| Face |
To machine a flat surface perpendicular to the axis at rotation on a lathe. |
| Fahrenheit |
The temperature scale based on the freezing point of water (32ºF) and the boiling point of water (212ºF). The interval between these points is divided into 180 equal parts. Although replaced by the Celsius scale, the Fahrenheit scale is still sometimes used for non-scientific measurements. |
| Failure |
The result when a body, component, or structure is incapable of performing the task for which it was designed. The term is often used without reference to what causes failure, such as fracture, buckling, excessive deformation, wear, or erosion. Failure criteria (failure theories, theories of strength) are mathematical expressions for the combinations of stress, strain, or strain energy at which materials fail, which are employed in design to dimension components. |
| Failure of the bolt |
Term implying that the bolt has broken or the threads have stripped. There can be many reasons for this. |
| Failure of the joint |
Failure of a bolted joint to behave as intended by the designer. Failure can be caused or accompanied by broken or lost bolts, but can also mean joint slip or leakage from a gasketed joint even if all bolts still remain whole and in place. Common reasons for joint failure include vibration loosening, poor assembly practices, improper design, unexpected service loads or conditions, etc. |
| Fastener |
A fastener is a mechanical device for holding two or more bodies in definite positions with respect to each other. |
| Fastener identification marking |
A stamp, paint, or other permanent identifier that may include manufacturer information and applicable grade markings for certification purposes. |
| Fastener manufacturer |
An organization that fabricates raw steel into a fastener meeting specified standards. |
| Fastener quality |
A fastener’s adherence to its specification for dimensional tolerances, mechanical properties, and other requirements stated under applicable standards. |
| Fastener specification |
A precise statement of set requirements to be satisfied by a fastener, its material, or its processing. It also indicates the procedure used to determine whether the requirements given are satisfied. |
| Fastener standard |
A document which details the attributes of a finished fastener and includes such characteristics as geometry, material or chemistry, heat treatment, finish, testing lot size, and packaging. |
| Fastener testing |
A determination or verification that the fastener meets its specification requirements. |
| Fastener with reduced shank |
Finished fastener with a shank diameter of ds ≈ d2. |
| Fastener with waisted shank |
Finished fastener with a shank diameter of ds < d2. |
| Fatigue |
The phenomenon leading to fracture under repeated or fluctuating stresses having a maximum value less than the ultimate tensile strength of the material. Fatigue failure generally occurs at loads that, applied statically, would produce little perceptible effect. Fatigue fractures are progressive, beginning as minute cracks that grow under the action of the fluctuating stress. |
| Fatigue |
A term referring, in components and structures subjected to either random or cyclic periodically-varying loads, to a progressive reduction in strength leading to failure at stresses lower than those that cause failure under monotonic loading. Variable loads arise from outof-balance machinery and other vibration sources, wind gusts, etc., and a large proportion of service failures is caused by fatigue. Fatigue results from the initiation and slow propagation of cracks. In manufactured components, crack initiation usually occurs at a point of stress concentration. After a period, often of millions of stress cycles, the crack reaches a critical length at which the next peak load causes sudden brittle or ductile fracture. Fracture surfaces resulting from fatigue display characteristic striations or progression marks emanating from the crack initiation site during the slow crack growth period, with a different surface appearance for the final fracture. |
| Fatigue crack growth rate (da/dN) |
The rate of crack extension caused by constant-amplitude fatigue loading, expressed in terms of crack extension per cycle of load application. |
| Fatigue failure |
Failure that occurs when a specimen undergoing fatigue completely fractures into two parts or has softened or been otherwise significantly reduced in stiffness by thermal heating or cracking. |
| Fatigue life (N) |
The number of cycles of stress or strain of a specified character that a given specimen sustains before failure occurs. |
| Fatigue life for p % survival |
An estimate of the fatigue life that p% of the population would attain or exceed at a given stress level. The observed value of the median fatigue life estimates the fatigue life for 50% survival. Fatigue life for p% survival values, where p is any number, such as 95, 90, etc., may also be estimated from the individual fatigue life values. |
| Fatigue limit |
The maximum stress that presumably leads to fatigue fracture in a specified number of stress cycles. The value of the maximum stress and the stress ratio also should be stated. Compare with endurance limit. |
| Fatigue limit for p % survival |
