Large Strain Compression of Two Tungsten Alloys at Various Strain Rates
Abstract
This report describes the material characterization of two tungsten alloys in terms of their modulus of elasticity, yield stresses, and true stress- true strain curves. These alloys are W2 (Kennametal) with 97.2% tungsten and X21 (Teledyne, Firth, and Sterling) with 93% tungsten. Both alloys were compressed to strains between 40% and 75%, and at strain rates between 0.0001/sec and 3000/sec. The experiments were conducted in the Medium Strain Rate Machine (MSRM) and Split Hopkinson Pressure Bar (SHPB) facilities at the U.S. Army Materials Technology Laboratory (MTL). The effect of strain rate was ascertained for each alloy and a comparison conducted on their stress-strain relationships. Metallographic examinations of the microstructure were conducted on both tungsten alloys to determine if adiabatic shear bands had developed. Zones of shear deformation were observed but were attributed to frictional effects at the ends of specimens. At large deformations, frictional effects cause specimen barrelling and a three-dimensional stress state. Annular grooves were machined into the ends of the specimens and, in addition, Teflon(TM) sheets provided lubrication thereby eliminating frictional effects. Both alloys are strain rate sensitive; however, the W2 alloy is somewhat more sensitive at higher strain- rates. No adiabatic shear bands were observed and shear deformation due to frictional effects was eliminated by using the modified specimen and Teflon(TM) sheeting.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1992
- Accession Number
- ADA258789
Entities
People
- John L. Green
- Paul Moy