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: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1993 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001INFORMATIONREPORTSubmitted for recognition as an American National Stand
4、ardJ1617ISSUEDNOV93Issued 1993-11-02BODY CORROSIONA COMPREHENSIVE INTRODUCTIONForewordThis Document has not changed other than to put it into the new SAE Technical Standards Boardformat.1. ScopeThe mechanism of automotive body corrosion is scientific, based on established laws of chemistryand physic
5、s. Yet there are many opinions related to the cause of body corrosion, not always based onscientific axioms. The purpose of this SAE Information Report is to present a basic understanding of the typesof body corrosion, the factors that contribute to body corrosion, the testing procedures, evaluation
6、 of corrosionperformance, and glossary of related terms.1.1 PurposeThe purpose of this document is to provide a basic understanding of body corrosion as influencedby materials, environment, design, pretreatment and paint systems, and evaluation thereof. If the readerrequires in-depth information on
7、these subjects, additional reading material and personal contacts should bepursued with raw material, paint, chemical, and equipment suppliers.2. References2.1 Applicable PublicationsThe following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated
8、 the latest revision of SAE publications shall apply.2.1.1 SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE 892578U.S. Automotive Corrosion Trends at 5 and 6 Years2.1.2 OTHER PUBLICATIONS1. Annual statistical report 1990, American Iron and Steel Institute, Was
9、hington, DC (1991), p. 2527.2. H. E. Townsend, “Coated Steel Sheets for Corrosion-Resistant Automobiles,“ Materials Performance,October 1991, p 60.; National Association of Corrosion Engineers, Corrosion 91, Paper # 91416,NACE, Houston, TX.3. Y. Miyoshi, “State of the Art in Precoated Steel Sheet fo
10、r Automotive Body Materials in Japan,“ ISIJInternational, 31,1,1991, p1.4. D. Quantin, D. Deparis, and J. C. Charbonnier, “Coated Steel Sheets for the Automotive Industry,“Steel Technology International, 1990/1991, p245.5. K. Yamoto, T. Ichida, and T. Irie, “Progress in Precoated Steel Sheets for Au
11、tomotive Use,“ KawasakiSteel Technical Report, #22, May 1990, p57.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1617 Issued NOV93-2-6. “Cracking Down on Corrosion,“ American Iron and Steel Institute, Washington, 1991.7. “Data on Aluminum Alloy Propertie
12、s and Characteristics for Automotive Applications,“ The AluminumAssociation, Washington, D.C., 4th Edition, February 1982.8. “Registration Record of International Alloy Designations and Chemical Composition Limits for WroughtAluminum and Wrought Aluminum Alloys,“ The Aluminum Association, Washington
13、, D.C., April 1991.9. “Aluminum Standards and Data, 1990,“ The Aluminum Association, Washington, D.C.10. “Formability of ABS,“ Alcoa paper for SAE 93.11. Aluminum: Properties and Physical Metallurgy, John E. Hatch ed., American Society for Metals, MetalsPark, OH, 1984.12. T. Komatsubara, T. Muramats
14、u, M. Matsuo; “Aluminum Alloy Rolled Sheet and Production Therefore,“U.S. Patent No 4,838,958, June 13, 1989.13. Metals Handbook Volume 13, Corrosion, American Society for Metals, Metals Park, OH, 1987.3. Definitions3.1 AcidAcids can be defined in several ways. For many purposes it is sufficient to
15、say that an acid is ahydrogen containing substance which dissociates on solution in water to produce one or more hydrogen ions.The Bronsted concept states that an acid is any compound that can furnish a proton. The more general Lewisdefinition of an acid is anything that can attach itself to somethi
16、ng with an unshared pair of electrons.3.2 AcidicAnything having a pH that is less than 7 is considered acidic.3.3 AcrylicResin polymerized from acrylic acid, methacrylic acid, esters of these acids, or acrylonitrile.3.4 ActiveA state in which a metal tends to corrode (opposite of passive).3.5 Active
17、 PotentialThe potential of a corroding metal.3.6 AlkalineFor aqueous solutions, anything having a pH that is greater than 7 is considered alkaline.3.7 AlkydResin used in coatings. Reaction products of polyhydric alcohols and polybasic acids.3.8 AlligatoringPronounced wide cracking over the entire su
18、rface of a coating having the appearance ofalligator hide.3.9 Aluminum CoatedAluminum coated steel is produced by hot-dip coating cold-rolled sheet steel oncontinuous lines. It provides a material with the superior strength of steel and the surface properties ofaluminum.3.10 Aluminum-Zinc CoatedAlum
