Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘Y’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘Y’
Yagi antenna – It is a type of radio antenna using a feeder element, one or more parasitic reflector elements, and one or more director parasitic elements to provide a directional characteristic. The classic YAG – It is acronym for yttrium aluminum garnet.
YAG laser – It is a type of solid-state laser which uses a crystal made of neodymium-doped yttrium aluminum garnet (YAG) as its active medium. In the context of lasers, it is the host crystal for neodymium ions which provide the lasing action. The most common type of YAG laser is the Nd:YAG laser, which uses neodymium-doped YAG. YAG lasers are classified as solid-state lasers since their active medium is a solid crystal (YAG).
‘Y’ and delta connections – These are the two common methods of connecting three-phase generators, motors, and transformers. In case of a delta connection, the diagram bears a close resemblance to the Greek letter ‘delta’. The other method is known as the star or ‘Y’ connection. The ‘Y’ differs from the delta connection in that it has two phases in series. The common point ‘O’ of the three windings is called the neutral since equal voltages exist between this point and any of the three phases. When windings are connected wye, the voltage between any two lines is 1.732 times the phase voltage, and the line current is the same as the phase current. When transformers are connected delta, the line current is 1.732 times the phase current, and the voltage between any two is the same as that of the phase voltage.
YAM – It is a synthetic crystalline material of the garnet group. It is a monoclinic yttrium aluminium oxide phase having chemical formula Y4Al2O9.
YAP – It is a synthetic crystalline material of the garnet group. It a hexagonal or an orthorhombic, perovskite-like form of yttrium aluminium oxide having chemical formula YAlO3.
Yard – It is a unit of length (or distance) which is equal to 3 feet or 36 inches. One yard is exactly 0.9144 meters in the metric system.
Yard conveyors – These are belt conveyors which are a critical part of bulk material handling systems. These belt conveyors are specifically designed to transport and store large quantities of loose materials like coal, ore, or aggregates. These conveyors integrate with different other equipment to create a comprehensive system for receiving, conveying, storing, and reclaiming materials, frequently in outdoor storage areas or yards.
Yard equipments – These are the equipments which are normally used in the open storage yards. Fork lift trucks, mobile cranes, portable conveyors, tractor and trailers are examples of yard equipment. Gantry crane is also used in some storage yards.
Yard machines – These machines are used in the bulk material storage yard. These machines are specialized equipment used in industrial settings to handle and store large quantities of loose, granular, or lumpy materials like coal, ore, or grains. These machines are crucial for efficiently moving, stacking, reclaiming, and managing these materials within a storage yard. There are three main types of yard machines which are used for stacking and reclaiming of materials. These are (i) stacker, (ii) reclaimer, and (iii) stacker cum reclaimer.
Yard management – It is a logistics strategy which is used to track, manage, and optimize the flow of vehicles, trailers, containers, and other assets in and out of a yard or distribution centre. Yard management includes activities such as the tracking of vehicles, trailers, and containers, ensuring efficient loading and unloading, and controlling the flow of inbound and outbound shipments.
Yard management system – It typically include software, hardware, and communication systems which track and communicate the movements of assets within a yard. This information is then used to optimize the flow of traffic, improve yard utilization, and reduce costs.
Yard, open storage – It refers to the practice of keeping goods, materials, or equipment in an open, frequently outdoor, area, typically within a fenced or gated space. This can include the storage of construction materials, or those items which do not need indoor climate-controlled storage.
Yardstick – It is something which a person compares another thing with, in order to judge how good or successful it is yardstick of. For example, productivity is the most important yardstick of success for a process as a yardstick.
Yard, shunting – It is also known as a classification yard or marshalling yard. It is a railway yard where railway cars / wagons are sorted, grouped, and assembled into new trains based on their destinations. These yards are necessary for efficiently managing freight traffic, allowing trains to be broken down and rebuilt with cars / wagons destined for different locations.
Yarn – It is an assemblage of twisted filaments, fibers, or strands, either natural or manufactured, to form a continuous length which is suitable for use in weaving or interweaving into textile materials.
Yarn bundle – It is a general term used for a collection of essentially parallel filaments or fibres.
Yarn, plied – It is the yarn made by collecting two or more single yarns. Normally, the yarns are twisted together, though sometimes they are collected without twist.
