Bend testing shall be performed in accordance with ASTM E290, unless otherwise specified by client. This procedure may be deviated from at the client's request. In this event the procedure or method that was used shall be notedon the Lab worksheet.
Various devices are suitable for bending. CMS uses Arrangement A and C of ASTM E290.
Arrangement A -Method of holding one end of the specimen (vice), a reaction pin or mandrel to bear at an intermediate location, usually the mid-length; and a device to apply the bending force (tensile machine) near the free end of the specimen.
Arrangement C-Method using a pair of pins, rollers, or radius flat support; a pin or mandrel for applying the bending force directly to mid-length.
The radius of the pin, mandrel or roller in each arrangement shall differ not more than 2% from the nominal value. The size of mandrel used is calculated by using customer or specification requirements for bend factor multiplied by thickness of material.
Place specimen with both ends on vice or rollers and lower cross-head of tensile machine or hydraulic press. The correct mandrel should be placed at mid-length of specimen and bend by applying load smoothly without shock. Continue bending until the specified angle of bend is achieved or failure occurs.
Examine the convex surface of the bent specimen for cracks or other open defects. When the test is conducted as an acceptance criterion, the allowable crack size shall be specified by the code or specification requiring the test.