GB/T 36174-2018 English PDF (GB/T36174-2018)

GB/T 36174-2018: Corrosion of metals and alloys -- Determination of resistance to intergranular corrosion of solution heat-treatable aluminium alloys
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GB/T 36174-2018
Corrosion of metals and alloys--Determination of resistance to intergranular corrosion of solution heat-treatable aluminium alloys
ICS 77.060
H25
National Standards of People's Republic of China
Corrosion solution heat treatment of metals and alloys
Determination of resistance to intergranular corrosion of aluminium alloys
(ISO 11846.1995, IDT)
Published on.2018-05-14
Implementation of.2019-02-01
State Market Supervisory Administration
China National Standardization Administration issued
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard uses the translation method equivalent to ISO 11846.1995 "Corrosion-resistant solid solution heat treatment of metal and alloy aluminum alloy resistant to intergranular corrosion
Determination of erosiveness.
The documents of our country that have a consistent correspondence with the international documents referenced in this standard are as follows.
GB/T 6682-2008 Analytical laboratory water specifications and test methods (ISO 3696.1987, MOD)
GB/T 10123-2001 Basic terms and definitions for corrosion of metals and alloys (eqvISO 8044.1999)
GB/T 16545-2015 Corrosion of metals and alloys Corrosion of corrosion products on specimens (ISO 8407.2009, IDT)
This standard was proposed by the China Iron and Steel Association.
This standard is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183).
This standard was drafted. Institute of Metal Research, Chinese Academy of Sciences, Institute of Metallurgical Industry Information Standards.
The main drafters of this standard. Wang Zhenduo, Liu Yuwei, Hou Jie, Li Qian.
Corrosion solution heat treatment of metals and alloys
Determination of resistance to intergranular corrosion of aluminium alloys
1 Scope
1.1 This standard specifies the test method for the resistance to intergranular corrosion of solid solution heat treated aluminum alloy without protective layer. Solution heat treatment aluminum alloy pair
The sensitivity of intergranular corrosion is related to the chemical composition of the alloy, the production method, the solution heat treatment, the quenching treatment and the precipitation hardening (aging) process.
The function of change. Under natural aging conditions, the sensitivity of intergranular corrosion of solid solution heat treated aluminum alloy is mainly quenched in the critical temperature range.
A function of the cooling rate in the process.
1.2 This standard applies to cast and forged heat treated aluminum alloys for castings, forgings, slabs, sheets, profiles and semi-finished or finished parts. suitable
Used for grade evaluation of alloys of different grades and thicknesses based on different chemical compositions and other factors and quality of heat treatment of materials.
The test results give information on determining the material's resistance to intergranular corrosion and heat treatment.
1.3 The test results are not absolute as they do not apply to all service environments. These test results are more suitable for comparing different
The intergranular corrosion resistance of the solution heat treated aluminum alloy at the heat treatment temperature.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
ISO 3696 Analytical Laboratory Water Specification and Test Method (Waterforanalyticallaboratoryuse; Specification
Andtestmethods)
ISO 8044 Basic terms and definitions for corrosion of metals and alloys (Corrosionofmetalsandaloys-Basicterms
Anddefinitions)
ISO 8407 corrosion of corrosive corrosion products on metals and alloys (Corrosionofmetalsandaloys-Re-
Movalofcorrosionproductsfromcorrosiontestspecimens)
3 Terms and definitions
The terms and definitions defined in ISO 8044 apply to this document.
4 sample
4.1 Sampling
The sample should be selected from the most typical areas of the material or the part being tested.
When controlling the solution heat treatment, the sample is taken from the semi-finished product where the quenching cooling rate is the smallest. When quenching small parts in the basket, the sample
Taken from the center of the basket. When quenching on a shelf, the sample is taken from the top or bottom of the shelf. If the pipe, sheet, thick
When semi-finished products such as plates are subjected to vertical quenching, the samples are selected from the bottom up. If there is no difference in the cooling method, the sample is randomly selected.
The sample should be taken from each solution treatment process.
The location of the sampling should be determined by both the supplier and the buyer.
4.2 Size, shape, quantity and surface requirements of the sample
The sample may be of any shape and size and should be consistent throughout each test. The surface area of the sample should be 20cm2~40cm2
between.
The flat specimen should be cut so that the longer side is parallel to the metal working direction.
