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[Display omitted] • Chips produced in cutting of pure iron turns into grains at cutting speed 8000 m/min. • Above 8000 m/min chips are formed by transgranular and intergranular fractures. • High ductile metals can be fabricated brittlely with a high deformation rate. Many materials have high-strain-rate-embrittlement effect (HSREE). This study tries to find weather the HSREE takes place in the high-strain rate deformation of a high ductile material pure iron DT8 to assess the possibility to cut the pure iron in its brittle state. Orthogonal high-speed cutting experiments were carried out with the highest cutting speed up to 9000 m/min. Chip formation by brittle fracture mechanism was captured when the cutting speed is higher than 8000 m/min. Brittle fracture characteristics, including transgranular and intergranular fracture morphologies in the chips at 8000 m/min show the pure iron becomes completely brittle at cutting speed of 8000 m/min. The result shows that it is possible to cut the high ductile material pure iron in its brittle state to avoid the problems incurred by its high ductility. [ABSTRACT FROM AUTHOR]

The contact stress and heating effect between the cutting tool and workpiece in metal machining is symmetrical. However, the symmetry may be destroyed by changes in the workpiece material mechanical properties, such as ductility. The goal of this study is to reveal the wear characteristics of the cutting tool in machining a ductile metal with the cutting speed at which the metal is embrittled by the high-strain-rate-embrittle effect (HSREE). Orthogonal high-speed turning experiments were carried out. Pure iron type DT8 was cut at different cutting speeds, ranging from 1000 m/min to 9000 m/min. The shape and morphology of the chips obtained in the experiment were observed and analyzed by optical microscope and scanning electron microscope (SEM). Tool wear characteristics at different cutting speeds were observed. It shows that the pure iron becomes completely brittle when the cutting speed is higher than 8000 m/min. On the rake face, the coating of the cutting tool bursts apart and peels off. A matrix crack originates in the cutting edge or rake face and extends to the flank face of the cutting tool. The effects of HSREE on the tool wear is discussed. The findings of this study are helpful for choosing a suitable tool for brittle cutting of the ductile metal pure iron with very high cutting speed and solving the problems in machining due to its high ductility and high stickiness. [ABSTRACT FROM AUTHOR]