Effect of Cold Rolling on the Mechanical Properties and Formability of FSWed Sheets in AA5754-H114

Giuseppe Casalino,Michela Simoncini,Mohamad El Mehtedi,Archimede Forcellese

doi:10.3390/met8040223

Giuseppe Casalino, Michela Simoncini + Show 2 more

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https://doi.org/10.3390/met8040223

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Abstract

The effect of cold rolling, performed after friction stir welding (FSW), on the mechanical properties and formability of joints in AA5754-H114 aluminium alloy was investigated. Friction stir welding was carried out on 2.5 mm thick sheets with constant values of rotational and welding speeds of 1200 rpm and 100 mm/min, respectively. Then, FSWed workpieces were cold rolled, with the rolling direction perpendicular to the welding line, in order to obtain height reductions ranging from 0.1 to 0.5 mm. Cold rolling with the same height reductions was also carried out on the base material in the as-received condition. The mechanical properties and formability of both friction stir welded joints and base material, before and after cold rolling, were evaluated by means of the uniaxial tensile and hemispherical punch tests. The nominal stress vs. nominal strain and punch force vs. punch stroke curves were analysed in detail. Finally, the scanning electron microscope fractography was used to evaluate the fractured surface of tensile samples.

Highlights

Friction Stir Welding (FSW) is a solid state process developed for the obtaining of joints with higher mechanical properties and formability than those provided by fusion welding technologies [1,2,3,4,5,6,7,8].Manufacturing of multi-sheet structures obtained by assembling two or more blanks, using different materials and/or thicknesses, is the industrial field able to obtain the greatest benefits by FSW
The nominal stress vs. nominal strain curves of AA5754-H114 aluminium alloy in the friction stir welded (FSWed)+CRed condition are shown in Figure 2a in which the S-e plot of FSWed workpiece before cold rolling is reported for reference
For a given strain, the S value obtained by deforming FSWed+CRed samples is higher than that given by FSWed one; such discrepancy monotonically increases with ∆h

Summary

Introduction

Manufacturing of multi-sheet structures obtained by assembling two or more blanks, using different materials and/or thicknesses, is the industrial field able to obtain the greatest benefits by FSW. Another area of interest is represented by the joining of un-weldable alloys through fusion technologies [1,9,10,11,12,13]. The FSW process exploits the frictional heat generated between tool and workpieces, along with that generated by the stirring action of the tool and the adiabatic heat within the material, to promote a strong plastic deformation of the workpieces and their complex mixing across the weld [1,14,15,16,17,18,19]

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