NDT.net Apr 2006, Vol. 11 No.4

Automated equipment for ultrasonic testing of bars and billets

A new «Volna-7» system for automated ultrasonic testing of bars and billets has been put into industrial operation at the Republican Unitary Enterprise «Byelorussian Steel Works» (Zhlobin) by Nordinkraft.

This ultrasonic inspection complex is a modern, high-tech, fully automated line that ensures 100% density of ultrasonic testing of bars and billets.

The system is intended to supplement and later on replace obsolete «MECHANA» equipment.

The new equipment allows detecting surface, subsurface and internal defects in special-purpose steel grades. The inspection fully meets all existing international norms and standards.

The line consists of two independent systems: one is for the detection of surface and subsurface defects and the other one is for the detection of internal imperfections. Each system comprises two submodules. One pair of submodules performs the inspection of billets; the other one provides the inspection of bars (up to 300 mm in diameter). The change-over from one type of test object to another is automatic and takes just minutes.

Rayleigh waves are used to detect surface defects. They are excited and received by non-contact electromagnetic acoustic transducers (EMAT). Of all known kinds of ultrasonic transducers, only EMAT excites “ideal” (in terms of the acoustic field characteristics) surface waves. This in many respects explains an extremely high sensitivity and noise immunity of the equipment produced by Nordinkraft, high efficiency of detection of defects opening at the surface and subsurface imperfections.

Internal defects are detected by piezoelectric phased arrays with controlled angles of excitation and reception of ultrasonic waves. The phased array technology that is successfully being developed by Nordinkraft allows one to solve the problem of 100% inspection of bars and billets. Internal imperfections from one and a half millimeter in diameter are detected in automatic mode.

«VOLNA-7-BMZ» is certified by GOSSTANDARD of Russia and by the corresponding authority in the Republic of Belarus.

The system is installed in the production line (mill 850) and has the productivity of at the minimum 50 bars (or billets) per hour.

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