Yaw – It is the horizontal moving part of the wind turbine. It turns clockwise or anti-clockwise to face the wind. The yaw has two main parts namely the yaw motor and the yaw drive. The yaw drive keeps the rotor facing the wind when the wind direction varies. The yaw motor is used to move the yaw.
y-axis – It is like a vertical ruler. It shows a person where an object on a Cartesian plane, a two-dimensional mathematical graph, is in the y or vertical direction. It is also the starting or zero point for measuring how far a point is to the right or left (horizontally) on a graph.
Y-block – It is a single keel block.
Y-body globe valve design – It is a remedy for the high-pressure drop inherent in globe valves. The seat and stem are angled at around 45-degres. The angle yields a straighter flow path (at full opening) and provides the stem, bonnet, and packing a relatively pressure resistant envelope. Y-body globe valves are best suited for high pressure and other severe services. In small sizes for intermittent flows, the pressure loss is not as important as the other considerations favouring the Y-body design. Hence, the flow passage of small Y-body globe valves is not as carefully streamlined as that for larger valves. The angle body globe valve design is a simple modification of the basic globe valve. Having ends at right angles, the diaphragm can be a simple flat plate. Fluid is able to flow through with only a single 90-degree turn and discharge down-ward more symmetrically than the discharge from an ordinary globe. A particular advantage of the angle body design is that it can function as both a valve and a piping elbow. For moderate conditions of pressure, temperature, and flow, the angle valve closely resembles the ordinary globe. The angle valve’s discharge conditions are favourable with respect to fluid dynamics and erosion.
Y-configuration – In a three-phase electrical system, a ‘Y’ (also called wye) configuration (also known as a star configuration) connects three voltage sources to a common point, creating a ‘Y’ or star shape. This configuration is characterized by having a neutral point, which allows for the connection of a neutral wire, and it is frequently used in power distribution systems to provide both single-phase and three-phase power. The wye differs from the delta connection in that it has two phases in series. The common point of the three windings is called the neutral since equal voltages exist between this point and any of the three phases. When windings are connected wye, the voltage between any two lines is 1.732 times the phase voltage, and the line current is the same as the phase current.
Y-coordinate – it is also called the ordinate. It represents the vertical position of a point on a graph or coordinate plane, specifically its distance from the x-axis. It is the second number in an ordered pair (x, y), indicating how far up or down the point is from the origin.
Y-delta transform – In circuit design, it is also written as wye-delta and is also known by several other names. It is a mathematical technique to simplify the analysis of an electrical network. The name derives from the shapes of the circuit diagrams, which look respectively like the letter ‘Y’ and the Greek capital letter delta. It is widely used in analysis of three-phase electric power circuits. The Y-delta transform can be considered a special case of the star-mesh transform for three resistors. In mathematics, the Y-delta transform plays an important role in theory of circular planar graphs.
Yellow brass – It is a name sometimes used in reference to the 65 % copper-35 % zinc type of brass.
Yellow (purple) hydrogen – It is produced by water electrolysis using energy from nuclear power.
Yield – It is the evidence of plastic deformation in structural materials. It is also known as plastic flow or creep. It is the ratio of the number of acceptable items produced in a production run to the total number which have been attempted to be produced. It is the comparison of casting weight to the total weight of metal poured into the mould. It is also the ratio of the weight of the output product to the weight of the input material.
Yield by volume – It is the mass of unshaped refractory, as delivered, which is necessary to place 1 cubic meter of material, expressed in tons to the nearest 1 %.
Yield criterion – It is a set of rules or conditions which predict when a material starts to deform plastically, transitioning from elastic to plastic behaviour. It essentially defines the limit of elasticity for a material under different stress states. Understanding yield criteria is crucial for designing structures and components which can withstand applied loads without permanent deformation or failure.
Yield function– It defines the conditions under which a material transitions from elastic to plastic behaviour. It is a mathematical representation which describes the stress state at which a material begins to deform permanently. Essentially, it separates the elastic region (where deformation is reversible) from the plastic region (where deformation is permanent).
Yielding – It is the evidence of plastic deformation in structural materials. It is also known as plastic flow or creep.
