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 1990 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National Sta
4、ndardJ1293REV.JAN90Issued 1980-01Revised 1990-01Superseding J1293 JAN80(R) UNDERVEHICLE COUPON CORROSION TESTSForewordSAE J1293 was prepared as a recommended practice for evaluating the corrosion resistance of steel inan undervehicle deicing salt environment. This procedure recommended locating samp
5、les on the rear controlarms of passenger vehicles. Due to the increasing use of unitized body designs, alternative sample mountinglocations are needed. This revised procedure recommends the use of undervehicle corrosion coupon racksattached to the chassis frame of a straight truck or box truck (with
6、out a detachable trailer), which also enables alarger number of samples to be evaluated. This revision is based on techniques reported by Neville and de Souza(see ASM 8512-004).1. ScopeThis document is a road test procedure for comparing the corrosion resistance of both coated anduncoated sheet stee
7、ls in an undervehicle deicing salt environment.2. References2.1 Applicable PublicationsThe following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated the lastest revision of SAE publications shall apply.2.1.1 ASMPUBLICATIONAvailable from ATTN: M
8、SC/Book Order, ASM International, PO Box 473, Novelty, OH44072-9901.R. J. Neville and K. M. de Souza, Undervehicle Corrosion Testing of Zinc and Zinc Alloy Coated Steels.American Society for Metals, Technical Paper Series No. 8512-004 (1985).2.1.2 SAEPUBLICATIONAvailable from SAE, 400 Commonwealth D
9、rive, Warrendale, PA 15096-0001.R. J. Neville, Results of a Test for Undervehicle Corrosion Resistance (SAE Task Force, Iron and SteelTechnical Committee, Division 32), SAE Paper 800144 (February 1980).2.1.3 ASTMPUBLICATIONSAvailable from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959
10、.ANSI/ASTM E 643-78Method of Conducting a Ball Punch Deformation Test for Metallic Sheet MaterialASTM D 1654-74Evaluation of Painted or Coated Specimens Subjected to Corrosive EnvironmentsANSI/ASTMG1-81Standard Practice for Preparing, Cleaning and Evaluating Corrosion Test SpecimensANSI/ASTM A 90-69
11、Tests for Weight of Coating on Zinc-Coated (Galvanized) Iron or Steel ArticlesCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-2-3. BackgroundA single result from one test material exposed on a given rack should not be compared to asingl
12、e result from a test material exposed on another rack. A suggestion for an evaluation would be to use aminimum of two vehicles with random placement of the panels on each test rack and then averaging theresults. However, the ranking of test materials from rack-to-rack should be similar.The key featu
13、res of this test are:a. Measurement of steel substrate corrosion rather than coating failure.b. Both exposed and crevice test conditions.c. Realistic comparison of precoated and postapplied coated material.The reliability and reproducibility of the test are demonstrated in ASM 8512-004 and SAEPaper
14、800144.4. MethodThe test method described herein should be followed carefully and any deviations reported, as theymay influence the results.4.1 Test Materials4.1.1 New coatings should be evaluated using a standard coated steel for which sufficient data have beenpreviously generated (i.e., hot dip ga
15、lvanized steel). Low carbon mild steel (uncoated) may be included toindicate the severity of the test environment.4.2 Test Coupon Preparation4.2.1 Sample thickness is optional but should be similar in a given test where galvanic edge protection is aconsideration. Steel coupons, 50 x 125 mm (2 x 5 in
16、), can be sheared directly from prefinished sheet.Postapplied coatings are applied after test coupon assembly (See 4.3).4.2.2 Prepare each test coupon as shown in Figure 1.FIGURE 1TEST COUPON DESIGNCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revi
17、sed JAN90-3-4.2.3 Identify coupons as shown in Figure 1 by XX.4.2.4 (Optional) If sample thickness and mechanical properties are appropriate, a ball punch deformation test (seeReference 3) may be drawn so that the coupons nest properly as follows: ball diameter, 22.2 mm (7/8 in);upper die diameter,
18、25.4 mm (1.0 in); and depth, 6.35 mm (0.250 in). The cup provides an indication ofleading surface abrasion and formability.4.2.5 (Optional) In the case of postapplied coatings, an X may be scribed between the cup and mounting holes onexposed surfaces only and should penetrate to the substrate metal
