ISO 148-1:2016

Overview

ISO 148-1:2016 - Metallic materials - Charpy pendulum impact test - Part 1: Test method - defines the standardized Charpy pendulum impact test procedure for determining the energy absorbed when a notched metallic specimen is fractured by a swinging pendulum. The standard covers both V‑notch and U‑notch specimens, specimen preparation, test equipment and operation, temperature control, and post‑test inspection. Instrumented impact testing is excluded (see ISO 14556). Annexes B and C draw on ASTM E23 with permission.

Key topics and requirements

• Test principle: Single blow from a pendulum hammer breaks a notched specimen; absorbed energy is measured (often reported as KV or KU for V and U notches).
• Specimen geometry: Standard specimen is 55 mm long with a 10 × 10 mm square cross‑section; sub‑size specimens (thicknesses 7.5 mm, 5 mm, 2.5 mm) are permitted when full size cannot be obtained.
• Notch preparation: Precise V‑ or U‑notch geometry and careful machining (no damaging marks at the root) are required for reproducible results.
• Test equipment and verification: Pendulum machine installation, striker type (different radii are specified), verification and friction checks are addressed (see ISO 148-2 for machine verification).
• Temperature control: Because absorbed energy commonly varies with temperature, specimens must be conditioned to the specified test temperature and transferred under controlled conditions.
• Measured outputs: Absorbed energy, lateral expansion, and shear fracture appearance are typically reported; incomplete fractures and jamming procedures are covered.
• Reporting: The test report must include key information about specimen, notch type, test temperature, equipment, and measured energy to ensure comparability.

Applications and users

ISO 148-1:2016 is widely used by:

• Materials testing laboratories and third‑party test houses for toughness and quality control
• Metallurgical and mechanical engineers assessing material performance at various temperatures
• Manufacturers in steel, aluminum and alloy production for routine pass/fail acceptance testing
• Welders and fabricators evaluating welded joint toughness
• Research and academic programs studying fracture behavior and transition temperature

The Charpy pendulum impact test is especially valuable for defining transition temperature, screening batches, and comparing material heat treatments.

Related standards

• ISO 148-2: Verification of testing machines
• ISO 148-3: Preparation and characterization of Charpy V‑notch specimens
• ISO 14556: Instrumented impact testing (excluded from Part 1)
• ASTM E23: Source for annex material (Annexes B and C)

Keywords: ISO 148-1:2016, Charpy pendulum impact test, metallic materials, V‑notch, U‑notch, absorbed energy, impact testing, transition temperature, specimen geometry.