Abstract
Since flow stress characteristic of material is the key factor in the analysis of cutting performance, an impact compression test of difficult-to-machine materials was conducted at high temperature and strain rate, which are usually observed in the shear zone of machining. History effects of strain rate and temperature upon flow stress were also investigated. As the result, constitutive equations of titanium alloy, stainless steel and nickel base superalloy are obtained in terms of strain rate, temperature and their history effects. It is found that these materials have very high flow stress and that the history effects are similar to those of α-brass reported previously. Yield stress and strain hardening of titanium alloy are high, but its fracture strain is small. Flow stress of stainless steel varies considerably with straining conditions, especially temperature, while little does so that of nickel base superalloy. A qualitative evaluation of tendency toward adiabatic deformation in terms of Pklet number and flow stress characteristic reveals that titanium alloy is more likely, to produce saw-toothed chips than others, and nickel base superalloy and stainless steel are ranked next in due order.