The limiting value of fatigue strength for p%survival as the number of stress cycles becomes very large; pmay be any number, such as 95, 90, etc. |
| Fatigue notch factor (Kf) |
The ratio of the fatigue strength of an unnotched specimen to the fatigue strength of a notched specimen of the same material and condition; both strengths are determined at the same number of stress cycles. |
| Fatigue strength |
The maximum stress that can be sustained for a specified number of cycles without failure. The value of the maximum stress and the stress ratio also should be stated. |
| Fatigue strength |
The stress to which a metal can be subjected for a specified number of cyclic changes of stress. |
| Fatigue striations |
Parallel lines frequently observed in electron microscope fractographs or fatigue-fracture surfaces. The lines are transverse to the direction of local crack propagation; the distance between successive lines represents the advance of the crack front during the one cycle of stress variation. |
| Fatigue test |
A method for determining the range of alternating (fluctuating)stresses a material can withstand without failing. |
| Fatigue wear |
Wear of a solid surface caused by fracture arising from material fatigue. |
| Feather key |
A parallel key fastened in either the shaft or in the hub of a member sliding on it. When fastened in the shaft, it must be long enough to hold or drive the sliding member in any of its positions on the shaft. When in the sliding member the key need only be as long as the hub. |
| Ferralium |
Ferralium is a type of Super Duplex Stainless Steel which is optimised for use within fasteners. |
| Ferrite |
A solid solution of one or more elements in body-centered cubic iron. Unless otherwise designated (for instance, as chromium ferrite), the solute is generally assumed to be carbon. On some equilibrium diagrams, there are two ferrite regions separated by an austenite area. The lower area is alpha ferrite; the upper, delta ferrite. If there is no designation, alpha ferrite is assumed. |
| Ferritic decarburization |
Decarburization with sufficient loss of carbon to cause a lighter shade of tempered martensite and a significantly lower hardness than that of the adjacent base metal, with the presence of ferrite grains or grain boundary network under metallographic examination. |
| Ferritic stainless steels |
Ferritic stainless steels have the ferrite (BCC) crystal structure and contain 10–28% chromium and typically 0.1–0.35% carbon (all in wt%). They are magnetic and can be hardened by cold working. They have good to moderate mechanical properties, good oxidation and corrosion resistance at elevated temperatures, and susceptibility to embrittlement at temperatures between 400 and 540°C. Used for turbine parts, hightemperature valves, automotive exhaust components, and nuclear reactor core components. |
| Ferritizing anneal |
A treatment given as-cast gray or ductile (nodular) iron to produce an essentially ferritic matrix. For the term to be meaningful, the final microstructure desired or the time-temperature cycle used must be specified. |
| Fibreglass |
Fibreglass is used in studs and nuts for applications when the fastener should be non-corrosive, low in conductivity, or transparent to electromagnetic waves. |
| Fillet |
Transition region between bolt head and shank, or between other changes in diameter. |
| Fillet radius |
Concave junction at two intersecting surfaces of a fastener. Often used to describe the junction between the head and the shank of a threaded fastener (under head fillet). |
| Fillister head |
Similar to a pan head but with a smaller head diameter and a taller head, with higher vertical sides. |
| Fin |
A thin projecting rib. |
| Fin neck carriage bolt |
A plain, circular, oval head bolt with two oppositely located fins to prevent rotation. |
| Final annealing |
An imprecise term used to denote the last anneal given to a nonferrous alloy prior to shipment. |
| Fine pitch |
Fine pitch threads are often used within the automotive industry. They are more easily tapped into harder materials and have less tendency to loosen. |
| Finish annealing |
A subcritical annealing treatment applied to cold-worked low- or medium-carbon steel. Finish annealing, which is a compromise treatment, lowers residual stresses, thereby minimizing the risk of distortion in machining while retaining most of the benefits to machinability contributed by cold working. Compare with final annealing. |
| Finished fastener |
Fastener for which all manufacturing steps have been completed, with or without any surface coating and with full or reduced loadability, and which has not been machined into a test piece. |
| Finished hexagon bolts |
A washer faced or chamfered bearing surface with a close body tolerance. |
| Finishing temperature |
The temperature at which hot working is completed. |
| Finishing washer |
A washer designed for use with countersunk screws. Used to enhance appearance in some applications. |
| Finishing washer |
A washer designed for use with countersunk screws. Used to enhance appearance in some applications. |
| Fit |
The general term used to signify the range of tightness which may result from the application of a specific combination of allowances and tolerances in the design of mating parts. |
