A simple formability test in which a strip of metal is bent over a mandrel of specified radius. The bend is then examined for cracks or tears. If present, these cracks or tears indicate a failure if they are greater than a specified length. Bend testing is performed on plate or sheet metal which is manufactured by passing the metal between rollers until the desired thickness is attained. The orientation of the bend test relative to this rolling direction produces quite different results, as rolled materials bend more easily across the rolling direction than parallel to it. Bend testing can be used to predict a material’s suitability to similar bending processes in manufacturing applications. However, it is not a good predictor of a material’s suitability for three dimensional forming processes, such as drawing operations used to form cup-shaped parts, or other three dimensional shapes.
Welds are also tested using a similar procedure called a guided bend test. This test uses one of several types of fixtures to bend the welded test coupon to determine the ductility and integrity of the weld. This test is specified for welder qualification and welding procedure requirements under ASME IX, EN 287 and 288, and ISO 15614 Part 1.