GB/T 8361-2021Ultrasonic testing method for the surface of cold drawn round steel (English PDF)

6.4 Time for testing

Unless otherwise specified by the supplier and the purchaser, the ultrasonic testing is carried out after the final heat treatment and surface processing.

6.5 Scanning area

100% of the round steel circumferential surface shall be scanned from two opposite incident directions, as shown in Figure 1.

6.6 Requirements for the tested round steel

6.6.1 Dimensions and allowable deviations

The allowable deviations of the length, diameter, straightness, and out-of-roundness of the tested round steel shall meet the requirements of the corresponding product standards and the requirements of the testing equipment.

6.6.2 Surface

The surface of the tested round steel shall be free of paint, iron filings, dirt, unevenness, and other foreign substances that affect the coupling effect, cause coupling failure, hinder the free movement of the probe, or cause judgment errors.

The surface roughness of the tested round steel shall meet the testing requirements, and no surface noise shall be generated to interfere with the testing.

7.1 Materials

The comparison sample shall have the same nominal diameter as the tested round steel; and its surface condition and acoustic performance shall be similar or close; without discontinuity affecting the evaluation of the test results.

7.2 Artificial tank

7.2.1 General requirements

An artificial tank parallel to the axis of the round steel and pointing to the centre of the round steel was machined on the round steel comparison sample as an artificial reflector.

7.2.2 Processing method of artificial tank

Use electric spark or machining methods to make artificial tanks for comparison […]

9.4 Probe clamping device

The probe clamping device should support precise adjustment of the probe; and it should have good tracking ability within a certain range; that is, to ensure that the incident angle and perpendicularity of the sound beam axis to the round steel are kept stable at a certain testing speed.

9.5 Mechanical transmission device

During automatic testing, the device shall smoothly transmit the round steel through the probe control device at the selected speed; and ensure that the relative position between the round steel and the probe is stable and has good concentricity.

9.6 Marking and sorting device

During automatic testing, round steels with qualified, unqualified or other set states shall be sorted accurately and placed in different baskets automatically. When needed, round steel in different states can be marked.

10.1 Sensitivity setting

10.1.1 Sensitivity static debugging

Each time the testing is carried out or the diameter of the tested round steel changes, the comparison sample shall be used to carry out the static debugging of the sensitivity according to the following steps:

a) When using liquid immersion technology, adjust the probe and the probe clamping device; set the appropriate water layer distance and the incident angle of the sound beam; generate the selected wave pattern; and obtain the reflected wave of the artificial tank of the comparison sample. At this time, the axis of the sound beam of the probe shall be perpendicular to the axis of the round steel.

When using a cylindrical focusing probe, the long axis of the focus shall be parallel to the round steel axis or the round steel surface. When using the contact testing technology, select the appropriate incident angle to obtain the reflected wave of the artificial tank of the comparison sample. […]