1、BRITISH STANDARD BS EN ISO 15324:2008 Corrosion of metals and alloys Evaluation of stress corrosion cracking by the drop evaporation test ICS 77.060 BS EN ISO 15324:2008 This British Standard was published under the authority of the Standards Committee and comes into effect on 15 February 2001 BSI 2
2、008 ISBN 978 0 580 60538 3 National foreword This British Standard is the UK implementation of EN ISO 15324:2008. It is identical with ISO 15324:2000. It supersedes BS ISO 15324:2000, which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosio
3、n of metals and alloys. A list of organizations represented on this committee can be obtained 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. Compliance with a British Standard ca
4、nnot confer immunity from legal obligations. Amendments/corrigenda issued since publication Date Comments 30 June 2008 This corrigendum renumbers BS ISO 15324:2000 as BS EN ISO 15324:2008EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 15324 April 2008 ICS 77.060 English Version Corrosion of
5、 metals and alloys - Evaluation of stress corrosion cracking by the drop evaporation test (ISO 15324:2000) Corrosion des mtaux et alliages - valuation de la rsistance la fissuration par corrosion sous contrainte par essai dvaporation goutte goutte (ISO 15324:2000) Korrosion von Metallen und Legierun
6、gen - Bewertung der Spannungsrisskorrosion mit der Tropfen- Verdampfungsprfung (ISO 15324:2000) This European Standard was approved by CEN on 21 March 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the
7、status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German
8、). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Rep
9、ublic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN D
10、E NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 15324:2008: EForeword The text of ISO 15324:2000 has been prepared by Te
11、chnical Committee ISO/TC 156 “Corrosion of metals and alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 15324:2008 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This European Stan
12、dard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2008, and conflicting national standards shall be withdrawn at the latest by October 2008. Attention is drawn to the possibility that some of the elements of
13、this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European S
14、tandard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingd
15、om. Endorsement notice The text of ISO 15324:2000 has been approved by CEN as a EN ISO 15324:2008 without any modification. BS EN ISO 15324:20081 Corrosion of metals and alloys Evaluation of stress corrosion cracking by the drop evaporation test 1 Scope 1.1 This International Standard specifies the
16、procedure for determining the relative resistance of stainless steels and nickel-base alloys to stress corrosion cracking in a sodium chloride drop evaporation system. 1.2 The method results in a threshold stress to fracture, the magnitude of which can be used to rank the relative performance of dif
17、ferent alloys for this environment. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publica- tions do
18、 not apply. However, parties to agreements based on this International Standard are encouraged to investi- gate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. M
19、embers of ISO and IEC maintain reg- isters of currently valid International Standards. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. ISO 4287:1997, Geometrical Product Specifications (GPS) Surface texture: Profile method Terms, definitions and surface texture par
20、ameters. ISO 4288:1996, Geometrical Product Specifications (GPS) Surface texture: Profile method Rules and proce- dures for the assessment of surface texture. ISO 7539-1:1987, Corrosion of metals and alloys Stress corrosion testing Part 1: General guidance on testing procedures. 3 Terms and definiti
21、ons For the purposes of this International Standard, the following terms and definitions apply. 3.1 threshold stress stress below which no fracture in is observed (see also 8.8) 3.2 time-to-fracture elapsed time from start of test until fracture of the specimen 4 Principle 4.1 A dilute salt solution
22、 is dripped on to a heated tensile specimen of the material under test which is held horizon- tally and subjected to a uniaxial load. 4.2 Tests are carried out at different applied stresses and the time to specimen fracture is recorded. A threshold stress is defined based on the principle of no obse
23、rved fracture in . 500 h 500 h BS EN ISO 15324:20082 4.3 The elevated temperatures, wetting and drying process and associated concentration of salt with the drop evaporation process represent a potentially severe environmental condition which could induce stress corrosion cracking in some alloys. As
24、 such, it represents a severe test for alloy performance. 4.4 Evaporation of salt solutions leading to salt concentration at elevated temperature is not uncommon in service and can arise, e.g., in sea water spray situations or as a result of solution leaks dropping on to hot surfaces. However, the v
25、ariability of service conditions means that this method is suitable only as a method of ranking performance, based on the magnitude of the threshold stress, and not as an acceptance test for service application. 5 Apparatus 5.1 System for applying a constant load to a specimen held in a horizontal c
26、onfiguration. 5.2 Equipment for applying an alternating or direct current of up to about thirty amperes current to the specimen at a voltage of two volts or less. NOTE The current required will depend on the dimensions of the specimen and the properties of the material. 5.3 A reservoir, (typically )
27、 for the sodium chloride solution connected to a vertical glass tube with internal and external diameters approximately and respectively. The bottom of the glass tube is held at a distance of approximately above the centre of the specimen (see Figure 1). Key 1 sodium chloride 2 Plastic shield to pro
28、tect electrical connections 3 A.C. or D.C. electrical supply 4 Vessel to collect solution a Direction of applied load (force). Figure 1 Schematic arrangement for drop evaporation tests 20 l 0,4 mm 4 mm 10 mm 0,1 mol/l BS EN ISO 15324:20083 The system shall be capable of delivering a controlled flow
