Deformation mechanisms and constitutive modeling for silicon nitride undergoing laser-assisted machining

Material deformation behavior has been studied for silicon nitride containi ng 10 wt% of YSiAlON glass under laser-assisted machining (LAM). Material r emoval mechanisms were inferred from scanning electron microscopy observati ons of the chips, and the shear zone stress was determined using three-dime nsional machining theory with a new approach to determining shear angles fo r segmented chips formed in LAM. The effects of operating conditions on the shear zone stress were determined from an experimental parametric study, a nd the results were used to develop a constitutive equation for the deforma tion process. (C) 2000 Elsevier Science Ltd. All rights reserved.