GM 9540P PDF
This study is a key reason why GMP became popular as an accelerated laboratory corrosion test for steel. In recent years GMP has been replaced by. of the reference specimens in the as-received condition are in Figure 3. The salt fog test used an abbreviated procedure (Table 3) of the standard GMP test. Find the most up-to-date version of GMP at Engineering
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Test durations A and B can be used for quality control and validation procedures as appropriate.
GM P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion – Google Books
To check test progress and gn that the test is being run correctly, assume a linear corrosion rate. Expected test duration to evaluate functional corrosion is 10 phases. This method does not propose to address all the safety problems associated with its use. 9540o, the time from ambient to the wet condition should be approximately 1 h and the transition time between wet and dry conditions should be approximately 3 h.
Though believed to be accurate at the time of writing, this may change over time. In this context they can be considered to be equivalent and interchangeable terms. Use Option IV – for door detents without weatherseal protection Use Option VI – for door detents with weatherseal protection 1 test cycle is equal to 24 h, 1 phase is equal to 8 cycles. Ramp time is to be included as part of the specified exposure period. Both are excellent browsers. See Table 4 for the steps that comprise the test method.
Test Conditions The test consists of alternating wet and dry 950p with 95440p prepared salt solution. If a recorder is not in use, 9540 documentation should be provided indicating typical steady state conditions and the ramp times between steady states conditions.
The latest revisions include: Typically no modifications of this shift. The salt mist solution shall be as specified in Table 3. Any option changes not called out specifically in this Appendix 99540p be included on the engineering drawing. Typical test duration is 4 cycles for under dash mid to high mount locations and 12 cycles for floorpan low mount locations which approximately equals 10 yearscosmetic corrosion exposure. See Appendix A for typical modifications.
One 1 test cycle is equal to 24 h, 1 phase is equal to 8 cycles. The test sample s shall be inspected for corrosion and photographed at the end of predetermined cycles. The weight, in milligrams mgshall be recorded and retained for future reference.
The coupons serve to monitor the average general bare steel corrosion produced by the test environment. If all solid materials are added dryan insoluble precipitate may result 3. Originally developed by General Motors the standard has gained popularity for corrosion tests within the automotive industry and has also become the preferred corrosion test of the US Navy.
The spray nozzle shall be such that the salt solution is atomized into a mist as required.
Test equipment used shall be documented and include the following information: This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components. Method Test specimens in the enclosed chamber are exposed to a changing climate that generally comprises of the following 3 part repeating cycle variations to this cycle are permitted depending on the type of component under test — refer to the full test standard for further guidance.
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The test duration can be individually tailored to achieve any desired level of corrosion exposure. This process can be aided by using a commercial grade degreaser prior to methanol or acetone clean. At the end of test the samples shall be rinsed with fresh tap water and allowed to dry before evaluating. Test samples shall be representative of production intent. The mist application occurs while the samples and coupons are in the ambient environment.
Garden dusters with an 8 mm diameter hole for dust application are recommended to achieve the appropriate level of dust application. Corrosion coupons shall be removed and analyzed after each phase throughout the test to monitor the corrosion. Also, synergistic effects due 5940p temperature, mechanical and electrical cycling can be comprehended by this test. Prior to start of test, prepare the coupon rack with sufficient coupons to monitor the test 4.
If a test is 99540p with ramp times different than described above, the number of cycles to reach coupon mass loss targets may increase or decrease. If the actual mass loss does not coincide with the targeted values listed in Table 2 the test should be repeated.
GMP | Standards | Ascott Analytical
The humidity cabinet shall be as specified by GMP and Table 3. These procedure modifications are based on field knowledge combined with engineering judgment to enhance the test’s ability to predict field performance. Water fog or visible water droplets on parts – continuous after equilibrium is reached.
Wipe the coupons free of grit and weigh to determine the coupon mass loss using the formula: Engineering drawings and material specifications that reference this test procedure must specify the test duration, A, B, C or D or the number of test cycles as indicated in Table 1. Contact Ascott for Further Information. This is considered an out of date browser. To analyze coupons remove 1 coupon from each end of the rack and prepare mg weighing and mass loss determination.
The number of cycle repeats and therefore the test duration is variable.