19、(see ASTMD1654-74). The X-scribecan provide a measure of the undercutting resistance of the coatings after test exposure.4.2.6 (Optional) Bare steel coupon weights of precoated materials can be estimated by nondestructivelymeasuring coating thickness and subtracting the weight calculated from this t
20、hickness (knowing coatingdensity) from the total coupon weight.Alternatively, a more accurate procedure is to evaluate the coating weight using a weigh-strip-weightechnique of an adjacent (scrap) piece of the precoated steel. This requires weighing of the sample,chemically removing the coating (See
21、5.4.4 and 5.5.3) and reweighing. The weight of the coating is thensubtracted from the total (sample) coupon weight.The base steel coupon weights of precoated materials should be recorded in milligrams.4.2.7 (Optional) Weigh metallic coated coupons and record total coupon weight in milligrams. These
22、data arerequired for coating weight loss determination when the steel substrate is not attacked during the exposureinterval.4.3 Test Coupon Assembly4.3.1 Assemble the test coupons as shown in Figure 2 (one-sided coated steels) and Figure 3 (two-sided coatedsteels). To ensure that the perforation of
23、the one-sided coated steels does not progress from the uncoatedsurface, the uncoated surface should be protected with an air-dry spray lacquer and electroplaters tape.4.3.2 Use 10 mm I.D. x 15 mm O.D. x 0.25 mm thick polyethylene shims. For postapplied coatings, select atemperature resistance materi
24、al, such as mica, to withstand the high temperature bake.4.3.3 The 6.35 mm (1/4 in) I.D. Neoprene rubber grommets, selected to withstand paint bake temperatures, can beobtained from an electrical supply house. A typical assembly for the rubber grommet is given in Figure 4.The rubber grommets are nec
25、essary to isolate the test samples from the metal bolts.4.3.4 Apply postapplied coatings to the coupon assembly after assembling the coupons as shown in Figures 2 or3. It will be necessary to have longer bolts (secured by a nut) at one end of the assembly to hold theassembly together during postcoat
26、ing. Another nut and washer would be necessary to secure the assemblyto the support rack (Figures 2 and 3).4.4 Test Rack Assembly4.4.1 A typical test rack assembly is shown in Figure 5. This figure displays recommended sample spacing.Coupon assemblies can be cantilevered off of both sides of the sup
27、port bar to increase the number ofavailable test sites.4.5 Test Rack Mounting4.5.1 Select a vehicle with expected high driving frequency.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-4-FIGURE 2ONE-SIDED COATED STEELS COUPON ASSEMBLYCO
28、PYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-5-FIGURE 3TWO-SIDED COATED STEELS COUPON ASSEMBLYFIGURE 4TYPICAL RUBBER GROMMET ASSEMBLYCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revi
29、sed JAN90-6-FIGURE 5TYPICAL TEST RACK ASSEMBLY WITH TWO SAMPLES - TOP VIEW4.5.2 Mount the test rack on the straight truck chassis frame as shown in Figures 6a and 6b. The test racks shouldbe located such that the coupons are horizontal, and are unlikely to receive mechanical damage. Avoiddirect impi
30、ngement of exhaust gases on the test coupons.FIGURE 6ASTRAIGHT TRUCK SHOWING UNDER VEHICLE TEST RACK LOCATIONCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-7-FIGURE 6BTEST RACK WITH EXPOSED COUPON ASSEMBLIES4.5.3 Record mounting date a
31、nd odometer reading.4.6 Exposure4.6.1 The test program should be initiated at the start of the winter season in the snow belt region. Ideally, the testis initiated in September or October.4.6.2 Test duration is optional but should be sufficient to allow ranking of material performance. For the newer
32、cathodic electrodeposited primers, the minimum exposure recommended is three winters.4.6.3 Test results should include a notation of the geographical area where the mileage was accumulated, e.g., cityand state or province.5. Evaluation5.1 General Inspection Before Disassembly5.1.1 Record removal dat
33、e, calculate total exposure time on vehicle in days, and total distance traveled.5.1.2 Inspect for mechanical damage or other unusual occurrences, such as foreign matter, and report.5.1.3 Report rack and sample position relative to the geometry of the truck.5.1.4 The evaluations that follow apply to
34、 each of the four surfaces of each coupon assembly (Figures 7 and 8).FIGURE 7SURFACE IDENTIFICATION FOR TWO-SIDED COATINGCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-8-FIGURE 8ALTERNATE TEST SETUP AND SURFACE IDENTIFICATIONFOR ONE-SI
