Notes Mla

WELDING TERMS 2 1.) DISCONTINUITY: an interruption of the typical structure of the weld. It may be a lack of uniformity in the mechanical, metallurgical, or physical characteristics of the weld. A discontinuity is not necessarily a defect. 2.) DEFECT: according to AWS, “A discontinuity of discontinuities, which by nature or accumulated affect (for example, total porosity or slag inclusion length that renders a part or product unable to meet minimum applicable acceptance standards or specifications). This term designates rejectability. 3.) POROSITY: results from gas that was dissolved in the molten weld pool, forming bubbles that are trapped as the metal cools to become solid. The bubbles that make up porosity form within the weld metal; for that reason they can not be seen as they form. 4.) UNDERCUT: is the result of the arc plasma removing more metal from a joint face than is replaced by weld metal. It can result from; excessive current, incorrect welding technique, such as incorrect electrode angle or excessive weave. To prevent undercutting, the welder can weld in the flat position by using multiple instead of single pass, change the shield gas, and improve technique. 5.) INCULSION: are nonmetallic materials, such as slag or oxides that are trapped in the weld metal, between weld beads, or between the weld and the base metal. This causes stresses to concentrate and reduces the structural integrity (loss in strength) of the weld.
6.) NONMETALLIC INCLUSION: are caused under the following conditions:
1.) Slag and/or oxides do not have enough time to float to the surface of the molten weld pool. 2.) There are sharp notches between weld beads or between the weld bead and the base metal that trap the material so that it can not float out. 3.) The joint was designed with insufficient room for the correct manipulation of the molten weld pool.
7.) INCOMPLETE FUSION: is the lack of coalescence between the molten filler metal and the