| Fitted bolt |
A bolt with a plain unthreaded portion immediately beneath the head. |
| Fitted bolt |
A bolt with a plain unthreaded portion immediately beneath the head. |
| Flame annealing |
Annealing in which the heat is applied directly by a flame. |
| Flame hardening |
A process for hardening the surfaces of hardenable ferrous alloys in which an intense flame is used to heat the surface layers above the upper transformation temperature, whereupon the workpiece is immediately quenched. |
| Flame straightening |
Correcting distortion in metal structures by localized heating with a gas flame. |
| Flange |
1. Annular rims at the ends of pipes (flanged pipe) or shafts by which they may be coupled together using bolts that pass through holes in the flanges (flange coupling, flange union), or by toggle clamps around the periphery. 2. An extended rim on a wheel that positions it laterally on a track. Commonly used for railway rolling stock. 3. The top and bottom parts of an I-beam. |
| Flange |
Flange refers to a head style for bolts where there is a circular ‘flange’ under the head that acts like a washer to distribute a load. A flange is a projected flat rim or collar. |
| Flange bolt |
A bolt with a built in washer-like flange just below the head. |
| Flange rotation |
Angular distortion of a flange under the influence of bolt and reaction forces. Measured with respect to the center of the cross section of the flange. |
| Flat head |
Flat top surface and a conical bearing surface. |
| Flattening test |
This term as applied to tubing refers to a method of testing a section of tubing by flattening it until the inside walls are parallel and separated by a given distanceusually equal to three times the wall thickness for seamless tubes and five times the wall thickness for lap-welded tubes. Boiler tubes subjected to this test should show no cracks or flaws. The flattening test applied to rivets, consists in flattening a rivet head while hot to a diameter equal to 21⁄2 times the diameter of the shank or body of the rivet. Good rivet steel must not crack at the edges of the flattened head. |
| Flexural strength |
The maximum stress in the outer fiber at the moment of crack or break. |
| Fluid mechanics |
The study of fluids in motion (fluid dynamics) or fluid statics where there is no relative motion between fluid particles. Fluid statics concerns primarily the variation of pressure with altitude or depth; it includes aerostatics and hydrostatics. Fluid dynamics includes the topics of aerodynamics, gas dynamics, hydraulics, hydrodynamics and many aspects of acoustics, chemical engineering, flight, lubrication, meteorology, non-Newtonian fluid flow, oceanography, power-plant technology, propulsion, and turbomachinery. |
| Fog quenching |
Quenching in a fine vapor or mist. |
| Following flank |
The flank of a thread opposite to the leading flank. |
| Force ratio |
The factor by which a simple machine multiplies an applied force. It is the ratio of the load (output force) to the effort (input force). |
| Forced-air quench |
A quench utilizing blasts of compressed air against relatively small parts such as a gear. |
| Forge |
To shape metal while holt and plastic by a hammering or forcing process. Dies used in process. |
| Forging |
forging 1. A method of component manufacture by hammering metal by hand or by machine (drop forge, press). 2. A part made by the process of forging. |
| Forging |
The process of forming raw steel into specified shapes. Some examples of forged products would be hex bolts, clevises, and barrier pins. |
| Forging cracks |
This may occur during fastener manufacturing at the cutting or forging operations and are located on the top of the head or on the raised periphery of indented head bolts. |
| Form of thread |
The profile of a thread in an axial plane for a length of one pitch. |
| Fracture |
(rupture) The separation of materials, components, or structures into two or more parts by the propagation of one or more cracks. Cracking may be globally elastic (brittle) or accompanied by varying degrees of plasticity (ductile). |
| Fracture mechanics |
The stress analysis of bodies containing cracks. The use of stressconcentration factors and other correction factors of traditional strength of materials is inadequate when flaws are present initially (or develop during loading), since fracture depends not only on stress but also the size of the crack. Traditional strength of materials stress calculations cannot predict either the safe working stress in the presence of a known flaw, or the critical size of flaw just tolerable with a given working stress. |
| Fracture mechanisms |
The microstructural mechanisms that cause fracture, such as void initiation, growth and coalescence, cleavage. |
| Fracture strength |
(fracture stress) (Unit Pa) The stress at which a material breaks. It is not absolute for a given material, as it depends on the laws of fracture mechanics and is size-dependent. |
| Fracture stress |
The true normal stress on the minimum cross-sectional area at the beginning of fracture. This term usually applies to tension tests of unnotched specimens. |
| Fracture surface |
The irregular surface produced when a piece of metal is broken. |
| Fracture test |