35、DED (DISSIMILAR) COATING5.2 Initial CleaningWash each panel with warm water using a nonmetallic brush, sponge, or cheesecloth, andwipe or blow dry.5.3 Carbon Steel Evaluation5.3.1 Examine for edge abrasion and note if present. Estimate percent red rust, ignoring the bolted area, anddescribe tightnes
36、s and color of scale.5.3.2 Immerse in Clarkes solution (see ANSI/ASTM G 1-81) until all corrosion products are removed. Wipe orblow dry. Record time required for use in 5.3.6.5.3.3 (Optional) Reweigh and record weight loss in milligrams and calculate thickness loss in micrometers using anominal area
37、 of 50 x 125 mm (see ANSI/ASTM G 1-81).5.3.4 Estimate visually or by the use of a low power microscope the percent area of base metal attack as indicatedby surface roughening or pitting. Treat the cup the same as the flat surface for a single evaluation on allsamples.5.3.5 Note the occurrence of per
38、foration. If perforated, no further measurements are required. If not perforated,examine for pitting using a microscope at 10X and measure the 10 deepest pits at 200X by focusing at thetop and bottom of the pits. Ignore the cup. Report the average depth and range of the 10 deepest pits inmicrometers
39、.If an insufficient number of pits is present (i.e., less than 10), report the average depth and range of the pitspresent and note with an asterisk the number of pits involved.5.3.6 (Optional) Reclean sample in Clarkes solution for same length of time as recorded in 5.3.2 for blank weightloss correc
40、tion.5.4 Metallic Coated Steel Evaluation5.4.1 Evaluate qualitatively as for carbon steel in 5.3.1.5.4.2 Immerse in appropriate cleaning solution (see ANSI/ASTM G 1-81) until clean, then wipe or blow-dry. Forexample, clean galvanized coupons in 15% ammonium hydroxide at room temperature followed by
41、a dip inboiling 5% chromic acid containing silver nitrate until clean.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-9-5.4.3 Weigh and report metallic coating weight loss in milligrams and calculate thickness loss in micrometers usinga
42、 nominal area 50 x 125 mm (see ANSI/ASTM G 1-81). Omit this step if a significant amount of red rust ispresent.5.4.4 Strip all remaining metal coating. Galvanized coatings can be stripped according to Reference 5. Cleancarbon steel substrate if necessary as in 5.3.2.5.4.5 Determine percent area of b
43、ase metal attack and extent of pitting of steel substrate as in 5.3.4 and 5.3.5.5.5 Organic Coated Steel Evaluation5.5.1 Evaluate qualitatively as for carbon steel in 5.3.1.5.5.2 If the coating was scribed, measure total width of creep back from the scribe and record half of the maximumwidth in mill
44、imeters. Note, (but do not include in scribe creep back measurements), the presence of filiformcorrosion.5.5.3 Remove organic coating using an appropriate solvent or stripping solution. Cathodic electrodeposited prim-ers can be removed using a 1:1 mixture of tetrahydrofurane and dimethylformamide at
45、 60C (appropriatesafety precautions are required when handling these two strong solvents). All stripping is enhanced by usinga soft bristle brush.5.5.4 Chemically clean as for carbon steel in 5.3.2.5.5.5 Estimate visually or by the use of a low power microscope the percent base metal attack as indic
46、ated byroughening or pitting.5.5.6 Examine for pitting as in 5.3.5.5.6 Evaluation of Steel Coated With Both Organic and Metallic Coatings:5.6.1 To remove the organic coating, use procedure found in 5.5.3.5.6.2 To remove the metallic coating, use procedure found in 5.4.4.5.6.3 To evaluate base metal
47、attack and pitting, use procedure found in 5.3.2 through 5.3.6.5.7 Reporting:5.7.1 Report each surface of the test materials separately according to percent base metal attack. Report basedon measurements obtained from 5.3.4, 5.4.5, 5.5.5, and 5.6.3 and include base metal attack resulting fromcreep b
48、ack.5.7.2 Report each surface of the test materials separately according to average pit depth and show range of pitdepths.5.7.3 (Optional) Report each material based on thickness loss as calculated from weight loss if available.5.7.4 (Optional) Report the results in 5.7.1, 5.7.2, and 5.7.3 to indica
49、te relative material performance.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1293 Revised JAN90-10-6. Notes6.1 Marginal IndiciaThe change bar (l) located in the left margin is for the convenience of the user in locatingareas where technical revisions have been made to the previous issue of the report. An (R) symbol to the leftof the document title indicates a complete revision of the report.PREPARED BY THE SAE ACAP DIVISION 3COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1