Yield point – It is the first stress in a material, normally less than the maximum attainable stress, at which an increase in strain occurs without an increase in stress. The yield point can be observed directly from the load-elongation diagram of the body centred cubic (bcc) metals such as iron and steel especially low carbon steels. Only certain materials, those which show a localized, heterogeneous type of transition from elastic to plastic deformation, produce a yield point. If there is a decrease in stress after yielding, a distinction can be made between upper and lower yield points. The load at which a sudden drop in the flow curve occurs is called the upper yield point. The constant load shown on the flow curve is the lower yield point. Material having a face centred cubic (fcc) crystal structure does not show the definite yield point in comparison to those of the body centred cubic structure materials, but shows a smooth engineering stress-strain diagram. The yield strength hence has to be calculated from the load at 0.2 % strain divided by the original cross-sectional area [Y(0.2 %) = F(0.2 %)/A0.
Yield point elongation – In materials which show a yield point, it is the difference between the elongation at the completion and at the start of discontinuous yield. The yield point elongation phenomenon shows the upper yield point followed by a sudden reduction in the stress or load till reaching the lower yield point. At the yield point elongation, the sample continues to elongate without a significant change in the stress level. Load increment is then followed with increasing strain. This yield point occurrence is associated with a small amount of interstitial or substitutional atoms. This is for example in the case of low-carbon steels, which have small atoms of carbon and nitrogen present as impurities. When the dislocations are pinned by these solute atoms, the stress is raised in order to overcome the breakaway stress required for the pulling of dislocation line from the solute atoms. This dislocation pinning is related to the upper yield point. If the dislocation line is free from the solute atoms, the stress required to move the dislocations then suddenly drops, which is associated with the lower yield point. Furthermore, it has been found that the degree of the yield point effect is affected by the amounts of the solute atoms and is also influenced by the interaction energy between the solute atoms and the dislocations.
Yield strength – It is the stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2 % is used for several materials, particularly metals. The determination of the yield strength at 0.2 % offset or 0.2 % strain can be carried out by drawing a straight line parallel to the slope of the stress-strain curve in the linear section, having an intersection on the x-axis at a strain equal to 0.002. An interception between the 0.2 % offset line and the stress-strain diagram represents the yield strength at 0.2 % offset or 0.2 % strain. The yield strength of soft materials showing no linear portion to their stress-strain diagram such as soft gray cast iron can be defined as the stress at the corresponding total strain. The yield strength, which indicates the onset of plastic deformation, is considered to be vital for engineering structural or component designs where safety factors are normally used. Safety factors are based on several considerations which include (i) the accuracy of the applied loads used in the structural or components, (ii) estimation of deterioration, and (iii) the consequences of failed structures (loss of life, financial, economic loss, etc.) Generally, buildings require a safety factor of 2, which is rather low since the load calculation has been well understood. Automobiles have safety factor of 2 while pressure vessels utilize safety factors of 3 to 4.
Yield stress -It is the stress level of highly ductile materials at which large strains take place without further increase in stress. By considering the stress-strain diagram beyond the elastic portion, if the tensile loading continues, yielding occurs at the beginning of plastic deformation. The yield stress, Ys, can be obtained by dividing the load at yielding (Fy) by the original cross-sectional area (A0) of the sample (Ys=Fy/A0).
Yield surface – It is defined by a yield criterion, which specifies the stress state at which plastic deformation begins. It is a boundary in stress space that separates elastic behavior from plastic behavior in a material. It represents the point at which a material begins to deform permanently (plastically) rather than elastically (reversibly). Yield surface is a five-dimensional surface in the six-dimensional space of stresses. The yield surface is normally convex and the state of stress of inside the yield surface is elastic. When the stress state lies on the surface the material is said to have reached its yield point and the material is said to have become plastic. Further deformation of the material causes the stress state to remain on the yield surface, even though the shape and size of the surface can change as the plastic deformation evolves.
Y-intercept – It is the point where a line or curve crosses the y-axis on a graph. It is the y-coordinate when the x-coordinate is zero. In the equation of a line (y = mx + b), the y-intercept is represented by the constant ‘b’.
Yoke – It is the inner part of an electromagnet or other electro-magnetic device. It greatly amplifies and leads the magnetic field flux. In case of valve, yoke is the structure which rigidly connects the actuator power unit to the valve.
