Surface Roughening Behavior of 6063 Aluminum Alloy during Bulging by Spun Tubes

Abstract

Severe surface roughening during the hydroforming of aluminum alloy parts can produce surface defects that severely restrict their application in the automobile and aerospace industry. To understand the relation between strain, grain size and surface roughness under biaxial stress conditions, hydro-bulging tests of aluminum alloy tubes were carried out, and the tubes with different grain sizes were prepared by a spinning and annealing process. The surface roughness was measured by a laser scanning confocal microscope to evaluate the surface roughening macroscopical behavior, and the corresponding microstructures were observed using electron back-scattered diffraction (EBSD) to reveal the roughening microscopic behavior. The results obtained show that the surface roughness increased with both strain and grain size under biaxial stress. No surface defects were observed on the surface when the grain size was less than 105 μm if the strain was less than 18%, or when the grain size was between 130 and 175 μm if the strain was less than 15.88% and 7.15%, respectively. The surface roughening microscopic behavior was identified as an inhomogeneous grain size distribution, which became more pronounced with increasing grain size and resulted in greater local deformation. Concentrated grain orientation also results in severe inhomogeneous deformation during plastics deformation, and serious surface roughening.

Numerical Optimization of the Blank Dimensions in Tube Hydroforming Using Line-Search and Bisection Methods

“…Finally, the part weight and dimensional accuracy are enhanced [1,2,7]. For its characteristics, THF is suitable for aeronautic [9], automotive [10,11] and pipe fields, mono [12] and bilayered [13] ones, as in the production of tubular components for fluids delivery, aero-engine, engine cradles, anti-intrusion bars, radiator supports or nozzle production.…”

Quantification of the Morphological Signature of Roping Based on Multiscale Analysis and Autocorrelation Function Description

“…More recently, Lee et al [ 12 ] used the ridging height to examine the relationship between grain size and ridging for ferritic stainless steel (as-cast and cold-rolled). Other researchers compared roping levels by using standard parameters such as the average surface roughness R a ([ 13 , 14 , 15 , 16 ]), the root-mean-square amplitude R q ([ 17 ]), the maximum profile peak height R p ([ 14 ]) or the peak-to-valley roughness ([ 13 ]). Lefebvre et al [ 17 ] also computed the Fourier transform of the average two-dimensional roughness profile to identify characteristic wavelengths for roping.…”