Metallic materials — Sheet and strip — Determination of forming-limit curves — Part 1: Measurement and application of forminglimit diagrams in the press shop ISO 12004-1

Metallic materials — Sheet and strip —
Determination of forming-limit curves —
Part 1:
Measurement and application of forminglimit
diagrams in the press shop
ISO
12004-1

Introduction
A forming-limit diagram (FLD) is a diagram containing measured major/minor strain points on a formed part.
An FLD can distinguish between safe and necked, or failed, points. The transition from safe to failed points is defined by the forming-limit curve (FLC).
To determine the forming limit of materials, two different methods are possible.
1) Strain analysis of failed press shop components to determine component and process dependent
FLCs: In the press shop, strain paths to reach these points are generally not known. Such an FLC depends on the material, the component and the chosen forming conditions. This method is described in this
part of ISO 12004.
2) Determination of FLCs under well-defined laboratory conditions:
For evaluating formability, one unique FLC for the defined material is necessary. The determination
of FLC has to be specific and it is necessary to use different linear strain paths. This method should
be used for material characterization as described in ISO 12004-2.

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