A comprehensive study on soundness, microstructure, and uniformity of 2024 aluminum cups hydro-mechanically drawn at elevated temperatures

Abstract

In the present research work, the hydro-mechanical deep drawing (HMDD) process of 2024 aluminum alloy is performed experimentally and numerically for elevated temperatures. The main variables of the forming process include the uid pressure, the pre-bulge pressure and the process temperature. The effects of these parameters on the thickness distribution and uniformity index of the nal product have been investigated. Using the hardness test, the preferred crystallographic orientation, the energy dispersive spectroscopy and microstructure images obtained from an optical microscope and a scanning electron microscope, the relationship between the grain size, hardness and the effective plastic strain are studied and discussed. The ndings imply that the HMDD process without the pre-bulge pressure reduces the uniformity of the nal product and, on the other hand, excessive increase in this parameter causes tearing of the workpiece. The hardness distribution along the cup wall was in agreement with grain re nement and the Hall-Petch relationship, but it was not correspond to the expectations made via the texture analyses. The images gained from the energy dispersive spectroscopy for different areas of the 2024 Al sample demonstrated that the Al 2 Cu precipitations in the product wall were ner than the other areas and mainly dispersed at the grain boundaries. This type of precipitation distribution was the main origin for increasing the hardness of the cup wall in comparison with the cup corner and bottom. In other words, the precipitation hardening overwhelmed the in uence of the preferred orientation of the grains in HMDD operation of Al 2024.