Characterization of the deformation field in large-strain extrusion machining

• A novel large strain extrusion machining (LSEM) method is developed in the paper.
• Based on the detailed observation, the constraint changes the velocity direction.
• A new model allowing for the extrusion process of constraint is proposed in LSEM.
• The new model is better consistent with the experimental data than Chiffre's model.

Large-strain extrusion machining (LSEM) has been emerged as a promising severe plastic deformation methodology for the creation of nano or ultra-fined grained materials. To realize deformation control, the key issue involved is the strain estimation in LSEM. In order to characterize the deformation field in LSEM, the experiments of LSEM oxygen-free high-conductivity copper were conducted by using a specially designed LSEM device. Based upon the deformation field measured by high speed imaging and digital image correlation (DIC), a new strain estimation model considering the extrusion process of constraint is proposed in this paper. The theoretical predicted strain agrees well with the measurements.