ASTM A956/A956M-22 PDF

Full title and description

Standard Test Method for Leeb Hardness Testing of Steel Products — designation A956/A956M-22. This ASTM test method specifies procedures for performing Leeb (rebound) hardness measurements on steel, cast steel, and cast iron, including instrument verification and calibration of reference test blocks.

Abstract

The standard defines the Leeb hardness test (a dynamic/rebound method) used to obtain superficial hardness values indicative of material condition and heat treatment. It covers test procedures, types of impact devices, surface preparation, measurement units (SI and inch‑pound), verification of portable instruments, and calibration of standardized blocks. The method is intended for rapid, nondestructive hardness assessment of steel products where conventional indentation tests are impractical or would be too slow.

General information

• Status: Active.
• Publication date: September 1, 2022 (A956/A956M‑22).
• Publisher: ASTM International.
• ICS / categories: 77.040.10 (Mechanical testing of metals).
• Edition / version: A956/A956M‑22 (current revision).
• Number of pages: 13.

Scope

This test method covers determination of Leeb hardness of steel, cast steel, and cast iron (Part A), methods for verification of Leeb hardness testing instruments (Part B), and calibration of standardized test blocks (Part C). Values are given in SI or inch‑pound units and each system is to be used independently. The standard notes that Leeb results are superficial and representative only of the tested surface location.

Key topics and requirements

• Definition and calculation of the Leeb hardness number (ratio of rebound to impact velocity, reported with HL and device suffixes).
• Test procedures: specimen and surface preparation, impact device selection, measurement technique, and number/location of indentations.
• Instrument verification procedures and recommended intervals (Part B) to ensure measurement accuracy and repeatability.
• Calibration and use of standardized test blocks, including block qualification and traceability (Part C).
• Conversion and reporting: guidance on units (SI vs inch‑pound) and limitations—do not combine unit systems; caution that values are surface‑specific and not subsurface indicators.

Typical use and users

Used by quality/control engineers, metallurgists, NDT technicians, and production inspectors in steel manufacturing, foundries, fabricators, and maintenance shops for rapid, nondestructive hardness screening, incoming inspection, process control, and verification of heat treatment. The method is particularly valuable when testing large or assembled components where portable testing is required.

Related standards

Related hardness and mechanical testing standards include ASTM standards for other hardness methods and conversions (for example ASTM E140 conversion tables, ASTM E18 Rockwell, ASTM E384 microindentation), as well as national and international hardness testing standards addressing calibration, instrument verification, and test block specifications.

Keywords

Leeb hardness; rebound hardness; portable hardness tester; HL; instrument verification; test block calibration; steel hardness; nondestructive testing; ASTM A956; A956/A956M‑22.

FAQ

Q: What is this standard?

A: ASTM A956/A956M‑22 is the Standard Test Method for Leeb Hardness Testing of Steel Products, specifying procedures for rebound (Leeb) hardness measurements on steel, cast steel, and cast iron.

Q: What does it cover?

A: It covers the Leeb hardness test definition and calculation, test procedures, surface preparation, types of impact devices, instrument verification (Part B), and calibration of standardized test blocks (Part C). The standard also clarifies unit usage (SI and inch‑pound) and limitations of surface‑only measurements.

Q: Who typically uses it?

A: Quality/control engineers, metallurgists, NDT technicians, inspection labs, foundries, fabricators, and maintenance teams that need rapid, portable hardness assessment of steel components.

Q: Is it current or superseded?

A: Current—designation A956/A956M‑22 (published 2022). It replaces the previous A956/A956M‑17a edition.

Q: Is it part of a series?

A: It is maintained by ASTM Committee A01 on Steel, Stainless Steel, and Related Alloys (subcommittee A01.13) and is one of several ASTM standards addressing hardness and mechanical testing methods for metals.

Q: What are the key keywords?

A: Leeb hardness, rebound hardness, HL, portable hardness tester, instrument verification, calibration blocks, steel hardness, ASTM A956/A956M‑22.