Specimen Size Effects on the Compressive Stress-Strain Response of Equal Channel Angular Extrusion (ECAE) Tantalum

Abstract

Compression tests were performed on tantalum over a range of strain rates using conventional servo-hydraulic load frames and the Kolsky (split-Hopkinson pressure) bar. To obtain a large range of strain rates (0.001/s to 500k/s), different diameter Kolsky bars were required: 3.18 mm, 1.59 mm, 794 um, and 305 um. These different bars were used to test different sample geometries: nominally 1.6-, 0.8-, and 0.4-mm cubes, and small cylinders with 60-um diameter and 30-um height. It was found that the four different sample sizes led to drastically different measured strengths, even for samples tested at the same strain rates. The tantalum studied has a fine grain structure (~2 um) so this is not believed to be due to the grain size. However, the reason for the discrepancy is unknown.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Jun 26, 2019
Accession Number
AD1076387

Entities

People

  • Brian E. Schuster
  • Daniel Casem
  • Daniel Magagnosc
  • Jonathan Ligda
  • Timothy N. Walter

Organizations

  • United States Army Research Laboratory

Tags

DTIC Thesaurus Topics

  • Chemical Analysis
  • Compression
  • Data Set
  • Diameters
  • Digital Data
  • Dynamic Tests
  • Elastic Waves
  • Extrusion
  • Fabrication
  • Geometry
  • Grain Size
  • Heat Treatment
  • Impurities
  • Materials
  • Materials Science
  • Measurement
  • Mechanical Properties
  • Mechanics
  • Microstructure
  • Military Research
  • Strain Rate
  • Stress Waves
  • Stresses
  • Tantalum
  • Wave Propagation

Fields of Study

  • Materials science

Readers

  • Mathematics or Statistics
  • Mechanical Engineering/Mechanics of Materials.
  • Powder metallurgy of Titanium alloys.