Determination of minimum flaw size detectable by ultrasonics in titanium alloy plates

Titanium alloys, due to their light weight, high strength, and corrosion resistant properties, are employed in many structural applications. For design purposes it is important to determine the limit of sensitivity of ultrasonic crack detection techniques for these alloys. This paper demonstrates that it is possible to detect electronic discharge mill (EDM) slots as small as 0.025 mm deep in thick plates, using commercial ultrasonic instrumentation. The effect of grain size, frequency and orientation of the flaw upon the limit of detection is also discussed.