SAE J2334 PDF

SAE J testing is offered by Micom as part of its corrosion testing services. This standard describes a cyclic corrosion test which assesses the corrosive performance of a coating system, process, substrate or design. SAE J is a method which specifies the test conditions that are required to perform a cyclic corrosion test that replicates, on an accelerated basis, an outdoor exposure. Actually, this protocol relies on three periodic segments: the humid, the spray application and the dry stages. The wet and the dry part of the cycle are there to mimic the natural cyclic conditions while the role of the spray application is to introduce the corrosive solution that is composed of 0. The goal of this standard is to foresee the corrosive performance of the sample in his conditions of use.

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SAE J Users are responsible for verifying references and continued suitability of technical requirements. Newer technology may exist. SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.

Results from this test will provide excellent correlation to severe corrosive field environments with respect to cosmetic corrosion performance. For historical information on the development of this test, refer to 2. A typical automotive paint system was used to develop this test. See 2. If a different type of coating system is used, field correlation must be determined. Scope—The SAE J lab test procedure should be used when determining corrosion performance for a particular coating system, substrate, process, or design.

Since it is a field-correlated test, it can be used as a validation tool as well as a development tool. If corrosion mechanisms other than cosmetic or general corrosion are to be examined using this test, field correlation must be established.

References Applicable Publications—The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest version of SAE publications shall apply. Townsend, H. Roudabush, L. Stephens, M. Lutze, F. Petschel, M. Davidson, D. Ostermiller, M. Granata, R. Townsend, D. Davidson, and M. Lutze, D. McCune, and K. McCune, H. Townsend, K. Smith, R. Shaffer, L. Thompson, and H.

McCune, J. Schaffer, K. Smith, L. See Reference Typically, this type of corrosion does not impact function but does compromise appearance. General Corrosion—Corrosion of a component that is typically bare no organic coating. Scribe Creepback—Coating creepback resulting from corrosion and undercutting from the scribe line. A scribe is a controlled simulated damage site designed to represent a scratch or chip.

Corrosion Coupons—Samples of bare metals, that are used to monitor and compare the corrosivity of laboratory corrosion tests in terms of mass-loss.

Test Controls—Components i. They can be used to control the test conduct and compare the test results also assist in evaluating reproducibility and repeatability.

Water fog method according to ASTM D , except that the collection rate is reduced from a range of 1. The use of this method requires that the collection rates be documented.

Steam vapor generator method. This method was used as the basis when comparing other methods of humidity generation as well as other variables. Air circulation must be sufficient to prevent temperature stratification and allow drying of test parts during the dry-off portion of the test cycle. Air circulation can be obtained through the use of a fan or forced air. Immersion Method—Test specimens are to be immersed in the salt solution for a minute interval of each test cycle.

Spray Method—A periodic or continuous direct impingement spray of the salt solution over the minute interval that ensures the test specimens are kept wet for the entire minute interval. Avoid a high intensity pressure spray that may affect test results. Note 5 Both direct solution displacement and atomized spray are suitable for this method. If a precipitate forms and a spray application is used to apply the solution, it may be necessary to remove the precipitate to avoid clogging of nozzles i.

Any filter media used must be inert to the solution being used. A 20 to micron cotton or nylon mesh filter would be suitable. Do not attempt to dissolve the precipitate by adding acid. Do not attempt to adjust the pH with any form of buffers. NOTE 3—The majority of the development of this specification was performed using the immersion method of salt solution application. This method was used as the basis when comparing other methods of salt solution applications as well as other variables.

NOTE 5—Careful attention should be paid to the spray method to avoid a high intensity spray that may affect test results by removal of the corrosion product, removal of the coating or driving solution into the corrosion products. It consists of three basic stages: 1. Salt Application Stage—15 min duration conducted at ambient conditions 3.

Fully automatic cabinets have the option of running during the weekends or programming in a dry stage soak for the weekends typically it would be desired to run on weekends and holidays to complete the test sooner.

