The hardenability of a material is usually expressed in terms of its carbon content or, when other elements are taken into account, its carbon equivalent (CE) value.Ĭracks are more likely to initiate at regions of stress concentration, particularly at the toe and root of the weld. This will have a major influence on hardenability and, with high cooling rates, the risk of forming a hard brittle structure in the HAZ. Hydrogen may also be derived from the surface of the material or the consumable. from the material, where processing or service history has left the steel with a significant level of hydrogen or moisture from the atmosphere. It is important to note that there can be other significant sources of hydrogen, e.g. Basic electrodes normally generate less hydrogen than rutile and cellulosic electrodes.

The amount of hydrogen generated is influenced by the electrode type. the coating of MMA electrodes, the flux in cored wires and the flux used in submerged arc welding. The principal source of hydrogen is moisture contained in the flux, i.e.

stresses acting on the weld during welding or imposed (shortly) after welding.

The main factors which influence the risk of cracking are: In low alloy steels, as the weld metal structure is more susceptible than the HAZ, cracking may be found in the weld bead. However, transverse weld metal cracks can occur, especially when welding thick section components the risk of cracking is increased if the weld metal carbon content exceeds that of the parent steel. With the correct choice of electrodes, the weld metal will have a lower carbon content than the parent metal and, hence, a lower carbon equivalent (CE). In C-Mn steels, because there is a greater risk of forming a brittle microstructure in the HAZ, most of the hydrogen cracks are to be found in the parent metal. It is caused by the diffusion of hydrogen to the highly stressed, hardened part of the weldment.

tensile stresses acting on the welded jointĬracking usually occurs at temperatures at or near normal ambient.

a hard brittle structure which is susceptible to cracking.

hydrogen generated by the welding process.

There are three factors which combine to cause cracking:

National Structural Integrity Research Centre.

Structural Integrity Research Foundation.

Crack para hydros v4