Yoke nut – A yoke nut is an internally threaded nut and is placed in the top of a yoke by which the stem passes. In a gate valve, for example, the yoke nut is turned and the stem travels up or down. In the case of globe valves, the nut is fixed and the stem is rotated through it.
Yoke, valve – A yoke connects the valve body or bonnet with the actuating mechanism. The top of the yoke holds a yoke nut, stem nut, or yoke bushing and the valve stem passes through it. A yoke normally has openings to allow access to the stuffing box, and actuator links etc. Structurally, a yoke is to be strong enough to withstand forces, moments, and torque developed by the actuator.
Yoshida buckling test (YBT) – It is an experimental method used to evaluate the wrinkling resistance of materials, particularly in sheet metal forming. It involves stretching a square sheet diagonally to induce compressive stresses and assess the material’s tendency to wrinkle. Yoshida buckling test consists of the uniaxial stretching of a square thin steel plate. It is performed on a range of high strength and low carbon coated and uncoated steels to investigate their behaviour regarding buckling during the loading and unloading, deflection and failure problems encountered in actual sheet metal forming operations. The Yoshida buckling test is a simplified, easily performed test used to study how materials behave under conditions which can lead to wrinkling in manufacturing processes.
Young’s modulus – It is a term used synonymously with modulus of elasticity. It is the ratio of tensile or compressive stresses to the resulting strain. During elastic deformation, the engineering stress-strain relationship follows the Hook’s Law and the slope of the curve indicates the Young’s modulus (E). E = S/e, where ‘S’ is the stress, and ‘e’ is the strain. Young’s modulus is of importance where deflection of materials is critical for the required engineering applications, e.g., deflection in structural beams is considered to be crucial for the design in engineering components or structures such as bridges, buildings, ships, etc. The applications of tennis racket and golf club also require specific values of spring constants or Young’s modulus values.
Y-pipe fitting – It is also known as a wye fitting. It is a type of pipe fitting shaped like the letter ‘Y’. It has one inlet and two outlets, with the outlets typically angled at 45-degree to the main pipe run. This design allows for the connection of three pipes, enabling a branch line to be introduced at an angle, frequently to reduce friction and improve flow.
Ytterbium (Yb) – It is a chemical element having atomic number 70. It is a metal, the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its + 2 oxidation state. Like the other lanthanides, its most common oxidation state is +3, as in its oxide, halides, and other compounds. In aqueous solution, like compounds of other late ianthamides, soluble ytterbium compounds form complexes with nine water molecules. Because of its closed-shell electron configuration, its density, melting point and boiling point are much lower than those of most other lanthanides.
Ytterbium compounds – These are chemical compounds that which contain the element Ytterbium (Yb). The chemical behaviour of ytterbium is similar to that of the rest of the lanthanides. Majority of the ytterbium compounds are found in the +3-oxidation state, and its salts in this oxidation state are nearly colourless. Like europium, samarium, and thulium, the trihalides of ytterbium can be reduced to the dihalides by hydrogen, zinc dust, or by the addition of metallic ytterbium. The +2-oxidation state occurs only in solid compounds and reacts in some ways similarly to the alkaline earth metal compounds, e.g., ytterbium (II) oxide (YbO) shows the same structure as calcium oxide (CaO)
Yttria – It is yttrium oxide (Y2O3). It is an air-stable, white solid substance. The thermal conductivity of yttrium oxide is 27 W/(m·K). It is widely used to make phosphors which give the red colour in colour television tubes.
Yttria lasers – Yttria (Y2O3) is a prospective solid-state laser material. In particular, lasers with ytterbium as dopant allow the efficient operation both in continuous operation and in pulsed regimes. At high concentration of excitations (of order of 1 %) and poor cooling, the quenching of emission at laser frequency and avalanche broadband emission takes place. Yttria-based lasers are not to be confused with YAG lasers using yttrium aluminium garnet, a widely used crystal host for rare earth laser dopants.
