The NIST Pulse-Heated Kolsky Bar Laboratory has been developed for the measure-ment of dynamic properties of metals, primarily for application to the study of high-speed machining processes. Because the work material in these processes can be subjected to extremely rapid heating, followed by rapid cooling, our research program has been di-rected in part at studying the influence on flow stress of the heating rate and the time-at-temperature prior to impact in rapid compression tests on carbon steels. The unique pulse heating capability of the NIST Kolsky bar system enables rapid uniform pre-heating of an experimental test sample from room temperature to several hundred de-grees C in less than a second, and then maintaining a set temperature for several sec-onds, prior to a Kolsky bar test. Although the heating rates obtained using this method are still orders of magnitude smaller than metal-cutting process heating rates, they are significantly higher than have been achieved with the more conventional testing meth-ods that are currently being used for the determination of the mechanical constitutive properties of metals. We present new results from pulse heated Kolsky bar tests on AISI 1075 steel, which demonstrate that this rapid heating technique reveals constitutive re-sponse behavior that cannot be predicted by the Johnson-Cook flow stress model that is widely used for the simulation of high-speed machining processes.
Proceedings Title: Proceedings of the 12th CIRP Conference on Modelling of Machining Operations
Conference Dates: May 7-8, 2009
Conference Location: San Sebastian, -1
Conference Title: 12th CIRP Conference on Modelling of Machining Operations
Pub Type: Conferences
metal cutting, AISI 1075, material behavior, SHPB, strain, strain rate, temperature, Johnson-Cook