ISO 12004-1-2020 pdf free download – Metallic materials — Determination of forming-limit curves for sheet and strip — Part 1: Measurement and application of forming-limit diagrams in the press shop.
The procedure for the determination of the forming limit is as follows:1) Take a representative sample of the material to be evaluated.
2) Apply a suitable grid pattern, that has been checked for accuracy of the initial gauge lengths, to the
surface of a test piece in areas of the part to be formed which are known, or have been establishedby investigation, to be critical.
3) Any test device that satisfies Clause 6 may be used to form the test piece, such as a universal
tensile testing machine, a stamping press, a cupping press, a hydraulic bulge machine and theircombinations or any other equipment capable of clamping the test piece and applying a plasticdeformation force in an area remote from the edge. A universal testing machine may be employedand forming limits established using a tensile test.
4)Test pieces shall be tested while clamped around the whole of their periphery or shall be cut into
strips of varying widths to give a range of strain conditions.The surface between the punch and thespecimen shall be suitably lubricated using a standard product for the operation. A combination ofpolyethylene sheet and lubricant can be used.
5) Stop the test at the first occurrence of fracture.
6) Determine the engineering strains e1and e, as follows:
a) Measure (for example with calliper or optical measurement system) three adjacent gauge
lengths in the direction of e; that were originally in a straight line.Repeat until the three valuesobtained are the same to within ±10 %.Record the average of these three values as l.A moreaccurate method may be prescribed as provided for in IS0 12004-2121.
NOTE Although engineering strain is specified in this document, true strain is specified in theforming limit determination for iSo 12004-2121.
b) Ilf it is not possible to obtain three values within ±10 %, form a new test piece and repeat the
measurements.
c)Select one of the gauge lengths measured in step 6) a) and measure the gauge length at 90° to
the original e1direction, and report this as l2.
7) Make measurements on a sufficient number of test pieces to plot a forming-limit curve.
8Interpretation of results
8.1 Plot e; against e,on a forming-limit diagram.As shown in Figure 1, the major engineering strain eis plotted along the Y-axis and the minor engineering strain e, is plotted along the X-axis.
8.2 Draw the forming-limit curve through the points of maximum e, strain (see Figure 1).
8.3The effect of a forming operation on a particular part may be estimated from the diagram bymeasuring the strains in critical areas and comparing the results with the curve for the material used.
9 Test report
9.1 The test report shall contain the following information:
a) a reference to this document, i.e. ISO 12004-1:2020;
b) the identification of the test piece;
c) the thickness of the test piece;
d) the forming-limit curve (FLC) plotted on the forming-limit diagram (FLD) (as shown in Figure 1);
e) the gauge length of the grid pattern used;
f) lubrication conditions.
9.2 The test report may also include the following information:
a) selected mechanical properties of the material tested;
b) the chemical composition (percentage content of major elements) of the material tested;
c) a description of the procedure used;
d) the type of grid pattern used;
e) details of any deviation from the procedure specified (see, in particular, Annex A).ISO 12004-1 pdf download.