Surface treatments, grinding and testing

Hard chrome may be deposited on a wide variety of metals. Steel, stainless steel, copper and brass are the most receptive to an adherent deposit. Exotic metals, such as aluminum, nickel-based alloys (Inconel, Hastelloy) and nitrided steels, are more difficult to chrome, but with proper pretreatment methods it can be achieved.

Deposit thicknesses range from “flash” (very thin deposits, 0.0005” to 0.001”) to “heavy build” (in some cases up to 0.040”). The final application of the part generally determines the thickness required.

As the thickness of hard chrome increases, surface defects and roughness are amplified, because hard chrome has no leveling effect. Usually a greater thickness than required is applied, and the part is then ground to the desired dimensions.

The hard chrome deposit has a hardness of about 900 HV (66 Rc). Hardness testing should be done in accordance with ASTM B-578, except that a Vickers indenter and a 100 g load must be used (QQ-C-320); higher loads would perforate the chrome layer and give erroneous results.

If you do not have a thickness requirement, drawing or specification, please contact us. We can help you discuss your application and determine the required thickness.

Agro Crom does not perform “decorative chrome”, such as that used on car bumpers, motorcycle fenders, tables, chairs, etc.

In most cases the existing chrome, whatever its thickness, can be removed by chemical stripping or grinding. In many cases chemical removal is recommended.

Yes, as in all electrochemical processes, hydrogen embrittlement occurs. This applies to steel parts with a hardness above 40 Rc, for which a de-embrittlement treatment is recommended.

A coating of nickel with a percentage of phosphorus.

It does not require anodes or an outside power source. Chemical reactions on the surface of the part cause the deposition of the nickel alloy on all wetted surfaces, which in turn produces a uniform thickness.

• Corrosion protection
• Excellent adhesion
• Hardness
• Wearability
• Uniform deposit regardless of the geometry of the part

• Uniformity of thickness
• Better corrosion protection
• Superior adhesion
• Better lubricity

An electroless nickel finish is similar to stainless steel in coloration. The surface finish replicates that of the base metal: a brightly polished surface will have a bright finish after plating, and a matte or satin surface will have a matte or satin finish after plating.

Yes, with proper pretreatment it is possible.

The thickness typically ranges between 0.0005” and 0.002”. Due to the uniformity and thickness control, parts do not require subsequent grinding.