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Porosity occurs when the gases produced by the weld flux insufficiently shield the molten weld metal. An overexposed weld bead absorbs nitrogen, oxygen, and hydrogen from the atmosphere; these gases form tiny voids in the weld bead and are released while the weld cools. Poor fusion also affects the strength of the weld and is often easily visible.
The poor overlap does not allow the slag from the previous weld to melt out and rise to the top of the new weld bead. It can also occur if the previous weld left an undercut or an uneven surface profile. To prevent slag inclusions, the slag should be cleaned from the weld bead between passes via grinding, wire brushing, or chipping. [21]
The symbolic representation of a V weld of chamfered plates in a technical drawing. The symbols and conventions used in welding documentation are specified in national and international standards such as ISO 2553 Welded, brazed and soldered joints -- Symbolic representation on drawings and ISO 4063 Welding and allied processes -- Nomenclature of processes and reference numbers.
Welding slag is a form of slag, or vitreous material produced as a byproduct of some arc welding processes, most specifically shielded metal arc welding (also known as stick welding), submerged arc welding, and flux-cored arc welding.
As the weld progresses, base metal ahead the keyhole melts, flow around the same solidifies and forms the weld bead. Key-holing aids deep penetration at faster speeds and produces high-quality bead. While welding thicker pieces, in laying others than root run, and using filler metal, the force of plasma jet is reduced by suitably controlling ...
Weld mapping is the process of assigning information to a weld repair or joint to enable easy identification of weld processes, production (welders, their qualifications, date welded), quality (visual inspection, NDT, standards and specifications) and traceability (tracking weld joints and welded castings, the origin of weld materials).
Trained welders are taught to keep the bead the same size at the beginning of the weld as at the end. If the bead gets too wide, the welder increases the speed of welding travel. If the bead gets too narrow or if the weld puddle is lost, the welder slows down the speed of travel. Welding in the vertical or overhead positions is typically slower ...
A submerged arc welder used for training Close-up view of the control panel A schematic of submerged arc welding Pieces of slag from submerged arc welding exhibiting glassy surface due to silica (SiO 2). Submerged arc welding (SAW) is a common arc welding process. The first SAW patent was taken out in 1935.