ISO 13573:2012
(Main)Corrosion of metals and alloys — Test method for thermal-cycling exposure testing under high-temperature corrosion conditions for metallic materials
Corrosion of metals and alloys — Test method for thermal-cycling exposure testing under high-temperature corrosion conditions for metallic materials
ISO 13573:2012 describes the methodology for thermal cycling corrosion testing (known as cyclic oxidation testing) of metallic materials in gaseous environments between ambient and elevated temperatures (series of measurements on a single test piece with repeated, regular and controlled temperature cycles). ISO 13573:2012 may be applicable to other materials with some modifications. Tests with ultra short dwell times in the range of minutes or seconds are outside the scope of ISO 13573:2012.
Corrosion des métaux et alliages — Méthode pour essais de corrosion à haute température, avec exposition à des cycles thermiques, sur des matériaux métalliques
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 13573
First edition
2012-12-15
Corrosion of metals and alloys —
Test method for thermal-cycling
exposure testing under high-
temperature corrosion conditions for
metallic materials
Corrosion des métaux et alliages — Méthode pour essais de corrosion
à haute température, avec exposition à des cycles thermiques, sur des
matériaux métalliques
Reference number
ISO 13573:2012(E)
©
ISO 2012
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ISO 13573:2012(E)
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ISO 13573:2012(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test method . 2
4.1 Reagents and materials . 2
4.2 Test apparatus . 4
4.3 Procedure . 9
4.4 Determination of mass change .13
4.5 Analysis of mass change .16
4.6 Post-test evaluation of test pieces .20
5 Report .20
5.1 Matters to be described .20
5.2 Supplementary note .22
Bibliography .23
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ISO 13573:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 13573 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys, Working
Group 13, High Temperature Corrosion.
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INTERNATIONAL STANDARD ISO 13573:2012(E)
Corrosion of metals and alloys — Test method for thermal-
cycling exposure testing under high-temperature corrosion
conditions for metallic materials
1 Scope
This International Standard describes the methodology for thermal cycling corrosion testing (known as
cyclic oxidation testing) of metallic materials in gaseous environments between ambient and elevated
temperatures (series of measurements on a single test piece with repeated, regular and controlled
temperature cycles). It also may be applicable to other materials with some modifications. Tests with ultra
short dwell times in the range of minutes or seconds are outside the scope of this International Standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ANSI B74.12-92, Specifications for the Size of Abrasive Grain – Grinding Wheels, Polishing and General
Industrial Uses
ASTM E1350-97, Standard Test Methods for Testing Sheathed Thermocouples Prior to, During, and
After Installation
ASTM E220-02, Standard Test Method for Calibration of Thermocouples By Comparison Techniques
ASTM E230-03, Standard Specification and Temperature-Electromotive Force (EMF) Tables for Standardized
Thermocouples
ASTM E3-01, Standard Practice for Preparation of Metallographic Specimens
ASTM E407-07e1, Standard Practice for Microetching Metals and Alloys
ASTM E633-00, Standard Guide for Use of Thermocouples in Creep and Stress Rupture Testing to 1800°F
(1000°C) in Air
FEPA 43-1984 R:1993, Grit Sizes for Coated Abrasives
ISO 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for
external measurements — Design and metrological characteristics
ISO 6344-3:1998, Coated abrasives — Grain size analysis — Part 3: Determination of grain size distribution
of microgrits P240 to P2500
ISO 13385-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1:
Callipers; Design and metrological characteristics
ISO 26146, Corrosion of metals and alloys – Method for metallographic examination of samples after
exposure to high temperature corrosive environments
JIS R6001-87, Bonded abrasive grain sizes
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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ISO 13573:2012(E)
3.1
scale
surface film and corrosion products produced on the surface of the test piece by high temperature corrosion
3.2
adherent scale
scale adhering to the test piece even after cooling
3.3
spalled scale
scale flaked from the test piece
3.4
delaminated scale
scale fully or partially detached from the surface but still in contact with the test piece
3.5
gross mass change
mass change of the test piece after cooling, including collected spalled scale
3.6
net mass change
mass change of the test piece after cooling, without including the mass of spalled scale
3.7
high temperature corrosion
corrosion occurring when the temperature is higher than the dew point of aqueous phases of the
environment but at least 100 °C
3.8
breakaway
rapid increase in corrosion rate following a change from protective to non-protective scale growth
3.9
thermal cycle
sequence of temperatures that is repeated throughout the test. A single thermal cycle consists of the
heating phase, the hot dwell time, the cooling time and the cold dwell time
4 Test method
4.1 Reagents and materials
4.1.1 Test pieces
The test pieces shall have the form of a rectangular plate, a disc or a cylinder with a surface area of
2
300 mm at minimum and a thickness of 1,5 mm at minimum.
If the test pieces cannot be made according to these specifications, the shape and dimensions of the test
piece shall be in accordance with the agreement between the parties involved.
The test pieces shall be finished by machining so that the strata affected by cutting do not remain.
