EN 13147-2001 pdf download.Copper and copper alloys – Determination of residual stresses in the border area of slit strip.
This EN 13147 specifies a method for the determination of residual stresses in the areas adjacent to the slit edges of wrought copper and copper alloy strip, by measurement of the angle of twist, longitudinal curvature and sideways curvature of test pieces cut from strip.
2 Terms and definitions
For the purposes of this standard, the following tems and definitions apply:
2.1
strip
flat rolled product of rectangular cross-section and uniform thickness from 0,08 mm up to and including 0,80 mm, supplied level wound as coils, or traverse wound on cores or spools, with slit edges. The thickness does not exceed one tenth of the width
2.2
sideways curvature 8
displacement from the fixed gauge length H of the distorted test piece perpendicular to the rolling direction and in the plane of the strip
2.3
longitudinal curvature
displacement from the fixed gauge length Ii of the distorted test piece perpendicular to the rolling direction and perpendicular to the plane of the strip
2.4
edge twist 13
twist angle from the fixed gauge length H of the distorted test piece
3 Principle
Test pieces are cut in the direction of rolling from the areas adjacent to the slit edges of a sample strip according to a set procedure. A test piece is clamped on the turntable of the measuring equipment described in 4.2, and the components of distortion, i.e. sideways curvature 6, longitudinal curvature A and edge twist 13. caused by the residual stresses, are measured.
4 Apparatus
4.1 Equipment for test piece preparation
Sawng. stamping, etching or wire eroding may be used for making the slits in the sampling unit, subject to agreement between the purchaser and the supplier. Most experience has been gained using the sawing method and it should be used as a reference method in cases of dispute (see annex A).
4.2 Measuring equipment
The measuring equipment see Figure 1) consists of a light source emitting mainly parallel light, a turntable carrying the test piece holder with the means to ensure that the original strip edge is fitted on the axis of the turntable, a scale showing the angular rotation of the turntable and a screen with an integrated scale at fixed height H. The zero pornt of the scale on the screen is located at the intersection of the horizontal bottom line of the scale with the axis of the turntable. The distance X of the light source from the test piece holder shall be significantly greater than the distance V of the test piece holder to the screen, so that a clear projection of the test piece can be seen on the screen.
NOTE To show the angular rotation of the turntable it is advisable to use a cgital display for the scale, which Is calibrated to permit direct reading in millimetres of the deflection of the test piece.
5 Preparation of test pieces
The following method shall be considered as one of the acceptable methods of test piece preparation. Other methods may be used subject to agreement between the purchaser and the supplier. e.g. etching.
Test samples with length I greater than 200 mm but less than 300 mm shall be cut from the sheared strip to be tested, exactly perpendicular to the rolling direction, using guillotine shears.
Two slits of width g 0,2 mm to 2,5 mm, shall be sawn, etched, stamped or wire eroded over a length x 150. mm, parallel to the rolling direction, and at a distance 2 mm to 5 mm from each edge of the test sample. Two test pieces shall be cut to the bottom of the slits, at 450 from these longitudinal edges. The left-hand and the right-hand test pieces shall be marked accordingly. Deformation of test pieces shall be avoided.
NOTE The preparanon of the test pieces is shown diagrammatically in Figure 2. A typical sawing method for preparing test pieces is described in annex A.EN 13147-2001 pdf download.