Incremental ECAP as a Method to Produce Ultrafine Grained Aluminium Plates

摘要

In this work, we propose a new approach to producing ultrafine grained plates using a modified ECAP method, namely incremental ECAP. Unlike conventional ECAP, incremental ECAP works step by step whereby deformation and feeding are performed with two different tools acting asynchronously. Incremental processing reduces forces and allows to process relatively large billets. The major advantage of this technique is that the specimens are in the form of plates with a rectangular shape, which makes them suitable for further processing, e.g. via deep drawing. This paper reports a study on microstructure development, mechanical properties and their anisotropy in aluminium plates processed by means of incremental ECAP. Eight passes applied (with the accumulated strain of 9.2) with the rotation about the Z axis brought about the reduction in the grain size down to 600 nm with the 80% fraction of high angle grain boundaries and a very homogenous equiaxial microstructure. This, in turn, resulted in a significant increase in mechanical strength with the ultimate tensile strength reaching 200 MPa and, more importantly, very low anisotropy with respect to the rolling direction.