Accession Number : ADA258789
Title : Large Strain Compression of Two Tungsten Alloys at Various Strain Rates
Descriptive Note : Final rept.
Corporate Author : ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB
Personal Author(s) : Green, John L ; Moy, Paul
Report Date : Sep 1992
Pagination or Media Count : 22
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.
Descriptors : *COMPRESSION , *STRAIN RATE , *TUNGSTEN ALLOYS , TEST AND EVALUATION , SHEAR PROPERTIES , STRESSES , ARMOR , MICROSTRUCTURE , MATERIALS , THREE DIMENSIONAL , ADIABATIC CONDITIONS , FRICTION , ARMY , RODS , LABORATORIES , MACHINES , YIELD , PRESSURE , SHEETS , ADDITION , TETRAFLUOROETHYLENE RESINS , METALLOGRAPHY , LUBRICATION , TUNGSTEN , COMPARISON , DEFORMATION , FACILITIES , MODULUS OF ELASTICITY , RATES , ALLOYS , REGIONS
Subject Categories : Inorganic Chemistry
Properties of Metals and Alloys
Distribution Statement : APPROVED FOR PUBLIC RELEASE