- Welding Terms
- Weld Toe
- Wheel Lug or Stud
- Wheel Stud Boss
- Wire Bundle (Plait)
- Working Load
- Wire Rope
- X-Ray Diffraction
- X-Ray Mapping
- Yield Strength
Washout: Erosion or wearing away of metal by a pressured gas or liquid flowing over or through a fracture.
Weld: Process that joins two or more pieces of metal by melting and re-solidification. May or may not include a filler metal between the two metals to be joined. The result is referred to as a weldment.
Lack of Fusion (LOF) – Also known as cold-lapping or cold shuts, LOF occurs when there is no fusion (melting and mixing) between the weld metal and the base metal. The most common cause of lack of fusion is a poor welding technique. Another cause is the use of a very wide weld joint. If the welding arc is directed down the center of the joint, the molten weld metal will only flow and be solidified and cast against the side walls of the base plate without melting them.
Lack of Penetration (LOP) – A weld defect where the welding process does not reach all the way into the seam between the pieces being welded. Incomplete penetration is usually caused by the use of too low a welding current and can be eliminated by simply increasing the amperage. Other causes can be the use of too slow a travel speed, an incorrect torch angle or too narrow of a gap between pieces.
Gusset: Triangular metal piece added to an interior corner to add strength to the joint.
Fitup: The initial positioning of pieces before welding or fastening.
Fitup Gap: A space or gap between pieces when they are being positioned for welding. The gap may remain after welding or it may be filled by the weld.
Tack Weld: A small, temporary weld placed at intervals along a joint to hold the joint in alignment.
Fillet Weld: A weld of approximately triangular cross section, as used in a lap joint, joining two surfaces at approximately right angles to each other.
Undercut: Undercutting is a defect that appears as a groove in the parent metal directly along the edges of the weld in the weld toe. This type of defect is most commonly caused by improper welding parameters; particularly the travel speed and arc voltage.
Re-Entrant Angle: The angle formed by the weld and base metal intersection after welding.
Capping Pass: The final pass in welding a joint, sometimes done for cosmetic purposes.
Weld Toe: The junction of the weld face and the base metal at the outside surface.
Weldment: A number of originally separate components that have been joined together by welding.
Wheel Lug or Stud: Threaded fastener that is attached to the hub and passes through one or more wheel rim boltholes. When tightened, the lug nut secures the wheel to the vehicle.
Wheel Stud Boss: The large mass of reinforcing metal that holds threaded studs thereby providing a method to join a wheel to a hub with the use of lug nuts. The joint is made when the nuts are torqued onto the wheel studs thereby providing proper clamping force between the wheel rim and the hub.
Wire Bundle (Plait): Individual groups of wires intertwined together make up a braid or plait of wires. The braiding is a crosshatched pattern of the woven wire bundles (plaits).
Working Load: The maximum load that is recommended for a particular component or machine, for example, a hook load on oilrig traveling blocks, limit on a wire rope, etc. The maximum breaking strength load divided by the safety factor will determine the working load limit.
Wire Rope: Metal ropes made from very small individual wires. Wire ropes are usually made from steel or iron, but stranded cable can be made of other materials such as copper and aluminum. Wire ropes and wire cables are complex and are in fact classified as a machine. This machine has many interconnected yet movable parts. Some wire ropes have as many as 200-300 individual independent wires. A picture of a wire rope and how it is put together is shown below and taken from the cover of the Wire Rope User’s Manual, Second Edition, American Iron and Steel Institute, Committee of Wire Rope Producers, 1981.
The wire rope shown above has six strands that are wrapped around a central core strand. In this photograph, the core is referred to as an independent wire rope core (IWRC), but the core can also be a lubricated natural fiber (sisal) core (FC) which is saturated with lubricant. Each of the 6 strands in this photograph is made up from individual wires.
A schematic, again taken from the Wire Rope User’s Manual American Iron and Steel Institute, Committee of Wire Rope Producers, 1981, of the manner in which a wire rope is constructed, is shown below.
The core, in this case, IWRC, is made up of individual wires wound together. Around that center core, (IWRC or FC) in this case six strands are wound around the core. These strands are pre-formed, that is they are formed so they do not easily spring out.
Each individual strand is also made up of some number of individual wires wound around a central core.
The cross section of the wire strands can range from simple 6X7 with a fiber core (FC) as shown below.
The most common wire rope variations are shown below.
X-Radiography: The use of x-rays to look into the interior of opaque objects. The use of x-rays to detect cracked or broken bones, tumors, etc. in humans is well known. X-rays will also pass through dense opaque metal objects to detect internal cracks, flaws and defects. X-rays are performed with x-ray sensitive film and/or more recently with electronic/digital x-ray detectors. Cracks and/or porosity, inclusions, etc. do not absorb x-radiation the same as the metal object being inspected and thus, cracks and other imperfections are revealed as darkened lines and/or areas in the x-ray film or image.
X-Ray Diffraction (XRD): A scientific technique that allows the investigator to determine which chemical compounds and the relative amounts of those compounds are present in a sample. Each element such as iron (Fe), sulfur (S), and copper (Cu) and each chemical compound, two or more chemical elements such as salt (NaCl), iron oxide (Fe2O3), iron sulfide (FeS), etc. has a unique structure. That is, the atoms in the element or compound are arranged in space on a repeatable lattice structure that extends for large atomic distances compared to the size of the atom). XRD is used to determine this unique spatial arrangement.
X-ray Mapping: In years past called a dot map, allows determination of the location in the sample of the chemical species and provides images of elemental distributions in a sample. This emits the characteristic X-ray and in turn, yields the EDS spectra, which allows determination of the chemical make-up of the sample. Assume that the sample is a chocolate chip cookie with pecans. EDS tells that it is a chocolate chip cookie with pecans. The X-ray map allows the determination of the location of the chocolate chips, the pecans and the rest of the cookie dough. The location of the various atomic species on the sample surface is mapped and displayed in various colors.
Yield Strength: The strength or stress level beyond which a metal will deform plastically. At stress levels less than the yield strength, the metal will stretch, however, when the load causing the stretch is removed the stretch disappears.