Chevron cracking is a form of hydrogen induced cold cracking taking place in the weld metal, typically on carbon manganese low alloy medium strength welds. It takes the name from the characteristics of the cracks, orientated approximately transverse to the welding direction and at 45° with the plane of the plates (assuming a butt joint). Longitudinal weld sections may show cracks intersecting at 90° producing the typical chevrons which give the name to the crack. At higher magnification the cracks show a step-like characteristic.
Longitudinal weld metal section showing 45° transverse or 'chevron' cracking
In practice, it has been found to occur more often in submerged arc (SAW) welds but is not confined to that process. This type of cracks can be avoided by careful control of moisture content in the consumables. Furthermore, as with any form of hydrogen cracking, its prevention follows the same basic factors.
Hydrogen cracking: its causes, costs and future occurrence.
Fabrication cracking mechanisms in ferritic steels
Job knowledge 45: Defects / hydrogen cracks in steels - identification