2
$\begingroup$

What does one have to look out in material properties when changing material grade in cold sheet forming operation (example: from DC04 to DC03 or to DC01). Operation is mostly made of 90°bends and punching (16 mm parts).

file:///C:/Users/abraniselj/Downloads/voestalpine_range_of_supply_cold-rolled_steel_strip_EN_270319.pdf

$\endgroup$
7
  • 1
    $\begingroup$ The springback, see engineering.stackexchange.com/q/47441/10902 $\endgroup$
    – Solar Mike
    Sep 27 at 10:18
  • 1
    $\begingroup$ They look very similar. Per your table, DC04 controls the additional parameter n_90, which has to do with strain hardening. A quick search shows this is relevant to deep draws. If you are optimizing a formed part, it may matter. If you're putting some bends with the radius from a table of recommended values for generic cold rolled steel, probably not. Not sure about the punching. Don't hesitate to call the material vendor! $\endgroup$
    – Pete W
    Sep 27 at 20:38
  • 1
    $\begingroup$ I should say, though, when having to modify a part someone else designed, and an unfamiliar material was picked, you should always ask why this material was picked. Often there's a good reason. $\endgroup$
    – Pete W
    Sep 27 at 20:58
  • 1
    $\begingroup$ Part is our own and the material change is purely economic improving delays and price. I have come across the fact that Rp0,2 and Young's modulus are the leading properties when it comes to springback. Does then a high fluctuation of Rm have a big impact on the springback fluctuation - seeing it can move the amount of spingback based on Young's modulus? (nice explanation: materion.com/-/media/files/alloy/newsletters/technical-tidbits/…) $\endgroup$
    – branexius
    Sep 28 at 5:38
  • 1
    $\begingroup$ nice link. also from there, talking about r and n values: materion.com/-/media/files/alloy/newsletters/technical-tidbits/… $\endgroup$
    – Pete W
    Sep 28 at 12:43
1
$\begingroup$

Springback will mostly be controlled by yield strength. And because all three materials have the same minimum yield (140 Mpa), the only option is to bend samples. You could get identical results with all three materials. Also , your material supplier has poor process control ; notice DC 01 has a range of yield from 140 to 280 MPa. You need luck or a new material supplier.

$\endgroup$
3
  • $\begingroup$ The yield strenght range is standard for these grades of steel usually expressed as only the max value of Rp0,2 (these specifications are from a random site btw). I agree with what you have said tho and this should be the main concern. What I am now thinking about is the influence of the range of tensile strenght. Assuming that the Young's modulus doesn't change would this mean that we have a larger springback effect with higher tensile strenght? See image in the link for visualisation. imgur.com/a/pFV9UNs $\endgroup$
    – branexius
    Sep 29 at 5:54
  • $\begingroup$ Tensile strength is the force applied to fracture a material; Presumably you do not want to fracture the sheet metal. $\endgroup$ Sep 29 at 14:26
  • $\begingroup$ Rm is just a specification but knowing it is higher means that all the forces up to that point are also higher (look at the red line in my previous linked image). This then means that the springback effect could be larger since according to the Young's modulus we follow the same inclination when unloading the part as when loading (see blue line in image). My worry here is that if you have a range 270-410 MPa then we might be facing quite a large range of springback angles which might give us issues in large serials where a lot of rolls of material are used. $\endgroup$
    – branexius
    Sep 29 at 19:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.