A New Ultrasonic-Assisted Simple Shear Extrusion Process in Production of Ultrafine Grained Copper

Abstract

In this research, a hybrid method of a simple shear extrusion (SSE) process is proposed with simultaneous application of ultrasonic vibrations at the beginning of the deformation zone in pure copper. A cylindrical-conical-cylindrical horn was designed to amplify and transmit the ultrasonic vibrations using modal analysis in Abaqus. The resonant frequency of 20.332 kHz was used with two amplitudes of 15 and 25 micrometers. Then, the produced ultra-fine grain copper samples after the first pass with and without ultrasonic vibrations were compared. A 54% and 65% reduction in grain size were reported in ultrasonic-assisted simple shear extrusion (USSE) with two amplitudes of 15 μm and 25 μm, respectively. Also, a significant increase in microhardness values in the USSE method compared to the SSE method indicated that the hardness increases significantly by increasing the amplitudes under the influence of acoustic hardening. In addition, the required force to extrude the samples with the presence of ultrasound was reduced under the effect of acoustic softening. In addition, finite element simulation of both SSE and USSE processes was performed in Abaqus/Explicit software. Higher equivalent plastic strain and plastic deformation along the length of the sample were reported in the USSE method. Additionally, in the USSE method compared to the SSE method, the maximum plastic strain distribution was improved by applying ultrasonic vibrations.