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Rockwell Hardness Testing Values
Scales, Values and Standards

Rockwell Hardness Testing - Scales, Values and Standards

 At this time there are a number of complementary scales, with the most generally utilized being the “B” and “C” scales. Each of those define hardness as some sort of subjective  dimensionless number.

Various Rockwell scales[1]

Scale

Abbreviation

Load

Indenter

Use

A

HRA

60 kgf

120° diamond cone

Tungsten carbide

B

HRB

100 kgf

1/16 in diameter steel sphere

Aluminium, brass, and soft steels

C

HRC

150 kgf

120° diamond cone

Harder steels

D

HRD

100 kgf

120° diamond cone


E

HRE

100 kgf

1/8 in diameter steel sphere


F

HRF

60 kgf

1/16 in diameter steel sphere


G

HRG

150 kgf

1/16 in diameter steel sphere


Also called a brale indenter

With the exception of one particular extremely specific exemption, the steel indenter balls currently in use are replaced with tungsten carbide balls with the various diameters. Scales making use of the ball indenter display a “W” suffix appended to the particular scale name to signify utilization of the carbide ball, for example “HR30T” is currently “HR30TW”.

The ” light ” Rockwell scales work with reduced loads as well as shallower indentations on easily breakable and relatively thin components. The 45N scale utilizes a 45-kgf tension on a diamond cone-shaped Brale indenter, and can easily be employed on compacted ceramics. The 15T scale uses a 15-kgf tension on a 1/16-inch diameter hardened steel ball, and may possibly be utilized with sheet metal.

Readings less than HRC 20 are most often regarded as fallible, as are readings significantly above HRB 100.

Common values:

  • Very hard steel (e.g. a good knife blade): HRC 55–62 (Hardened tool steels such as D2)[2]
  • Axes, chisels, etc.: HRC 40–45 (about 1045 carbon steel)[citation needed]
  • Brass: HRB 55 (Low brass, UNS C24000, H01 Temper) to HRB 93 (Cartridge Brass, UNS C26000 (260 Brass), H10 Temper)[3]

A variety of alternative scales, which include the voluminous A-scale, are generally utilized with regard to specific applications. Presently there happen to be select scales for the purpose of testing case-hardened specimens.

  • International (ISO)
  • ISO 6508-1: Metallic materials — Rockwell hardness test — Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T)
  • ISO 2039-2: Plastics — Determination of hardness — Part 2: Rockwell hardness
  • ASTM E18 : Standard methods for Rockwell hardness and Rockwell superficial hardness of metallic materials
  • US standard (ASTM International)

References

  1. ^ Smith, William F.; Hashemi, Javad (2001), Foundations of Material Science and Engineering (4th ed.), McGraw-Hill, p. 229, ISBN 0-07-295358-6
  2. ^ Knife blade materials
  3. ^ matweb.com, accessed 2010-06-23



For more information, contact

Nancy Baddaker
Customer Service Rep.
Clarcorp Industrial Sales
1209 Marlin Court
Waukesha, WI  53186
(P) 262-549-3762 Ex 118
(F) 262-549-1140
nancy@clarcorp.com

Clarcorp Industrial Sales

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