Bend Test for Steel — Bend Weld Testing

Bend test is one of the commonly used destructive tests to determine the ductility and soundness (for the presence porosity, inclusion, penetration and other macro size internal weld discontinuities) of the weld joint produced using under one set of welding conditions.

There are following two types of bend test:

• Free bend test
• Guided bend test

Free bend test:

The free bend weld testing approach has been devised to measure the ductility of the weld metal deposited in a weld joint. A physical weld testing specimen is machined from the welded plate with the weld located as shown.

Each corner lengthwise of the specimen shall be rounded in a radius not exceeding one-tenth of the thickness of the specimen. Two scribed lines are placed on the face 1.6 mm from the edge of the weld. The distance between these lines is measured and recorded as the initial distance x as. The ends of the test specimen are then bent through angles of about 300 and these bends are being approximately one-third of the length in from each end. The weld is thus located centrally to ensure that all of the bending occurs in the weld.

The specimen bent initially is then placed in a machine capable of exerting a large compressive force as shown and bent until a crack greater than 1.6 mm in any dimension appears on the face of the weld. If no cracks appears, bending is continued until the specimens 6.4 mm thick or under can be tested in vise.