1、 WORLDWIDE ENGINEERING STANDARDS General Specification GMW16600 Susceptibility to Chloride Stress Corrosion Cracking Copyright 2011 General Motors Company All Rights Reserved June 2011 Originating Department: North American Engineering Standards Page 1 of 4 1 Introduction Note: Nothing in this stand
2、ard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Scope. This standard is an aggressive characterization of the susceptibility of a plastic component to Stress Corrosion Cracking.
3、It accomplishes this by exposing it to different artificial environments with the presence of chlorides. It requires that an appropriate stress level be imparted on the component. The tests are not a direct comparison to field exposure and can only indicate whether the component is susceptible to at
4、tack at the stress level that was induced on it. The two chlorides identified in this standard are calcium chloride and zinc chloride. Calcium Chloride is a common chemical used in de-icing solutions and gravel road dust control. Zinc Chloride only occurs from a reaction of zinc and other chlorides
5、(e.g., sodium or calcium). It is not recommended to directly fasten any plastic component which is susceptible to chloride stress corrosion cracking directly to a zinc surface. 1.2 Mission/Theme. Testing is recommended for certain polymers (as defined in Table 1) exposed to the underbody and lower u
6、nderhood atmosphere in critical applications. If the polymer is not identified within the table, GM Materials Engineering shall be consulted to determine the appropriate disposition. Table 1: Material List Testing Recommended Testing Not Recommended Polyamide (including but not limited to PA46, PA6,
7、 PA66, PA12, PA612) Polyphthalamide (PPA) Polyketone (PK) Acetal (POM) Polyethylene (PE) Polyester (PBT or PET) Polypropylene (PP) Polyphenylene Sulfide (PPS) The chloride tests are intended to be a quick determination of the susceptibility of the plastic component to Stress Corrosion Cracking. A po
8、sitive result should be a strong indication that the component is not adequately stress crack resistant. 1.3 Classification. Not applicable. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. None 2.2 GM Standards/S
9、pecifications. None 2.3 Additional References. None. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16600 Copyright 2011 General Motors
10、Company All Rights Reserved June 2011 Page 2 of 4 3 Test Preparation and Evaluation 3.1 Resources. 3.1.1 Calibration. The test facilities and equipment shall be in good working order and shall have a valid calibration label. 3.1.2 Alternatives. Alternative test facilities and equipment may also be u
11、sed. However, all measuring variables as specified in this standard shall be determined correctly with respect to their physical definition. 3.1.3 Facilities. Not applicable. 3.1.4 Equipment. Not applicable. 3.1.4.1 Container. Recommended material for the container is High Density Polyethylene or Au
12、stenitic Stainless Steel. 3.1.4.2 Deflection Fixture. Recommended deflection fixture should be made out of Austenitic Stainless Steel. 3.1.5 Test Vehicle/Test Piece. Test pieces shall be the production intent plastic components. Prototype components can be substituted if determined to be sufficientl
13、y similar to production. In the case where the component would contain fluid, the area that would contain fluid shall be sealed off preferably with the production intent connectors. Any electrical ports shall also be sealed with the appropriate production intent connector. Exposed metal components o
14、f an assembly could have an adverse effect on the solution and/or the remaining structure and should not be included in the test of the plastic component if possible. 3.1.6 Test Time. Calendar time: 17 days Test hours: Up to 400 hours Coordination hours: 4 hours 3.1.7 Test Required Information. Not
15、applicable. 3.1.8 Personnel/Skills. Not applicable. 3.2 Preparation. 3.2.1 Calcium Chloride Test Fluid. Mix a 50% aqueous solution (by weight) of calcium chloride in water. 3.2.2 Zinc Chloride Test Fluid. Mix a 50% aqueous solution (by weight) of zinc chloride in water. 3.3 Conditions. 3.3.1 Environ
16、mental Conditions. Not applicable. 3.3.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. 3.4 Instructions. Not applicable. 3.5 Data. Not applicable. 3.6 Safety
17、. This standard may involve hazardous materials, operations, and equipment. This standard does not propose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicab
18、ility of regulatory limitations prior to use. 3.7 Documentation. Samples of components or material released to this standard shall be tested for conformity with the requirements of this standard and approved by the responsible GM department prior to the start of delivery of production level componen
19、ts or materials. Any change to the component or material, e.g., design, function, properties, manufacturing process and/or location of manufacture requires a new release of the product. It is the sole responsibility of the supplier to provide the customer, unsolicited, with documentation of any chan
20、ge or modification to the product/process, and to apply for a new release. If not otherwise agreed to, the entire verification test shall be repeated and documented by the supplier prior to start of delivery of the modified or changed product. In some cases, a shorter test can be agreed to between t
21、he responsible GM department and the supplier. 3.7.1 Test Results. Not applicable. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16600
22、Copyright 2011 General Motors Company All Rights Reserved June 2011 Page 3 of 4 4 Requirements and Procedure 4.1 Calcium Chloride Exposure. 4.1.1 Apply a simulated deflection, representative of the parts usage in the assembly, to the part. 4.1.2 Immerse the external surfaces of the part in the calci
23、um chloride solution for 200 h at 60 2 C. 4.1.3 Remove samples from the solution and let dry for 200 h at 23 2 C. 4.1.4 The sample may be rinsed with fresh water to clear salt residue at this time. There shall be no cracking, crazing, or other damage to the plastic used in the housing and the cover.
24、 4.1.5 Review the surface of the component in the high stress area under 10X magnification. There shall be no evidence of cracking, crazing or other damage. 4.1.6 Apply load to failure. Apply graduated load until failure in the exact same direction as the simulated deflection. Document load to failu
25、re. Note: This section shall be run only if documented within requirements or agreed upon prior to testing. 4.2 Zinc Chloride Exposure. 4.2.1 Apply a simulated deflection, representative of the parts usage in the assembly, to the part. 4.2.2 Immerse the external surfaces of the part in the zinc chlo
26、ride solution for 200 h at 23 2 C. 4.2.3 Remove samples from the solution. At this time the sample may be rinsed with fresh water to clear salt residue. There shall be no cracking, crazing, or other damage to the plastic used in the housing and the cover. 4.2.4 Review the surface of the component in
27、 the high stress area under 10X magnification. There shall be no evidence of cracking, crazing or other damage. 4.2.5 Apply load to failure. Apply graduated load until failure in the exact same direction as the simulated deflection. Note: This section shall be run only if documented within requireme
28、nts or agreed upon prior to testing. 5 Provisions for Shipping Not applicable. 6 Notes 6.1 Glossary. Not applicable. 6.2 Acronyms, Abbreviations, and Symbols. PA6, PA12, PA46, PA66, PA612 Polyamide PBT Polyester PET Polyester PE Polyethylene PK Polyketone POM Acetal PP Polypropylene PPS Polyphenylen
29、e Sulfide 7 Additional Paragraphs Not applicable. 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: GMW16600 Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted
30、 without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16600 Copyright 2011 General Motors Company All Rights Reserved June 2011 Page 4 of 4 9 Release and Revisions This standard was originated in April 2011. It was first approved by Plastics GSSLT in June 2011. It was first published in June 2011. Issue Publication Date Description (Organization) 1 JUN 2011 Initial publication. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
