1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (412) 772-8512 FAX: (412) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (412) 776-4970 FAX: (412) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1989 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001INFORMATIONREPORTAn American National StandardJ1950ISSUEDMAY89Issued 198
4、9-05PROVING GROUND VEHICLE CORROSION TESTINGForewordThis Document has not changed other than to put it into the new SAE Technical Standards BoardFormat.1. ScopeThe facilities used by domestic automotive manufacturers to provide accelerated corrosion aging ofcomplete vehicles are described in general
5、. The types of vehicles tested, general test methodology, andtechniques used to determine test-to-field correlation are discussed. The different procedures usedthroughout the industry produce different results on various vehicle coatings, components, and systems. Thekey to successful interpretation
6、of test results is a thorough understanding of the corrosion mechanismsinvolved and the effects of test limitations on these mechanisms.1.1 PurposeThe purpose of this information report is to provide a general overview of some proving groundprocedures and facilities used in the United States to eval
7、uate the corrosion protection performance ofvehicles. Because of limitations involved with any accelerated testing procedure, and despite the use ofcomplete vehicles and attempts to make test environments all-inclusive, test results require knowledgeableinterpretation.Proving grounds are, in effect,
8、 large laboratories. As with different laboratory test procedures, different testtechniques will produce different results. Consideration of the various techniques and analysis tools discussedin the following sections may give the reader an understanding of the environments that vehicles must bedesi
9、gned to survive and may aid in the further development of accelerated corrosion tests.2. References2.1 Related PublicationsThe following publications are provided for information purposes only and are not arequired part of this document.G. Hook; “The Historical Development of a Proving Ground Accele
10、rated Corrosion Test.“ Presented atNACE Corrosion/80, March 1980, Chicago, IL.R. Ericsson, S. Haagenrud, and J. Henriksen; “Simultaneous Measurements of Corrosiveness andEnvironment on Different Parts of the Automotive Body.“ Presented at NACE Corrosion/82, March 1982,Houston, Texas (Paper No. 260).
11、COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-2-3. Locations Of Corrosion Testing FacilitiesAlthough laboratory tests of vehicle components and systemsare conducted at various locations within an automotive company and it may have more
12、 than one provingground facility, each company performs proving ground corrosion tests at one location only. (As of this writing,although Chrysler and AMC have merged, they have not yet consolidated proving ground testing.) Thelocations of these facilities are shown in Figure 1. They are centered ei
13、ther in southeastern Michigan (GM andChrysler) or in Arizona (Volkswagen of America, Navistar, American Motors Corporation, Ford).FIGURE 1PROVING GROUND CORROSION TESTING LOCATIONSEach testing location has certain advantages. Locations in Southeast Michigan have the advantage of beingnear to corpora
14、te design and engineering activities so communication of test information may be optimized.Persons responsible for system corrosion performance can easily view interim test results without extensivetime or travel. Locations in Arizona have the advantage of fairly consistent weather, particularly hum
15、idity.Because ambient environment has a large effect on vehicle corrosion in Michigan, test corrosion ratedifferences on the order of 2:1 summer-to-winter have been observed if corrective measures are not used.Arizonas low relative humidity ensures that test vehicle corrosion occurs mainly under con
16、trolled conditions intemperature/humidity chambers.4. Vehicles TestedVarious types of vehicles are proving ground tested by the automotive manufacturers.These include audit testing of production vehicles, validation testing of preproduction vehicles (prototype, pilotline, etc.), and development test
17、ing for evaluation of new designs, materials, coatings, assembly andprocessing techniques, etc. Vehicles tested include the full range of each manufacturers product fromsubcompact cars to highway trucks and buses.5. Test Methods And FacilitiesTest methods used by the various manufacturers are often
18、different inenvironmental content because each test evolved separately; thus, the final results are often different. Thegeneral test methods presently in use are as follows:COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-3-5.1 General Mo
