GB/T 34904-2017Spheroidal graphite iron castings—Ultrasonic testing (English PDF)

3.1 dross

fine slag particles (oxides, sulphides, etc.) in the rim zone of castings, as well as slag that has a lower density than molten metal and accumulates on the surface of the molten pool or the castings

4.1 Order information

The following information shall be available at the time of order:

a) the areas of the spheroidal graphite iron casting and the number or percentage of castings subjected to ultrasonic testing;

b) quality level of each part of the spheroidal graphite iron casting;

c) requirements for testing process;

d) other special requirements for testing, if any.

4.2 Personnel qualification

The ultrasonic testing personnel shall obtain corresponding qualification certificates in accordance with GB/T 9445 or other standards which are considered to be equivalent.

4.3 Testing equipment

4.3.1 Ultrasonic instrument

4.3.1.1

The ultrasonic instrument shall meet the requirements given in GB/T 27664.1 in terms of performance and shall have the following characteristics:

a) range: from at least 10 mm to 2,000mm continuously selectable, for longitudinal and transverse waves transmitted in steel;

b) gain: adjustable in 2dB maximum steps over a range of at least 80dB with a measuring accuracy of 1dB;

c) it shall at least meet the requirement that two types of probes, i.e., dual-element probe and single-element probe, are adjustable for nominal frequencies from 0.5MHz to 5MHz.

4.3.1.2

The combined equipment for ultrasonic testing shall be checked regularly by the operator according to GB/T 27664.3.

4.3.2 Probes

4.3.2.1

Dual-element probe shall be used for the testing of areas close to the test surface. For the detection of near-surface defects, the use of dual-element or angle-beam probe is recommended.

4.3.2.2

For areas with special geometry, angle-beam probes can be used for the testing. Generally, the angle-beam probe shall be with a nominal refraction angle of 45° to 70° and a maximum detectable sound path of 100 mm.

4.3.3 Ultrasonic instrument and probe

4.3.3.1

The frequency of the instrument and the probe shall meet the requirements of GB/T 27664.2 and GB/T 27664.3 respectively.

4.3.3.2

Probes with higher frequencies are normally used to test castings with small wall thicknesses and high quality requirements. The zoning for casting based on the wall thickness is as shown in Figure 1.