**Process Specification for Electrodeposited Chromium Plating**

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| **Engineering Directorate**                                           |
|                                                                       |
| **Structural Engineering Division**                                   |
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| **October 2004**                                                      |
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| ![](media/image1.png){width="1.4027777777777777in"                    |
| height="1.1534722222222222in"}                                        |
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| National Aeronautics and                                              |
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| Space Administration                                                  |
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| **Lyndon B. Johnson Space Center**                                    |
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| Houston, Texas                                                        |
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**Process Specification for Electrodeposited Chromium Plating**

+-----------------+----------------------------------+------+---------+
| **Prepared      | #####                            |      |         |
| by:**           |                                  |      |         |
+-----------------+----------------------------------+------+---------+
|                 | Julie A. Henkener                |      | Date    |
|                 |                                  |      |         |
|                 | Materials and Processes          |      |         |
|                 | Branch/ES4                       |      |         |
+-----------------+----------------------------------+------+---------+
|                 |                                  |      |         |
+-----------------+----------------------------------+------+---------+
|                 |                                  |      |         |
+-----------------+----------------------------------+------+---------+

+-----------------+----------------------------------+------+---------+
| **Approved      | #####                            |      |         |
| by:**           |                                  |      |         |
+-----------------+----------------------------------+------+---------+
|                 | Brad S. Files, Acting Chief      |      | Date    |
|                 |                                  |      |         |
|                 | Materials and Processes Branch   |      |         |
|                 | /ES4                             |      |         |
+-----------------+----------------------------------+------+---------+

  ----------- --------------------------------------------- ---------------
  REVISIONS                                                 

  VERSION     CHANGES                                       DATE

  \--         Original version                              5/96

  A           Formatting; mandates 23 hour hydrogen bakeout 7/26/99
              for steel alloys.                             

  B           Changed EM references to ES                   9/2002

  C           Updated specification reference to            10/2004
              AMS-QQ-C-320                                  

                                                            
  ----------- --------------------------------------------- ---------------

**1.0 [SCOPE]{.underline}**

This process specification establishes technical requirements for the
application of electrodeposited chromium plating on steel, copper and
copper alloys, and zinc and zinc alloys.

**2.0 [APPLICABILITY]{.underline}**

This process specification applies to the electrodeposition of chromium
plating on substrates of steel, copper, zinc, and their alloys.

**3.0 [USAGE]{.underline}**

This process specification shall be called out on the engineering
drawing by using a drawing note that identifies the process
specification, the class, and the type. For example:

**CHROMIUM PLATE PER NASA/JSC PRC 5003, CLASS 1, TYPE II.**

The two classes of electrodeposited chromium plating are:

Class 1 Corrosion protective chromium plating (\>0.00001 in. thick)

Class 2 Engineering chromium plating (\>0.002 in. thick)

Class 1 plating is used to protect iron, copper, or zinc alloys against
corrosive attack in rural, industrial, or marine environments, which
varies depending on the thickness of the chromium deposit. It may also
be used as an undercoat for a chromium plating or for aesthetic
purposes.

Class 2 plating is used primarily for wear resistance, abrasion
resistance, and incidental corrosion protection. Heavy deposits of Class
2 plating, such as those produced by the Watts bath process, may be used
for build-up of worn or undersized parts.

Class 1 chromium plating shall be one of the following types,
as-specified on the engineering drawing:

Type I -- Bright Finish

Type II -- Satin Finish

**3.1 WORK INSTRUCTIONS**

Work instructions shall be generated for implementing this process
specification. The work instructions shall contain sufficient detail to
ensure that the manufacturing process produces consistent, repeatable
products that comply with this specification.

**4.0 [REFERENCES]{.underline}**

The following references were used in developing this process
specification:

SOP-007.1 *Preparation and Revision of Process Specifications*

JSC 8500C *Engineering Drawing System Requirements*

The following document is called out as an extension of the requirements
given in this specification:

AMS-QQ-C-320 *Aerospace Material Specification/Chromium Plating
(Electrodeposited)*

**5.0 [MATERIALS REQUIREMENTS]{.underline}**

The materials used shall meet the requirements of AMS-QQ-C-320.

**6.0 [PROCESS REQUIREMENTS]{.underline}**

All electrodeposited chromium plating shall be applied according to the
technical requirements of AMS-QQ-C-320 with the following exception:

All steel parts which have a hardness of Rockwell C40 and higher shall
be subjected to a hydrogen bakeout procedure immediately following
plating. Within 4 hours of the chromium electrodeposition, the plated
parts shall be "baked out" at a minimum temperature of 375 +/- 25°F for
a duration of 23 hours or longer to provide hydrogen embrittlement
relief.

**7.0 [PROCESS QUALIFICATION]{.underline}**

Not required.

1.  **[PROCESS VERIFICATION]{.underline}**

The process verification shall include visual examination, adhesion
tests, and thickness measurements, as-specified by AMS-QQ-C-320. In
addition, steel parts shall be tested for hardness. If the hardness is
greater than Rockwell C40, the parts are subject to hydrogen bakeout as
described in section 6.0.

**9.0 [TRAINING AND CERTIFICATION OF PERSONNEL]{.underline}**

This chromium plating process shall be performed by personnel qualified
to conduct the process through training or experience. If this process
is performed by an outside vendor, the development of an appropriate
training program shall be the responsibility of the vendor.

**10.0 [DEFINITIONS]{.underline}**

Electrodeposition The electrodeposition process consists of putting a
conductive material from a plating solution onto a substrate by the
application of an electric current.

Substrate The material, component, or workpiece to which the chromium
plating is deposited. May also be called "base metal."