FORMABILITY OF STAINLESS STEEL TAILORED BLANKS

摘要

As tailored blanks, AISI 304 and AISI 316, nearly have identical levels of formability. In arnnumber of systematic tests, the formability of tailored blanks consisting of even and differentrncombinations of AISI304 and AISI 316 in thickness of 0.8 mm and 1.5 have beenrninvestigated.rnIn order to analyse the formability of tailored blanks with different sheet thickness, a methodrnbased on bulge testing was developed by IPU. The bulge tests performed were all made inrnorder to analyse the strain range above zero, thus establishing points in the right side of thernso-called Forming limiting diagram (FLD).rnIn the investigations, three different types of bulge testing were performed. Initially, the fourrntypes of base materials were formed. Then a series of different welding speeds test was madernin order to identify and optimise the welding speed. Finally a series of tailored blanks wasrnmade, with both AISI 304 and AISI 316 welded in the combination 0.8 mm to 1.5 mm.rnThe results showed that AISI 316 generally has a better formability in the strain range thanrnAISI 304. The improvement in strain is typically 5 to 10 %.rnThe tests showed that generally there is not a large difference in formability at differentrnwelding speeds. A small (max. 5 percent) improvement may be found at speeds of 6 or 7.2rnm/min. as compared to speeds of 3 to 4 m/min.rnA reduction in formability of welded sheets is observed as compared to the base material. Arnlarge reduction is especially seen for AISI 316, which is reduced as much as 50 % asrncompared to the formability of a 0.8 mm base material.