EPRI 2000 Session: Material Properties Measurement
New NDE Method for Structural Integrity of Materials Under Load
V. Kisel, Institute of Solid State Physics, RAS
ABSTRACT
The remarkable findings of this work are the scaling between the threshold stresses of various stages of plasticity and fracture (at atomic, meso- and macroscopic scales) and the close correlation between the fracture surface roughness and deformation properties in model alkali halide, single/polycrystals, severe deformed metal alloys and high strength composites, Fe-based amorphous alloys and ceramics under different tests and environments. This universal correlation is fulfilled in a wide range of temperatures (T = (0.001 to 0.9)Tm, Tm is the melting or crystallization point), at stress rates from quasistatic to shock wave tests (0.0001 to 1 000 000 000 MPa/s), and with various impurity state/content and environments. The next finding of this work is the proportionality between the sizes of deformation structure units: dislocation spacing in amorphous solids, grains in nano-/polycrystalline materials with constant chemical composition, and the reciprocal value of their microhar dness (flow stress). The proportionality between flow stress and volume fraction of amorphous, nano-/coarse grains; between the Young's moduli and threshold stresses of atomic, mesoscopic and macroscopic stages of plastic flow and fracture; scaling of the dependences of total crystal density change and strain versus deformation stress points to the vital role of dislocation cross-slip, climb and the Orowan bowing mechanisms in the strict chain of deformation stages: dislocation motion and multiplication, drag, cell/grain boundary nucleation [1-2], the transformation of low-angle boundaries into the high-angle ones, microcrack initiation and coagulation into macrocracks (macrofracture and damage with size (mass) distribution of fracture products governed by the precursor plastic flow). This governing law optimizes the preparation treatments and the NDE forecast of deformation parameters of materials under various tests.
Publication Source: 2nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, May 24-26, 2000, New Orleans, Louisiana USA. Publisher: EPRI - [Homepage]
