【国外标准】 Standard Reference Radiographs for Tin Bronze Castings

4.1 Personnel utilizing reference radiographs to this standard shall be qualified to perform radiographic interpretation in accordance with a nationally or internationally recognized NDT personnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS 410, ISO 9712, or a similar document and certified by the employer or certifying agency, as applicable. The practice or standard used and its applicable revision shall be identified in the contractual agreement between the using parties. Personnel shall be authorized to perform radiographic interpretation by the employer. A certified Level III shall be available to assist with interpreting specifications and product requirements as applied to the reference radiographs (if the Level III is the radiographic interpreter, this may be the same person).4.2 Reference radiographs for tin bronze and related alloy castings are intended to be used as a guide to the recognition of common discontinuities and their differentiation both as to type and severity level. Discontinuity types most common to these alloys are illustrated. For reference, descriptions of typical casting defects and corresponding radiographic indication types are contained in Section 5. Purchasers and suppliers may, by mutual agreement, select particular discontinuity categories (see 1.2) to serve as standards representing minimum levels of acceptability (see Sections 7 and 8).4.3 Reference radiographs represented by this standard may be used, as agreed upon in a purchaser supplier agreement, for energy levels, thicknesses, or both, outside the range of this standard when determined applicable for the casting service application. Section 10 addresses purchaser supplier requisites where weld repairs may be required.4.4 Procedures for evaluation of production radiographs using applicable reference radiographs of this standard are prescribed in Section 9; however, there may be manufacturing-purchaser issues involving specific casting service applications where it may be appropriate to modify or alter such requirements. Where such modifications may be appropriate for the casting application, all such changes shall be called-out in the purchaser supplier agreement or contractual document.4.5 The following ASTM specifications illustrate alloys covered by these standards; however, it is intended that these reference radiographs also apply to related government and commercial material specifications:Valve bronze castings B61AComposition bronze or ounce metal castings B62BTin bronze sand castings B584Leaded red brass sand castings B584Copper-base alloy centrifugal castings (as applicable) B271(A) Similar to MIL-B-16541.(B) Similar to MIL-B-16444.1.1 These reference radiographs illustrate various categories, types, and severity levels of discontinuities occurring in tin bronze and related alloy castings. The reference radiograph films are an adjunct to this document and must be purchased separately from ASTM International if needed (see 2.2). Categories and severity levels for each discontinuity type represented by these reference radiographs are described in 1.2.NOTE 1: The basis of application for these reference radiographs requires a prior purchaser supplier agreement of radiographic examination attributes and classification criterion described in Sections 4, 7, 8, 9, and 10 of this standard.1.2 These reference radiographs consists of twenty-two 21/2 by 51/2-in. (63.5 by 139.7-mm) nominal size reproductions originally exposed with low voltage X-rays. Fifteen of these were produced with 1 in. (25.4 mm) plate castings and seven (sand inclusions, inserts, chaplets) were produced with 3/4-in. plate castings originally derived for NAVSHIPS 250-537-1 and -2. The 1-in. plate castings cover gas porosity, linear shrinkage, and feathery shrinkage discontinuity types. The original radiographs illustrate discontinuities in sand cast 88:8:4 Cu-Sn-Zn, “G” type, bronze alloy plates and are representative of those found in wide solidification range copper-tin base alloys. Following is a list of discontinuity categories, types, and severity levels for the adjunct reference radiographs of this standard:1.2.1 Category A—Gas porosity; severity levels 1 through 5 for up to and including 2 in. (50.8 mm). (Called “Code A discontinuity type” in previous revisions.)1.2.2 Category B—Sand inclusions; severity levels 1 through 5 for up to and including 2 in. (50.8 mm). (Called “Code B discontinuity type” in previous revisions.)1.2.3 Category C—Shrinkage; two types (Called “Code C discontinuity type in previous revisions).1.2.3.1 Ca—Linear shrinkage; severity levels 1 through 5 for up to and including 2 in. (50.8 mm). (Called “Code Ca discontinuity type” in previous revisions.)1.2.3.2 Cd—Feathery and spongy shrinkage (see Note 2); severity levels 1 through 5 for up to and including 2 in. (50.8 mm). (Called “Code Cd discontinuity type” in previous revisions.)NOTE 2: The feathery shrinkage discontinuity type is used to illustrate aggregate severity levels for either feathery or spongy shrinkage discontinuity types (see 6.1).1.2.4 Category D—Hot tear; one illustration (Called “Code Da discontinuity type” in previous revisions).1.2.5 Category E—Inserts, chaplets; one illustration (Called “Code Eb discontinuity type” in previous revisions).1.3 From time to time, there may be minor changes to the process for manufacturing of the reference radiograph adjunct materials. These changes could include changes in the films or processing chemicals used, changes in the dies or printing for the cardboard mats, etc.; however, in all cases, these changes are reviewed by the Illustration Monitoring Subcommittee and all reference radiographs are reviewed against a fixed prototype image to ensure that there are no changes to the acceptance level represented by the reference radiographs. Therefore, the adjunct reference radiographs remain valid for use with this standard regardless of the date of production or the revision level of the text standard.1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.