... for inspection of billets
A key property of this billet inspection system is the coupling technique. The coupling of the ultrasound is achieved with guided water jets (squirter technique), which allows almost wear-free probe holders and short changeover times for different billet diameters. The distance between probe and billet surface is in the order of several centimetres which leads to long-lasting probes. Instead of dual-element probes (used for gap coupling in older testing systems), immersion type probes with large bandwidth are used. In combination with the electronic distance amplitude correction (DAC) a constant testing sensitivity is produced for all flaw depths.
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