COMPARISON OF VARIOUS TEST SPECIMENS FOR THE DETERMINATION OF NOTCH SENSITIVITY AND FRACTURE TOUGHNESS OF HIGH-STRENGTH SHEET MATERIALS.
ARMY MATERIALS RESEARCH AGENCY WATERTOWN MASS
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A variety of test specimens and test methods are currently being used by several investigators to evaluate materials for space applications. In general, these tests are being conducted on high-strength sheet materials using specimens containing notches of one sort or another. The purpose of this program was to compare various test specimens for the determination of notch sensitivity and fracture toughness. Specimens considered were 1 1-inch-wide edge-notched, 2 1.5-inch-wide center-notched, and 3 3-inch-wide center-notched. Notch sensitivity data were obtained from all specimens fracturetoughness data, based upon the ink stain and percent shear method, were gathered primarily from the 3-inch-wide specimen. Materials considered include AMS 6434, H11, 300M, and PH 15-7 molybdenum steels and 6A1-4V titanium. Two or more strength levels per alloy were investigated and testing temperatures ranged from 165 to -80F. Results of this investigation indicate that, of the designs considered, the 3-inch-wide specimen generally offers the best test to measure notch sensitivity or fracture toughness. Author