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Stainless Steel 316L Bent Plate

Stainless Steel 316L Bent Plate

Stainless Steel 316L Bent Plate

(OP)
Does anyone know of any minimum bend radii requirements for stainless steel type 316L.

RE: Stainless Steel 316L Bent Plate

(OP)
Thanks Aviat.
The plate I'm using is 1/2" thick though.

RE: Stainless Steel 316L Bent Plate

To what specification was the 316L was supplied?
Is it hot rolled or cold rolled to a certain hardness? TS, YS and elongation?
 As the amount of hard working increases, elongation and bendability decrease, so minimum bend radius increases.  

ASTM A666 gives the following data for 316L  (UNS S31603):
Condition    YS, ksi      TS, ksi    % elongation
Annealed       25           70             40
1/16 Hard      45           85             35
1/8  Hard       55         100             25
¼    Hard       75         127              8
½    Hard      110        150              6


ASTM A666 only gives bend test requirements for thicknesses up to 0.1874”.

ASTM A480 gives requirements for 316L supplied in the solutionized-annealed state. YS, TS and elongation are the same as given above for the annealed state in A666 (and also ASTM A167 & A240).
ASTM A480 Bend Test requirements are given in paragraphs 13.3 and 13.4:
13.3.1  [Unless otherwise agreed] “the axis of bend shall be parallel to the direction of rolling.”

13.3.7  The bend test specimen shall withstand cold bending through the bend angle specified without cracking on the outside of the bend.

13.4.2    Material over 3/8” [9.5 mm] and up to and including 1 in. [25.4 mm] in thickness shall be bent over a piece (or pieces) of flat stock equaling two times the thickness of the material being tested (2T), allowing the test material to form its natural curve.”

So, if you have hot rolled material, it is close to the annealed condition, and an inside radius slightly greater than 1” (liberal interpretation of para. 13.4.2).  
If the material has been cold rolled to ¼ hard, estimating from the elongation values of ASTM A480, the inside radius should be 5X that of the annealed state, i.e., 5 inches.  
If ½ hard, use an inside radius of 7 inches.

Alternatively, calculate the inside radius of curvature such that the given % elongation is not exceeded in the outer surface. This gives slightly more conservative values.  
For the 40% elongation value of the annealed condition, a simplified solution gives r + 0.5” = 1.40 r, so r = 1.25”.
For 8% elongation, r = 8.33 inches.

Hope this helps,
Ken

RE: Stainless Steel 316L Bent Plate

Have you been able to find any good references for stainless steel in general?  I'm trying to find out the minimum bend radius for 304 stainless.  Any help would be appreciated.

RE: Stainless Steel 316L Bent Plate

(OP)
Try the Specialty Steel Industry of North America's website.
www.ssina.com

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