Standard Number:<\/strong> GB\/T 13305-2008 This standard replaces GB\/T 6401-1986 and GB\/T 13305-1991. The main changes compared with GB\/T 13305-1991 and GB\/T 6401-1986 are as follows:<\/p>\n This standard was proposed by the China Iron and Steel Association. This standard specifies the micrographic methods for determining the area content of the \u03b1-phase in stainless steels. These methods are applicable to austenitic stainless steels, ferritic-austenitic duplex stainless steels, and other stainless steel products.<\/p>\n The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition applies.<\/p>\n Specimens shall be cut from steel materials (or billets) in the delivered condition. The sampling location and quantity shall be in accordance with the corresponding product standards or technical specifications. The examination surface of the specimen shall be parallel to the longitudinal section of the steel (or billet), with one edge coinciding with the axis of the steel (or billet).<\/p>\n Specimens shall be cut by mechanical methods in cold state. When gas cutting or hot cutting methods are used, the melted zone, plastically deformed zone and heat affected zone must be completely removed. The distance between the cutting surface and the examination surface depends on the cutting method, generally not less than 0.5 mm.<\/p>\n The sampling method for steel pipes is specified in the standard with reference diagrams.<\/p>\n The sampling method for steel plates, steel strips and flat steel is specified in the standard with reference diagrams.<\/p>\n For castings and other specimens without obvious axial symmetry, the examination surface orientation shall be specified by the corresponding product standards or technical specifications. The specimen examination surface area shall be not less than 10 mm\u00b2.<\/p>\n Specimens shall be ground and polished with appropriate grinding papers, using correct grinding and polishing procedures with strict operations. The specimen etching shall reveal the \u03b1-phase structure clearly. For chemical etching, the following etching reagents are recommended:<\/p>\n The acceptable range of the \u03b1-phase area percentage shall be in accordance with the corresponding product standards or technical specifications.<\/p>\n Place the specimen under a metallographic microscope in bright field. First observe the entire examination surface with lower magnification to select the area with the most severe \u03b1-phase content. For determination, the microscope magnification can be 280\u00d7\u2013320\u00d7, preferably 300\u00d7, with an actual field diameter of 0.267 mm.<\/p>\n The standard rating charts for austenitic stainless steel consist of 4 grades (6 charts, see Appendix A):<\/p>\n Observe the entire examination surface under appropriate magnification. The magnification shall be 500\u00d7. The standard series images are divided into two series: Strip Series<\/strong> and Network Series<\/strong>. Each series contains charts with \u03b1-phase area content from 35% to 75% in 5% increments (see Appendix B).<\/p>\n For more precise measurements, quantitative analysis methods may be used in accordance with GB\/T 18876.1, supplementing the comparison method in Section 4.1.<\/p>\n The test report shall include the following items:<\/p>\n The standard rating charts consist of 6 charts covering grades 0.5, 1.0, 1.5, 2.0, 3.0, and 4.0. The \u03b1-phase content ranges from \u22642% to >20%~35%.<\/p>\n Two series of standard images (Strip Series and Network Series), each containing charts with \u03b1-phase area content from 35% to 75% in 5% increments (35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%).<\/p>\n You can download and view the original Chinese version of this standard below:<\/p>\n
\nICS:<\/strong> 77.040.99
\nIssued:<\/strong> August 19, 2008
\nEffective:<\/strong> April 1, 2009
\nIssuing Authority:<\/strong> Standardization Administration of the People’s Republic of China
\nReplaces:<\/strong> GB\/T 13305-1991 and GB\/T 6401-1986<\/p>\n
\nPreface<\/h2>\n
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\nThis standard is under the jurisdiction of the National Technical Committee on Steel Standardization.
\nDrafting organizations: Central Iron and Steel Research Institute, Northeast Special Steel Group Co., Ltd. (Dalian), Metallurgical Industry Information & Standards Institute.<\/p>\n
\n1. Scope<\/h2>\n
\n2. Normative References<\/h2>\n
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\n3. Specimen Selection and Preparation<\/h2>\n
3.1 Sampling Method<\/h3>\n
3.1.1 Bars and Round Steel<\/h4>\n
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3.1.2 Steel Pipes<\/h4>\n
3.1.3 Steel Plates, Steel Strips and Flat Steel<\/h4>\n
3.1.4 Other Methods<\/h4>\n
3.2 Specimen Preparation<\/h3>\n
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\n4. Determination Methods for \u03b1-Phase Area Content<\/h2>\n
4.1 Standard Rating Chart Comparison Method<\/h3>\n
4.1.1 Austenitic Stainless Steel \u03b1-Phase Determination<\/h4>\n
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\n \u0e40\u0e01\u0e23\u0e14<\/th>\n \u03b1-Phase Area Content<\/th>\n<\/tr>\n \n 0.5<\/td>\n \u2264 2%<\/td>\n<\/tr>\n \n 1.0<\/td>\n > 2% ~ \u2264 5%<\/td>\n<\/tr>\n \n 1.5<\/td>\n > 5% ~ \u2264 8%<\/td>\n<\/tr>\n \n 2.0<\/td>\n > 8% ~ \u2264 12%<\/td>\n<\/tr>\n \n 3.0<\/td>\n > 12% ~ \u2264 20%<\/td>\n<\/tr>\n \n 4.0<\/td>\n > 20% ~ \u2264 35%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n 4.1.2 Ferritic-Austenitic Duplex Stainless Steel \u03b1-Phase Determination<\/h4>\n
4.2 Quantitative Analysis Method for Metallographic Image<\/h3>\n
\n5. Test Report<\/h2>\n
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\nAppendix A \u2014 Standard Rating Charts for Austenitic Stainless Steel<\/h2>\n
Appendix B \u2014 Metallographic Spectrum for Ferritic-Austenitic Duplex Stainless Steel<\/h2>\n
\nOriginal PDF Document<\/h3>\n