MIL-STD-868 Nickel Plating, Low Embrittlement, Electro-DepositionThis standard covers the process and materials required for the electro-deposition of nickel on high strength steel substrates. Electro-deposited nickel is used for wear resistance, heat resistance, and as an undercoat for precious metals. Subsequent heat treating techniques needed to insure low hydrogen embrittlement of steel are also described. This standard meets the performance requirements of SAE-AMS- QQ-N-290 and may be used when SAE-AMS-QQ-N-290 is specified provided any unique requirements of SAE-AMS-QQ-N-290 are complied with.

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MIL-STD-868B CHANGE 2

4.5   Embrittlement.  Qualification test specimens and process control test specimens shall be subjected to a sustained load test at 75 percent of the ultimate notched tensile strength.  The specimens shall endure this sustained load for 200 hours minimum without failing or cracking.

4.6   Re-processing.   Parts rejected for defective plating, requiring stripping and re-plating, shall include all of the pre-plating steps of this standard.  Parts shall be stripped in accordance with MIL-STD-871.

4.7   Plating thickness.  The plating thickness shall be as specified on the engineering drawing or other applicable directives.  Unless otherwise specified the minimum thickness shall be 0.05mm (0.002 inch) and the maximum thickness shall be

0.2mm (0.008 inch) on the finished parts.

4.8   Type I plating.   For Type I plating, the item shall be plated to the dimension and surface finish specified on the drawing.  The surface finish of the item before plating shall be equal to or better than the required finish after plating.   Type I plating may be buffed or lapped after plating if dimensional tolerances and surface conditions cannot be controlled in the plating operation.

4.9   Type II plating.   For Type II plating a minimum of 0.05mm (0.002 inch) more nickel than desired shall be deposited (per surface).  The excess shall be ground off to give the final dimension and surface finish desired.  The minimum thickness for Type II shall be 0.05mm (0.002 inch) on the finished part.  Steel parts heat treated to 1240 MPa (112 kg/mm2) (180,000 psi) shall be ground in accordance with MIL-STD-866.

4.10   Reclaimed materials.   Reclaimed materials shall be utilized to the maximum extent possible with the quality limits required by this document and to fulfill compliance with the Resource Conservation/Recovery Act of 1976 (Public law 94-580,

21 October 1976).

5.   DETAILED REQUIREMENTS

5.1   General.    The information contained in this section provides the process and procedures to follow when performing the plating process.

5.1.1   Prior to plating.   Prior to plating, except for finish grinding operations, all machining, forming, welding, and shot peening shall be completed.

5.1.2   Baking.   Parts shall be baked for stress relief before plating for four hours minimum at 191 ± 14'C (375 ± 25'F).  Shot peening shall be performed before plating and after stress relieving.

5.1.3   Storage of parts.   Storage of parts between stress relief and cleaning shall be controlled to prevent contact with water or other corrosive materials. Parts shall be stored to permit free circulation of air around the parts.

5.1.4   Handling of parts.  After the parts have been cleaned, they shall be handled in such a manner (white gloves, etc) that will ensure a minimum of contamination.

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