The final finishing of the surface of the test pieces shall be performed with abrasives with mean particle
diameter of approximately 15 µm. This can be achieved by the use of abrasives according to Table 1.
If another surface finish is required by the parties involved, the surface finish condition shall be described.
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ISO 13573:2012(E)
Table 1 — Designation and mean diameter of particles of coated abrasives according to
regional standards
Standard Designation Mean diameter Region
µm
a
FEPA 43-1984 R:1993, Grit Sizes for Coated Abrasives
ISO 6344-3:1998, Coated abrasives – Grain size analysis –
P1200 15,3 ± 1,0 Europe
Part 3: Determination of grain size distribution of microgrits
P240 to P2500
JIS R6001-87, Bonded abrasive grain sizes #1000 15,5 ± 1,0 Japan
ANSI B74.12-92, Specifications for the Size of Abrasive Grain
600 16,0 America
– Grinding Wheels, Polishing and General Industrial Uses
a
Federation of European Producers of abrasives
Sharp edges of the test pieces may give anomalous behaviour. These shall be slightly rounded during the
final stages of the test piece preparation.
The surface of the test pieces shall not be deformed by marking, stamping or notching. Identification
of the test pieces shall be solely on the basis of recording the relative position within the test chamber,
however, holes for the test piece support (Figure 5) and or reference marking are permissible.
Where holes are used for the test piece support, they shall be drilled prior to final finishing or application
of coatings. These have to be taken into account when calculating the surface area.
The dimensions of the test pieces shall be measured prior to exposure at a minimum of three positions
for each dimension with a precision of ±0,02 mm by means of the measuring instruments specified in
ISO 3611 and ISO 13385-1.
The test pieces shall be dried after degreasing by ultrasonic cleaning using iso-propanol or ethanol.
If it is suspected that specimens may adsorb significant amounts of atmospheric contaminants such as water,
it is recommended that the cleaned test pieces are stored in a desiccator prior to weighing and exposure.
The mass of the test pieces shall be determined prior to exposure. At least two measurements shall be
made for each test piece. The difference between the measurements shall not exceed 0,05 mg.
It is recommend that duplicate test pieces are used each time.
4.1.2 Gas supply for closed system operation
The gas supply system shall be capable of supplying the test gases at a constant rate to the test piece chamber.
When a humidifying regulator is used, it shall be capable of adjusting to the desired humidity. Deionized
−1
water of a conductivity less than 1 µS cm shall be used, unless otherwise specified.
The space between the humidifying regulator and the test piece chamber shall be kept above the dew
point in order to avoid condensation.
The gas flow shall be monitored by a gas flow meter. The flow meter shall be located as close as practicable
to the inlet of the test piece chamber except where a humidifying regulator is used, in which case it shall
be located upstream to the humidifier.
For testing in air, a specific humidity (mass fraction of water in air) of ~20 g/kg is recommended. This
corresponds to a relative humidity of 100 % at 25 °C (dew point) and is easy to obtain by bubbling
through a water bath of 25 °C.
If any other humidity is employed, it shall be agreed between the parties concerned.
In the case that the gas is humidified the water vapor content shall be measured. For example, this can
be achieved by the use of a hygrometer before the test piece chamber or by measuring the amount of
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ISO 13573:2012(E)
water after condensation of the exhaust gases or by measuring the water consumption of the humidifier
over the course of the experiment.
The formation of condensed phases from the test gas during the cooling cycle shall be avoided. This may
be achieved by turning off the humidification or by switching to an inert gas.
4.2 Test apparatus
4.2.1 Design of apparatus
The apparatus shall be comprised of a set-up that will transition the test pieces between hot and cold
environments in a controllable and reproducible manner. Ideally, the heating device should be equipped
with a testing portion capable of separating the test piece from outside air (this assembly is referred to
as a closed system) unless this is impracticable for the tests planned. When applicable, a humidifying
regulator should be used to continuously supply the gas kept at a constant humidity which should
be monitored with a hygrometer. The gas supply shall be controlled by a gas flow meter. A facility to
accelerate cooling may also be included. Examples of basic designs are shown in Figures 1 and 2.
The heating device shall be constructed such that the test piece chamber is isolated from the external
environment. It shall be ensured that a continuous gas flow within the prescribed range passes over
the test pieces.
The test piece chamber shall not be composed of a material that reacts with the test atmosphere during
the test to a degree that it changes the composition of the atmosphere.
If a closed system with a test piece chamber cannot be used, then the tests may be performed in an open
system with laboratory air. In this case the humidity of the air shall be recorded and the laboratories
should be kept free from temperature changes and influences from weather conditions, as far as possible.
Ideally, however, closed systems should be used.
The furnace shall be characterized at the exposure temperature prior to the testing to determine the
length of the isothermal zone inside the furnace. A common method is by the use of an independent
moveable thermocouple.
The time-dependent temperature response during the thermal cycling at a position at, or near to, the
test piece shall be recorded prior to the testing in order to allow definition of the parameters of a thermal
cycle, according to 4.3.3. This can be achieved by using dummy test pieces and appropriate thermometry.
