Standard Practice for Electromagnetic (Eddy Current) Examination of Ferromagnetic Cylindrical Bar Product Above the Curie Temperature

Importancia y uso:

5.1 The purpose of this practice is to describe a procedure for in-line-eddy-current examination of hot cylindrical bars in the range of diameters listed in 1.2 for large and repetitive discontinuities that may form during processing.

5.2 The discontinuities in bar product capable of being detected by the electromagnetic method are listed in 1.3.1. The method is capable of detecting surface and some subsurface discontinuities that are typically in the order of 0.030 in. (0.75 mm) and deeper, but some shallower discontinuities might also be found.

5.3 Discontinuities that are narrow and deep, but short in length, are readily detectable by both probe and encircling coils because they cause abrupt flux changes. Surface and subsurface discontinuities (if the electromagnetic frequency provides sufficient effective depth of penetration) can be detected by this method.

5.3.1 Discontinuities such as scratches or seams that are continuous and uniform for the full length of cut length bars or extend for extensive linear distances in coiled product may not always be detected when encircling coils are used. These are more detectable with probe coils by intercepting the discontinuity in their rotation around the circumference.

5.3.2 The orientation and type of coil are important parameters in coil design because they influence the detectability of discontinuities.

5.4 The eddy current method is sensitive to metallurgical variations that occur as a result of processing, thus all received signals above the alarm level are not necessarily indicative of defective product.

Subcomité:

E07.07

Referida por:

E0543-21, E0543-21

Volúmen:

03.03

Número ICS:

77.140.40 (Steels with special magnetic properties)

Palabras clave:

artificial discontinuity; curie temperature; electrical transient noise; electronically generated signal; encircling coil; ferromagnetic cylindrical bar; flux change; in-line-eddy-current examination; magnetic or electrostatic shield; phase; sensor coil; signal amplitude; suppression circuit; system reliability; transport mechanism ;