Overview
ISO 17642-3:2005 - “Destructive tests on welds in metallic materials - Cold cracking tests for weldments - Arc welding processes - Part 3: Externally loaded tests” defines an externally loaded implant test to assess cold cracking sensitivity during arc welding. The standard specifies backing plate and implant specimen sizes, welding and loading procedures, and examination methods. It applies primarily to C–Mn and low alloy steels and to arc welding processes such as covered-electrode MMA, gas‑shielded metal‑arc (solid and cored wire) and submerged‑arc welding.
Key topics and technical requirements
- Purpose: Determine cold‑cracking sensitivity and crack/no‑crack boundaries for variables such as preheat, heat input, diffusible hydrogen and applied stress.
- Specimen geometry: Backing plate typical dimensions - 20 mm thickness, 200 mm width, 300 mm length. Implant diameters normally 8 mm (6 mm allowed for small beads) with a sliding fit clearance of 0.05–0.15 mm between implant and hole.
- Notch details: Notch types (helical, circular, V‑notch); notch angle (40 ± 2)°, depth (0.5 ± 0.05) mm, radius (0.1 ± 0.01) mm, pitch (1 ± 0.02) mm.
- Welding/deposition: Welds deposited in flat position, single pass, using automated/mechanized equipment (manual difficult to control is not permitted). Fusion should place the notch in the coarse‑grain HAZ.
- Preheat and temperature control: Backing plate and implant preheat must be measured with calibrated thermocouples; temperatures of implant and plate in the test area shall not differ by more than 5 °C.
- Loading procedure: Implant is subjected to a tensile static load applied soon after welding (reach specified load within 20–60 s), held for at least 16 h. The applied stress is related to the notch‑root cross section and is often chosen equal to the implant material’s Rp0.2. Load must be set/maintained with ±1% accuracy.
- Thermal cycle and hydrogen: Measure cooling times t8/5 and t3/1 where applicable; determine diffusible hydrogen per EN ISO 3690.
- Examination: If no gross fracture, metallographic examination at 400–600× on three longitudinal sections, oxidation/fatigue method (1 h at 250–300 °C) to reveal hidden cracks, and HAZ hardness per EN 1043‑1 (HV‑10).
Applications and users
ISO 17642-3 is used by:
- Welding engineers and metallurgists assessing susceptibility to hydrogen‑induced cold cracking
- QA/QC and NDT laboratories conducting welded joint qualification
- Consumable and procedure developers establishing allowable heat input, preheat and hydrogen limits
- Research labs comparing materials and welding processes for crack resistance
Practical outcomes include defining minimum preheat, maximum acceptable diffusible hydrogen, heat input windows and allowable applied stresses to avoid cold cracking.
Related standards
Keywords: ISO 17642-3, cold cracking tests, implant test, externally loaded, weld testing, C‑Mn steel, diffusible hydrogen, preheat, heat input, welding qualification.
Open preview (PDF)Destructive tests on welds in metallic materials — Cold cracking tests for weldments — Arc welding processes — Part 3: Externally loaded tests