The temperature regulating device shall be capable of guaranteeing that the temperature of the test
piece is kept within the permissible range given in Table 2. The temperature of the furnace may vary or
fluctuate due to movement of the furnace (less pronounced when the test piece supports are moved).
The control system used shall ensure that the desired temperature inside the furnace is reached rapidly
without being exceeded.
The heating device thermocouples for temperature control shall be as follows: The material for
thermocouple shall fully withstand the test temperature. Moreover, the diameter of wire is recommended
to be as small as possible, within the limit where the thermoelectric power does not change in service.
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ISO 13573:2012(E)
a)
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ISO 13573:2012(E)
b)
Key
1 Blower 11 Test piece support
2 Humidifying regulator (electronic type) 12 Shielding plate (movable type)
3 Hygrometer 13 Cooling chamber
4 Air flow meter 14 Test piece carrier
5 Heating zone with ribbon heater 15 Temperature regulating device
6 Testing portion 16 Power control device
7 Heating zone 17 Measuring instrument
8 Cooling zone 18 Thermocouples
9 Heating furnace 19 Crucible
10 Test piece
Figure 1 — Basic design of a closed horizontal (a) and a vertical (b) apparatus,
examples for setups with movable test piece support
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ISO 13573:2012(E)
a)
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ISO 13573:2012(E)
b)
Key
1 Gas supply 9 Test piece chamber
2 Gas flow meter 10 Test piece
3 Valves 11 Test piece support
4 Humidifying regulator (electronic type) 12 Thermocouples
5 Hygrometer 13 Power/Temperature control device
6 Heating device containing catalyst for non-equilibrium gas mixtures 14 Direction of furnace movement
7 Heating zone with ribbon heater 15 Gas exhaust
8 Heater 16 Measuring instrument
Figure 2 — Basic design of a closed horizontal (a) and a vertical (b) apparatus,
examples for setups with movable furnace
Table 2 — Permissible tolerance of temperature of test pieces
1 000 to 1
Temperature range, °C ≤ 300 300 to 600 600 to 800 800 to 1 000 > 1 200
200
Temperature tolerance,
±2 ±3 ±4 ±5 ±7 By agreement
°C
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ISO 13573:2012(E)
4.2.2 Temperature monitoring
The temperature shall be measured by a suitable device, according to ASTM E633-00. Thermocouples
of type S (Pt – 10 % Rh/Pt) or type R (Pt – 13 % Rh/Pt) are preferred for the temperature range: room
temperature up to 1 700 °C. A thermocouple should be positioned close to the test piece surface and
shall be calibrated according to the following paragraph. If, however, the environment does not allow the
use of such thermocouples in this way, the test piece temperature has to be deduced from the furnace
calibration using dummy test pieces and appropriate thermometry in an inert environment.
Calibration of thermocouples shall be performed in accordance with ASTM E220-02, ASTM E230-03, or
ASTM E1350-97. A representative thermocouple taken from the batch of wire may be calibrated.
It is recommended that thermocouples are recalibrated annually or at the beginning and the end of each
experiment, if there is uncertainty about thermocouple stability.
The thermocouple shall be capable of confirming the temperature of the test piece to be within the
range given in Table 2. It has to be on a defined, fixed place as close to the test pieces as possible.
Thermocouple sheaths shall be used to protect the thermocouple wires. The thermocouple sheaths shall
fully withstand the test temperature and environment.
4.3 Procedure
4.3.1 Support of test pieces
The test pieces shall be supported, according to the following principles:
The test piece shall be supported by a material that does not react at the test temperature. Contact
between the test piece and support shall be minimized.
The support of the test piece to be used shall be designed to be able to collect the scale, even if it flakes
during testing or during cooling after finishing the test.
When testing multiple test pieces simultaneously, each test piece shall be inserted into an individual test
piece support in order to enable the collection of all scale, including the scale spalled from each test piece.
The support design shall ensure that no major faces of the test pieces are shielded from the test atmosphere.
Examples of suitable test piece supports and basic layout of test piece arrangement are shown in
Figures 3 to 5.
Where the possibilty of the depletion of active species in the test atmosphere is a concern, the exchange
of the test atmosphere can be improved by the use of holes or slots in the bottom area of the side walls
of the test piece support.
When only net mass change data are required, multiple test pieces may be inserted in a single test
piece support.
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ISO 13573:2012(E)
Key
1 High purity alumina tube for supporting test piece
2 Test piece
NOTE left = side view; right = cross sectional view
Figure 3 — Test piece support and basic layout of test piece arrangement — tube design
(this type of support is not suitable for rapid heating and cooling)
Key
1 holes
NOTE left = side view; centre = cross sectional view; right = top view
Figure 4 — Test piece support and basic layout of test piece arrangement — round crucible
Key
1 holes
2 alumina rod
NOTE left = side view; centre = cross sectional view; right = top view
Figure 5 — Test piece support and basic layout of test piece arrangement — rod supported design
4.3.2 Test environment
The gas flow sha
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