GB/T 18852-2020 Active National standards

GB/T 18852-2020 Non-destructive testing—Ultrasonic testing—Reference blocks and test procedures for the characterization of contact probe sound beams

Publish Date: 2020-11-19 Implement Date: 2021-06-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

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Basic Information

Standard Code: GB/T 18852-2020

Standard Type: National standards

Standard Status: Active

is_force_gb: no

CCS Name: Basic standards and general methods

ICS Name: Non-destructive testing

Publish Date: 2020-11-19

Implement Date: 2021-06-01

Pages: 24 pages

Scope

This standard specifies the measurement method of the acoustic field and acoustic beam characteristics in the workpiece when the probe contacts the workpiece. The probes include straight probes, oblique probes (refracted longitudinal waves and refracted transverse waves), focused probes, and dual-crystal probes. This standard recommends two metal reference blocks, namely the half-round step block (HS block) and the transverse hole block (SDH block). The diameter or edge length of the probe chip should not exceed 25 mm.
This standard specifies the measurement guidelines for the acoustic beam characteristics of probes suitable for inspecting forged steel, rolled steel, aluminum alloy, or titanium alloy products. The applicable frequency range of the probes in this standard is 1 MHz to 15 MHz. The frequency range of 1 MHz to 5 MHz is most suitable for the inspection of steel products, while the frequency range of 5 MHz to 15 MHz is most suitable for the inspection of fine-grained products (such as aluminum alloy products).
If this standard is applied to inspections other than steel products, inspectors should note that the sound velocity of the material is different from that of steel, and the nominal refraction angle of oblique probes is usually designed for inspection in steel. This standard provides Snell's law to enable inspectors to calculate the refraction angle in other isotropic and fine-grained materials. This standard applies to oblique probes, focused probes, and dual-crystal probes with an actual refraction angle range of 0° to 70°. This standard does not apply to surface wave (Rayleigh) probes.
This standard does not address the evaluation of the size of the flaw equivalent using flat-bottomed hole blocks. This standard does not specify acceptance criteria, but it establishes a technical basis for inspectors to formulate acceptance criteria for probe performance.