METALLURGICAL CHARACTERISTICS OF HIGH STRENGTH STRUCTURAL MATERIALS
Quarterly progress rept. no. 7
NAVAL RESEARCH LAB WASHINGTON DC
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A progress report covering research studies in high strength structural materials is presented. Fracture toughness index diagrams are presented for titanium and aluminum that define the expected yield strength region of high fracture toughness, requiring plastic overloads for fracture propagation, and low fracture toughness, requiring elastic stresses for fracture propagation, and linear elastic fracture mechanics techniques for determining elastic stress level required for fracture. Results on heat treatment and alloy development studies are reported for several titanium alloys and drop-weight tear test results on some commercially produced aluminum alloys are described. Results of plane strain fracture toughness tests on unalloyed titanium using single-edge-notched and side-notched specimens are reported. Explosion bulge tests on a series of 5Ni-Cr-Mo-V and maraging steel weldments are described in which the results appear encouraging. Low cycle fatigue crack propagation studies on D6AC and 4335 high strength steels are described in which an acceleration of fatigue crack growth rate was seen for each steel in a salt water environment. The 4335 steel test results indicated a stress corrosion cracking condition operating in addition to the action of fatigue cracking.
- Properties of Metals and Alloys