ASTM A578/A578M-17 pdf free download.Standard Specification for Straight-Beam Ultrasonic Examination of Rolled Steel Plates for Special Applications.
1.1 This specificationcovers the procedure and acceptance standards for straight-beam. pulse-echo, ultrasonic examination of rolled carbon and alloy steel plates. [10 mm] in thickness and over, for special applications. The method will detect internal discontinuities parallel to the rolled surfaces. Three levels of acceptance standards are provided. Supplementary requirements are provided for alternative procedures.
1.2 Individuals performing examinations in accordance with this specification shall be qualified and certified in accordance with the requirements of the latest edition of ASNT SNTTC-1A or an equivalent accepted standard. An equivalent standard is one which covers the qualification and certification of ultrasonic nondestructi ‘e examination candidates and which is acceptable to the purchaser.
1.3 The values stated in either SI units or inch-pound units are to he 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.
5. Apparatus
5.1 The ultrasonic instrument shall be a pulse echo type instrument capable of addressing either a mono-element probe or a phased-array probe and shall be equipped with a standardized dB gain or attenuation control stepped in increments of I dB minimum. The system shall be capable of generating and displaying A-scans.
5.2 Vertical and horizontal linearity and amplitude control linearity shall be checked in accordance with Practice E317, Guide E2491. or another procedure approved by the users of this specifIcation. An acceptable linearity performance may be agreed upon by the manufacturer and purchaser.
5.4 Other search units may he used for evaluating and pinpointing indications.
6. Procedure
6.1 Perform the inspection in an area free of operations that interfere with proper performance of the test.
6.2 Unless otherwise specified, make the ultrasonic examination on either major surface of the plate.
6.3 The plate surface shall be sufficiently clean and smooth to maintain a first reflection from the opposite side of the plate at least 50 % of full scale during scanning. This may involve suitable means of scale removal at the manufacturer’s option. Condition local rough surfaces by grinding. Restore any specified identification which is removed when grinding to achieve proper surface smoothness.
6.4 Perform the test by one of the following methods: direct contact, immersion, or liquid column coupling. Use a suitable couplant such as water, soluble oil, or glycerin. As a result of the test by this method, the surface of plates may be expected to have a residue of oil or rust or both.
6.5 A nominal test frequency of 2¼ MHz is recommended. When testing plates less than ¾ in. [20 mm] thick a frequency of 5 MHz may be necessary. Thickness, grain size or micro- structure of the material and nature of the equipment or method may require a higher or lower test frequency. Use the transducers at their rated frequency. A clean, easily interpreted A-scan display should be produced during the examination.
6.6. 1 Scanning shall he along continuous perpendicular grid lines on nominal 9-in. 1225-mm] centers, or at the option of the manufacturer, shall be along continuous parallel paths, transverse to the major plate axis, on nominal 4-in. 1100-mm I centers, or shall be along continuous parallel paths parallel to the major plate axis, on 3-in. 175-mini or smaller centers. Measure the lines from the center or one corner of the plate with an additional path within 2 in. [50 mm] of all edges of the plate on the examination surface.ASTM A578/A578M pdf download.