19、torsSeveral different test schedules are used, each having a particular area of emphasis but allhaving similar corrosive inputs. The “full corrosion/durability“ schedule requires approximately 10 months tocomplete and is intended to relate to 160 000 km (approximately 10 years) of severe customer se
20、rvice. Majortest inputs are shown in Figure 2. Rather than driving a totally preset cycle, events are combined to provideproportional corrosion (chemical) and durability (mechanical) input fitting schedule needs. This test can bemodified by removing some or most of the “mild“ durability inputs while
21、 leaving corrosive inputs essentiallyunchanged. This allows testing to be completed more rapidly while not largely affecting general and cosmeticcorrosion results. However, corrosion mechanisms, which are dependent upon stress cycles or other operationcycles, will not be accelerated as greatly. Beca
22、use it is believed that durability inputs (such as operation onrough roads, brake applications, operation of electrical systems, etc.) can affect corrosion results, and viceversa, these two types of test content (durability and corrosion) usually are run concurrently on a vehicle. Thefastest GM Prov
23、ing Ground corrosion test, which contains only the most significant durability inputs, requiresabout ten weeks to complete.General Motors corrosion test inputs are intended to relate directly to metallic general corrosion, cosmeticcorrosion, and functional corrosion of systems, assemblies, electrica
24、l connectors, etc. that occur in the field.Actual perforations of body panels usually are not produced within the time frame of these tests. However,these may be predicted with some confidence using metal thickness loss measurements and perforationacceleration factors known from past experience. Som
25、e uncertainty always exists because the test timerequired to cause deterioration of protective organic coatings is not always known.The General Motors corrosion test environment consists of alternate exposure to a shallow salt splash road(5% NaCl in water), an exterior salt spray (5% NaCl in water),
26、 gravel roads (portions treated with calciumchloride), a grit trough (containing sand, clay, and coal cinders in deep water), and 8 h periods of elevatedtemperature and relative humidity (RH) (49 C, 100% RH). Near the beginning of each test, the vehicle isdriven through deep mud to provide poultice
27、accumulation. (See Reference 1.)Test vehicle general corrosion exposure is monitored using bare steel coupons. Coupon weight loss ischecked periodically throughout the test, and results are compared to test objectives (known general corrosionrates from field vehicles). To adjust for corrosion rate v
28、ariations which might be caused by weather differences(for example, winter vs. summer testing) or test length (for example, full test or accelerated version), thenumber of exposures to 49C/100% RH is varied while all other inputs remain constant.5.2 FordThe Ford corrosion test daily cycle is diagram
29、med in Figure 3. It includes 1.5 h of driving on dirt andgravel roads and a paved road onto which a thin layer of 5% salt solution is sprayed, and through a salt trough(5% NaCl), a salt spray (5% NaCl, 15 min total time), and a mud bath containing 4 parts NaCl to 1 part CaCl2for a total of 3% salt c
30、oncentration in the mud. This is followed by 22.5 h in a humidity chamber at 49C/85%RH. This constitutes one cycle; five cycles per week are run and the vehicle is left in the humidity chamber onweekends and holidays. Total test duration is 100 cycles which approximates five years of severe fieldcor
31、rosion.Minimal variation is observed among tests run at different times of the year due to minimal variation inArizonas climate and the high percentage of time that vehicles spend in controlled temperature and humidity.The Ford test is intended primarily to disclose perforation-susceptible areas, al
32、though some cosmetic corrosioninformation also is obtained. Because of the severe nature of the test environment (able to cause perforationsin body panels), the test is not used to judge the performance of items such as drive shafts, springs, etc. Insome cases, trailers with body panel test specimen
33、s attached are towed behind test vehicles. Specimens arerotated to ensure that all experience the same conditions. The results obtained in this way correlate well withthose from test cars.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-4
34、-FIGURE 2GENERAL MOTORS CORPORATION VEHICLE CORROSION TESTINGCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-5-FIGURE 3FORD MOTOR COMPANY CORROSION TESTING CYCLECOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handl
