1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards SALT SPRAY TEST Do Not Use on New Programs. Being Replaced by GMW3286 EDS-T-7143 ISSUED DATE: 1993. 11. 09 REVISED DATE: 2008. 10. 15 VERSION: 5 (Superceded) EDS-T-7143SALT SPRAY TEST PAGE: 1/6 ISSUED DATE: 1993. 11.
2、09 REVISED DATE: 2008. 10. 15 VERSION: 5 GM DAEWOO Auto & Technology Note: This standard may be applied only for current project (incl. T255 Program). It is Superceded for all future projects and replaced by GMW3286. 1. PURPOSE The purpose of this standard is to determine the resistance of metals, m
3、etallic and other protective coatings to corrosive atmospheres by salt spray fog test. This standard is used to carry out the test by the appropriate test method. 2. SCOPE This standard specifies the test method which determines the resistance to corrosion by salt spray fog test. 3. TEST PIECE 3.1.
4、Preparation of test piece 3.1.1. Where possible test shall be conducted on complete components. The test can also be conducted on specially prepared test panels of a minimum area 250cm2. 3.1.2. Where the dimension and shape of the component prohibit the testing of the complete components, test piece
5、 shall be cut from the component. Such test pieces shall have the largest possible size and shall be cut such that the edges are not heavily mechanically deformed nor subjected to excessive temperatures. All cut edges shall be protected in a suitable manner(e.g. with adhesive tapes, protective paint
6、s, etc.) during test. 3.1.3. For initial sample approval and arbitration purposes, at least 3 test pieces shall be tested. For routine quality control purposes, at least 1 test piece shall be tested. 3.2. Cleaning of test piece 3.2.1. Metallic and metal coated test pieces shall be degreased and clea
7、ned using a non chlorinated solvent(e.g. Xylene, Petroleum Ether, Petroleum benzene). For soft coatings such as Pb-Sn, care must be exercised to avoid smearing the coatings. The cleaning shall be carried out immediately prior to test. 3.2.2. Anodized aluminum test pieces shall be cleaned with acid f
8、ree dichloromethane immediately prior to testing. 3.2.3. The test pieces with protective coatings other than those defined in clause 3.2.1 and 3.2.2 shall not be cleaned prior to testing. 3.2.4. The regulation for cleaning of the test piece on the test material or the component specification shall b
9、e preferred. 4. TEST APPARATUS 4.1. Composition of apparatus EDS-T-7143SALT SPRAY TEST PAGE: 2/6 ISSUED DATE: 1993. 11. 09 REVISED DATE: 2008. 10. 15 VERSION: 5 GM DAEWOO Auto & Technology The apparatus required for salt spray fog testing shall consist of a fog chamber, a salt solution reservoir, at
10、omizing nozzles for supply of suitably compressed air, specimen supports, provision for heating the chamber, and necessary means of control. Test apparatus in accordance with DIN 50021 and ASTM B117 is suitable for testing. The below picture shows a diagrammatic representation of test apparatus. All
11、 materials of construction shall not affect, or be affected by the test solution. 4.2. Test chamber (fog chamber) 4.2.1. The test chamber shall have a minimum volume of 0.4m3and shall be insulated to prevent moisture and heat losses. It shall be provided with a thermostatically controlled heating sy
12、stem such that the temperature of the chamber can be controlled to 352K. 4.2.2. The test chamber shall be so constructed that drops of solution that accumulate on the ceiling or cover of the chamber shall not be permitted to fall on the test pieces under test. 4.2.3. Once the test solution has been
13、sprayed, it shall not be reused and it therefore shall not be returned to the reservoir. 4.3. Atomizing nozzles 4.3.1. There shall be a minimum of one nozzle per 3m3capacity of the test chamber. Nozzles shall be so arranged that there is a uniform and even distribution of the mist over the entire te
14、st area. 4.3.2. The nozzle shall be placed so that the mist is not directly sprayed on the test piece. Direct spraying of the test pieces or production of mist under test pieces shall not be allowed. 4.4. Humidifier This shall be so designed and constructed that the compressed air is saturated with
15、water at the required temperature during the entire test period. The quantity, temperature, and water content of the compressed air shall be adjustable. 4.5. Frame (specimen support) The frame shall be arranged in the effective area of the test chamber, such that the test piece are not permitted to
16、touch one another, no drops of test solution shall fall from one test piece to another and the test surfaces shall be inclined at approximately 60 to 75 to the horizontal. EDS-T-7143SALT SPRAY TEST PAGE: 3/6 ISSUED DATE: 1993. 11. 09 REVISED DATE: 2008. 10. 15 VERSION: 5 GM DAEWOO Auto & Technology
17、EDS-T-7143SALT SPRAY TEST PAGE: 4/6 ISSUED DATE: 1993. 11. 09 REVISED DATE: 2008. 10. 15 VERSION: 5 GM DAEWOO Auto & Technology 4.6. Compressed air The compressed air used for production of the spray fog, shall have a pressure of 10.2 bar and shall be largely free from dirt, oil and other impurities
18、. Such compressed air shall subsequently be saturated with water in the humidifier and the temperature adjusted such that, when released at the nozzle, the saturated compressed air temperature is approximately 35. 4.7. Test solution 4.8. The test solution shall be prepared by dissolving 5 parts by w
19、eight reagent grade salt in 95 parts by weight distilled or deionized water. 4.8.1. The pH of the solution shall then be adjusted, by the addition of diluted chemically pure hydrochloric acid or chemically pure sodium hydroxide, so that collected condensate has a pH of 6.5 to 7.5 at 232K. 4.8.2. The
20、 pH value shall be measured electrometrically at 232K using a glass electrode, or colourimetrically using bromine thymol blue as an indicator. 5. TEST CONDITION 5.1. Test temperature During testing, the temperature in the exposure zone of the closed test chamber shall be 352K. 5.2. Amount of the fog
