The Effect of Hydraulic Bulge Process on the Surface Topography of Annealed AISI 304 Stainless Steel

• Published in: Procedia manufacturing Vol. 10; pp. 243 - 252
• Main Authors: Olayinka, Ayotunde, Emblom, William J., Pasacreta, Thomas C., Wagner, Scott W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2017
• Subjects: Hydraulic bulge forming; Multiscale; Sheet metal; Surface-roughness; Surface-roughness; Hydraulic bulge forming; Sheet metal; Multiscale
• ISSN: 2351-9789; 2351-9789
• DOI: 10.1016/j.promfg.2017.07.052

In this study, the relationship between surface topography and strain was established for annealed 0.2mm thick AISI 304 stainless steel sheet that had been hydroformed. The effect of the die diameter on the surface topography was also examined. Sheets were bulged using stepwise application of hydraulic pressure; forcing the sheet metal through 5mm and 11mm diameter open dies. The strains at the pole of the bulge of the work pieces were determined analytically using the Jovane analytical method, this was achieved by measuring the height of the pole of the bulge for every applied hydraulic pressure for a particular die. The surface topography at the micro level was found by scanning the bulge of the sample using an atomic force microscope over an area of 60μm × 60μm. The results of this study indicate that the bearing ratio was unaffected by the change in strain for both the 5mm die and the 11-mm diameter dies and that roughness decreases as the diameter decreases for similar strains. The average, root mean square, peak-to-peak roughness and the maximum depth of the surface profile show a linear relationship with the strain