The surface of the sample should be kept in the initial state of the material or finished part, or it should be machined to a surface roughness Ra ≤ 2.5 μm.
Specimens with surface defects (metallurgical or mechanical defects) are not suitable for testing.
Samples with an aluminum-clad layer shall be tested after removing the surface-coated aluminum layer. The aluminum layer on the upper and lower sides is treated by mechanical or chemical etching.
Except, the etch is a full chemical etch performed in solution or see 5.2. In order to ensure that the aluminum layer is removed, the thickness should be greater than the thickness of the aluminum layer.
At least 0.1mm.
Note. The temperature of the sample should not exceed 60 °C during processing.
Each test should have at least 3 parallel specimens of the same structure, size and surface condition.
5 surface treatment
5.1 Before the test, the surface of the sample is degreased with an organic solvent (gasoline or acetone).
5.2 The sample is then processed according to any of the methods described below.
--- Soak the sample in a NaOH solution (mass fraction 5%~10%) from 50 °C to 60 °C for 2 min~5 min and then use it.
Rinse with water, soak in concentrated HNO3 solution (ρ=1.4g/mL) for 2min, rinse with tap water, and finally rinse with distilled water.
Wash and dry.
--- Soak the sample at 50 °H ± 3 ° C per liter containing 50 mL HNO3 (ρ = 1.4 g/mL) and 5 mL HF (ρ =
1.15g/mL) solution for 1min, then rinse with tap water, then concentrated HNO3 solution at room temperature (ρ=
Immerse for 2 minutes in 1.4g/mL), rinse with tap water, and finally rinse with distilled water and blow dry.
6 test
6.1 Naturally aged alloys are tested after 24 h of quenching, while artificially aged alloys can be tested at any time.
6.2 The test is carried out by any of the methods described in 6.2.1 to 6.2.3.
6.2.1 Method A
Used to determine the quality of quenching.
Soak the sample at 30 °C ± 3 °C containing 57g/L ± 1g/L NaCl and 10mL ± 1mL H2O2 [30% (volume fraction)]
6h in solution. After the test, the sample was rinsed with tap water and blown dry. Non-metallic brushes can be used to remove corrosion products and/or during rinsing
It is best to immerse in concentrated HNO3 [70% (mass fraction) HNO3, ρ = 1.4g/mL] for a few minutes until the corrosion product is completely dissolved, then use
Rinse thoroughly with water (see ISO 8407).
6.2.2 Method B
It is used to compare the intergranular corrosion resistance of each solution-treated heat-treated aluminum alloy based on different chemical compositions and heat treatment processes.
The sample was immersed in a solution containing 30 g/L NaCl and 10 mL ± 1 mL of concentrated HCl (ρ = 1.19 g/mL) at room temperature.
In 24h. After the test, the samples were washed with tap water and distilled water, respectively, and dried. Non-metallic brushes can be used to remove corrosion during the rinsing process.
And/or preferably immersed in concentrated HNO3 [70% (mass fraction) HNO3, ρ = 1.4g/mL] for a few minutes until the corrosion product is completely dissolved,
Rinse thoroughly with tap water (see ISO 8407).
6.2.3 Method C
Used to evaluate the sensitivity of intergranular corrosion of aluminum-lithium alloys.
This method involves the anodic polarization of the sample in a NaCl solution, the polarization potential is as high as the intergranular corrosion sensitivity of the alloy, and
Continue to be exposed under Eicc (as shown in Figure 1).
Note. Method C is equally applicable in other alloy systems.
Description.
Epf---pitting formation potential;
Eicc=Epf 20mV;
A---intergranular corrosion area.
Figure 1 Typical anodic polarization curve
The test was carried out in a thermostatically controlled electrolytic cell (including working electrode, auxiliary electrode and reference electrode). Working electrode is passed
A mechanically polished or electrochemically polished sample having a surface area of 1 cm 2 ; the auxiliary electrode is platinum; and the reference electrode is saturated calomel or silver/silver chloride.
The electrolyte solution is a 0.01% (mass fraction) NaCl solution, which is polarized by a potentiostat at a controlled scan rate and potential Eicc.
Working electrode.
First, the anodic polarization curve of the sample was tested at a scan rate of 0.6 V/h, and the potential scan range was -1.16 V to the pitting potential Epf.
