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Open Access Publications from the University of California

Correlation of Nanohardness to Bulk Mechanical Tensile and Shear Properties through Direct Characterization and Comparison of Neutron-Irradiated Steels

  • Author(s): Krumwiede, David Lewis
  • Advisor(s): Hosemann, Peter
  • et al.
Abstract

Nanoindentation has been used for decades to assess materials on a local scale and to obtain fundamental mechanical property parameters. Nuclear materials research often faces the challenge of testing rather small samples due to the hazardous nature, limited space in reactors, and shallow ion-irradiated zones, fostering the need for small-scale mechanical testing (SSMT). As such, correlating the results from SSMT to bulk properties is particularly of interest. This thesis compares macroscopic tensile (σy, σflow, and σuts) and shear punch (τy and τmax) test results to nanoindentation hardness data (H) obtained on a number of different neutron-irradiated materials in order to understand the relationship and scaling behavior on radiation-damaged samples. Various empirical relationships are employed and compared. In addition, multiple methods for obtaining hardness numbers from the load-displacement (LD) curves generated during instrumented indentation testing (IIT) are analyzed. After investigating many permutations of LD curve analysis methods and empirical relationships, combinations for specific cases are suggested based on expected material behavior. Utilizing these suggestions, efficacious relationships are found between hardness, tensile yield, tensile flow, and shear max.

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