Accession Number : AD0431612


Title :   CRACK INITIATION IN METALLIC MATERIALS,


Descriptive Note : Final rept.,


Corporate Author : SYRACUSE UNIV N Y METALLURGICAL RESEARCH LABS


Personal Author(s) : Schroder,K ; Packman,P ; Nash,G ; Weiss,V


Report Date : Jan 1964


Pagination or Media Count : 78


Abstract : The effect of surface structure on the fracture strength has been studied on commercially pure tungsten 2.5A1-16V titanium alloy and LiF specimens. Brittle titanium alloy specimens with piggy back notches, tested at room temperature, showed that the decrease in fracture strength due to small grooves in large notches was less than one would expect from an elastic stress analysis. Similar results were obtained from tensile tests on notched tungsten specimens, tested in the as-received and the recrystallized condition at room and liquid nitrogen temperature. Various surface preparation techniques were used. Microplasticity at the surface seems to influence crack initiation. Bend test on notched LiF specimens at room temperature showed that small cleavage cracks at the surface are not necessarily responsible for crack initiation. The following stages of crack initiation were observed: slip bands were formed near the notch, high stress fields were found where these slip bands intersected and the first microcracks were formed in such areas, probably unconnected with the notch surface. (Author)


Descriptors :   *ALLOYS , *FRACTURE(MECHANICS) , FRACTURE(MECHANICS) , FRACTURE(MECHANICS) , METALS , TITANIUM ALLOYS , TUNGSTEN , LITHIUM COMPOUNDS , FLUORIDES , RECRYSTALLIZATION , PLASTIC PROPERTIES , SURFACE PROPERTIES , STRESSES , BRITTLENESS , DEFORMATION , SINGLE CRYSTALS , GRAIN BOUNDARIES , CRYSTAL DEFECTS , TEMPERATURE , MICROSCOPY , HEAT TREATMENT , TOUGHNESS , TENSILE PROPERTIES


Distribution Statement : APPROVED FOR PUBLIC RELEASE