(The pitting potential is the potential at which the current density increases by at least one order of magnitude during anodic polarization). Then, another sample will be
It was placed in the same electrolytic cell for 5 min and the electric displacement was Eicc=Epf 20 mV. The time to continue exposure at this potential is as follows.
a) copper-containing alloy. 15 min ± 1 min;
b) Copper-free alloy. 90 min ± 5 min.
After the end of the test, the sample was taken out from the electrolytic cell, washed with distilled water, dried, and subjected to metallographic analysis.
6.3 Prior to the test, the solution is prepared with distilled water or deionized water with a conductivity below 10 μS/cm (see ISO 3696). Solute
Analyze the purification reagents.
6.4 The solution volume and sample area ratio should not be lower than 5cm3/cm2.
6.5 When the sample is placed in the container, it is not in contact with each other and does not touch the wall of the container. The distance between the solution surface and the upper surface of the sample should not be less than
20mm, and all samples should be consistent. Do not place different alloy samples of the system in the same solution.
6.6 The test is carried out in a glass container or a container made of inert organic material.
7 Metallographic analysis
Each test specimen was observed at a magnification of 5 times and the two areas with the most severe corrosion were marked. Take from these two areas
The sample was used for microscopic analysis. The swatch is usually taken from the largest surface area of the specimen and as far as possible from the edge of the specimen to avoid edges
The effect of the effect.
The cross section of the non-eroded sample was observed under a microscope magnification of 100 to 500 times. If it is not certain that this corrosion is intergranular corrosion
Etching, metallographic etching can be used to identify the actual grain boundaries.
8 Test results evaluation
The evaluation of intergranular corrosion sensitivity of solution heat treated aluminum alloy is based on the type of erosion, pitting or intergranular corrosion, as well as corrosion depth and invasion.
The relative extent of the eclipse (the length along the surface of the metallographic cross section). This sensitivity is usually expressed as a percentage.
When used to assess the quality of solution heat treatment, the acceptance of the sensitivity to intergranular corrosion is determined by the supplier and the buyer.
9 test report
The test report should include the following.
a) the name and chemical composition of the alloy;
b) the type of semi-finished product or part;
c) methods of manufacturing products or parts;
d) heat treatment;
e) surface state;
f) sample size;
g) application test methods (for this standard);
h) exposure time;
i) Rating criteria and rating numbers for alloys resistant to intergranular corrosion.
references
[1] USAMilitarySpecificationMIL-H-6088F, Heattreatmentofaluminiumaloys.
[2] DIN50905-3. 1987, Corrosiontesting-Corrosion characteristics undernonuniformandlo-
Calizedcorrosionattackwithoutmechanicalstress.
[3] ASTMStandard G3-89, ConventionsApplicabletoElectrochemicalMeasurementsinCor-
rosionTesting.
[4] ASTMStandard G110-92, PracticeforEvaluatingIntergranularCorrosionResistanceof
HeatTreatableAluminiumAloysbyImmersioninSodiumChlorideandHydrogenPeroxydeSolu-
Tion.
[5] GOST9.021-88, Aluminiumandaluminiumaloys-Methodofacceleratedintercrystaline
Corrosiontests.
[6] VIAMAssociationStandard1-595-5-180-86.
[7] Jirnov, ADand Karimova, SA, SomePeculiaritiesofΑl-LiAloysCorrosionBehaviour.
SixthInternational Aluminium-Lithium ConferenceGarmisch-Partenkirchen,.1991, volume 2, pp.
825-829.
[8] Lifka, BWandSprowls, DO, Significance of IntergranularCorrosionofHighStrength
AluminiumAloyProducts, inLocalizedCorrosion, CauseofMetalFailure, ASTMSTP516 (1972),
Pp.120-144.
GB/T 36174-2018
Corrosion of metals and alloys--Determination of resistance to intergranular corrosion of solution heat-treatable aluminium alloys
ICS 77.060
H25
National Standards of People's Republic of China
Corrosion solution heat treatment of metals and alloys
Determination of resistance to intergranular corrosion of aluminium alloys
(ISO 11846.1995, IDT)
Published on.2018-05-14
Implementation of.2019-02-01
State Market Supervisory Administration
China National Standardization Administration issued
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard uses the translation method equivalent to ISO 11846.1995 "Corrosion-resistant solid solution heat treatment of metal and alloy aluminum all...