Issued:<\/strong> 1995-10-10 \u00a0|\u00a0 Implemented:<\/strong> 1996-03-01<\/p>\n Proposed by:<\/strong> National Technical Committee on Steel Standardization<\/p>\n Drafting Units:<\/strong> Dalian Steel Works, Information and Standards Research Institute, Ministry of Metallurgical Industry<\/p>\n Main Drafters:<\/strong> Zhang Shumin, Liu Zhaohui<\/p>\n This standard is developed on the basis of YB 47-64, with non-equivalent adoption of ISO 3763:1976 “Forged steel products \u2014 Macroscopic method for the assessment of non-metallic inclusion content.”<\/p>\n This standard retains the scientifically sound and reasonable content from the original YB 47-64 standard that ensures the continuity of inspection standards and product standards, and can correctly display and inspect hairline cracks. On the tower-shaped specimen, the l\/D ratio coefficient specified in ISO 3763 is adopted non-equivalently, representing a significant modification from the original YB 47-64 standard. This standard also revises the measurement method for the distance between two hairline cracks on the same straight line of the specimen inspection surface, and removes the “magnetic flaw detection method.”<\/p>\n This standard is implemented from March 1, 1996. From the date of implementation, the original YB 47-64 “Tower-shaped Turning Hairline Inspection Method” is invalidated.<\/p>\n This standard specifies the selection and preparation of tower-shaped specimens for inspecting hairline cracks in steel products, the inspection method, the representation and evaluation of inspection results, and the inspection report.<\/p>\n This standard is applicable to the etch test method using tower-shaped specimens to inspect the quantity, length, and distribution of hairline cracks in steel products.<\/p>\n The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest editions of the standards listed below.<\/p>\n GB 226-91 \u2014 Test method for macrostructure and defect etching of steel<\/p>\n This standard employs tower-shaped specimens. Unless otherwise specified by product standards or special agreements, the applicable dimensions for tower-shaped hairline inspection of steel products (or steel billets) range from \u03c616 to \u03c6150 mm.<\/p>\n Specimens are cut from steel products (or steel billets) in the delivered condition.<\/p>\n Specimens shall be cut by mechanical means in a cold state. If gas cutting or hot cutting methods are used, the melted zone, plastically deformed zone, and heat-affected zone must be completely removed.<\/p>\n The sampling quantity and location shall be as specified by the corresponding product standards or special agreements. If there are no explicit provisions, it is recommended to take three specimens.<\/p>\n 3.3.1<\/strong> For square or round steel specimens, the inspection surface consists of three concentric cylindrical surfaces parallel to the axis of the steel product (or steel billet) (see Figure 1); for flat steel specimens, the inspection surface is the longitudinal section parallel to the axis of the steel product (or steel billet) (see Figure 2).<\/p>\n D \u2014 Steel diameter or side length<\/p>\n Figure 1<\/strong> \u2014 Tower-shaped specimen for square or round steel<\/p>\n Figure 2<\/strong> \u2014 Tower-shaped specimen for flat steel<\/p>\n 3.3.2<\/strong> The dimensions of tower-shaped specimens are shown in Table 1.<\/p>\n Note: D \u2014 Steel diameter or side length<\/em><\/p>\n 3.3.3<\/strong> During specimen processing, reasonable cutting techniques should be used to prevent overheating. The processed specimen surface shall be smooth, with a surface roughness Ra value of 1.6 \u03bcm after processing.<\/p>\n 3.3.4<\/strong> Acid etching of the specimen surface shall be performed in accordance with GB 226.<\/p>\n 4.1<\/strong> Observe with the naked eye and inspect the quantity, length, and distribution of hairline cracks on the entire surface of each step. If necessary, a magnifying glass of no more than 10\u00d7 magnification may be used for inspection.<\/p>\n 5.1<\/strong> The inspection results of hairline cracks shall include:<\/p>\n a) Number of hairline cracks on each step;<\/p>\n b) Total length of hairline cracks on each step, in mm;<\/p>\n c) Total number of hairline cracks on each specimen;<\/p>\n d) Total length of hairline cracks on each specimen, in mm;<\/p>\n e) Maximum length of hairline cracks on each specimen, in mm.<\/p>\n 5.2<\/strong> The starting length for counting hairline cracks shall be as specified by the corresponding product standards or special agreements.<\/p>\n Note: If two hairline cracks exist on the same straight line of the specimen inspection surface, and the distance between them is less than the starting length, they shall be counted as one hairline crack, with the hairline crack length including the distance between them.<\/em><\/p>\n 5.3<\/strong> The acceptance limits for hairline cracks in steel products shall be as specified by the corresponding product standards or special agreements.<\/p>\n The inspection report shall include the following items:<\/p>\n a) This standard number;<\/p>\n b) Steel grade, heat number, specification, and specimen number;<\/p>\n c) Inspection results;<\/p>\n d) Inspection report number, date, and inspector.<\/p>\n
\nForeword<\/h2>\n
\n1 Scope<\/h2>\n
2 Referenced Standards<\/h2>\n
3 Selection and Preparation of Specimens<\/h2>\n
3.1 Sampling Method<\/h3>\n
3.2 Sampling Quantity and Location<\/h3>\n
3.3 Specimen Preparation<\/h3>\n
Table 1 \u2014 Tower-shaped Specimen Dimensions (mm)<\/h3>\n
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\n Steel Diameter D<\/th>\n Step 1 Diameter<\/th>\n Step 2 Diameter<\/th>\n Step 3 Diameter<\/th>\n Each Step Length L<\/th>\n<\/tr>\n \n < \u03c650<\/td>\n \u2014<\/td>\n \u2014<\/td>\n 0.90D<\/td>\n 50<\/td>\n<\/tr>\n \n \u03c650 ~ \u03c680<\/td>\n \u2014<\/td>\n 0.90D<\/td>\n 0.75D<\/td>\n 50<\/td>\n<\/tr>\n \n \u03c680 ~ \u03c6150<\/td>\n 0.90D<\/td>\n 0.75D<\/td>\n 0.60D<\/td>\n 50<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n 4 Inspection Method<\/h2>\n
5 Representation and Evaluation of Inspection Results<\/h2>\n
6 Inspection Report<\/h2>\n
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