Enhancing surface quality in cutting of gummy metals using nanoscale organic films

A macroscopic ductile-to-brittle transition in chip formation with ductile gummy metals, arising from 3.5 to 100 nm thick organic films on the workpiece surface, is demonstrated. The principal characteristics of phenomenon, annealed aluminum, are change flow mode one dominated by large-strain plasticity controlled fracture; and up 70% reduction cutting force. This embrittlement has important benefits for machined surface quality – nearly an order magnitude roughness, > 50% residual plastic strain, smaller hardness change. Implications phenomenon material removal processes beyond discussed.