ASTM-A388/A388M:19 pdf free download – Standard Practice for Ultrasonic Examination of Steel Forgings.
6.2 Search Units, having a transducer with a maximum active area of tin.2 [650 mm2I with ½ in. 113 mm] minimum to 1½ in. [30 mml maximum dimensions shall he used for straight-beam scanning (see 9.2); and search units having a transducer with ½ in. 113 mmj minimum to I in. [25 mm] maximum dimensions shall be used for angle-beam scanning (see 9.3).
6.2.1 Transducers shall be utilized at their rated frequencies.
6.2.2 Other transducers may be used for evaluating and pinpointing indications.
6,3 couplanex. having good wetting characteristics such as SAE No. 20 or No. 30 motor oil. glycerin, pine oil, or water shall be used. Couplants may not be comparable to one another and the same couplant shall be used for calibration and examination.
6,4 Refrreace Blocks, containing flat-bottom holes may be used for calibration of equipment in accordance with 6.1.2 and may be used to establish recording levels for straight-beam examination when so specified by the order or contract.
6.5 DGS Scales, matched to the ultrasonic test unit and transducer to be utilized. may be used to establish recording levels for straight or angle beam examination, when so specified by the order or contract. The DGS scale range must be selected to include the full thickness cross-section of the forging to be examined. An example of a DGS overlay is found in Appendix X3.
6.5.1 As an alternative to using DGS overlays, an ultrasonic instrument having DGS software, integral decibel gain or attenuator controls in combination with a specifically paired transducer and DGS diagram may be used to evaluate ultrasonic indications.
7. Personnel Rcquircment.s
7.1 Personnel performing the ultrasonic examinations to this practice shall be qualified and certified in accordance with a written procedure conforming to Recommended Practice No. SNT-TC- I A (1988 or later) or another national standard that is acceptable to both the purchaser and the supplier.
8. Preparation of Forging for Ultrasonic Lxamination
8.1 Unless otherwise specified in the order or contract, the forging shall be machined to provide cylindrical surfaces for radial examination in the case of round forgings: the ends of the forgings shall be machined perpendicular to the axis of the forging for the axial examination. Faces of disk and rectangular forgings shall be machined flat and parallel to one another.
8.2 The surface roughness of exterior finishes shall not exceed 250 iin. 16 p.im] where the definition for surface finish is as per Specification A788/A788M unless otherwise shown on the forging drawing or stated in the order or the contract.
8.3 The surfaces of the forging to be examined shall be free of extraneous material such as loose scale, paint, dirt, and so forth.
6.2 Search Units. having a transducer with a maximum active area of tin.2 1650 mm2I with ½ in. 113 mml minimum 10 1½ in. 130 mml maximum dimensions shall be used for
straight-beam scanning (see 9.2); and search units having a transducer with ½ in. 113 mmj minimum to I in. 125 mmj maximum dimensions shall be used for angle-beam scanning (see 9.3).
6.2.1 Transducers shall be utilized at their rated frequencies.
6.2.2 Other transducers may be used for evaluating and pinpoiniing indications.
6.3 Coi.p!ants. having good %e1ting eharactemistics such as SAE No. 20 or No. 30 motor oil, glycerin, pine oil, or water shall be used. Couplants may not be comparable to one another
and the same couplant shall be used for calibration and examination.