A test in which a specimen is broken and its fracture surface is examined with the unaided eye or with a low-power microscope to determine such factors as composition, grain size, case depth, or internal discontinuities. |
| Fracture test |
1. The recording of load-deflexion (or stress–strain) in a specimen loaded monotonically until it breaks in tension, compression, shear, or torsion. 2. In fatigue, determination of the number of cycles to fracture for a specimen under different patterns of repeated loading. 3. Experiments to determine fracture toughness. |
| Fracture toughness |
A generic term for measures of resistance to extension of a crack. The term is sometimes restricted to results of fracture mechanics tests, which are directly applicable in fracture control. However, the term commonly includes results from simple tests of notched or precracked specimens not based on fracture mechanics analysis. Results from tests of the latter type are often useful for fracture control, based on either service experience or empirical correlations with fracture mechanics tests. |
| Free carbon |
The part of the total carbon in steel or cast iron that is present in elemental form as graphite or temper carbon. Contrast with combined carbon. |
| Free ferrite |
Ferrite that is formed directly from the decomposition of hypoeutectoid austenite during cooling, without the simultaneous formation of cementite. Also proeutectoid ferrite. |
| Free joint |
The joint on a robot arm and wrist that causes the greatest end-effector movement when a specified force is applied to the end effector, i.e. that has the lowest stiffness with regard to the force. |
| Free machining |
The property that makes machining easy because of the forming of small chips, a characteristic imparted to steel by sulfur, etc. |
| Freezing point |
The temperature at which a substance changes phase (or state) from liquid to solid. The freezing point for most substances increases as pressure increases. The reverse process, from solid to liquid, is melting; melting point is the same as freezing point. |
| Freezing range |
That temperature range between liquidus and solidus temperatures in which molten and solid constituents coexist. |
| Frequency |
(temporal frequency, f) (Unit Hz) The number of cycles per second in an oscillation or the repetition rate for a cyclic process. |
| Fretting corrosion |
(1) The accelerated deterioration at the interface between contacting surfaces as the result of corrosion and slight oscillatory movement between the two surfaces. (2) A form of fretting in which chemical reaction predominates. Fretting corrosion is often characterized by the removal of particles and subsequent formation of oxides, which are often abrasive and so increase the wear. Fretting corrosion can involve other chemical reaction products, which may not be abrasive. |
| Fretting fatigue |
Fatigue fracture that initiate at a surface area where fretting has occurred. The progressive damage to a solid surface that arises from fretting. |
| Friction |
The resistance that a body encounters when sliding over another body, or experiences when a viscous fluid flows over its surface. |
| Friction loss (Unit J) |
The conversion of mechanical energy to heat due to friction within a machine, mechanism, linkage, etc. |
| Friction materials |
Materials having a high coefficient of friction which, when coupled with a long life, may be employed as brake linings or the facing of the plates of a clutch. |
| Full annealing |
An imprecise term that denotes an annealing cycle to produce minimum strength and hardness. For the term to be meaningful, the composition and starting condition of the material and the time-temperature cycle used must be stated. |
| Full annealing |
Annealing a ferrous alloy by austenitizing and then cooling slowly through the transformation range. |
| Full hard |
A temper of nonferrous alloys and some ferrous alloys corresponding approximately to a coldworked state beyond which the material can no longer be formed by bending. In specifications, a full hard temper is commonly defined in terms of minimum hardness or minimum tensile strength (or, alternatively, a range of hardness or strength) corresponding to a specific percentage of cold reduction following a full anneal. For aluminum, a full hard temper is equivalent to a reduction of 75% from dead soft ; for austenitic stainless steels, a reduction of about 50 to 55%. |
| Full size body |
The body of a bolt or screw which has a diameter between the minimum and maximum limits of the major diameter of the thread. |
| Full-size fastener |
Finished fastener with a shank diameter of ds ≈ d or ds > d, or screw threaded to the head, or fully threaded stud. |
| Furnace |
1. A type of combustion chamber in which solid, liquid, or gaseous fuels are burned to supply hot gases to a boiler or other process plant. Examples include the firebox, boiler furnace (steam-generating furnace), hot-air furnace, oil-fired furnace, updraught furnace, and water-cooled furnace. 2. A chamber, sometimes having a controlled atmosphere or under vacuum (vacuum furnace), for heating and melting materials. Examples include the blast furnace, direct- and indirect-arc furnaces, the induction furnace (high-frequency furnace), muffle furnace, reverberatory furnace, and solar furnace. |
