ASTM E18 Rockwell Hardness Testing Standard

Standard test methods for Rockwell hardness testing of metallic materials used in key manufacturing and automotive components, providing comprehensive procedures for hardness measurement, calibration, and quality control.

Standard Overview

Standard Code

ASTM E18-22

Publication Date

2022-11-01

Status

Active ASTM Standard

Application

Material Testing

Rockwell Hardness Scales

Scale A (HRA)

Diamond cone indenter with 60 kgf test force

Indenter: Diamond cone (120°)
Test Force: 60 kgf (588.4 N)
Application: Hard materials, thin sheets

Scale B (HRB)

Steel ball indenter with 100 kgf test force

Indenter: 1.588 mm steel ball
Test Force: 100 kgf (980.7 N)
Application: Medium hardness materials

Scale C (HRC)

Diamond cone indenter with 150 kgf test force

Indenter: Diamond cone (120°)
Test Force: 150 kgf (1471 N)
Application: Hard steels, key materials

Test Procedures

1

Sample Preparation

Prepare test specimen with smooth, flat surface free from scale, oxide, or foreign material. Minimum thickness requirements must be met.

2

Machine Setup

Select appropriate indenter and test force. Verify machine calibration using certified reference blocks within specified time intervals.

3

Preliminary Force

Apply preliminary force of 10 kgf (98.07 N) to establish contact and eliminate surface irregularities. Set dial to zero position.

4

Major Force Application

Apply major force smoothly without shock. Maintain force for specified dwell time (typically 10-15 seconds for metals).

5

Force Removal

Remove major force while maintaining preliminary force. Read hardness value directly from dial or digital display.

6

Result Recording

Record hardness value with appropriate scale designation (HRA, HRB, HRC, etc.). Document test conditions and specimen details.

Frequently Asked Questions

What is ASTM E18?

ASTM E18 is a standard test method for Rockwell hardness testing of metallic materials, providing procedures for measuring material hardness using diamond or steel ball indenters.

What are the Rockwell scales in ASTM E18?

ASTM E18 defines multiple Rockwell scales including A, B, C, D, E, F, G, H, and K scales, each using different indenters and test forces for specific material types.

How does ASTM E18 apply to key manufacturing?

ASTM E18 is essential for key manufacturing as it ensures proper material hardness for durability, wear resistance, and proper function in lock mechanisms.

What is the difference between HRC and HRB scales?

HRC uses a diamond cone indenter with 150 kgf force for hard materials like hardened steel keys, while HRB uses a steel ball with 100 kgf force for softer materials.

Official Standards Authority

ASTM International

Access the official ASTM E18 standard documentation for Rockwell hardness testing procedures and calibration requirements.

Visit ASTM Official Site

Material Testing Standards

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