1. Specimen Preparation and Dimensional Requirements
Specimen Type: Preferred are standard Charpy V-notch specimens with dimensions of 10 × 10 × 55 mm, a notch angle of 45° ± 2°, and a root radius of 0.25 mm.
Machining Precision: The notch root must avoid burrs and work hardening. Precision cutting or electrospark machining is recommended.
Temperature Control: For low-temperature impact testing, specimens must be held in a cooling medium (e.g., liquid nitrogen) for at least 5 minutes (extended to 15 minutes for -196°C).
New Requirements (2025 Edition):
Specimen processing parameters (e.g., tool type, feed rate) must be digitally recorded and must comply with ASTM E3066 data traceability standards.
2. Testing Machine Calibration and Verification
Energy Range: The testing machine's rated energy must cover the expected impact energy (typically ≥ 300 J). Regular calibration is recommended, as per ASTM E23 Appendix A1. Pendulum Speed: The pendulum linear velocity at the moment of impact should be 3.0–5.0 m/s, verified weekly using a photoelectric velocimeter.
Anvil Gap: Ensure the support span is 40.0 ± 0.2 mm, and the anvil corner radius is 1.0–1.5 mm.
Common Errors:
Failure to promptly replace worn pendulum blades (resulting in higher energy absorption values).
3. Testing Environment and Operating Specifications
Temperature Uniformity: During low-temperature testing, the specimen cooling tank temperature fluctuation must be ≤ ±1°C (a mixture of alcohol and dry ice is recommended).
Transfer Time: The interval between specimen transfer from the cooling tank to the testing machine must be ≤ 5 seconds (an automatic transfer device must be used for high-temperature testing).
Data Recording: The fracture morphology (e.g., complete fracture, partial fracture) and lateral expansion value must be recorded.
Safety Tips:
When working with liquid nitrogen, wear antifreeze gloves, and set up a safety enclosure around the testing machine. 4. Data Interpretation and Reporting Requirements
Invalid Data Determination: If the specimen does not completely break or the hammer is stuck, note the failure and retest.
Result Rounding: Impact energy values are rounded to 1 J/cm², and lateral expansion values are rounded to 0.1 mm.
Report Content: Must include specimen orientation (e.g., transverse/longitudinal), test temperature, and standard number (ASTM E23-25).
Industry Practice:
Petroleum pipeline steel generally requires an impact energy ≥ 40 J at -40°C (referring to API 5L standard).
5. Interoperability with Other Standards
ISO Comparison: ASTM E23 is equivalent to ISO 148-1, but differs in specimen size and energy units (ISO uses joules, while ASTM typically uses ft-lbf).
Material Standard References: For example, the impact test section of ASTM A370 (Mechanical Testing of Steel Products) directly references the E23 method.
Special Applications: Nuclear power materials (e.g., ASME SA-508) may require an additional drop hammer test (ASTM E208).
