Overview
ISO 4545-4:2017 - Metallic materials - Knoop hardness test - Part 4: Table of hardness values - provides a standardized table of Knoop hardness (HK) values for use with Knoop hardness tests carried out in accordance with ISO 4545‑1. The values in the table were calculated from the Knoop hardness formula specified in ISO 4545‑1 and are intended to simplify conversion of measured indentation diagonals to HK values across a range of test forces.
Key topics
- Purpose: A reference table giving Knoop hardness (HK) values calculated from the ISO 4545‑1 formula.
- Scope of values: The table covers HK values for multiple test forces (including micro‑forces such as HK 0,001; HK 0,002; HK 0,005 and larger forces up to HK 2) and a range of indentation diagonal measurements in millimetres.
- Calculation source: Values are derived from the Knoop hardness formula defined in ISO 4545‑1 - ISO 4545‑4 does not redefine calculation methods but provides tabulated results for practical use.
- Edition changes: The 2017 (second) edition adds data for several low and high test forces and removes the explicit calculation clause from the earlier edition.
- Normative linkage: ISO 4545‑1 (Knoop test method) is the normative reference; users must follow ISO 4545‑1 for test procedures and measurement practice.
Applications
ISO 4545‑4:2017 is directly useful for:
- Metallurgical and materials testing laboratories converting measured Knoop indentation diagonals to HK values quickly and consistently.
- Quality control and inspection where Knoop hardness values are required for product acceptance or process control.
- Research and development involving microhardness measurement of coatings, thin sections, small parts or brittle materials where Knoop testing is preferred.
- Instrument manufacturers and calibration services providing reference tables and firmware that report HK values from measured diagonals.
Using the standardized table helps ensure repeatable, comparable Knoop hardness results across labs and industries.
Related standards
- ISO 4545‑1 - Metallic materials - Knoop hardness test - Part 1: Test method (normative reference for test procedure and formula).
- ISO 4545 series (other parts) and ISO/TC 164 publications on mechanical testing of metals.
Keywords: ISO 4545-4:2017, Knoop hardness, HK values, metallic materials, hardness testing, Knoop hardness table, ISO 4545-1, microhardness testing.