THE TENSILE, NOTCHED TENSILE AND TENSILE IMPACT PROPERTIES OF CROSS-ROLLED - 100 MESH QMV BERYLLIUM SHEET. Progress Report No. 1

Technical Report · Tue Sep 13 00:00:00 EDT 1960

OSTI ID:4036894

The notched strength-to-unnotched strength ratio in slow tension was larger than one at all test temperatures. This indicates that beryllium is not notch sensitive to a theoretical concentration factor of four (K/sub t/ = 4) at the strain rate used. The results of the tensile and tensile-impact tests suggest that there is a definite relation between ductility, repeated yielding, and the change in fracture mode. Unlike in the case of many metals ductility does not always increase with decreasing strain rate. A brittle-to-ductile transition range in static tension exists between 0 to 200 deg F. The range was found to occur in the impact tests at 0 to 575 deg F and 175 to 440 deg F for the transverse and longitudinal directions, respectively. A 1.8 x lO/sup 6/ fold increase in tensiontest velocity broadened the transition range and displaced it upward by approx 500 deg F. Twinning is the probable primary mode of deformation below the transition temperature. Twinning probably precedes crack nucleation and propagation in the brittle range, and yielding in and above the transition range. It is believed that twinning influences fracture by determining the extent of local slip at the ends of the twins and/or by acting as barriers to dislocations attempting to move from the high stress areas. A change occurred in fracture mode (intercrystalline to trans-crystalline) in static tension at 500 deg to llOO deg F. The equicohesive temperature was found to be 775 deg F and 1250 deg F in static tension and tensile impact, respectively. (auth)

• Research Organization: Curtiss-Wright Corp. Wright Aeronautical Div., Wood-Ridge, N.J.
• NSA Number: NSA-15-016059
• OSTI ID: 4036894
• Report Number(s): NP-10001; D-848
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BARRIERS
BERYLLIUM
BRITTLENESS
CRACKS
CRYSTALLIZATION
CRYSTALS
DEFECTS
DEFORMATION
DUCTILITY
EFFICIENCY
FAILURES
IMPACT SHOCK
LATTICES
METALS, CERAMICS, AND OTHER MATERIALS
NUCLEATE BOILING
PROPAGATION
QUANTITY RATIO
ROLLING
SENSITIVITY
SHEETS
TEMPERATURE
TENSILE PROPERTIES
TESTING
TRANSIENTS
TWINNING
VARIATIONS
VELOCITY