An investigation of resolved shear stress on activation of slip systems during ultraprecision rotary cutting of local anisotropic Ti-6Al-4V alloy : models and experiments

Abstract

Ti-6Al-4V alloy with local anisotropic characteristics is produced by electropulsing treatment (EPT) and used in ultraprecision rotary diamond cutting to explore the deformation mechanism of the alloy. Two different orientations of lamellar martensite α give rise to the local anisotropic behaviour. Critical resolved shear stress (CRSS) is introduced in this paper to investigate the slip modes of the hexagonal closest packing martensite. A geometrical and physical model is also proposed for calculation of resolved shear stresses on various slipping systems. The results show that glide occurs in some certain directions on the condition that resolved shear stress equals or exceeds the CRSS. The cutting force varies with martensitic orientations, which is supposedly due to the combined effects of lamellar α phase sizes and the coordination or competition of diverse slipping directions.