GB/T 7998-2023 PDF EnglishUS$350.00 · In stock · Download in 9 seconds
GB/T 7998-2023: Method for evaluating the susceptibility to intergranular corrosion of aluminum alloys Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 7998: Historical versions
Similar standardsGB/T 7998-2023: Method for evaluating the susceptibility to intergranular corrosion of aluminum alloys---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT7998-2023 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 77.040.30 CCS H 25 Replacing GB/T 7998-2005, GB/T 26491-2011 Method for evaluating the susceptibility to intergranular corrosion of aluminum alloys Issued on. MAY 23, 2023 Implemented on. DECEMBER 01, 2023 Issued by. State Administration for Market Regulation; National Standardization Administration. Table of ContentsForeword... 3 1 Scope... 5 2 Normative references... 5 3 Terms and definitions... 5 4 Principle... 6 5 Test conditions... 6 6 Reagents... 6 7 Instruments and materials... 7 8 Specimens... 8 9 Test procedure... 19 10 Result processing and result expression... 23 11 Test report... 251 ScopeThis document describes the evaluation method of intergranular corrosion sensitivity of aluminum alloy products. This document is applicable to the determination of intergranular corrosion sensitivity of 2××× series, 5××× series, 6××× series, 7××× series aluminum alloy products.2 Normative referencesThe contents of the following documents constitute essential clauses of this document through normative references in the text. Among them, for dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document. GB/T 3246.1 Inspection method for structure of wrought aluminum and aluminum alloy products - Part 1.Inspection method for microstructure GB/T 6682 Water for analytical laboratory use - Specification and test methods GB/T 6684-2002 Chemical reagent - Hydrogen peroxide 30% GB/T 8170 Rules of rounding off for numerical values and expression and judgement of limiting values JJG (Education committee) 012 Calibration procedures for metallographic microscopes3 Terms and definitionsThe following terms and definitions apply to this document. 3.1 Intergranular corrosion Corrosion that develops along the grain boundary of a metal or alloy or its adjacent area.4 PrincipleAccording to the principle of cathode depolarization, the aluminum alloy specimen is placed in a specific test solution for a certain period of time, to accelerate the corrosion of the alloy grain boundary or near the grain boundary; the corrosion depth or mass loss is measured to evaluate the intergranular corrosion sensitivity of the aluminum alloy.5 Test conditionsThe test environment temperature shall not be higher than the test temperature; ventilation facilities shall be configured.6 ReagentsWarning - The inorganic acids used in the analysis are corrosive to the human body. The test personnel shall wear personal protective equipment to reduce the danger caused by direct contact. 6.1 Nitric acid (ρ = 1.40 g/mL). 6.2 Nitric acid (1 + 4). 6.3 Sodium hydroxide solution A. 100 g/L. 6.4 Sodium hydroxide solution B. 50 g/L. 6.5 Sodium chloride-hydrogen peroxide solution. Dissolve 57 g of sodium chloride in a small amount of water; stir evenly; dilute to 990 mL with water. During the test, first heat the test solution to the test temperature; add 10 mL of hydrogen peroxide (mass fraction 30%). 6.6 Sodium chloride-hydrochloric acid solution. Dissolve 30 g of sodium chloride in a small amount of water; stir evenly; dilute to 990 mL with water; add 10 mL of hydrochloric acid (ρ = 1.19 g/mL); stir evenly. 6.7 Etching agent. Mix hydrofluoric acid (ρ = 1.15 g/mL), hydrochloric acid (ρ = 1.19 g/mL), nitric acid (ρ = 1.40 g/mL), water in a volume of (2 + 3 + 5 + 190); mix evenly.7 Instruments and materials7.1 Conduction constant temperature device. The temperature control accuracy shall comply with the provisions of Table 1. 7.2 Test liquid container (with lid). Beaker or other container with lid. 7.3 Specimen holder. Made of glass, plastic or other inert materials. 7.4 Sandpaper. Particle size is 35 μm. 7.5 Optical (metallographic) microscope. In accordance with JJG (Education Committee) 012, it shall be equipped with an eyepiece micrometer 0.1 mm scale plate (or integrated with the eyepiece); the magnification should be 100X ~ 500X. 7.6 Metallographic grinding and polishing machine. 7.7 Ultrasonic cleaning machine. Working frequency 30 kHz ~ 60 kHz. 7.10 Micrometer. The graduation value shall not be greater than 0.01 mm; the maximum allowable deviation is ±4.0 μm.8 Specimens8.1 The samples shall be cut from the products and retain the original surface. The number of samples shall comply with the requirements of the relevant product standards or the agreement between the supplier and the buyer. 8.2 The specimens shall be cut from the samples; at least one surface of the cut specimens shall be the original surface of the product. The original surface shall be clean and shall not have defects such as bumps and scratches that affect the test results. The length direction of the specimen is the main deformation direction of the product. 8.3 The specimen shall not be cut at the flange or rib of the product, or the weld of the seamed extruded material. 8.4 The type, shape, size, quantity of the specimen shall comply with the requirements of Table 2. 8.6 Corrosion depth method specimens can be directly marked; the marking shall be carried out on the non-test surface. Mass loss method specimens should be marked with hanging tags. 8.7 If there are a large number of specimens, through-holes with a diameter not greater than 4 mm may be drilled on the surface of the specimens shown in Figures 5 ~ 7 for ease of cleaning.9 Test procedure9.1 Pretreatment of specimens Before pretreatment of the mass loss method specimen, use a fine file or sandpaper (7.4) to grind all edges to remove burrs, scratches and other defects that may affect the test results; then measure the length, width, thickness of the specimen, accurate to 0.02 mm. 9.2 Calculation and weighing The total surface area (S) of the mass loss method specimen shall be calculated; the additional surface of the hole wall of the perforated specimen shall be ignored. Then it shall be placed on an electronic balance and weighed (m1), accurate to 0.1 mg. 9.3 Corrosion 9.4 Measurement 9.4.1 Corrosion depth method 9.4.2 Mass loss method 9.4.2.1 Take out the mass loss method specimen; rinse it with water to remove the acid. 9.4.2.2 Immerse the specimen (see Figure 18) or hang it (see Figure 19) in an ultrasonic cleaning machine for 1 min ~ 2 min; rinse with water; air dry or blow dry with clean compressed air.10 Result processing and result expression10.1 Corrosion depth method The test results are divided into two types. no intergranular corrosion (see Figures 20 and 21) and intergranular corrosion (see Figures 22 and 23). Intergranular corrosion shall be graded according to the maximum corrosion depth D as specified in Table 8.11 Test reportThe test report shall include at least the following contents. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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