ISO 14271:2017

Overview

ISO 14271:2017 defines standardized procedures for Vickers hardness testing (low‑force and microhardness) of etched cross‑sections from resistance spot, projection, and seam welds. The standard targets welds in ferrous and non‑ferrous sheets with thicknesses from 0.5 mm to 6 mm, and specifies how to locate and perform hardness traverses to determine hardness in the weld nugget, heat affected zone (HAZ), and parent material.

Key Topics

• Scope and purpose: Procedures for hardness testing of etched cross‑sections to obtain Vickers hardness (HV) in low‑force and microhardness ranges.
• Force ranges:
  • Low‑force Vickers: defined between 1.961 N and 9.807 N; recommended test forces 1.961 N or 9.807 N for traverses.
  • Microhardness: defined as forces < 1.961 N; recommended microhardness force 0.9807 N.
• Specimen preparation:
  • Cross‑section plane should pass through the weld nugget.
  • Test piece thickness shall be at least 1.5 × the diagonal length of the hardness indentation.
  • Etching to reveal weld structure is required for microhardness measurement.
• Section orientation:
  • For near‑circular electrode indentations, sections may be taken in any direction through the nugget.
  • For elongated electrode or embossment traces (projection or some seam welds), sections shall be taken perpendicular to sheet surfaces along the weld longitudinal axis.
• Hardness traverses and indentation positions:
  • Two recommended traverse types: vertical + horizontal (legacy consistency) or oblique.
  • Horizontal traverse is positioned between t/4 and t/2 from the faying surface (t = plate thickness).
  • Vertical traverse should be at or near weld nugget centre to avoid shrinkage cavities.
• Equipment and calibration: Test machines and procedures must comply with ISO 6507 series (Parts 1–4) for method, verification, calibration and tables.
• Test reporting: Minimum items include reference to ISO 14271:2017, test type and force, indentation positions (sketch/photo), single and mean hardness values, welding process, conditions, equipment and material specification.

Applications and Users

Who uses ISO 14271:2017:

• Welding engineers and metallurgists performing quality control on resistance welds.
• Laboratories and inspection bodies conducting hardness characterization of spot, projection and seam welds.
• Automotive, appliance, aerospace and fabrication industries where resistance welding is common and hardness mapping of nugget/HAZ affects performance. Practical uses include weld qualification, process development, failure analysis and correlation of hardness profiles with mechanical properties.

Related Standards

• ISO 6507‑1, ‑2, ‑3, ‑4 (Vickers hardness test method, verification, calibration, tables)
• ISO 17677‑1 (Resistance welding vocabulary)
• ISO 14271:2017 was prepared by the IIW (International Institute of Welding) technical committee for fatigue of welded components.