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 In recent years GMP has been replaced by.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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Website design by Peter Bourne Communications. Do not intermix different coupon thickness on the same coupon rack. But we haven’t supported older browsers like IE8. The test duration is dictated by the number of test cycles.
Please note The test standard summaries are for general guidance only. Contact Ascott for Further Information. The spray nozzle shall be such that the salt solution is atomized into a mist as required. Engineering drawings and material specifications that reference this test procedure must specify the 954p duration, A, B, C or D or the number of test cycles as indicated in Table 1.
If gravelometer exposure is required, test samples not coupons may be exposed to gravelometer testing per GMP before or during exposure. The test consists of alternating wet and dry cycles with precisely prepared salt solution. The number of coupons required for different test 9504p are shown in Table tm.
These procedure modifications are based on field knowledge combined with engineering judgment to enhance the test’s ability to predict field performance. Test acceleration can be optimized and tracked by using standard corrosion coupons as monitoring devices. The fm environment area shall be maintained with sufficient air circulation to prevent temperature stratification, and also allow thorough drying of the material.
See Table 4 for the steps that comprise the test method. In recent years GMP has been replaced by its successor; GMW, but this is all but identical in terms of the test conditions required. This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components.
The temperature and humidity conditions are shown in 9450p 3.
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This standard was written by a task group and approved by the Letter Ballot Committee in February Both are excellent browsers. Also, the reasons why the targeted value s was not obtained should be investigated and corrected before resuming the test.
A phase is made up of a predetermined number of cycles, 8 cycles constitute 1 phase. The mist application occurs while the samples and coupons are in the ambient environment. Typically no modifications of this shift. This procedure supersedes any old procedures that may have referenced an “A” or “B” Test Method Method A is eliminated. Prior to start of test, prepare the coupon rack with sufficient coupons to monitor the test 4.
Typically, 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. The coupons serve to monitor the average general bare steel corrosion produced by the test environment. Test samples shall be representative of production intent. Expected test duration to evaluate functional corrosion is 10 phases.
This study is a key reason why GMP became popular as an accelerated laboratory corrosion test for steel. The solution shall be sprayed as a mist for example, from a plastic bottle onto the test samples and coupons. Humidity ramp times between the ambient 99540p wet condition and between the wet and dry conditions are critical to test acceleration this is because corrosion rates are highest during this transition period.
The procedure is effective for evaluating a variety of corrosion mechanisms, such as general, galvanic, crevice, etc.
This method may involve hazardous materials, operations and equipment. Also, synergistic effects due to temperature, mechanical and electrical cycling can be 5940p by this test. If gj test is conducted with ramp times different than 95540p above, the number of cycles to reach coupon mass loss targets 954p increase or decrease. Refer to Table 2 for targeted mass loss values, in milligrams, for various test durations as a function of the coupon’s original thickness.
In addition to the sample data and test results, reports must indicate the total number of cycles run, any modifications to the test see Appendix Athe Equipment and Test Record Form Appendix Gk and should include photographic documentation and the coupon mass loss values. The test can be started at any time with the understanding that 24 h constitutes 1 cycle. Four 4 coupon thicknesses are available as shown in Table 2.
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. Method Test specimens in the enclosed chamber are exposed to 954p0 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.
GM P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion – Google Books
Though believed to be accurate at the time of writing, this may change over time. Test Conditions The test consists of alternating wet and dry cycles with precisely prepared salt solution. 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.
Repeat the cycle daily as necessary until the test duration requirements are met. This is considered an out of date browser. This method also includes measurement of corrosion creepback from a scribe line, and describes how to evaluate corrosion formation in unscribed areas.
Coupons consist of See Appendix A for typical modifications.
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. The humidity cabinet shall be as specified by GMP and Table 3. Hudson Sprayer, Hudson Mfg. This process can be aided by using a commercial grade degreaser prior to methanol or acetone clean. If the actual mass loss does not coincide with the targeted values listed in Table 2 the test should be repeated.