Regulation 57

For both cold and temper bends the test-piece shall withstand, without fracture, being doubled over until the internal radius is equal to 1½ times the thickness of the test-piece, and the sides are parallel.

The temper bending test-pieces shall be similar to those used for cold bending tests. The test-pieces shall be heated to a blood-red colour, judged indoors in the shade, and quenched in water at a temperature not exceeding 80° Fahr.