Overview
ISO 3887:2023 - Steels - Determination of the depth of decarburization defines decarburization and specifies methods to measure the depth of decarburization in steel products. The fourth edition (2023) standardizes terminology (partial, complete, functional, total decarburization), sampling practices, specimen preparation, and three principal measuring approaches so that manufacturers and laboratories can consistently evaluate surface carbon loss and its effect on steel performance.
Key topics and technical requirements
- Definitions: clear terms for partial, complete (ferrite), functional and total decarburization, plus depth- and carbon-profile concepts.
- Sampling: samples shall be cut perpendicular to the product axis (transverse plane); avoid corner regions; small cross-sections (≤ ~2.5 cm) may be examined full-section; larger sections require agreed sampling schemes.
- Three measuring methods:
- Metallographic method (clause 5.2) - microstructural examination after standard polishing and etching (nital or picral). Recommended magnification guidance (×100 often useful); measurement by the “worst field” or “average” method. Automatic image analysis may be used if validated.
- Micro‑indentation hardness (clause 5.3) - Vickers or Knoop hardness profiling appropriate for quenched/hardened steels; sample prep and measurement per referenced hardness standards.
- Carbon-content methods (clause 5.4) - chemical analysis, spectrographic analysis, EPMA (electron probe microanalysis) and GDOES (glow discharge optical emission spectrometry) for carbon depth profiling and interpretation.
- Method selection: depends on degree of decarburization, steel microstructure, carbon content and component geometry; if no agreement exists, the metallographic method is preferred.
- Specimen preparation & measurement practice: avoid edge rounding during polishing, protect surfaces if needed, use calibrated measurement equipment, and report results in a standardized test report (clause 6).
Applications and who uses this standard
ISO 3887:2023 is used for quality control and acceptance testing where surface carbon loss affects mechanical properties or performance. Typical users include:
- Steel producers and mills
- Heat‑treatment and surface‑treatment shops
- Metallurgical and materials testing laboratories
- OEMs and inspection authorities specifying decarburization limits in product standards
- R&D teams developing steels or processes where surface carbon profile matters
Practical applications: assessing case integrity, ensuring hardness and fatigue performance, validating heat-treatment processes, and verifying compliance with product standards.
Related standards
Normative references in ISO 3887:2023 include:
Keywords: ISO 3887:2023, decarburization, depth of decarburization, steel testing, metallographic method, Vickers, Knoop, EPMA, GDOES, carbon profiling.
