A method for testing elongation at break of metal materials

Abstract

The present invention discloses a method for testing elongation at break of a metal material. The method comprises the following steps: labeling a metal material requiring detection as a plurality of equal parts along a stretching direction, labeling a position of every separation point on a longitudinal center line of the metal material requiring detection along the stretching direction, and recording a distance between the two adjacent separation points before stretching as a; respectively measuring a distance between the two adjacent separation points of every part of the broken metal material, recording the distance as a1, and respectively selecting and labeling points having a local elongation of more than a preset value according to a local elongation between the two adjacent separation points and requirements; measuring a distance between critical points having a local elongation of more than a preset value, recording the distance as Lp, and recording an original distance between the critical points as Lo; and calculating elongation at break Ap according to the following formula: Ap=((Lp-Lo) / Lo)*100%. With the method, molding abilities of different metal materials having the same elongation at break can be distinguished, and the method is simple.

Description

technical field [0001] The invention relates to a method for testing the elongation at break of metal materials. Background technique [0002] Formability is one of the important properties of metal materials, especially metal sheets. Good formability means that metal materials are not easy to break during cold deformation. The quality of formability directly affects designers’ material selection, mold design and forming virtual analysis. . Although it is possible to draw a more complete forming curve of the metal sheet according to the method of "Part 2 of GB / T 24171.2-2009 Determination of Forming Limit Curve of Metal Materials (Sheet and Thin Strip) - Determination of Laboratory Forming Limit Curve" , to fully illustrate its performance, but this method is very complex and not practical at the design stage. The method of measuring the elongation at break of metal materials according to "GB / T228 Greenhouse Tensile Test Method for Metal Materials" is widely used in applic...

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Problems solved by technology

Although it is possible to draw a relatively complete forming curve of the metal sheet according to the method of "Part 2 of the determination method of the forming limit curve of metal materials (thin plate and thin strip) - the determination of the laboratory forming limit curve" , to fully illustrate its performance, but this approach is too complex to be practical at the design stage

The method of measuring the elongation at break of metal materials according to "GB / T228 Greenhouse Tensile Test Method for Metal Materials" is widely used in applications, and can intuitively show the approximate forming ability of metal sheets. However, because this method treats The original gauge length of the measured metal is limited, which determines that it cannot fully reflect the metal material, especially the forming ability of the metal sheet

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