21、 spray 5.2.1. To identify the amount and distribution condition of the fog spray, at least 2 clean collection vessels shall be installed at the same height as the test pieces. Care shall be taken so that no drops of test solution fall from one test piece to another. The collection vessels shall be p
22、laced near the test piece. One vessel shall be installed most near the nozzle, and another shall be away from it. 5.2.2. 1.50.5ml/hour condensate per an 80 cm2surface, shall accumulate on each collection vessel after spray for at least 16 hours. 5.2.3. The collected condensate shall contain 505g/l s
23、odium chloride and shall have a pH of 6.5 7.5 at +232K. 5.3. Test periods Test period is defined for test material and product specification. In case of no such definition, test period shall be determined through consultation among related personnel. Recommended test hours are 2h, 6h, 24h, 48h, 96h,
24、 168h, 240h, 480h, 720h and 1000h. However, in case of looking for corrosion, test may be conducted until corrosion is found. 5.4. Calibration of test apparatus EDS-T-7143SALT SPRAY TEST PAGE: 5/6 ISSUED DATE: 1993. 11. 09 REVISED DATE: 2008. 10. 15 VERSION: 5 GM DAEWOO Auto & Technology The corrosi
25、on effect of this apparatus is variable according to the test condition. The corrosion of effect of this test shall be regularly calibrated by exposing steel panels(steel panel for spray coating : SPCC or equivalent) to the test and determining mass loss. (Calibration method) 5.4.1. The steel panel(
26、50 80mm, thickness 1mm) shall be cleaned with petroleum alcohol using a soft brush or line-free cloth, and weighed to the nearest 1mg using an analytical balance. 5.4.2. The side of the test panel not exposed directly to the salt spray fog medium shall be suitably masked(using self adhesive tape, la
27、cquer or wax). The unprotected side of test panel shall be located in the test chamber uppermost and inclined at an angle of approx. 70to the horizontal and exposed for 96 hours to the salt spray fog medium. 5.4.3. At the end of 96 hours, the test panel shall be removed from the test chamber, rinsed
28、 in clean running water and the protective film on the unexposed surface to the salt spray fog medium shall be taken off. 5.4.4. The corrosion products of the exposed surface shall be removed using inhibited acid solution containing 770ml distilled(or deionized water),m 230ml HCl, 1ml isopropyl alco
29、hol or an equivalent solution, and a suitable brush. 5.4.5. After removal of corrosion products, the test piece shall be thoroughly rinsed in clean running water followed by acetone rinsing and allowed to dry. Thereafter, the mass loss after weighing to the nearest mg shall be recorded and calculate
30、d in g/m2. 5.4.6. The mass loss shall be 140 to 160g/m2after exposure for 96 hours. 6. PROCEDURE After the test equipment has been prepared in accordance with clause 4, test piece or component shall be exposed to the uninterrupted effects of the spray fog during the test period. Interruption of spra
31、ying during the test period is only allowed if the test chamber must be opened to remove components under test for evaluation and to place them back if necessary. The opening time shall be as short as possible. At the end of test period, test piece shall be removed from the test chamber, washed with
32、 clean running water at 40 to remove all remaining salt, dried immediately and evaluated. If not otherwise sated, test pieces shall be evaluated at 235K after washing and drying. 7. EVALUATION Visual evaluation of the test pieces shall be carried out immediately after the specified test period. (see
33、 clause 5.3) For test pieces with a scribed line corrosion creepback of the organic coating either side of the scribed line shall be determined by carefully separating loosely adhered coating from firmly adhered areas using a scalpel or equivalent blade, and rinsed in clean running water. Alternativ
34、ely, after (60 3)minutes at 213K (unless otherwise specified) following removal of test piece from the test chamber, the surface along the length of the EDS-T-7143SALT SPRAY TEST PAGE: 6/6 ISSUED DATE: 1993. 11. 09 REVISED DATE: 2008. 10. 15 VERSION: 5 GM DAEWOO Auto & Technology scribed line shall
35、be blown with compressed air at 5.5 to 6.2 bar from a 3mm diameter nozzle held lightly and perpendicularly to the surface. The average width of corrosion creepback for evaluation purpose shall be determined by measuring values at different points along the length of the scribed line and the average
36、calculated. The corrosion creepback Wdin mm shall be calculated as follows: 20ddWd= Where, d = width of corrosion creepback (average value) in mm d0= width of original scribed line in mm (Generally d0shall be 0.5mm) Dependent upon the substrate or surface coating the requirements are allocated accor
37、ding to the following gradings : 7.1. Grade 1 : No change of the surface. 7.2. Grade 2 : Corrosion of coating allowed but no corrosion of the base material. 7.3. Grade 3 : Specially defined. 7.4. Grade 4 : Substrate corrosion, except along scribed line, blisters or other adverse surface defects shal
38、l not be permitted unless otherwise specifically negotiated. Corrosion creepback when determined at any one position shall not exceed 3 mm on either side of the scribed lone and the calculated Wdshall be 1mm max. Slight rust is permitted but shall be within 20% of the total length of exposed edges.
39、8. EXPRESSION OF RESULTS The test pieces or components shall be evaluated against the requirement of the relevant engineering drawings or material specifications and reported with reference to this test method. 9. CODING SYSTEM The requirements for salt spray fog testing shall be specified on engineering drawings, material specifications etc. as follows : Example 9.1. Salt spray test EDS-T-7143 - 120 - GRADE 1 . Requirement grade (See clause 7) Test period (hours) Specification Designation
