GB/T 3246.1-2024 PDF in English
GB/T 3246.1-2024 (GB/T3246.1-2024, GBT 3246.1-2024, GBT3246.1-2024)
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Inspection method for structure of wrought aluminium and aluminium alloy products - Part 1: Inspection method for microstructure
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| GB/T 3246.1-2012 | English | 315 |
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Inspection method for structure of wrought aluminum and aluminum alloy products -- Part 1: Inspection method for microstructure
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| GB/T 3246.1-2000 | English | 759 |
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Wrought aluminium and aluminium alloys products inspection method for microstructure
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| GB/T 3246-1982 | English | RFQ |
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Aluminum and aluminum alloys--Inspection method of microstructure for wrought products
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Standards related to (historical): GB/T 3246.1-2024
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GB/T 3246.1-2024: PDF in English (GBT 3246.1-2024) GB/T 3246.1-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.99
CCS H 25
Replacing GB/T 3246.1-2012
Inspection method for structure of wrought aluminum and
aluminum alloy products - Part 1.Inspection method for
microstructure
ISSUED ON. MARCH 15, 2024
IMPLEMENTED ON. OCTOBER 01, 2024
Issued by. State Administration for Market Regulation;
National Standardization Administration.
Table of Contents
Foreword... 3
Introduction... 5
1 Scope... 6
2 Normative references... 6
3 Terms and definitions... 7
4 Optical (metallographic) microscopy... 17
5 Scanning electron microscopy... 29
6 Transmission electron microscopy... 29
7 Result expression... 30
8 Test report... 30
Appendix A (Informative) Typical microstructure of wrought aluminum and aluminum
alloy products... 32
Appendix B (Normative) Determination of grain size... 78
Appendix C (Normative) Determination of the second phase and particle size... 89
References... 92
Inspection method for structure of wrought aluminum and
aluminum alloy products - Part 1.Inspection method for
microstructure
1 Scope
This document describes the inspection method of microstructure of wrought aluminum
and aluminum alloy products.
This document is applicable to the microstructure inspection of wrought aluminum and
aluminum alloy ingots (or ingots), plates, strips, foils, tubes, bars, molds, wires,
forgings and other processed products, using optical (metallographic) microscopes,
scanning electron microscopes, transmission electron microscopes and other
instruments.
2 Normative references
The contents of the following documents constitute the essential terms of this document
through normative references in the text. Among them, for dated references, only the
version corresponding to that date applies to this document; for undated references, the
latest version (including all amendments) applies to this document.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 8005.1 Aluminium and aluminium alloy terms and definitions - Part 1.
Product and method of processing and treatment
GB/T 8170 Rules of rounding off for numerical values and expression and
judgement of limiting values
JJF 1914 Calibration specification for metallurgical microscopes
YS/T 1623 Inspection of aging precipitated phases of aluminum alloys transmission
electron microscope method
YS/T 1624 Method for evaluating the homogenization effect of aluminum alloy
ingots
- The fine new particles that are precipitated from the matrix phase by the deformation
aluminum alloy below the end of crystallization temperature (i.e., within the solid
temperature range) are called precipitation phases, which has a size of 0.001 μm ~ 0.5 μm,
as shown in Figure 10.According to the alloy process characteristics, the precipitation
phase can be subdivided into aging precipitation phase and sediment precipitation phase.
Usually, the sediment precipitation phase is also called the category II particles; the aging
precipitation phase is also called the category III particles. Precipitation phases can be
further divided into the following categories.
● The phase that precipitates from the supersaturated solid solution obtained after solution
treatment at the aging temperature is called the aging precipitation phase, or aging phase
for short. This phase appears in alloy systems that can be strengthened by heat treatment.
● The phase that precipitates from the saturated solid solution during the soaking/annealing
process or when the temperature is lowered above the aging temperature is called the
sediment precipitation phase, or precipitation phase for short.
- In particle-reinforced wrought aluminum alloys, the externally or internally added
reinforcing particles are called reinforcing phases, including SiC, Al2O3, TiB2, TiO2 and
other particles, which have a particle size of 0.05 μm ~ 10 μm, see Figure 11.
Note 2.According to the different distribution characteristics of the second phase, it mainly
includes the following two types.
- Dispersed phase. In a broad sense, it refers to the fine dispersed solid phase, which is
precipitated from the supersaturated solid solution or formed in the chemical heat
treatment layer and formed under other production conditions, including aging phase,
precipitation phase, reinforcing phase. In a narrow sense, it specifically refers to the
particles with submicron/nanoscale precipitated in the homogenization heat treatment
temperature range of 2×××, 6×××, 7××× wrought aluminum alloys, containing transition
metal elements, with a size of generally 0.01 μm ~ 0.5 μm, including Al20Mn3Cu2,
Al12Mg2Cr, Al3Zr, Al3Sc, etc.
- Coarse phase. It refers to the coarse non-dispersed solid phase. It is mainly the residual
crystalline phase, including the primary phase and the eutectic phase.
4.2.16 Plush cloth.
4.2.17 Synthetic leather.
4.2.18 Diamond. The particle size is 3 μm.
4.2.19 Diamond. The particle size is 9 μm.
4.2.20 Silica suspension. The particle size is 0.04 μm.
4.2.21 Alumina suspension. The particle size is 0.05 μm.
4.2.22 Rough polishing agent. Use a suspension of chromium trioxide mixed with water
with high concentration and coarse particles or other polishing materials.
