Determination of the Interface Heat Transfer Coefficient for Non-Isothermal Bulk-Forming Processes

Abstract

Experimental and analytical techniques have been developed for the determination of the interface heat transfer coefficient for nonisothermal bulk-forming processes. A fixture consisting of two flat IN-100 alloy dies was instrumented with high-response thermocouples. With this tooling, heat-transfer experiments were conducted in which (1) the two dies were heated to different temperatures and brought together under varying pressure levels and (2) the two dies were heated to the same temperature and were used to upset an aluminum alloy 2024-0 ring specimen heated to a higher temperature. Data from both sets of tests were analyzed to determine heat-transfer coefficients by using calibration curves derived from analytical and finite-difference method solutions. By this means, the effects of interface pressure, deformation, and deformation rate on the heat-transfer coefficient were established.