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GB/T 3246.1-2012 English PDF (GBT3246.1-2012)

GB/T 3246.1-2012 English PDF (GBT3246.1-2012)

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GB/T 3246.1-2012: Inspection method for structure of wrought aluminum and aluminum alloy products -- Part 1: Inspection method for microstructure

This Part of GB/T 3246 specifies the test solution and sample preparation, etching, anodized film formation, structure inspection, grain size determination and test report, etc. for microstructure detection of aluminum and aluminum alloy ingots (or billets), wrought aluminum and aluminum alloy plates, strips, foils, tubes, rods, profiles, wires, forgings (hereinafter referred to as processed products). This Part applies to the microstructure inspection of aluminum and aluminum alloy ingots (or billets) and processed products. 2 Test solutions 2.1 Nitric acid solution (1+4). 2.2 Perchloric acid ethanol solution (1+9). 2.3 Nitric acid solution (1+2.5) ~ nitric acid solution (1+1). 2.4 Etching agent No. 1: hydrofluoric acid solution (1+200). 2.5 Etching agent No. 2: hydrofluoric acid solution (1+1). 2.6 Etching agent No. 3: phosphoric acid solution (1+9). 2.7 Etching agent No. 4: sulfuric acid solution (1+9) ~ sulfuric acid solution (2+8). 2.8 Etching agent No. 5: nitric acid solution (1+3). 2.9 Etching agent No. 6: mix hydrofluoric acid (???? 1.15 g/mL), hydrochloric acid (???? 1.19 g/mL), nitric acid (???? 1.40 g/mL) and water in a volume of (2+3+5+190); mix well. 2.10 Etching agent No. 7: mix hydrofluoric acid (???? 1.15 g/mL), hydrochloric acid (???? 1.19 g/mL), nitric acid (???? 1.40 g/mL) and water in a volume of (2+1+1+76); mix well. 2.11 Etching agent No. 8: mix hydrofluoric acid (???? 1.15 g/mL), hydrochloric acid (???? 1.19 g/mL), nitric acid (???? 1.40 g/mL) and water in a volume of (2+3+5+250); mix well. GB/T 3246.1-2012 www.ChineseStandard.net ? Buy True-PDF ? Auto-delivery. Page 6 of 29 2.12 Nitric acid solution (1+19) ~ nitric acid solution (1+3). 2.13 Sulfuric acid-phosphoric acid solution: mix sulfuric acid (???? 1.84 g/mL), phosphoric acid (???? 1.70 g/mL) and water in a volume of (38+43+19); mix well. 2.14 Fluoroboric acid solution (25 g/L). 2.15 Fluoroboric acid solution (16.8 g/L): weigh 117 g of boric acid into a plastic container; add 500 mL of water and 333 mL of hydrofluoric ...
GB/T 3246.1-2012
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.040.99
H 24
Replacing GB/T 3246.1-2000
Inspection method for structure of wrought aluminum and
aluminum alloy products - Part 1: Inspection method for
microstructure
ISSUED ON: DECEMBER 31, 2012
IMPLEMENTED ON: OCTOBER 01, 2013
Issued by: General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of the PEOPLE Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Test solutions ... 5
3 Sample preparation ... 6
4 Sample etching ... 9
5 Anodized film formation ... 10
6 Structure inspection ... 12
7 Determination of grain size ... 19
8 Test report ... 29
Inspection method for structure of wrought aluminum and
aluminum alloy products - Part 1: Inspection method for
microstructure
1 Scope
This Part of GB/T 3246 specifies the test solution and sample preparation, etching, anodized film formation, structure inspection, grain size determination and test report, etc. for microstructure detection of aluminum and aluminum alloy ingots (or billets), wrought aluminum and aluminum alloy plates, strips, foils, tubes, rods, profiles, wires, forgings (hereinafter referred to as processed products).
This Part applies to the microstructure inspection of aluminum and aluminum alloy ingots (or billets) and processed products.
2 Test solutions
2.1 Nitric acid solution (1+4).
2.2 Perchloric acid ethanol solution (1+9).
2.3 Nitric acid solution (1+2.5) ~ nitric acid solution (1+1).
2.4 Etching agent No. 1: hydrofluoric acid solution (1+200).
2.5 Etching agent No. 2: hydrofluoric acid solution (1+1).
2.6 Etching agent No. 3: phosphoric acid solution (1+9).
2.7 Etching agent No. 4: sulfuric acid solution (1+9) ~ sulfuric acid solution (2+8). 2.8 Etching agent No. 5: nitric acid solution (1+3).
2.9 Etching agent No. 6: mix hydrofluoric acid (?? 1.15 g/mL), hydrochloric acid (?? 1.19 g/mL), nitric acid (?? 1.40 g/mL) and water in a volume of (2+3+5+190); mix well. 2.10 Etching agent No. 7: mix hydrofluoric acid (?? 1.15 g/mL), hydrochloric acid (?? 1.19 g/mL), nitric acid (?? 1.40 g/mL) and water in a volume of (2+1+1+76); mix well. 2.11 Etching agent No. 8: mix hydrofluoric acid (?? 1.15 g/mL), hydrochloric acid (?? 1.19 g/mL), nitric acid (?? 1.40 g/mL) and water in a volume of (2+3+5+250); mix well. perpendicular to the main deformation direction, the other structure inspection surfaces of the plate shall be longitudinal sections parallel to the main deformation direction, and the structure inspection surfaces of other processed products shall be transverse sections perpendicular to the main deformation direction.
3.4 Clamping and mounting
Samples for measuring the thickness of the cladding layer and the depth of copper diffusion to check the surface layer structure of the product shall be clamped or mounted; small samples can be mounted. An annealed pure aluminum plate must be placed between the samples of the clamping method and the outside of the outer sample of the sample clamp, to ensure that there is no gap between the samples after clamping, and the grinding surface of the outer sample of the sample clamp is smooth. 3.5 Rough processing of samples
