1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 21608:2012Corrosion of metals and alloys Test method for isothermal-exposure oxidation testing under high-temperature corrosion conditions for metallic materialsBS ISO 216
2、08:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 21608:2012. The UK participation in its preparation was entrusted to T e c h n i c a l Committee ISE/NFE/8, Corrosion of metals and alloys.A list of organizations represented on this committee can be obtai
3、ned on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 72169 4 ICS 77.060 Compliance with a
4、 British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2012.Amendments issued since publicationDate T e x t a f f e c t e dBS ISO 21608:2012 ISO 2012Corrosion of metals and all
5、oys Test method for isothermal-exposure oxidation testing under high-temperature corrosion conditions for metallic materialsCorrosion des mtaux et alliages Mthode dessai pour les essais doxydation en exposition isotherme des matriaux mtalliques dans des environnements corrosifs haute tempratureINTER
6、NATIONAL STANDARDISO21608First edition2012-03-15Reference numberISO 21608:2012(E)BS ISO 21608:2012ISO 21608:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any for
7、m or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-
8、mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 21608:2012ISO 21608:2012(E) ISO 2012 All rights reserved iiiContents PageForeword iv1 Scope 12 Normative references . 13 Terms and definitions . 24 Test method 24.1 Principle . 24.2 Reagents and materials . 24.3 Test apparatus 44.4 P
9、rocedure 54.5 Determination of mass change 84.6 Analysis of mass change 114.7 Post-test evaluation of test pieces .125 Report .125.1 Matters do be described 125.2 Supplementary note .13Bibliography .14BS ISO 21608:2012ISO 21608:2012(E)ForewordISO (the International Organization for Standardization)
10、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 repres
11、ented 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 d
12、rafted 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 S
13、tandard 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 21608 was prepared
14、by Technical Committee ISO/TC 156, Corrosion of metals and alloys.iv ISO 2012 All rights reservedBS ISO 21608:2012INTERNATIONAL STANDARD ISO 21608:2012(E)Corrosion of metals and alloys Test method for isothermal-exposure oxidation testing under high-temperature corrosion conditions for metallic mate
15、rials1 ScopeThis International Standard specifies the method for continuous (single post-exposure mass measurement on each of a series of specimens without intermediate cooling) and discontinuous (series of mass measurements on a single specimen with intermediate cooling at predetermined times not n
16、ecessarily regular, and relatively few in number) isothermal-exposure testing under high-temperature corrosion conditions of metallic materials in gaseous environments. In contrast, thermal-cycling oxidation testing (series of mass measurements on a single specimen with frequent regular cooling in o
17、rder to accelerate high-temperature corrosion) is not included in this International Standard.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edit
18、ion of the referenced document (including any amendments) applies.ISO 3611, Geometrical product specifications (GPS) Dimensional measuring equipment: Micrometers for external measurements Design and metrological characteristicsISO 6344-3:1998, Coated abrasives Grain size analysis Part 3: Determinati
19、on of grain size distribution of microgrits P240 to P2500ISO 13385-1, Geometrical product specifications (GPS) Dimensional measuring equipment Part 1: Callipers; Design and metrological characteristicsISO 26146, Corrosion of metals and alloys Method for metallographic examination of samples after ex
20、posure to high-temperature corrosive environmentsANSI B74.12-09, Specifications for the Size of Abrasive Grain Grinding Wheels, Polishing and General Industrial UsesASTM E3-11, Standard Guide for Preparation of Metallographic SpecimensASTM E220-07a, Standard Test Method for Calibration of Thermocoup
21、les By Comparison TechniquesASTM E230/E230M-11e1, Standard Specification and Temperature-Electromotive Force (emf) Tables for Standardized ThermocouplesASTM E407-07e1, Standard Practice for Microetching Metals and AlloysASTM E633-00, Standard Guide for Use of Thermocouples in Creep and Stress-Ruptur
22、e Testing to 1 800F (1 000 C) in AirASTM E1350-07, Standard Guide for Testing Sheathed Thermocouples, Thermocouples Assemblies, and Connecting Wires Prior to, and After Installation or ServiceFEPA 43-1984 R:1993, Grit Sizes for Coated AbrasivesJIS R6001-98, Bonded abrasive grain sizes ISO 2012 All r
23、ights reserved 1BS ISO 21608:2012ISO 21608:2012(E)3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1scalesurface film and corrosion products produced on the surface of the test piece by high-temperature corrosion3.2adherent scalescale adhering to
24、the test piece after cooling3.3spalled scalescale flaked from the test piece3.4gross mass changemass change of test piece after cooling including collected spall3.5net mass changemass change of test piece after cooling without spall3.6high-temperature corrosioncorrosion occurring when the temperatur
