Fatigue of Ti-3A1-2.5V Alloy Tube and Rod
NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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The hydraulic impulse fatigue of Ti-3Al-2.5V alloy tube was studied under cyclic hydraulic pressurization and the low cycle fatigue LCF of the alloy tube and rod under cyclic axial straining. Employing a newly fabricated test frame, the cyclic-pressurization-induced fatigue crack growth through the tube wall thickness was characterized quantitatively. On the basis of the results, a relationship between electric potential drop and crack depth was established and a method of determining fatigue crack initiation, growth, and fracture lives was also defined. The LCF behavior of the alloy tube and rod was investigated, examining the shape change of load-displacement hysteresis loop and the drop of load and elastic modulus with increasing strain cycle. The LCF crack initiation and growth lives were defined. They were found to follow the Coffin-Manson relation with relatively longer LCF crack initiation life. The LCF lives were longer for the tube than the rod. This is attributable to the greater cold work done in the tube forming process, evidenced by the smaller in size and hi her tensile strength.
- Properties of Metals and Alloys