Use a milling cutter (or file) to remove 1 mm ~ 3 mm from the inspected surface of the sample, and mill or file it into a plane. Then, use sandpaper (whose abrasive particle size should be 68 ??m ~ 100 ??m) on the grinder for rough grinding along the direction vertical to the knife mark; kerosene or water should be used for cooling and lubrication. Grind off all the knife marks; turn the sample 90??; then use sandpaper (whose abrasive particle size should be 18 ??m ~ 35 ??m) for fine grinding, until all rough grinding marks are removed.
3.6 Mechanical polishing
3.6.1 Rinse the ground sample with water and polish it on a polishing machine. Usually, the rotation speed of the polishing machine is 300 r/min ~ 600 r/min. During fine polishing, the rotation speed should be 150 r/min ~ 200 r/min.
3.6.2 Rough polishing
Perform rough polishing on a polishing disc fitted with baize. Use a suspension of chromium trioxide powder of high concentration and coarse particles mixed with water or other polishing materials as a rough polishing agent. Polish perpendicular to the grinding marks until all the grinding marks disappear, and the grinding surface is smooth and bright without dirt.
3.6.3 Fine polishing
Use water to rinse the roughly polished sample; finely polish it on a polishing disc equipped with fine wool (or other silk fabrics with soft fibers). Use a suspension of chromium trioxide powder of low concentration and fine particles mixed with water or other polishing materials as a fine polishing agent. Polish it perpendicular to the traces of rough polishing until there are no traces and dirt on the surface, until a clear structure can be observed on the microscope.
5.2 The anodizing device is the same as that in Figure 1. During the process of film formation, the sample surface (anode) shall be kept at an appropriate distance from the surface of the cathode plate.
5.3 For 1??????, 3??????, 5?????? and 6?????? series samples, the anodic film-making solution should be phosphoric acid and sulfuric acid solution (2.13). Parameters of the filming process are:
a) voltage 20 V ~ 30 V;
b) current density 0.1 A/cm2 ~ 0.5 A/cm2;
c) time 1 min ~ 3 min;
d) temperature 10 ??C ~ 40 ??C.
5.4 Fluoroboric acid solution (2.14 or 2.15) should be selected as the anodic film- making solution for other aluminum and aluminum alloys. Parameters of the filming process are:
a) voltage 20 V ~ 30 V;
b) current density 0.1 A/cm2 ~ 0.5 A/cm2;
c) time 1 min ~ 3 min;
d) temperature 10 ??C ~ 40 ??C.
6 Structure inspection
6.1 Requirements for microscopic samples
Observe the sample under a microscope. The surface of the sample shall be clean, dry, free of water marks, clear and true in structure, and free of corrosion holes. 6.2 Microstructure inspection of cast ingot (billet)
Usually, observe the shape of the phase and defects such as looseness and inclusions in the alloy on the unetched sample, and observe the dendrite structure on the etched sample, identify the components of the phase, and observe the burnt structure in the homogenized state.
6.3 Inspection of quenched and annealed samples of processed products
Check the grain state and burnt structure on the prepared sample, usually magnified 200 ~ 500 times for observation and photography.
6.4 Distinguishment of burnt structure of aluminum alloy
calculation of this method can be done by means of various types of test instruments. For example, quantitative microscopes and image analyzers, etc.
7.4.2 When using the intercept method to measure the grain size, measure the grain size by calculating the average intercept, on the frosted glass or within the representative field of view of the sample, by counting the number of grains intersected by one or several straight lines (usually called the detection line) (the total length of the straight line shall not be less than 50 intercepted gains).
7.4.3 Grain measurement shall be carried out at 3 ~ 5 fields of view randomly selected and separated far away, so as to obtain a reasonable average grain size of the sample. 7.4.4 Calculate the average intercept l according to Formula (9).
Where:
l ?€? average intercept, in microns (??m);
L ?€? the total length of the detection line, in microns (??m);
N ?€? the total number of intersections between the detection line and the grain boundary, in points.
g ?€? magnification.
7.4.5 The length of the average intercept l, which is slightly lower than the average diameter of grains, can be considered as the average diameter of grains in normal measurement. Reference can be made to the relevant grain size data given in Table 4. 7.4.6 For non-equiaxed grains, the number of grains per cubic millimeter is calculated according to Formula (10).
Where:
nv ?€? the number of grains per cubic millimeter, in grains per cubic millimeter (grains/mm3);
ne ?€? the average number of grains per millimeter intersected by a straight line in the longitudinal direction, in grains per millimeter (grains/mm);
nc ?€? the average number of grains per millimeter intersected by a straight line in the horizontal direction, in grains per millimeter (grains/mm);

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