ULTREX II™ – Room Temperature “Off-Line” Ultrasonic Inspection Equipment
The Ultrex II™ “non-submerge” ultrasonic instrumentation was developed by Almex for inspection of scalped slabs and machined billets. The system detects internal defects of an extremely fine size. It is based on the “pulse-echo” principle but uses a large probe, approximately 25 mm diameter, and works at the 2.25 Megahertz frequency. It is well known that a defect in the cast product of the size of 75 microns (0.003”) is “large” enough to cause the rejection of finished forging, extrusion or rolled plate since the original defect undergoes substantial enlargement in size during the subsequent thermo-mechanical working of the material. Accordingly, Almex’s Ultrex II™ ultrasonic testing equipment and procedures are designed to inspect such “small” sizes of discontinuities.
Typically in 2XXX and 7XXX series aluminum alloys, these discontinuity indications on the ultrasonic testing screen provide a reflection of the following types of defects:
Agglomerated gas porosity
Metallic inclusions (such as early precipitates of Ti-B-Zr and Chromium)
Very large primary phase segregation
Incipient melting during homogenization
It is important to note that all of the above issues are causes for rejection in aircraft metal. Therefore, Almex’s Ultrex II Ultrasonic Inspection Equipment is designed to assure inspection of the machined billet to the highest possible resolution. Each machined surface should conform to 250 RMS.
Of utmost importance, the attenuation of the machine is designed such that any subtle changes on the screen can be seen in the “baseline” of the reflection. The controlled gain amplification of the signal, coupled with a noise reduction hardware module, allow the operator to discriminate clearly between a “defect” in the metal and just the “baseline noise”.
Depending on the diameter of the billet to be inspected, a series of custom-made standards are furnished with the equipment. These standards are traceable to standards laboratories specified in the US military Ultrasonic Standard MIL-2154, Class AA