Overview
ISO/TS 19096:2023 - Metallic materials - Instrumented indentation test for hardness and materials parameters - Evaluation of stress change using indentation force differences - specifies a method to evaluate stress change between a reference and a target state by comparing instrumented indentation force–displacement responses. The technique is aimed at near-surface, plane-stress measurements on metallic materials and is intended for point measurements and comparative mapping across locations.
Key topics and requirements
- Principle: Stress changes shift the instrumented indentation force/indentation-depth curve. The standard quantifies stress change from the force difference between reference and target curves (constant-depth or constant-load approaches).
- Scope of measurement: Primarily measures average near-surface stress change in the plane of the surface (the method yields the change equal to half the first invariant of the stress tensor when normal stress is zero).
- Test equipment & calibration: Uses instrumented indentation systems complying with ISO 14577 series requirements (machine verification and calibration).
- Test piece and procedure: Specifies sample selection, acquisition of reference and target states, indentation arrays (1D or 2D) and procedures for controlling local hardness variations (see Annex A).
- Data processing: Calculation of projected areas, force differences, and average stress change; guidance on uncertainty estimation (ISO/IEC Guide 98-3 referenced).
- Verification and combination methods: Includes normative and informative annexes for hardness uniformity verification (A), combining with stress relief methods (B), Knoop indenter usage (C), verification by bending specimens (D), and comparison with hole‑drilling/saw‑cutting (E).
Practical applications
- Rapid semi‑destructive evaluation of residual/stress change after processes such as heat treatment, welding, forming, shot peening, coating and surface modification.
- Localized stress mapping (1D/2D indentation arrays) to identify regions of tensile or compressive change.
- In-field quality control where minimal surface preparation and fast point measurements (