Charpy Program
Summary:The Charpy impact test uses a swinging pendulum to assess the resistance of a material to fracture, and characterize the ductile-to-brittle transition in steel. The energy absorbed by the material being tested is measured by determining the energy lost by the pendulum during the impact. The low cost and simple configuration of the test have made it a common requirement in codes for critical structures such as pressure vessels and bridges. However, the test is not useful if the variation in test results between laboratories is not tightly controlled. The control is accomplished by requiring the indirect verification of impact machines. NIST certifies SRMs used for the verification of impact machines. Description:
The NIST Charpy Program provides certified reference materials (SRMs), supported by a traceable measurement system, to facilitate accurate predictions of structural steel reliability.
The program maintains an accurate target for the verification of absorbed energy measurements, supplies SRMs for the indirect verification of impact machines, assists our SRM users in meeting and documenting their contractual requirements for impact testing, and supports our customer's standardization needs. NIST SRMs for Indirect Verification of Charpy Impact Machines:
NIST SRMs for Indirect Verification of Izod Impact Machines:
The analysis of the indirect verification test depends on whether the SRM is provided with full or limited service. Please see the details for the particular SRM tested (above). Additional Technical Details:Major Accomplishments: |
 End Date:OngoingLead Organizational Unit:MSELFacilities/Tools Used:
ASTM E23 defines 3 of the NIST reference impact machines as the target for absorbed energy. The 3 reference machines are: (1) a 400 J AC-type, (2) a 360 J U-type, and a 400 J U-type machine.
Other pendulum impact machines serve a back-ups for the reference machines, and are used for research.
Useful Links Staff:Tom Siewert – Group Leader 
General Information: |