Yttria-stabilized zirconia (YSZ) – It is a ceramic material composed of zirconium dioxide (ZrO2) stabilized in its cubic phase at room temperature by the addition of yttrium oxide (Y2O3). This stabilization is crucial since zirconia naturally transforms between different crystal structures at different temperatures, which can lead to cracking and failure. Before zirconia is stabilized, it has monoclinic, tetragonal, or cubic crystal phases. However, after it is stabilized by yttrium oxide, it has a cubic phase alone. Yttria stabilized zirconia is a wear-resistant and strong material. Similar materials include magnesia-stabilized zirconia, calcia-stabilized zirconia, and ceria-stabilized zirconia. These materials have similar properties and applications. Yttria-stabilized zirconia is known for its excellent mechanical, thermal, and electrical properties, making it suitable for a wide range of applications.
Yttrium (Y) – It is a chemical element having atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has frequently been classified as a ‘rare-earth element’. Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. ‘89Y’ is the only stable isotope and the only isotope found in the earth’s crust. The most important present-day use of yttrium is as a component of phosphors, especially those used in light-emitting diodes (LEDs). Yttrium is also used in the production of electrodes, electrolytes, electronic filters, lasers, superconductors, and tracing different materials to improve their properties.
Yttrium aluminum garnet (YAG) – It is a compound of yttrium, aluminum, and oxygen, with a specific ratio of these elements. It has a cubic crystal structure, which contributes to its isotropic optical properties. It is a synthetic crystalline material with the chemical formula Y3Al5O12. It is a synthetic crystalline material of the garnet group. It is a cubic yttrium aluminium oxide phase. Because of its broad optical transparency, low internal stress, high hardness, chemical and heat resistance, yttrium aluminum garnet is used for a variety of optics. Its lack of birefringence (unlike sapphire) makes it an interesting material for high-energy / high-power laser systems. It is particularly known for its use as a laser medium, especially when doped with elements like neodymium or ytterbium. Laser damage levels of yttrium aluminum garnet ranged from 1.1 kilojoules per square centimeter to 2.2 1 kilojoules per square centimeter.
Yttrium barium copper oxide (YBCO) – It is a ceramic material known for its high-temperature super-conductivity. It is a crystalline compound, specifically a type of perovskite, which shows super-conductivity at temperatures above the boiling point of liquid nitrogen (77 K), making it a practical material for several applications. The formula for yttrium barium copper oxide is typically YBa2Cu3O7₋x, where the ‘-x’ indicates a slight oxygen deficiency which can affect its super-conducting properties. Many YBCO compounds have the general formula YBa2Cu3O7-x (also known as Y123), although materials with other Y:Ba:Cu ratios exist, such as YBa2Cu4Oy (Y124) or Y2Ba4Cu7Oy (Y247).
Yttrium compounds – These are chemical substances which incorporate the element yttrium (Y), a silvery-metallic transition metal. Among these compounds, yttrium normally has a +3 valence. The solubility properties of yttrium compounds are similar to those of the lanthanides, e.g., oxalates and carbonates are hardly soluble in water, but soluble in excess oxalate or carbonate solutions as complexes are formed. Sulphates and double sulphates are normally soluble. They resemble the ‘yttrium group’ of heavy lanthanide elements.
Yttrium-iron garnet (YIG) – It is a synthetic material with a garnet crystal structure, specifically a ferrimagnetic material with the chemical formula Y3Fe2(FeO4)3 or Y3Fe5O12. It is known for its narrow ferromagnetic resonance linewidth and is widely used in microwave and optical devices.
Yttrium oxide – It is also known as yttria. It is a white, air-stable solid compound with the chemical formula Y2O3. It is a rare-earth oxide and is used in several applications, including phosphors for televisions.
Y-Y connected transformers – These are also written as Wye-wye connected transformers. These are seldom, if ever, used to supply plant loads or as generator set-up units, because of the inherent third harmonic problems with this connection. Delta-delta, delta-Y, and Y-delta are used extensively at several facilities. Some rural electric facilities use Y-Y connections which are supplying to structures in remote areas. There are three methods to negate the third harmonic problems found with Y-Y connections. These are (i) primary and secondary neutrals can be connected together and grounded by one common grounding conductor., (ii) primary and secondary neutrals can be grounded individually using two grounding conductors, and (iii) the neutral of the primary can be connected back to the neutral of the sending transformer by using the transmission line neutral.
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