3, and its Effect on the Local Electronic Properties

1999 ◽  
Vol 5 (S2) ◽  
pp. 792-793
Author(s):  
J.A. Zaborac ◽  
J.P. Buban ◽  
H.O. Moltaji ◽  
S. Stemmer ◽  
N.D. Browning
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Electronic Properties ◽  
Defect Formation ◽  
Boundary Structure ◽  
Polycrystalline Materials ◽  
Dominant Effect ◽  
Grain Boundary Structure ◽  
Charge Potential ◽  
Cation Coordination

Grain boundaries have long been known to have a dominant effect on the electronic properties of polycrystalline materials. In the case of electroceramic oxides, the thermodynamics of defect formation (vacancies or interstitials, cations or anions) are usually invoked to predict the presence of a space charge potential at the grain boundaries. The relative energetics for the formation of each type of defect determines the size and sign of this potential barrier and thus, the effect that boundaries have on the overall electronic properties of the materials. However, a limitation to this continuum thermodynamics approach is that it does not consider the effect of the grain boundary structure.To investigate whether the grain boundary atomic structure can have an effect on the energetics of defect formation and hence the electronic properties, here we examine the structure of Σ5 boundaries in two systems, SrTiO3 (perovskite) and TiO2(rutile).

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