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| ASTM A388 / A388M Standard Practice for Ultrasonic Examination of Steel Forgings | |
| This practice covers the examination procedures for the contact, pulse-echo ultrasonic examination of heavy steel forgings by the straight and angle-beam techniques. An ultrasonic, pulsed, reflection type of instrument shall be used and shall provide linear presentation for at least 75% of the screen height. The 5% linearity referred to is descriptive of the screen presentation of amplitude. The electronic apparatus shall contain an attenuator, search units, transducers, couplants, reference blocks, and DGS scales. 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. The procedures to be performed are as follows: ultrasonic examination of the forgings; straight-beam examination with establishment of the instrument sensitivity and calibration either by the reflection, reference-block technique, or DGS method; and angle-beam examination used for rings and hollow forgings. | |
| Significance and Use | |
This practice shall be used when ultrasonic inspection is required by the order or specification for inspection purposes where the acceptance of the forging is based on limitations of the number, amplitude, or location of discontinuities, or a combination thereof, which give rise to ultrasonic indications. The ultrasonic quality level shall be clearly stated as order requirements. |
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| 1. Scope | |
1.1 This practice covers the examination procedures for the contact, pulse-echo ultrasonic examination of steel forgings by the straight and angle-beam techniques. The straight beam techniques include utilization of the DGS (Distance Gain-Size) method. See Appendix X3. 1.2 This practice is to be used whenever the inquiry, contract, order, or specification states that forgings are to be subject to ultrasonic examination in accordance with Practice A388/A388M. 1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementary requirements shall apply only when specified individually by the purchaser in the purchase order or contract. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.5 This specification and the applicable material specifications are expressed in both inch-pound units and SI units. However, unless the order specifies the applicable “M” specification designation [SI units], the material shall be furnished to inch-pound units. |
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| 2. Referenced Documents | |
ASTM Standards A469/A469M Specification for Vacuum-Treated Steel Forgings for Generator Rotors Other Document RecommendedPracticef (1988 or later) |
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| Index Terms | |
| angle beam examination; back-reflection; DGS; reference-block; straight beam examination; ultrasonic; Forgings; Heavy steel materials/applications; Steel forgings; Ultrasonic testing--steel; | |
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