Chevron cracking in steel weld metals

A less well known form of transverse cracking in carbon manganese and low alloy steel weld metals, generally referred to as chevron cracking, has been found in a large number of industrial welds. These cracks are characterized by their macroscopic orientation, which is approximately transverse to the welding direction and at 45 with the plane of the plates (in a butt joint), and by the staircase morphology, which is easily recognized under microscopical examination. A special test was designed to reproduce these cracks under laboratory controlled conditions and a large number of welds was carried out. Chevron cracks were found in the tests with medium strength weld metals deposited by submerged arc with a basic agglomerated flux and by manual metal arc with basic and cellulosic electrodes. No chevron cracks were observed in the welds with rutile electrodes. High temperature baking of the submerged arc flux and the basic electrodes eliminated or reduced markedly the incidence of cracking in all cases indicating that hydrogen was the main factor controlling the cracking occurrence. Cont/d.