35、ing ServicesSAE J1950 Issued MAY89-6-5.3 ChryslerThe Chrysler test is diagrammed in Figure 4. It has a duration of up to two years. It involves a 48 hcycle of driving (contamination), elevated temperature and humidity (38 C, 100% relative humidity), anddrying. Salt splash and spray are provided by a
36、 single facility using 0.5% NaCl, 0.5% CaCl2, and 0.125%sodium metabisulfite.Fifty test cycles are believed to correspond to 2.5-3.0 years of field exposure; tests frequently are run forseveral hundred cycles in order to evaluate long-term field exposure. Although good cosmetic corrosionresults are
37、obtained, some uncertainty exists in evaluating perforation corrosion. Slight differences in theenvironment have been found to cause relatively large differences in corrosion of bare steel coupons. Chrysleris considering the use of a controlled environment for drying periods. However, the fact that
38、the test may lastfor two years should tend to minimize long-term test result differences, which might be caused by day-to-dayweather variations.5.4 NavistarThe Navistar test cycle, shown in Figure 5, is designed to indicate perforation corrosionsusceptibility of medium and heavy-duty truck cabs. Whi
39、le the test track has facilities for stone pecking andsalt and mud splash exposures, previous tests have shown these have little effect on a truck cab. The cab sitshigh enough off the road to normally avoid this environment. Also, these tests are extremely hard on chassiscomponents which are not the
40、 subject of the cab corrosion test. In fact, chassis components are sometimescoated with rust inhibiting compounds or oils to extend their lives for possible use in additional tests.Cabs are prepared in accordance with the test objectives. Blower motors are installed so that when inoperation they wi
41、ll create a vacuum of approximately 25 mm of water inside the cab. This approximates thevehicle traveling in rain, at highway speeds, with the wing vents open. Panels may be scribed and intentionalleaks may be added. Observation ports are installed in areas of interest.Different test cycles have bee
42、n tried, but the one which has shown the best correlation to actual field data in theshortest test time is alternate exposures to a 5% NaCl salt spray and a dirt road run at 3035 mph. These areperformed with vacuum motors to ensure penetration of the salt solution into every possible crevice. After
43、afinal exposure to the salt spray, the test truck is driven into a humidity chamber and exposed to a relativehumdity of 100% at 38 C. This cycle is repeated four times per week and includes an average ofapproximately 39 h of chamber time per cycle. Test duration is 100 cycles.As there is little or n
44、o effect from stone pecking or other road hazards in this test, two cabs can be mounted onthe same chassis. This reduces total test time and costs. Also, this is very helpful in comparing alternatematerials or manufacturing processes as both cabs are exposed to exactly the same environment.Navistar
45、has recently closed their Phoenix test facility; future corrosion tests will be conducted at a new facilityin Ft. Wayne, IN.5.5 Volkswagen of AmericaThe VWoA corrosion test, diagrammed in Figure 6, is basically the same as theVWAG EK2 (Germany) corrosion test with minor variations. Essentially the E
46、K2 test was developed tocomprehensively simulate the extent of corrosion damage on cars in North America for up to six years.The test consists of subjecting a vehicle to a total of 36 h of low temperature condition at 35 C, 700 h of drycondition at 20 C, 1140 h in damp heat chamber at 45/50 C and 95
47、% RH, 60 h in salt spray chamber at 35 Cand 5% NaCl salt spray plus road cycle of a total of 7500 km on salt splash, gravel/rough, chip, mud andaccelerated durability track loops, thus inducing a corrosive stress such as would occur in cars in service for sixyears in extreme corrosion prone areas.CO
48、PYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-7-FIGURE 4CHRYSLER CORPORATION ACCELERATED CORROSION CYCLECOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-8-FIGURE 5NAVISTAR COR
49、ROSION TESTING CYCLECOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-9-FIGURE 6AVW CORROSION TEST PROCEDURE EK2 PRECONDITIONING (DURATION: FOUR DAYS)COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-10-FIGURE 6BVW CORROSION TEST PROCEDURE EK2 60 CYCLETEST(1 CYCLE 24 H) (CONTINUED)COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1950 Issued MAY89-11-Two control systems (test panels, paint scribe
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