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ASTM Hardness Testing Standards Diverge

ASTM E10 Brinell and E18 Rockwell hardness testing standards for metallic materials have only included rules for fixed-location testing machines since their inception in 1924 and 1932 respectively. In 2018, these ASTM standards added “portable” and “movable” hardness testing machines for the first time. However, the ASTM A370 Standard Test Methods and Definitions for Mechanical Testing of Steel Products has not included these changes.


Also, these changes have many domino effects since many current codes and standards have referenced past editions of ASTM E10, E18, or ASTM A370, and may not have considered the newly added E10 and E18 “portable” and “movable” hardness testing machines. For example, ANSI/NACE MR0175/ISO 15156-2 references ASTM E10 and E18, but does not identify the year-date edition, i.e., ASTM E10 is referenced and not ASTM E10-18.


Probably the most important item to know is that “portable hardness testing machines” are not all manufactured equally, based on the E10-18 and E18-18 definitions, as follows.


E10-18 Standard Test Method for Brinell Hardness of Metallic Materials

3.1.10 portable Brinell hardness testing machine—a Brinell hardness testing machine that is designed to be transported, carried, set up, and operated by the users, and that measures Brinell hardness by the Brinell hardness test principle.


E18-18a Standard Test Methods for Rockwell Hardness of Metallic Materials

3.1.7.3 portable Rockwell hardness testing machine—a Rockwell hardness testing machine that is designed to be transported, carried, set up, and operated by the users, and that measures Rockwell hardness by the Rockwell indentation hardness test principle.


The key words of these definitions are:

“…and that measures Brinell hardness by the Brinell hardness test principle.”

“…and that measures Rockwell hardness by the Rockwell indentation hardness test principle.”


In each case, the “measuring based on test principle” means that the E10 and E18 specified applied load and dwell time must be met. Consequently, only some of the more recently made “portable hardness testing machines” can meet the E10-18 and E18-18 definitions, while the majority of them do not meet these definitions because the E10 and E18 specified applied load and/or dwell time are/is not met.


For example, portable hardness testing machines that have been designed and manufactured to meet the following ASTM standards would not meet the E10-18 and E18-18 definitions.


  • ASTM E110 (e.g., previous King Brineller®, Rockwell C-clamp)
  • ASTM A833 (Telebrineller®)
  • ASTM A956 (Leeb®)
  • ASTM A1038 (Microdur®)
  • many others

Now…you are probably asking the question: “Why did ASTM do this?”


The answer to this simple question is not so simple! In fact, it is a very long and complex answer with lots of history involved. So I will do my best to give the simplest logistical answer, based on my active ASTM subcommittee involvement for all of these standards.


  1. The ASTM E10 and E18 standards fall under the jurisdiction of:

ASTM Committee E28 on Mechanical Testing and is the direct responsibility of Subcommittee E28.06 on Indentation Hardness Testing.

  1. The ASTM A370 standard falls under the jurisdiction of:

ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and are the direct responsibility of Subcommittee A01.13 on Mechanical and Chemical Testing and Processing Methods of Steel Products and Processes.

  1. The ASTM E10 and E18 standards are written more broadly for many industries using all “metallic materials” (e.g., aluminum, copper, iron, nickel, titanium, zinc, and their alloys, etc.).
  2. The ASTM A370 standard is written more narrowly for “steels” (e.g., carbon steel, alloy steel, stainless steel, and cast irons).
  3. The ASTM subcommittee memberships of E28.06 and A01.13 are also different; although there are people with membership in both subcommittees, like myself. The differing subcommittee memberships and their differing industries that they serve have led to addressing different concerns by different people.

As a long-time codes and standards committee volunteer, I can appreciate these differences and accept their differing logistical results.


However, since most codes and standards users never participate in volunteer committee work, my simplified answer may not be readily apparent to the original question of:

“Why did ASTM do this?


My common suggestion to codes and standards users that do not like the manner in which they are written is:

“If you don’t like what’s in a code or standard, then volunteer your time and money to join the committee to find consensus among all of its members to improve them.”


In the next article, the ASTM E10-18 and E18-18 addition of: “movable Brinell and Rockwell hardness testing machines”  will be addressed. Followed by an article addressing the use the current ASTM E10, E18, and A370 standards and their correct application with referenced codes and standards covering fixed-location, portable, and movable hardness testing machines and test procedures.