ISO 148-2:2016

Overview - ISO 148-2:2016 (Charpy pendulum impact test - Verification of testing machines)

ISO 148-2:2016 specifies requirements and procedures for the verification of pendulum-type impact testing machines used for Charpy tests. It applies to machines fitted with 2 mm or 8 mm strikers and covers constructional elements, overall machine performance and the accuracy of absorbed-energy results. The standard addresses both common “industrial machines” and machines of higher stringency (reference machines are covered in ISO 148-3). Verification includes both static and dynamic approaches to ensure reliable Charpy impact testing.

Key topics and technical requirements

• Two verification methods
  • Direct (static) verification: measurement of critical machine geometry, pendulum mass/elevation, anvils, supports, indicating equipment and traceable calibration instruments (see Clause 6).
  • Indirect (dynamic) verification: use of reference test pieces to verify points on the absorbed-energy scale (see Clause 7). Requirements for these reference pieces are defined in ISO 148-3.
• Mandatory dual verification: A machine is not compliant until it has been verified by both direct and indirect methods and meets the requirements of Clauses 6 and 7.
• Energy accounting: the standard explains assessment of total absorbed energy as the sum of the energy to fracture the specimen plus internal energy losses of the machine (air resistance, bearing friction, pointer friction). Some internal loss sources (foundation shock, frame vibration) are noted as not currently measurable by suitable methods.
• Ancillary requirements: provisions for foundation/installation, pendulum geometry, anvils/supports, indicating equipment, frequency of verification, and the content of verification reports.
• Measurement uncertainty and calibration: informative annexes cover uncertainty analysis for both direct and indirect verification and methods (including a jig method) for geometric checks.

Applications and users

Who uses ISO 148-2:2016 and why:

• Materials testing laboratories - to ensure Charpy machines produce traceable, comparable results.
• Calibration and metrology labs - for machine verification against national standards.
• Manufacturers and fabricators - to validate test equipment used for material acceptance testing.
• Quality assurance / procurement - to define acceptance criteria when buying materials or specifying test methods.
• Standards bodies and researchers - for consistent inter-laboratory comparisons and reference-machine setup.

Practical benefits:

• Improves confidence in Charpy absorbed-energy results.
• Reduces disputes caused by machine-to-machine variability.
• Provides documented verification procedures and reporting practices.

Related standards

• ISO 148-1 - Charpy pendulum impact test - Part 1: Test method
• ISO 148-3 - Part 3: Preparation and characterization of reference Charpy V‑notch test pieces
• ISO 7500-1:2004 - Verification of static uniaxial testing machines (relevant calibration traceability)

Keywords: ISO 148-2:2016, Charpy pendulum impact test, verification of testing machines, direct verification, indirect verification, reference test pieces, pendulum impact testing machines.