19、inum-zinc alloy coated steel is produced by hot-dip coating cold-rolled sheetsteel on continuous lines. It has the superior strength of steel and excellent corrosion resistance.3.11 AnionA negatively charged ion or radical (for example Cl- or SO4=) which migrates toward the anode underthe influence
20、of a potential gradient.3.12 Anode/AnodicAn electrode or portion of an electrode at which a net oxidation reaction occurs. This is theelectrode, or area, that has the greater tendency to dissolve or corrode.3.13 Anodic CoatingA coating that is anodic to the underlying substrate. Anodic coatings offe
21、r sacrificialprotection to the substrate.3.14 Anodic InhibitorA chemical substance or combination of substances that prevent or reduce the rate of theanodic or oxidation reaction by a physical, physico-chemical, or chemical action.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Informatio
22、n Handling ServicesSAE J1617 Issued NOV93-3-3.15 Anodic PotentialElectronegative potential.3.16 Anodic ProtectionA technique to reduce corrosion of a metal surface under some conditions by applyingsufficient anodic current to it to cause its electrode potential to enter and remain in the passive reg
23、ion.3.17 AnodizingOxide coating formed on a metal surface (generally, aluminum) by an electrolytic process.3.18 Barrier ProtectionA type of protection that relies on the coating preventing access of moisture or oxygen tothe material being protected. Organic coatings often offer barrier protection to
24、 underlying substrates.3.19 BaseBases can be defined in several ways. For many purposes it is sufficient to say that a base is asubstance which dissociates on solution in water to produce one or more hydroxyl ions. The Bronsted conceptstates that a base is any compound that can accept a proton. The
25、more general Lewis definition of a base isanything that has an unshared pair of electrons.3.20 Base MetalA metal that is usually high in the Electromotive Force Series. Base metals have relatively poorcorrosion resistance.3.21 BasicFor aqueous solutions, anything having a pH that is greater than 7 i
26、s considered basic.3.22 Bimetallic CorrosionCorrosion resulting from dissimilar metal contact; galvanic corrosion.3.23 Bituminous CoatingCoal tar or asphalt based coating.3.24 BlisterA region of lifted paint typically caused by loss of adhesion within the paint system or between thepaint and metal s
27、urface.3.25 Block Coat/BlockingTie coat (adhesive) between noncompatible paints.3.26 BlushingWhitening and loss of gloss of a coating due to moisture; blooming.3.27 CatalystA substance which alters the rate of a reaction by its presence and may be recovered unaltered innature or amount at the end of
28、 the reaction.3.28 CathodeThe electrode of an electrolytic cell at which reduction occurs. In corrosion processes, usually thearea at which metal ions do not enter the solution. Typical cathodic processes are cations taking upelectronsand being discharged, oxygen being reduced, and the reduction fro
29、m a higher to a lower valencestate.3.29 Cathodic CoatingA coating that is cathodic to the underlying substrate.3.30 Cathodic CorrosionAn unusual condition in which corrosion is accelerated at the cathode because thecathodic reaction creates an alkaline condition which is corrosive to certain metals
30、(esp. with Al, Zn, Pb).3.31 Cathodic DelaminationType of corrosion damage caused by loss of adhesion between the paint finish andthe metal.3.32 Cathodic InhibitorA chemical substance or combination of substances that prevent or reduce the rate ofcathodic or reduction reaction by a physical, physico-
31、chemical, or chemical action.3.33 Cathodic PotentialElectropositive potential.3.34 Cathodic ProtectionReduction or elimination of corrosion by making the metal a cathode by means ofimpressed direct current or attachment to a sacrificial anode (usually Mg, Al, or Zn).COPYRIGHT Society of Automotive E
32、ngineers, Inc.Licensed by Information Handling ServicesSAE J1617 Issued NOV93-4-3.35 CationA positively charged ion or radical (for example Fe+ or NH4+) which migrates toward the cathodeunder the influence of a potential gradient.3.36 Cavitation CorrosionCavitation Corrosion occurs on the low pressu
33、re side of propellers and pumpimpellers where interruption in smooth flow causes vapor bubbles to form. When these bubbles collapse, theycan destroy any protective coating and remove minute particles of metal.3.37 CellElectrochemical system consisting of an anode and a cathode immersed in an electro
34、lyte. The anodeand cathode may be separate metals or dissimilar areas on the same metal. When the electrodes are inelectrical contact with each other, they develop a difference in potential which causes current to flow andproduces corrosion at the anode. A cell involving an electrolyte in the corros
