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Initial Fractures in Steels for Nuclear Reactors

#G-1386


Study of the Initiating Physical Aspects of Nucleation and Growth of Microscopic Сracks and the Processes Taking Place Ahead of Microcrack (Ultra Micro) Tip at LCF in Austenitic Steels Used in Nuclear Reactors

Tech Area / Field

  • FIR-MAT/Materials and Materials Conversion/Fission Reactors
  • MAT-ALL/High Performance Metals and Alloys/Materials
  • PHY-SSP/Solid State Physics/Physics

Status
3 Approved without Funding

Registration date
20.01.2006

Leading Institute
Georgian Technical University, Georgia, Tbilisi

Collaborators

  • University of British Columbia / Department of Mechanical Engineering, Canada, BC, Vancouver\nSCK-CEN, Belgium, Mol\nFachhochschule Osnabrück, University of Applied Sciences, Germany, Osnabrück\nHelsinki University of Technology / Laboratory of Engineering Materials, Finland, Helsinki\nTechnical University of Crete, Greece, Chania\nUniversity of California / School of Engineering and Applied Science, USA, CA, Los-Angeles\nMississippi University / Center for Advanced Vehicular Systems, USA, MS, 39762\nUniversity of California, USA, CA, Santa Barbara

Project summary

Contemporary industry still remains in need of such conventional materials as steel as a structural material that is able to support most of the loading. However, a long-period operation leads it to degradation and premature failure caused by fatigue, dynamic deformation, thermal cycling and irradiation, and in some cases it results in catastrophe. This project deals with the study of physical reasons and mechanism of fatigue failure of structural steels used in nuclear reactors, turbo generators, aircrafts and other power generating machines. The integrity of steel components and a corpus of a reactor is usually assessed according to the brittle strength criteria. For this purpose it is necessary to establish changes in cracking resistance depending on fatigue, temperature and irradiation of the material. Therefore, among the problems of nuclear power stations’ safety, the main task is to study the unclear features of physics of fracture, taking into consideration a lack in experimental researches dealing with nucleation and growth of ultra-microcracks (the microcracks of nano-dimensions) in the steels used for power generating machines. Solution to the above tasks will provide a deeper understanding of physical aspects of degradation and damage, that in turn will support design of other innovative, advanced materials with significantly enhanced performance parameters and market potential. In addition, the acquired results may be applied to improve computer simulation of: 1. advanced alloys and steels; 2. prediction of the expected premature damage (fatigue, brittle or ductile) and catastrophes.

A promising approach to prediction of crack-resistance of nuclear materials, which is currently developing, is based on a local approach to the analysis of brittle and ductile fracture. For this purpose special software are used in Europe (PERFECT) and in Russia (PROMETEI), however, location, reasons of their initiation and the mechanisms of ultra-microcrack nucleation are not taken into account. Consequently, the latter will considerably affect the accuracy of the acquired results of modeling. The results of the proposed project may also be applied to the international research programs such as EUROATOM, FUSION, TACIS, and PHARE etc.


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