scope:

This standard covers the engineering requirements for electrodeposition of a hard chromium on high strength steel substrates and the properties of deposit. Subsequent heat treating techniques needed to insure low hydrogen embrittlement of steel are also described.

This standard meets and exceeds the requirements of QQ-C-320 and can be used when plating in accordance with QQ-C-320.

Chrome plating is applied for wear resistance, reconditioning worn or undersize parts, and such incidental corrosion protection as the specified thickness of the deposit may afford. Where corrosion protection is desired, an undercoat of nickel 0.025 to 0.050 millimeters (0.001 to 0.002 in) thickness is recommended.

Chromium plating covered by this standard shall be of the following classes:

a. Class 1 - Crack free (see 4.8)

b. Class 2 - Limited cracking allowed (see 4.9)

c. Class 3 - Moderate cracking allowed (see 4.10)

NOTE: When not specified, plating class shall be Class 3.

Chrome plating covered by this standard shall be of the following types:

a. Type I - Plated to specified dimensions (see 4.11)

b. Type II - Processed to specified dimensions after plating (see 4.12)