Quality Control Specimens
MPM can supply low cost Charpy Quality Control Specimens (QCS) prepared in conformance with ASTM E 23 for internal test machine performance verification. The specimens provided are manufactured using the same materials as the NIST verification specimens used for yearly test machine verification. The energy ranges cover the standard verification energy ranges: Low – 13 to 20 J; High – 88 to 136 J; and Super High – 176 to 244 J. As with the NIST specimens, acceptable machine performance will produce average values within 1.4 J or 5 % of the MPM supplied energy values. While the QCS specimens are not intended for annual machine verification, they are very useful for periodic machine performance verification.
When the quality control specimens are delivered, MPM provides a data sheet similar to the one shown below. The data provide the opportunity to compare results from customer test machines with MPM test machines, which are traceable to NIST through the MPM Quality Assurance Program.
Heat LA1 (Low Energy)
Charpy Impact Test Data for Low Impact Energy 4340 Steel Specimens Conducted at RT and -40 C
Rockwell C Hardness Data for this Heat Resulted in an Average of 45.2 with a Standard Deviation of 0.36.
NOTE: It is recommended that low energy quality control testing for U-hammer test machines be performed at -40 C since the specimens exit the rear of the machine and thereby minimize interaction with the striker which can result in larger data scatter.