35、ion process is referred to as anelectrolytic cell.3.38 ChalkingThe development of loose removable powder at or just beneath a coating surface.3.39 CheckingSurface cracking in a checkerboard-like pattern; this may be in a surface layer (coating) or on themetal surface itself.3.40 Chemical Conversion
36、CoatingA protective or decorative coating produced in situ by chemical reaction of ametal with a chosen environment.3.41 ChromatedParts treated with chromic acid to improve their corrosion resistance.3.42 Clear CoatA paint without pigment applied over a color basecoat to enhance the appearance and d
37、urabilityof the total paint system.3.43 Concentration CellA cell involving an electrolyte and two identical electrodes, with the potential resultingfrom differences in the chemistry of the environments adjacent to the two electrodes.3.44 ConductivityThe ability of a material to transfer heat or elec
38、tricity. Copper is a good conductor of electricity.3.45 Contact CorrosionA term mostly used in Europe to describe galvanic corrosion between dissimilar metals.3.46 Conversion CoatingAn adherent reaction product layer on a metal surface formed by reaction with asuitable chemical; such as an iron phos
39、phate film on iron developed by H3PO4.3.47 CorrosionThe deterioration of a material, usually a metal, because of a reaction with its environment.3.48 Corrosion FatigueEffect of the application of repeated or fluctuating stresses in a corrosive environmentcharacterized by shorter life than would be e
40、ncountered as a result of either the repeated or fluctuatingstresses alone or the corrosive environment alone.3.49 Corrosion PotentialThe potential that a corroding metal exhibits under specific conditions of concentration,time, temperature, aeration, velocity, etc. Also called: rest potential, open
41、 circuit potential, freely corrodingpotential.3.50 Corrosion RateThe speed (usually an average) with which corrosion progresses (it may be linear forawhile); often expressed as though it was linear, in units of mdd (milligrams per square decimeter per day) forweight change, or mpy (mils per year) fo
42、r thickness changes. Corrosion rates may be reported as: (a) A weightloss per area divided by the time (a milligram is 1/1000th of a gram) (there are 453.6 g/lb); and a decimeter is3.937 in, or (b) The depth of metal corroded, divided by the time (a “mil“ is 1/1000th of an inch).3.51 Cosmetic Corros
43、ionCorrosion typically characterized by blistering and/or rusting that is aestheticallydispleasing, but may not result in catastrophic failure of the item.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1617 Issued NOV93-5-3.52 CoupleA cell developed in a
44、n electrolyte resulting from electrical contact between two dissimilar metals.3.53 CrackingFracture of a metal in a brittle manner along a single or branched path.3.54 CrazingA network of checks or cracks appearing on a surface.3.55 CreepbackThe undercutting or the separation of paint from the subst
45、rate from an edge, damage site, or ascribe line.3.56 Creep/CreepbackTime-dependent strain occurring under stress.3.57 Crevice CorrosionLocalized corrosion resulting from the formation of a concentration cell in a creviceformed between a metal and a nonmetal, or between two metal surfaces.3.58 Critic
46、al HumidityThe relative humidity above which the atmospheric corrosion rate of a given metalincreases sharply.3.59 CurrentThe “flow“ of electricity expressed in amperes, milliamperes, and microamperes.3.60 Current DensityThe current per unit area; generally expressed as amps per sq cm.3.61 Cyclic Te
47、stingAccelerated testing and simulation of service conditions by the use of controlled alternatingexposures to at least two corrosive environments, such as, salt or other chemical exposure, water immersion,temperature variations, humidity variations, ultraviolet (UV) light exposure, mud or clay cont
48、amination, gravel orshot blasting, and driving.3.62 Deicing SaltSalts, typically NaCl and/or CaCl2, applied to highways to aid in seasonal deicing.3.63 Deionized WaterWater that has had the charged species (Cl-, Ca2+, etc.) removed from it.3.64 DepositA foreign substance, which comes from the enviro
49、nment, adhering to a surface of a material.3.65 Deposit AttackCorrosion occurring under or around a discontinuous deposit on a metallic surface.3.66 Dew PointTemperature at which condensation of water vapor from air occurs.3.67 Differentially Zinc CoatedA sheet (usually steel) with a zinc coating of a different thickness on one sidethan on the other side.3.68 DiffusionThe movement of one substance through another. Diffusion of contaminants into a paint system isoften the cause of corrosion attack.3.69 Direct Curren
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