ASTM E384-17
Standard Test Method for Microindentation Hardness of Materials

Standard No.

ASTM E384-17

Release Date

2017

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E384-22

Latest

ASTM E384-22

Scope

5.1 Hardness tests have been found to be very useful for materials evaluation, quality control of manufacturing processes and research and development efforts. Hardness, although empirical in nature, can be correlated to tensile strength for many metals and alloys, and is also an indicator of machinability, wear resistance, toughness and ductility.

5.2 Microindentation tests are utilized to evaluate and quantify hardness variations that occur over a small distance. These variations may be intentional, such as produced by localized surface hardening, for example, from shot blasting, cold drawing, flame hardening, induction hardening, etc., or from processes such as carburization, nitriding, carbonitriding, etc.; or, they may be unintentional variations due to problems, such as decarburization, localized softening in service, or from compositional/microstructural segregation problems. Low test forces also extend hardness testing to materials too thin or too small for macroindentation tests. Microindentation tests permit hardness testing of specific phases or constituents and regions or gradients too small for evaluation by macroindentation tests.

5.3 Because microindentation hardness tests will reveal hardness variations that commonly exist within most materials, a single test value may not be representative of the bulk hardness. Vickers tests at 1000 gf can be utilized for determination of the bulk hardness, but, as for any hardness test, it is recommended that a number of indents are made and the average and standard deviation are calculated, as needed or as required.

5.4 Microindentation hardness testing is generally performed to quantify variations in hardness that occur over small distances. To determine these differences requires a very small physical indentation. Testers that create indents at very low test forces must be carefully constructed to accurately apply the test forces exactly at the desired location and must have a high-quality optical system to precisely measure the diagonal (or diagonals) of the small indents. Test forces in the upper range of the force range defined in 1.2 may be used to evaluate bulk hardness. In general, the Vickers indenter is better suited for determining bulk (average) properties as Vickers hardness is not altered by the choice of the test force, from 25 to 1000 gf, because the indent geometry is constant as a function of indent depth. The Knoop indentation, however, is not geometrically identical as a function of depth and there will be variations in Knoop hardness, particularly at test forces <200 gf, over the force range defined in 1.2 (and above this range); consequently, Knoop hardness is not normally used to define bulk hardness, except at 500 gf where E140 gives conversions to other test scales, and Knoop tests should not be performed at test forces above 1000 gf. The majority of Knoop tests of case hardness variations are conducted at forces from 100 to 500 gf. If the test is being conducted to meet a specified bulk hardness value, such as HRC, then most such tests will be conducted with Knoop at a 500 gf load. Because of the large difference between the long and short Knoop diagonals, the Knoop indenter is often better suited for determining variations of hardness over very small distances compared to the Vickers indenter. Vickers and Knoop tests at forces ≤25 gf are susceptible to imprecision due to the difficulty in measuring extremely small indents (<20 x0

ASTM E384-17 Referenced Document

• ASTM C1326 Standard Test Method for Knoop Indentation Hardness of Advanced Ceramics
• ASTM C1327 Standard Test Method for Vickers Indentation Hardness of Advanced Ceramics
• ASTM E1268 Standard Practice for Assessing the Degree of Banding or Orientation of Microstructures
• ASTM E140 Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, and Scleroscope Hardness
• ASTM E175 Standard Terminology of Microscopy
• ASTM E177 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E2554 Standard Practice for Estimating and Monitoring the Uncertainty of Test Results of a Test Method Using Control Chart Techniques
• ASTM E2587 Standard Practice for Use of Control Charts in Statistical Process Control*， 2024-04-20 Update
• ASTM E3 Standard Practice for Preparation of Metallographic Specimens
• ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• ASTM E7 Standard Terminology Relating to Metallography
• ASTM E766 Standard Practice for Calibrating the Magnification of a Scanning Electron Microscope
• ASTM E92 Standard Test Method for Vickers Hardness of Metallic Materials
• ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories [Standard in French]

ASTM E384-17 history

• 2022 ASTM E384-22 Standard Test Method for Microindentation Hardness of Materials
• 2017 ASTM E384-17 Standard Test Method for Microindentation Hardness of Materials
• 2016 ASTM E384-16 Standard Test Method for Microindentation Hardness of Materials
• 2011 ASTM E384-11e1 Standard Test Method for Knoop and Vickers Hardness of Materials
• 2011 ASTM E384-11 Standard Test Method for Knoop and Vickers Hardness of Materials
• 2010 ASTM E384-10e2 Standard Test Method for Knoop and Vickers Hardness of Materials
• 2010 ASTM E384-10e1 Standard Test Method for Knoop and Vickers Hardness of Materials
• 2010 ASTM E384-10 Standard Test Method for Microindentation Hardness of Materials
• 2009 ASTM E384-09 Standard Test Method for Microindentation Hardness of Materials
• 2008 ASTM E384-08ae1 Standard Test Method for Microindentation Hardness of Materials
• 2008 ASTM E384-08a Standard Test Method for Microindentation Hardness of Materials
• 2008 ASTM E384-08 Standard Test Method for Microindentation Hardness of Materials
• 2007 ASTM E384-07a Standard Test Method for Microindentation Hardness of Materials
• 2007 ASTM E384-07 Standard Test Method for Microindentation Hardness of Materials
• 2006 ASTM E384-06 Standard Test Method for Microindentation Hardness of Materials
• 2005 ASTM E384-05a Standard Test Method for Microindentation Hardness of Materials
• 2005 ASTM E384-05 Standard Test Method for Microindentation Hardness of Materials
• 1999 ASTM E384-99e1 Standard Test Method for Microindentation Hardness of Materials
• 1999 ASTM E384-99 Standard Test Method for Microindentation Hardness of Materials