ASTM E2218-14e1
Standard Test Method for Determining Forming Limit Curves

Standard No.

ASTM E2218-14e1

Release Date

2014

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E2218-15

Latest

ASTM E2218-23

Scope

5.1 A forming limit curve (FLC) defines the maximum (limiting) strain that a given sample of a metallic sheet can undergo for a range of forming conditions, such as deep drawing, stretching and bending over a radius in a press and die drawing operation, without developing a localized zone of thinning (localized necking) that would indicate incipient failure.

5.1.1 FLCs may be obtained empirically by using a laboratory hemispherical punch biaxial stretch test and also a tension test to strain metal sheet specimens from a material sample beyond their elastic limit, just prior to localized necking and fracture.

5.1.1.1 Since this cannot be predetermined, one or both surfaces of specimens are covered with a grid pattern of gauge lengths usually as squares or small diameter circles, by a suitable method such as scribing, photo-grid, or electro-etching, and then each specimen is formed to the point of localized necking, or fracture.

5.1.2 Strains in the major (e₁) and minor (e₂) directions are measured using points on the grid pattern in the area of the localized necking or fracture.

5.1.2.1 Blanks of varied widths are used to produce a wide range of strain states in the minor (e₂) direction.

5.1.2.2 The major (e₁) strain is determined by the capacity of the material to be stretched in one direction as simultaneous surface forces either stretch, do not change, or compress, the metal in the (e₂) direction.

5.1.2.3 In the tension test deformation process, the (e₂) strains are negative and the metal is narrowed both through the thickness and across its width.

5.1.3 These strains are plotted on a forming limit diagram (FLD) and the forming limit curve (FLC) is drawn to connect the highest measured (e₁ and e₂) strain combinations that include good data points.

5.1.3.1 When there is intermixing and no clear distinction between good and necked data points, a best fit curve is established to follow the maximum good data points as the FLC.

r for Sheet Metal

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ASTM E2218-14e1 history

• 2023 ASTM E2218-23 Standard Test Method for Determining Forming Limit Curves
• 2015 ASTM E2218-15 Standard Test Method for Determining Forming Limit Curves
• 2014 ASTM E2218-14e1 Standard Test Method for Determining Forming Limit Curves
• 2014 ASTM E2218-14 Standard Test Method for Determining Forming Limit Curves
• 2002 ASTM E2218-02(2008) Standard Test Method for Determining Forming Limit Curves
• 2002 ASTM E2218-02 Standard Test Method for Determining Forming Limit Curves

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