Innovative Stainless Steel Applications in transport ... - Euro Inox

values are shown in Table 20. A comparison between Table 19 and Table 20 shows that
if the values in brackets are used (including those in the highest strength category),
DIN 6935 values are too low for the C1000 grades and too high for the others.
Table 20. Minimum bending radii according to Ordenbach (1989).
Material t (mm) rmin (mm)
1.4318 C1000 (301LN) 1.9 4.75
1.4318 C850 (301LN) 1.0 1.0
1.4301SP 2B (304SP) 1.0 0.5
1.4318 C1000 (301LN) 1.2 3.0
1.4318 C850 (301LN) 1.5 1.5
4.1.1 Verification of minimum sheet bending radius
The minimum bending radius of the different grades has been investigated
experimentally, using bending machines and tools with different radii. After bending,
the outer surfaces of the samples were visually inspected for cracks. The results are
summarized in Table 21.
Table 21. Outer surface of V-bends for various materials (DOLTRAC p. 49). RD = rolling
direction, TD = transverse direction, OK = no macro cracks, NOK = cracks.
Material Direction Bending radius (mm)
R1 R1.5 R2 R2.5 R4
304SP 2B 1.0 mm RD OK - - - -
TD OK - - - -
1.4318 2B 1.0 mm RD OK - - - -
TD OK - - - -
1.4318 2H C850 1.5 mm RD OK - - - -
TD OK - - - -
1.4318 2H C1000 1.2 mm RD OK - - - -
TD OK - - - -
1.4318 2H C1000 1.9 mm RD OK - - - -
TD NOK NOK NOK OK OK
Visual assessment of the outer surfaces is difficult, however. Only large cracks could be
detected. Further bending investigations were performed using so-called T-tests. The
principle is explained schematically in Figure 54. The figure preceding T describes the
inner bending radius in terms of sheet-thickness multiples (e.g. for ½T the inner radius
is 0.5 times the sheet thickness).
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