The Influence of Rate of Strain-Hardening in Machining

Abstract

In order to determine the influence of the rate of strain-hardening (that is, rate of increase of flow stress with straining) on the machining process, cutting tests were carried out on a material with a high rate of strain-hardening and on a material with a relatively low rate of strain-hardening. All external parameters of the process such as cutting force, chip thickness ratio, angle of tool-chip interface friction etc., were measured and a slip-line analysis of the plastic zone was made using strain-hardening slip-line theory. It was found that although externally the process was virtually the same for each material the plastic zones were distinctly different. The relation between the stress distribution in the plastic zone and an independently obtained stress-strain curve of the machined material was clearly shown. Finally new suggestions were made regarding the nature of the tool-chip interface contact.