Experimental investigation of pure aluminum sheets processed by constrained groove pressing

Abstract

Recently, a new severe plastic deformation method named constrained groove pressing (CGP) has been invented for producing ultra-fine grained sheet metals. Here, a multi-pass CGP is carried out on 1060 commercially pure aluminum sheets. Through a series of experimental research, the evolutions of microstructure, tensile properties, forming load and surface residual stress during the process are investigated. The grain size is greatly refined from 29 μm of annealed samples to about 18 μm after pass four. Polygonized and dislocation-free substructures of submicron level with well-defined boundaries is obtained. The ultimate tensile strength and yield strength increase continuously until pass three and then decrease by further deformation. Residual tensile stress is observed on the surface of all pressed samples due to the unique stress-strain state, and it increases dramatically during the first pass. The results show that lubrication reduces the average residual tensile stress and its distribution homogeneity along the longitudinal direction.