Thursday, November 7th, 2024 at 6:00 PM MDT
Lecture Room 202 in Hill Hall (920 15th St, Golden, CO 80401)
Please RSVP by Monday, November 4th, 2024 to asmrockymountain@gmail.com
The Charpy Verification Program at NIST: Ensuring Reliability and Consistency of Impact Machines Around the World
The Charpy impact test, which was introduced at the turn of the 20th century,
measures the energy absorbed by a standardized test piece as it is fractured by a swinging mass (hammer). This absorbed energy provides an indirect measure of fracture toughness of the tested material. Despite its relative ease of use, complex energy loss mechanisms are involved that make it impossible to verify test machine performance directly. Periodic testing of impact machines with certified test specimens is therefore necessary to indirectly verify machine performance. The Charpy Impact Verification Project provides certified standard reference materials (SRMs) for the indirect verification of Charpy impact machines that are supported by a traceable measurement system to facilitate accurate predictions of structural steel reliability. Three of the NIST reference machines in Boulder, CO are defined as the reference (master) machines according to ASTM Standard E23, and all ASTM E23 impact machine verifications are directly traceable to the NIST Charpy Verification Program. NIST has been providing this indirect verification service for 26 years, with the basic procedures dating back more than 35 years to the US Army arsenal in Watertown, MA. Currently the program services about 1600 customers in more than 60 countries around the world.
This talk will provide an overview of the operating procedures of the NIST Charpy program, as well as some historical information about the development of the Charpy test, and will show that the program, in conjunction with the requirements in ASTM E23, has produced a population of industrial impact machines with lower scatter than any other system in the world.