Overview
EN ISO 17642-3:2005 - "Destructive tests on welds in metallic materials - Cold cracking tests for weldments - Arc welding processes - Part 3: Externally loaded tests" specifies the implant (externally loaded) cold‑cracking test method used to assess the susceptibility of weldments to hydrogen‑induced cold cracking. The standard defines specimen and backing‑plate sizes, preparation, welding and loading procedures, and acceptance/reporting criteria. It applies primarily to C‑Mn and low‑alloy steels and to arc‑welding processes (SMAW, GMAW with solid or cored wire, SAW).
Key topics and technical requirements
- Test principle: implant specimen is welded into a backing plate, then subjected to a static tensile load during and after welding to produce/ reveal cold cracks.
- Specimen geometry:
- Backing plate typical dimensions: 20 mm thickness, 200 mm width, 300 mm length (specified tolerances apply).
- Implant diameters commonly 8 mm (6 mm allowed for small weld beads).
- Hole clearance (implant in backing plate): 0.05–0.15 mm sliding fit.
- Notch types: helical, circular or V‑notch with defined notch depth, radius and pitch.
- Welding requirements:
- Welds deposited in flat position, single pass, direction controlled; automated or mechanized welding required (manual not permitted except where controllable).
- Fusion penetration must locate the notch in the coarse‑grain HAZ.
- Heat input should be calculated (kJ/mm); preheat applied where required and backing plate/implant temperatures measured with thermocouples (temperatures must not differ by >5 °C).
- Loading and timing:
- Implant loaded in tension after welding following specified temperature rules; load must be set and maintained with ±1% accuracy, specimen largely free from bending/torsion.
- Holding time: minimum 16 h (or until fracture if it occurs).
- Measurements and detection:
- Cooling times t8/5 and t3/1 recorded (when applicable).
- Diffusible hydrogen measured per EN ISO 3690.
- Hardness of implant HAZ per EN 1043‑1 (HV‑10).
- Crack detection via metallography (400–600× on three longitudinal sections), oxidation + fatigue method, and fracture recording.
Applications and users
- Practical uses:
- Establishing minimum preheat, maximum diffusible hydrogen, maximum heat input or applied stress limits to avoid cold cracking.
- Welding procedure qualification, consumable selection, and R&D evaluation of new steels or filler metals.
- Failure investigation and quality assurance in fabrication of pressure vessels, pipelines, structural steel and heavy engineering components.
- Typical users:
- Welding engineers, metallurgists, materials laboratories, QA/QC personnel, NDT specialists, and standards/approval bodies.
Related standards
Keywords: EN ISO 17642-3:2005, cold cracking tests, implant test, externally loaded tests, welds, arc welding, diffusible hydrogen, preheat, heat input, C‑Mn steels.
