An experiment study of the lubrication behavior of graphite in hot compression tests of Ti-6Al-4V alloy

The compression test has been used widely in obtaining flow stress data at hot working temperatures. In order to obtain reliable data, uniform deformation must be ensured by having adequate lubrication throughout testing. In this paper, the lubrication behavior of graphite was investigated by ring compression tests of Ti-6Al-4V alloy at temperatures from 750 to 1000 degreesC and constant strain rates from 0.05 to 15 s(-1). It was found that the friction factor m increases with the increase of temperature and with the decrease of strain rate. At temperatures below 800 degreesC, the friction factor m is less than 0.3, so that graphite can be used effectively as a lubricant in this range of temperature for compression tests. (C) 2001 Elsevier Science B.V. All rights reserved.