An exception to this rule would be if comparisons to other laboratories who do not have fully automatic capabilities is desired for manual operations, the weekend exposure is typically maintained at dry stage conditions unless 7 day operations are available. Total test duration and weekend conditions must be documented in the test results.

Ramp time between the salt application stage 2 and dry stage 3 are part of the dry stage time. Similarly, ramp time between the dry stage 3 and humid stage 1 are part of the humid stage. Ramp times should be documented for each test set-up. For cosmetic corrosion evaluations of coatings susceptible to damage, test samples will be scribed prior to exposure Reference ASTM D Scribe length should be a minimum of 50 mm.

Scribe creepback measurements are to be taken at predetermined intervals depending on the level of corrosion resistance desired. Scribe orientation, on the specimen, must be specified and documented for typical flat panel specimens, it is recommended that panels be oriented 15 degrees from the vertical such that no one panel shadows another and that the scribe line be made in a diagonal across the panel face.

Longer durations may be required to observe performance differences in the heavier weight metallic precoats. Different test durations may be appropriate based on other materials, corrosion mechanisms of interest, or past history. Corrosion coupons generally consist of The sheet metal coupon will always include low-carbon cold rolled steel sheet SAE to SAE , and may also include other bare metals, such as zinc.

Each coupon shall be permanently identified by stamping a number onto the surface. Then the mass in milligrams shall be recorded and retained for future reference.

The coupons shall be secured to an aluminum or nonmetallic coupon rack. The coupons shall be electrically isolated from the rack by using fasteners and washers made from a non-black plastic material, preferably nylon. Allow a minimum 5 mm spacing between the coupons and the rack surface. All coupons shall be secured at a maximum 15 degrees from vertical and must not contact each other.

The coupon rack shall be placed in the general vicinity of the samples being tested, such that the coupons receive the same environmental exposure. Coupons shall be removed and analyzed after a predetermined number of cycles throughout the test to monitor corrosion. To analyze coupons, remove 1 coupon from each end of the rack and prepare for weighing and mass loss determination. Insure enough coupons are exposed in the test so monitoring frequency can be accomplished.

Additional unexposed coupons can be added throughout the test to obtain interval data in addition to cumulative data. Once clean, wipe the coupons with methanol and weigh to determine the coupon mass loss using Equation 1: Eq.

This will be a cumulative value. Additional unexposed coupons can be installed and removed after the next set of cycles to obtain interval coupon data if desired. Test Samples—The test samples will have scribe creepback values or corrosion rate measurements recorded at predetermined intervals typically, 20 cycles — in a rinsed only condition. At end-of-test two sets of creepback values will be recorded if coated samples are to be evaluated one set in a rinsed only condition and one set after the scrape and tape process Reference SAE Automotive Corrosion and Prevention Conference P, pages , see 2.

As a guideline, scribe creepback measurements of average, maximum, and minimum total width will be recorded. Total Width Creepback—A measurement of the distance between the unaffected paint film areas, in millimeters, on each side of the scribed line measured across and perpendicular to the scribe line.

Loss of adhesion between paint film and substrate. Average—The mean of a set of measurements of Total Width Creepback, at points spaced equidistant apart centered on the scribed line.

Maximum—A measurement of the Total Width Creepback at the point with the most extensive adhesion loss, discounting the areas at the ends of the scribed line.

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SAE J Users are responsible for verifying references and continued suitability of technical requirements. Newer technology may exist. SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.

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There are several problems with ASTM B salt spray test when trying to rank the corrosion performance of automotive parts. Several studies have come to the conclusion that ASTM B does not provide a good test for coated aluminum alloys, or fails to predict the composition effects of aluminum-zinc alloy coatings on cold-rolled steel, or any other coatings for this matter. The reason that the ASTM B test methods do not accurately reproduce corrosion performance for auto parts is that they do not accurately reproduce the conditions in which automotive parts must exist. For one thing, parts tested in a salt-spray cabinet are continuously wet, while those parts on a vehicle experience periods of wetness and dryness. Another difference between the conditions in a salt spray test and real-world conditions is the salt concentration. Other differences include the temperature changes that occur in the real world and the fact that real-world conditions include salts other than NaCl.

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