4.2.23 Fine polishing agent. Use a suspension of chromium trioxide mixed with water
with a relatively low concentration and fine particles, or other polishing materials.
4.2.24 Fine polishing agent. Use a suspension of magnesium oxide or extremely fine
aluminum trioxide mixed with water, or other polishing materials.
4.2.25 Water-based lubricant.
4.2.26 Kerosene.
4.3 Instruments and equipment
4.3.1 Optical (metallographic) microscope. In accordance with JJF 1914, it shall be
equipped with an eyepiece scale plate of not less than 0.1 mm (or integrated with the
eyepiece). The magnification should be 50 times ~ 500 times.
4.3.2 Metallographic polishing machine.
4.3.3 Vibration polishing machine.
4.3.4 Electrolytic polishing and anode film-making device, see Figure 15.Lead plate or
stainless steel plate shall be used as the cathode.
the cladding layer thickness along the length direction using an eyepiece micrometer.
The measurement points shall be no less than 5 and the average value shall be calculated.
4.5.3.2 When required by the purchaser, the cladding ratio V can be calculated
according to formula (1). The value is expressed as a percentage. The calculation result
is expressed to two decimal places. The value is rounded off according to the provisions
of GB/T 8170.
Where.
t - Average cladding layer thickness, in millimeters (mm);
h - Total plate thickness, in millimeters (mm).
4.5.4 Copper diffusion inspection
When preparing the specimen for copper diffusion depth inspection, electrolytic
polishing can be used to check whether the copper diffusion penetrates or the maximum
depth of copper diffusion in the aluminum cladding on both sides can be measured with
an eyepiece micrometer.
4.5.5 Inspection of remaining casting structure
Inspect the microstructure. If the wrought aluminum and aluminum alloy products show
a microstructure in which the dendrites are not completely broken [see Figure 14b)], it
is judged that there is remaining casting structure.
4.5.6 Determination of grain size
The grain size determination is carried out in accordance with Appendix B. The typical
anodic film polarized grain structure is shown in Figure A.1 ~ Figure A.88.
4.5.7 Determination of the second phase and particle size
The determination of the second phase and particle size is carried out in accordance
with Appendix C.
4.5.8 Observation and analysis of the morphology and distribution of the second
phase
4.5.8.1 The type of the second phase (such as primary phase, eutectic phase,
precipitation phase, etc.) can be determined, by observing the microstructural
characteristics of the second phase, such as morphology, size, distribution; then the
phase composition of some phases can be preliminarily determined. The method for
determining the phase composition of the primary phase and eutectic phase is shown in
T/CNIA 0161.
4.5.8.2 Observation and analysis of the aging phase is carried out in accordance with
the provisions of YS/T 1623.
4.5.9 Homogenization effect evaluation
The homogenization effect evaluation method shall be carried out in accordance with
the provisions of YS/T 1624.
4.5.10 Microscopic slag inspection
Use 200 times magnification to scan within the inspection area of the specimen
(preferably 10 mm × 10 mm). Use 500 times magnification to judge the observed
suspected slag inclusions. Use 200 times magnification to measure and count the
maximum intercept size and number of slag inclusions for each slag inclusion.
4.5.11 Sell zone inspection
On the microscopic cross section of the sell zone of the specimen, use the eyepiece
micrometer to measure the thickness of the sell zone along the length direction. The
measurement points shall be no less than 5 points; the maximum thickness is taken.
4.5.12 Looseness inspection
For looseness inspection method, see T/CNIA 0179.
4.5.13 Inspection of inclusion content in aluminum alloy melt
For inspection of inclusion content in aluminum alloy melt, see T/CNIA 0150.
5 Scanning electron microscopy
For microscopic morphology inspection of wrought aluminum and aluminum alloy
structures, composition analysis of second phases and defects, determination of average
grain size and recrystallization area fraction, auxiliary judgment of eutectic melting
structures, failure analysis methods, see T/CNIA 0161.
6 Transmission electron microscopy
According to YS/T 1623, microscopic analysis of aging phases is carried out; typical
spectra are shown in T/CNIA 0176 (all parts).
Appendix B
(Normative)
Determination of grain size
B.1 Method overview
The following methods can be used to determine grain size based on the number of
grains per unit area or the number of intercepts per unit length.
- Comparison method. Compare the grain image observed on the specimen with the
standard image of known grain size, to obtain the grain size of the inspected
specimen. It is applicable to the measurement of grain size of ingot, equiaxed or
nearly equiaxed crystals (aspect ratio not greater than 3.1) or fully recrystallized
grain size of wrought aluminum and aluminum alloy materials.
- Planar grain calculation method. Calculate the number of grains in a known area;
use the number of grains per unit area to determine the grain size grade.
- Intercept method. It is used for non-uniform equiaxed grain structure. For
anisotropic structure, the grain size in three main directions can be measured
separately. Under appropriate circumstances, the average grain size can be
measured more reasonably. Measurement and calculation can be completed with
the help of various types of test instruments. For example, quantitative microscopes
and image analyzers.
B.2 Comparison method
B.2.1 Figures B.1 ~ B.8 are standard rating diagrams for wrought aluminum and
aluminum alloy grain sizes, magnified 100 times. The Table in each Figure gives the
magnification and the corresponding grain grade index G. At a magnification of 100
times, when the number of grains on the detection area is known, the grain grade index
G can be calculated according to formula (B.1).
Where.
N - Number of grains, in pieces;
A - Detection area, in square millimeters (mm2).
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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