GB/T 46654-2025 Radiographic testing for titanium alloy castings - Defect levels English, Anglais, Englisch, Inglés, えいご
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ICS 13.220.10
CCS H 57
National Standard of the People's Republic of China
GB/T 46654-2025
Radiographic testing for titanium alloy castings - Defect levels
钛合金铸件射线照相检测 缺陷分级
Issue date: 2025-10-31 Implementation date: 2026-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Basic Requirements
5 Defect Classification
6 Grade Evaluation
1 Scope
This document specifies the basic requirements for radiographic testing of titanium and titanium alloy castings (hereinafter referred to as "castings") and describes corresponding methods for defect classification and grade evaluation.
This document applies to the classification of gas hole type, inclusion type, and shrinkage type defects in titanium alloy castings with thicknesses not exceeding 50.8 mm by radiographic testing. Castings with thicknesses greater than 50.8 mm may refer to this document.
This document does not apply to the classification of defects such as cracks, segregation, cold shuts, and lack of penetration or lack of fusion resulting from weld repairs.
2 Normative References
The following documents contain provisions that, through normative reference in this text, constitute essential provisions of this document. For dated references, only the edition corresponding to that date applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 5611 Casting terminology
GB/T 5677 Castings—Radiographic inspection
GB/T 12604.2 Non-destructive testing—Terminology—Terms used in radiographic testing
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 5611, GB/T 12604.2, and the following apply.
3.1
single gas hole
An isolated, non-interacting cavity formed by gas inside a casting.
3.2
scattered gas holes
Multiple sparsely distributed, weakly interacting cavities formed by gas inside a casting.
3.3
clustered gas holes
A group of densely distributed, strongly interacting cavities formed by gas inside a casting.
3.4
less-dense inclusions
Foreign matter present inside a casting, with lower density and lesser attenuation of radiation compared to the base material.
3.5
more-dense inclusions
Foreign matter present inside a casting, with higher density and greater attenuation of radiation compared to the base material.
3.6
scattered shrinkage cavity
A dispersed, non-dense area composed of multiple tiny, dot-like or strip-like cavities formed during the solidification process of a casting due to cooling shrinkage.
3.7
centerline shrinkage
A relatively concentrated, non-dense area with a larger main body composed of tiny cavities formed during the solidification process of a casting due to cooling shrinkage.
3.8
shrinkage cavity
A cavity with clearly defined boundaries formed within a casting during solidification due to a lack of feeding metal.
4 Basic Requirements
The radiographic technique, image quality, and radiographs shall comply with the provisions of GB/T 5677.
5 Defect Classification
5.1 There are three main categories of internal casting defects suitable for classification: gas hole type, inclusion type, and shrinkage type.
Note: Typically, unclassified defects such as cracks, segregation, cold shuts, and lack of penetration or lack of fusion from weld repairs are considered harmful.
5.2 According to the defect morphology and distribution characteristics, the three main categories of internal casting defects can be divided into eight subcategories: single gas hole, scattered gas holes, clustered gas holes, less-dense inclusions, more-dense inclusions, scattered shrinkage cavity, centerline shrinkage, and shrinkage cavity, as specified in Appendix A.
5.3 Each subcategory of defect is classified into grades 1 through 8 based on the severity of the defect. Appendix B provides 26 sets of reference illustrations representing the eight grades. The dimensions of each grade illustration shall be 50 mm × 50 mm.
6 Grade Evaluation
6.1 Selection of Evaluation Area
Select the area with the most severe defects as the evaluation area, and compare it with the reference illustrations corresponding to the relevant thickness for evaluation.
6.2 Size of Evaluation Area
6.2.1 The size of the evaluation area shall be 50 mm × 50 mm. If an evaluation area cannot be defined as a square, a rectangle of equal area may be used.
6.2.2 If the inspected area is smaller than the specified evaluation area, the entire inspected area should be used as the evaluation area.
6.3 Evaluation Method
6.3.1 Compare the evaluation area with the reference illustrations of the corresponding thickness to evaluate the nature and grade of the defects. During evaluation, consider the defect morphology, size, quantity, area, spacing, and degree of clustering.
6.3.2 If two or more types of defects exist within the same evaluation area, they shall be evaluated separately. The severity of defects in the reference illustrations represents the maximum allowable value for that grade.
6.3.3 If the inspected area is smaller than the specified evaluation area, the evaluation requirements shall be more stringent. When the inspected area is less than 50% of the specified evaluation area, comparison shall be made with the reference illustrations that are one grade stricter.
6.3.4 If the casting thickness exceeds the range specified in Appendix A, both parties may negotiate to use reference illustrations from the applicable maximum thickness with the same or higher grade.
6.3.5 Unless otherwise specified, the evaluation method and quality requirements for castings subjected to weld repair shall be the same.
6.4 Evaluation Notation
The defect evaluation and grading may be represented using the defect type or abbreviation code specified in Appendix A, along with the defect grade.