25、e is higher than the dew-point of aqueous phases of the environment but at least 100 C3.7breakawayrapid increase in corrosion rate following a change from protective to non-protective scale growth4 Test method4.1 PrincipleSeveral test pieces exposed for different times are necessary to define oxidat
26、ion kinetics of the material. It is recommended that duplicate test pieces are used for each time. Data should be measured after at least four times with time intervals that increase progressively (e.g. 10 h, 30 h, 100 h, 300 h, 1 000 h).4.2 Reagents and materials4.2.1 Test piecesThe test pieces sha
27、ll have the form of a rectangular plate, a disc or a cylinder with a minimum surface area of 300 mm2and a minimum thickness of 1,5 mm.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
28、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 a mean particle diameter of approximately 15 m. This can be achieved by the use of abrasiv
29、es according to Table 1.If another surface finish is required by the parties involved, the surface finish condition shall be described.2 ISO 2012 All rights reservedBS ISO 21608:2012ISO 21608:2012(E)Table 1 Designation and mean diameter of particles of coated abrasives according to regional standard
30、sStandard DesignationMean diameter mRegionFEPAa43-1984 R:1993ISO 6344-3:1998P1200 15,3 1,0 EuropeJIS R6001-87 #1000 15,5 1,0 JapanANSI B74.12-01 600 16,0 AmericaaFederation of European Producers of Abrasives.Sharp edges of test pieces may give anomalous behaviour. These shall be slightly rounded dur
31、ing the final stages of 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 test piece support (Figur
32、e 4) and or reference marking are permissible.Where holes are used for 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 exp
33、osure 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
34、adsorb significant amounts of atmospheric contaminants such as water, it is recommended that the cleaned test pieces be 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
35、. The difference between the measurements shall not exceed 0,05 mg.It is recommended that duplicate test pieces be used for each time.4.2.2 Gas supplyThe 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,
36、it shall be capable of adjusting to the desired humidity. Deionized water of a conductivity less than 1 S cm-1shall 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
37、 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 of the humidifier.For testing in air, a specific humidity (mass fraction o
38、f 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 at 25 C.If any other humidity is employed, it shall be agreed between the parties concerned.In the case that the gas is humidified, t
39、he water vapour content shall be measured. This can be achieved by, for example, the use of a hygrometer before the test piece chamber or by measuring the amount of water after condensation of the exhaust gases or by measuring the water consumption of the humidifier over the course of the experiment
40、. ISO 2012 All rights reserved 3BS ISO 21608:2012ISO 21608:2012(E)4.3 Test apparatus4.3.1 Design of apparatusThe apparatus shall be composed, as a whole, of the temperature-regulating device for heating the test piece uniformly at a constant temperature. Ideally, the heating device should be equippe
41、d with a test 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 s
42、hould be monitored with a hygrometer. The gas supply shall be controlled by a gas flow meter.An example of a basic design of a closed, horizontal, apparatus is shown in Figure 1. Other designs may use a vertical orientation.Key1 gas supply2 gas flow meter3 valves4 humidifying regulator5 hygrometer6
43、heating device containing catalyst for non-equilibrium gas mixtures7 heating zone with ribbon heater8 heating device9 test piece chamber10 test piece11 test piece support12 thermocouples13 power/temperature control device14 gas exhaust15 measuring instrumentFigure 1 Basic design of a closed apparatu
44、sThe 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
45、test atmosphere during the test to a degree that it changes the composition of the atmosphere.4 ISO 2012 All rights reservedBS ISO 21608:2012ISO 21608:2012(E)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 ca
46、se, 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 testi
47、ng to determine the length of the isothermal zone inside the furnace. A common method is by the use of an independent moveable thermocouple.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.
48、The heating-device thermocouples for temperature control shall be as follows: The material for the 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 ser
49、vice.4.3.2 Temperature monitoringThe temperature shall be measured by a suitable device, which is separate from the thermocouple used for control (see heating-device thermocouple described in 4.3.1), according to ASTM E633-00. Thermocouples of type K (Ni/Cr - NiAl) up to 800 C, type S (10 %Rh/Pt Pt) and type R (Pt/13 %Rh Pt) up to 1 100 C or type B (Pt/30 %Rh Pt/6 %Rh) above 1 100 C are preferred. A thermocouple should be positioned close to the test piece surface and must be calibrated according to the
