Glossary - D
Constitution Diagram used for the estimation of ferrite and other metallurgical phases present in stainless steel weld metal derived from Chromium and Nickel contents and their equivalents. A weld containing one or more defects. The sudden combustion of a gas, generally accompanied by a flame and a cracking sound. The speed of the flame is less than the speed of sound. The weight of a substance per unit volume. Where the combustion wave or flame travels into the un-reacted gas as a steep pressure wave faster than the speed of sound. Dip, also known as Short Arc Transfer. In this mode of transfer the welding wire is feed down to the parent plate were it dips into the weld pool, causing a short circuit to occur. The welding current rises rapidly and the short circuit ruptures to detach some of the wire and re-establish the arc. The composition of weld metal is a result of a mixture of the consumable and melted parent metal taken into the weld pool. The metal deposited from the consumable is said to have been 'diluted' by the parent metal, and 'dilution' is expressed as 'the percentage of parent metal included in the weld bead'. It should be noted that previously deposited weld metal can also 'dilute' a subsequent weld bead. An interruption of the typical structure of the weldment such as a lack homogeneity in the mechanical or metallurgical or physical characteristics of the material or weldment. A discontinuity is not necessarily a defect. A steel filler metal which relies on two elements in its make up, usually manganese and silicon, for deoxidation of the weld pool. The percentage of time the welder is welding or welding equipment is being used, measured again a standard working day.
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