On the values of material property data used in hot isostatic pressing models

Abstract

Hot Isostatic Pressing (HIP) is used extensively for consolidation of powers and particulates and near net shape fabrication of powder metallurgy products. The last few years have seen significant refinement of the HIP model proposed by Ashby and co-workers. It has been acknowledged by the developers of the maps that the accuracy of the predictions is limited by the precision with which material property data, used in the HIP Maps program are known. Even for materials processed similarly, there are, typically, variations in the values of material properties due to the inherent inaccuracies in the methods used to determine these properties. Such variations significantly affect the accuracy of the HIP model predictions. The objective of the present investigation is to determine the effect of variations in the values of material properties on the HIP model predictions by performing a sensitivity analysis with respect to material property data. The values for material property data used in the HIP Maps program are typically determined in one of the following ways: (a) experimental measurements at consolidation conditions; (b) estimates based on data on other materials; (c) through back calculations using the experimentally determined HIP data; and (d) by extrapolations to get appropriate materialmore » property values for the consolidation conditions. Methods other than (a) could result in the determination of a material property value which is highly unrealistic. The present study discusses this with respect to a recent experimental study [10] on TiAl and resolves the discrepancy by using PLC material parameters determined experimentally for conditions close to the actual HIP process conditions.« less