AN INVESTIGATION OF METHODS FOR DETERMINING THE CRACK-PROPAGATION RESISTANCE OF HIGH-STRENGTH ALLOYS
Summary technical rept. 14 Oct 1959-14 Jan 1961
SOUTHERN RESEARCH INST BIRMINGHAM AL
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Attempts were made to 1 devise a simple crack-propagation specimen for evaluating high-strength sheet materials, 2 determine the crack-propagation characteristics of several high-strength sheet materials, 3 determine the effects of several experimental variables on the crack-propagation characteristics of some of these materials, and 4 determine the validity of the crack-propagation specimen for predicting the biaxial strength of the high-strength sheet materials. A sheet specimen called the shear-cracked specimen with a central transverse crack or notch produced by means of a simple punch-anddie fixture was devised. The crack-propagation properties obtained with the shear-cracked specimen were very similar to those obtained with fatigue-cracked specimens of the quench-hardenable and age-hardenable materials. The sheet-type crack-propagation specimen may be useful in predicting the biaxial strength of materials heat treated to very high strength levels in excess of about 250,000 psi. At lower nominal strength levels, the crack-propagation specimen is apparently too severe a criterion.
- Metallurgy and Metallography