Rockwell / Superficial Rockwell Hardness Measurement ASTM E 18 / ISO 6508 / ASTM D 785 / ISO 2039

By applying a predetermined force to a material's surface and measuring the depth or penetration of an indenter, the non-destructive testing technique known as "rockwell hardness measurement" determines the material's hardness. Several plastics and composites, as well as some metallic materials, can be tested for hardness using the Rockwell hardness measurement.

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Rockwell / Superficial Rockwell Hardness Measurement ASTM E 18 / ISO 6508 / ASTM D 785 / ISO 2039

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Overview
Scope, Applications, and Benefits
Test Process
Specifications
Instrumentation
Results and Deliverables

Overview

Rockwell hardness testing is a very common technique for evaluating the hardness of metals and plastics by determining the depth of indentation under a known load. The process is described in various standards, including ASTM International’s ASTM E18 and ASTM D785 for metals, and ISO 6508 and ISO 2039 for plastics, published by the International Organization for Standardization.

The process involves applying a minor load, then a major load, to a diamond cone indenter or a steel ball indenter, and automatically determining the difference in indentation depth, which is then converted to a hardness value, e.g., HRC, HRB, etc. Superficial Rockwell testing involves smaller loads for shallow materials, often for surface treatments.

Scope, Applications, and Benefits

Scope

The Rockwell and Superficial Rockwell hardness tests measure the resistance of metals and plastics to indentation under given loading conditions. The standards establish the forces used to perform the tests, the type of indenter used, the specimen to be tested, and the manner in which the results are presented.

Applicable to metals (ASTM E18 / ISO 6508).
Applicable to plastics (ASTM D785 / ISO 2039).
Covers regular and superficial Rockwell scales.
Defines indenter types and test forces.

Applications

Material quality control.
Heat treatment verification.
Incoming material inspection.
Plastic component evaluation.
Manufacturing process control.

Benefits

Fast and direct hardness reading.
Minimal specimen preparation.
Suitable for production environments.
Wide range of hardness scales.
Standardized global acceptance.

Test Process

Specimen Preparation

Ensure flat, clean surface with adequate thickness to prevent substrate influence.

Minor Load Application

Apply minor load to seat the indenter and establish reference position.

Major Load Application

Apply major load for specified dwell time, then remove it while maintaining minor load.

Hardness Reading

Measure indentation depth difference and display hardness value directly.

Technical Specifications

Parameter	Details
Indenter Types	Diamond cone (Brale) or hardened steel ball
Minor Load	Typically 10 kgf
Major Load	60, 100, 150 kgf
Superficial Loads	15, 30, 45 kgf
Dwell Time	Specified holding duration
Specimen Thickness	Minimum thickness per scale requirement
Hardness Scales	HRA, HRB, HRC, HR15N, HR30T, etc.
Measured Parameter	Indentation depth converted to hardness number
Environment	Room temperature testing

Instrumentation Used for Testing

Rockwell Hardness Testing Machine
Diamond Cone Indenter
Steel Ball Indenter
Anvil (Flat / V-type)
Calibration Test Blocks
Micrometer

Results and Deliverables

Rockwell Hardness Value
Superficial Rockwell Value
Test Scale Identification
Applied Load Details
Indenter Type Used
Specimen Details and Thickness
Calibration Verification Record
Complete Test Report as per ASTM / ISO standard

Why Choose Infinita Lab for Rockwell Hardness Testing?

With Infinita Lab (www.infinitalab.com), you are guaranteed a Nationwide Network of Accredited Laboratories spread across the USA, the best Consultants from around the world, Convenient Sample Pick-Up and Delivery, and Fast Turnaround Time.

Our team understands the stakes and subtleties of every test. Whether you’re validating a new Product, de-risking a prototype, or navigating complex compliance requirements, our specialists guide the process with rigor and clarity.

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Frequently Asked Questions

Rockwell hardness tests involve determining the resistance of a material to indentation by applying a small load followed by a major load, then determining the hardness through the depth of indentation with scales.

Superficial Rockwell uses lower test forces compared to standard Rockwell, making it suitable for thin materials, surface-treated components, and small parts where deeper indentation must be avoided.

Proper surface preparation ensures accurate indentation measurement, prevents reading errors caused by roughness or coatings, and ensures reliable, repeatable hardness results.

A sample with a flat, smooth surface. Ideally, the sample should be at least 10 times thicker than the depth of the expected indentation to avoid "anvil effects." For most parts, a small coupon or the actual finished part (if it has a flat area of at least 1/2 inch) is perfect.

ASTM E18 and ISO 6508 apply to metallic materials, while ASTM D785 and ISO 2039 are used for plastics and polymer-based materials.