Curated with aloha by
Ted Mooney, P.E. RET

The authoritative public forum
  for Metal Finishing 1989-2025
  

HRc hardness of hard chrome plating

Quickstart:
     Readers may wish to start with our "Introduction to Chrome Plating" if they don't know much about it. Hard chrome plating is frequently applied to machine parts because it is hard, wear resistant, and has a low efficient of friction. In some cases, such as on hydraulic piston rod, its miniaturized "dried mud bed" topography is important for holding oil.

[editor appended this entry to this thread which already addresses it in lieu of spawning a duplicative thread]
Q. Hi, I am Masoud, I am working at aluminum rolling company for aluminum foil production. I would like to use chrome plating on the surface roll after grinding, can iI achieve hardness up to 1000 to 1200 BH with chrome plating while hardness in our steel rolls is 66RC? Can you help me?

Ed. note: Yes! Toby Padfield has answered that on this page. Good luck.

⇩ Related postings, oldest first ⇩

Q. It was mentioned in your Chrome Plating Tutorial that the hard chrome plating is usually applied to a "hardened" surface. Could you please tell me how hard the actual plating is and what the recommended min. hardness level (HRc) the steel should be to support it?

SUGGESTED HARD CHROME PLATING BOOKS

Hard chromium plating: A handbook of modern practice by Greenwood (1981)
avail from eBay or Amazon

"Hard Chromium Plating"
by Robert K. Guffie (1986)
avail from AbeBooks, or Amazon

"Chromium Plating"
by Weiner & Walmsley (1980)
avail from eBay, AbeBooks, or Amazon

(as an Amazon Associate & eBay Partner, we earn from qualifying purchases)

A. The substrate hardness is usually specified as 40 HRC minimum (390 HV minimum), but more typically ranges from 45-50 HRC (450-515 HV). Since the chromium plating is so thin (typically 15-25 micrometers) it cannot be directly tested using HRC, but it can be measured using Vickers microhardness and then converted to an approximate HRC number. Cr plating is usually a minimum of 900 HV (67 HRC), but is more typically around 1000-1100 HV. 940 HV is ~ 68 HRC which is the last data point in ASTM E140 or ISO 18265.

Toby Padfield
Automotive module supplier - Michigan

A. We commonly plated to 0.010 and you still use a Vickers or Knoop hardness. It does not exactly relate to HRC, but it is more than close enough for government work.

James Watts
- Navarre, Florida

A. Try this web-site:

www.efunda.com/units/hardness/show_hardness.cfm

Remember when converting between the various scales that each is only an approximation for the other.

Brian Terry
Aerospace - Yeovil, Somerset, UK

[editor appended this entry to this thread which already addresses it in lieu of spawning a duplicative thread]
Q. What is the actual hardness of hard chromium plated ground steel rod.
Material: CK 45 / EN8D,
Chromium Thickness: 25 micron minimum on radius
Surface Roughness: Ra MAX. 0.2 micron

Ed. note: Toby Padfield has answered that above. Good luck.