Overview
ISO/TR 17641-3:2005 - "Destructive tests on welds in metallic materials - Hot cracking tests for weldments - Arc welding processes - Part 3: Externally loaded tests" describes standard test methods and procedures for externally loaded evaluations of hot cracking susceptibility in weldments. The Technical Report documents three principal externally loaded techniques: the hot tensile test, Varestraint / Transvarestraint tests, and the flat tensile (programmable deformation/PVR) test. Assessment is centred on measuring the brittle temperature range (BTR) where hot cracks form. The guidance applies primarily to austenitic stainless steels, nickel and nickel‑base alloys, and nickel‑copper alloys, and can be extended to other materials by agreement.
Key topics and technical requirements
- Test types covered
- Hot tensile test (Procedure A for solidification cracking; Procedure B for HAZ liquation cracking). Specimen sizes are defined (e.g., 130 mm × 10 mm for solidification, 110 mm × 6 mm for liquation).
- Varestraint and Transvarestraint tests - externally imposed deformation during solidification to reveal solidification and ductility‑dip cracking.
- Flat tensile / PVR test - programmable deformation to detect critical strain for first crack.
- Measurement and assessment
- Critical parameters include BTR, nil strength temperature (NST), ductility recovery temperature (DRT) and crack length/critical strain metrics.
- Tests impose external loads to create measurable strain and strain rate during BTR; results are quantitative and useful for ranking materials and consumables.
- Test environment
- High‑temperature tests require controlled atmospheres (e.g., specimens back‑filled with argon, oxygen ≤ 0.1 %).
- Limitations
- Methods do not exactly replicate all welding conditions (restraint, thermal cycles) and inter‑laboratory equipment differences limit absolute reproducibility. Tests are intended primarily for ranking and comparative evaluation.
Applications and users
- Practical uses:
- Material selection and qualification for weld metal, parent materials and welding consumables.
- Welding procedure development and validation to minimize solidification, liquation and ductility‑dip cracking.
- Assessment of multipass weldments and HAZ susceptibility.
- Typical users:
- Welding engineers, metallurgists, QA/QC laboratories, welding consumable manufacturers, and R&D teams addressing high‑alloy fabrications (stainless steel and nickel‑base systems).
Related standards
- ISO 17641 series:
- Part 1 - General (EN ISO 17641‑1:2004)
- Part 2 - Self‑restraint tests
- Part 3 - Externally loaded tests (this Technical Report)
Keywords: ISO/TR 17641-3:2005, hot cracking tests, Varestraint, Transvarestraint, hot tensile test, flat tensile test, brittle temperature range, weldability testing, austenitic stainless steel, nickel alloys.