FORD FLTM AB 106-1-2002 STRESS CORROSION CRACKING POTENTIAL OF COPPER ALLOYS.pdf

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1、 FORD LABORATORY TEST METHOD AB 106-01 Date Action Revisions 2002 06 12 Revised Rev Test Vessels, Samples & Test Procedure G. Weber 2002 03 15 Activated J. Lott Printed copies are uncontrolled Page 1 of 3 Copyright 2002, Ford Global Technologies, Inc. STRESS CORROSION CRACKING POTENTIAL OF COPPER AL

2、LOYS Application This test method describes the procedure used to evaluate the stress corrosion cracking (SCC) potential of components made of copper alloys, particularly copper-zinc alloys. It should be used as a method of comparing various copper alloys to determine if one material is more prone t

3、o SCC than another. Test results have not been correlated to real world conditions and cannot be used to predict actual time to crack formation in a vehicle. Apparatus Required Test Vessels Must be capable of being tightly sealed or closed and holding at least 10 liters of liquid. Examples are desic

4、cators or glass pans with ground edges and covers. NOTE: tightly sealed vessels will result in a more severe test but may discolor samples, making examination more difficult. Closed vessels, as opposed to sealed vessels, will result in a less severe test but cleaner samples. All tests should be run

5、in the same kind of test vessel for consistent results. Trays or Hanging Fixtures Used in the test vessels to keep samples out of the liquid. Must be made of materials that are not affected by ammonia vapors, e.g., glass or porcelain. Oven Large enough to hold test vessels and keep a steady temperat

6、ure of 30 C +/- 1 C. Safety Equipment Full face shield, gloves, tongs, hood (with a face velocity of at least 100 ft/min) Stereomicroscope or Binocular Microscope Capable of 6 - 46x magnification pH Meter Equipment capable of measuring and adjusting pH to within +/- 0.02 must be used. FORD LABORATOR

7、Y TEST METHOD AB 106-01 Page 2 of 3 Copyright 2002, Ford Global Technologies, Inc. Materials Required Ammonium Chloride (NH4Cl) 30 % Caustic Soda (made from NaOH and distilled or desalinated water) Distilled or Desalinated Water Samples Use actual components or sections of components made of the cop

8、per alloy(s) in question. Samples should be tested under normal stress conditions. The number of samples tested will depend on the size of the test vessels and does not influence test results. However, if possible a minimum of 10 samples should be used to compensate for test scatter. Degrease sample

9、s prior to testing. Handle samples so that additional degreasing can be avoided. Test Solution For 1 liter of solution: Dissolve 107 g of ammonium chloride (NH4Cl) in approximately 0.75 liters of distilled or completely desalinated water. Add a sufficient amount of 30 % caustic soda until a pH value

10、 of 10 is achieved at a temperature of 22 C. During final pH adjustment, temperature must be held constant to within +/- 1 C. The corresponding pH values for other temperatures are shown in Table 1. After the pH has been obtained, adjust the solution amount to equal 1 liter with distilled or desalin

11、ated water. At this point the pH will not change again. The pH value of the test solution should be checked every three weeks and corrected if necessary. Table 1 Temperature C pH Value 22 +/- 1 10.0 +/- 0.1 25 +/- 1 9.9 +/- 0.1 27 +/- 1 9.8 +/- 0.1 30 +/- 1 9.7 +/- 0.1 FORD LABORATORY TEST METHOD AB

12、 106-01 Page 3 of 3 Copyright 2002, Ford Global Technologies, Inc. Test Procedure Add ammonia solution to the test vessel so that a 20:1 to 10:1 ratio between the internal vessel volume and solution volume is maintained. For example, 0.5 - 1.0 liter of test solution should be used with a 10 liter te

13、st vessel. Testing is to be performed at 30 C +/- 1 C. Separately preheat the samples and bring the test vessel and solution up to this temperature. Place samples in test vessel, preferably hanging, so that the samples are exposed to vapor. Samples must not be submerged in solution and must be kept

14、from coming into contact with each other. Seal vessel and place in oven. At the examination times specified in Table 2, and wearing appropriate safety equipment, remove test vessel from oven. Place vessel under the hood, open vessel, and remove samples. Close vessel and return to oven. Immediately e

15、xamine the samples for the presence of cracks and record the results (see Evaluation, below). Immediately after examination, return samples to the test vessel and place vessel in oven until the next scheduled examination time. Table 2 Examination Time (Exposure Time to Vapor) 4 hours 8 hours 24 hour

16、s 32 hours 48 hours 56 hours 72 hours 96 hours 120 hours 144 hours 168 hours Evaluation All evaluations are to be made by the same person throughout the duration of the test. Record total exposure hours of samples to ammonia vapor at each examination. Do not count time that samples are out of the oven as exposure time. Use stereomicroscope or binocular microscope to examine parts. Record presence and location of cracks. Cracked parts should continue to be tested and examined for crack growth or formation of new cracks.