BS M 36:1970

This standard BS M 36:1970 Method for ultrasonic testing of special forgings by an immersion technique using flat-bottomed holes as a reference standard is classified in these ICS categories:

• 49.025.01 Materials for aerospace construction in general

1.1.1 This British Standard applies to the ultrasonic inspection by an immersion technique of special forgings used primarily for rotating parts, e.g. turbine discs. It accordingly describes the method of testing by which the acceptability of such forgings can be assessed, and specifies flat-bottomed hole reference standards, apparatus requirements, and control and test procedures.

1.1.2 The method, which is confined to pulse echo techniques and the use of single crystal transceiver probes, is limited to use on forgings having a thickness of not less than twice the near surface resolution of the probe (as determined in 2.1.4) which lend themselves, by virtue of their form, to mechanical scanning in which the incident beam is approximately normal to the surface of the section being scanned.

1.1.3 The method is primarily intended and recommended for use on forgings when these are in the raw material state only. However, it can be used during manufacture on machined or part-machined components, provided that these components comply with the shape and thickness described in 1.1.2.

1.1.4 By agreement, the standard may also be used for tests on other types of forgings and wrought forms manufactured in all metallic materials, in which case due allowance has to be made for the differences in ultrasonic attenuation and transmission factors presented by each material. Factors affecting the apparent flaw size when estimated by comparison with the reference standards, and procedures which will enable due allowance to be made for them are described.