29、of solution of (see annex A). The composition of the solution in the reservoir shall be maintained constant. 5.4 A suitable calibrated device for measuring the surface temperature of the specimen. Surface tempera- ture measurement is important because of the need to ensure that the method of measure
30、ment itself does not affect the temperature. Applicable methods are described in annex B. 5.5 A device for detecting specimen fracture and recording the time to fracture. A microswitch attached to the specimen mounting and associated with an electric timer is suitable. 5.6 Some degree of containment
31、 of the test system, to limit the possibility of fluctuations in temperature due to air currents, as necessary. 6T e s ts p e c i m e n 6.1 The specimens shall be tensile specimens with a circular cross section in the gauge length. 6.2 The specimens shall be prepared from thick sheet, plate, bar, st
32、rip or tube. 6.3 The specimens shall be cut such that the longitudinal direction of the specimen is parallel to the rolling direction of the original processed material. 6.4 The specimen shall have a gauge length of and a gauge diameter of . The gauge length should be faired into the grip section wi
33、th suitable gradual radii. The dimensions of the main body of the specimen affect heat transfer and the currents required. NOTE A diameter of or a square cross section is effective. The overall length of the specimen should be about . 6.5 The specimen shall be produced to a fine ground finish ( ) pr
34、eferably by grinding in the longitudinal direction as any grinding flaws are then parallel to the stress axis. The surface texture can be measured in accord- ance with ISO 4287 or ISO 4288 by conventional stylus or laser profilometry. The texture should be measured along the longitudinal axis and th
35、e process repeated a number of times (typically about six) after rotating the specimen. It should be emphasised that the value, although most commonly quoted is not necessarily the critical parameter with respect to stress corrosion cracking and can be useful in evaluating and reporting other measur
36、es of surface tex- ture as discussed in annex C. NOTE Residual stresses and strain-hardened layers can have an influence on stress corrosion cracking. The effect can be sig- nificant when test specimens are removed from material in which complete stress relief is impractical, such as weldments, as-
37、quenched materials and complex forged or extruded shapes. In addition, near-surface residual stresses can be introduced during machining and surface grinding and these processes should be undertaken in such a way as to minimize the generation of resid- ual stress. In some cases, relief of surface re
38、sidual stress may be undertaken provided that this does not lead to a change in microstructure. The surface cold worked layer induced by the grinding process may also be removed by electrolytic polishing. Measurement of residual stress is desirable. 6.6 After surface finishing, surface contaminants
39、shall be removed by an appropriate cleaning procedure. NOTE Rinsing with distilled water, followed by alcohol and a non-chlorinated solvent is adequate for most cases. The use of an ultrasonic bath is recommended. 7 Test solution The test solution is NaCI, prepared from analytical reagent grade chem
40、icals and distilled or deionised water of conductivity , see ISO 3696. The solution in the reservoir shall be maintained at a temperature of . The initial pH of the solution shall be in the range to in this temperature range. NOTE By agreement, the method can be used to evaluate performance in other
41、 solutions, e.g. sea water. The use of sea water results in formation of a more acidic salt during drying and will tend to be more aggressive than NaCl. 10 drops/min ( 10 %) 10 mm 1,8 mm 5mm 2mm 100 mm Ra 1 m Ra 0,1 mol/l 6 10 Scm 1 (23 3) C 5,7 7,0 0,1 mol/l BS EN ISO 15324:20084 8 Procedure 8.1 Th
42、e specimen is attached to the gripping devices. 8.2 The specimen is resistance heated until a steady temperature of is attained. The current required to maintain this temperature is noted. NOTE The method described in annex B can be used to define the current required to achieve the desired temperat
43、ure. How- ever, it is recommended that the surface temperature be measured in each test using a small contact thermometer or thermocou- ple calibrated as described in annex B. 8.3 The solution is dripped on to the specimen at a rate of . 8.4 The load is then applied. The load to be applied shall be
44、a fraction of the load corresponding to the proof stress at a temperature of . A binary search procedure may be employed to determine the threshold stress as described in ISO 7539-1, although judicious selection of the stress for the first test should be used based on the an- ticipated resistance of
45、 the alloy. NOTE Because of the dependence of yield stress on temperature, application of the load prior to dripping of the solution would not be appropriate as a general rule because it may result in exceeding the yield stress of the specimen. 8.5 The specimen fracture detection system is activated
46、. 8.6 The applied current is increased by . This gives rise to a situation in which the specimen just dries out be- tw ee nea chd ro p . NOTE The application of the final current prior to wetting will cause the temperature to increase to an unacceptable level in terms of material property change, bu
47、t such a current increase is necessary to establish test conditions severe enough to cause fracture in a reasonable timescale. 8.7 The temperature of the specimen shall be measured in the dry region at least once during the test, see annex B. 8.8 The test is continued until the specimen fractures, u
48、p to a maximum of . The time to fracture is recorded. NOTE By agreement, the maximum exposure time can be increased and the threshold stress redefined accordingly. Neverthe- less, the value corresponding to of testing should be quoted. 8.9 The fractured specimen shall be examined to confirm that the
49、 failure was due to stress corrosion cracking, e.g. by fractographic or metallographic methods. 8.10 The test is repeated at other fractions of the yield strength until the minimum stress to cause fracture in is determined. The value shall be that fraction of the yield strength at which fracture did occur, but which was just above the stress at which no fracture occurred in . 9 Test report The test report shall include the following info
