Materials that are to be deformation processed by being subjected to bending loads and materials that may have been affected by localized heating, such as in welding, are sometimes tested by bend tests to provide comparative data.

Free Bend Test – Free bends are accomplished by prebending a flat specimen slightly to produce eccentricity and then loading the specimen in compression (column) until failure occurs or a 180º bend is produced. Normally, the loads to accomplish this are so variable that they are of little value and are not recorded. Instead, the angle of bend at failure is compared with results of other tests.

Guided Bend Test – In guided bend tests, the test specimen is bent about a fixed radius to 180º. The bend angle of a failure before 180º bending usually cannot be satisfactorily compared with other test results because of non-uniform plastic flow of material in the specimen caused by pressures set up by the guided bend fixture. Multiple-radius guided bends may be used for rating specimens by determining the smallest radius about which a standard specimen will bend 180º.