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| The common name of the face-centered-cubic structure of pure iron in honor the metallurgist Sir Robert Austen. Key features are high formidability, high ductility, and chemical uniformity. |
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| One of the two major effects that Silicon has in Cast Iron. It partially substitutes for carbon, so that use of the phase diagram requires replacing the weight percent carbon scale with a carbon equivalent. |
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| General term that classifies all iron-carbon alloys containing more than 2.11 percent carbon that experience the eutectic region. Term applies to an entire family of metals with a wide variety of properties |
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| The fourth single-phase of steel which is the intermetallic compound Fe C, and is also known as iron-carbide |
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| Compacted Graphite Cast Iron |
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| (Also known as vermicular graphite iron, seminodular iron, or quasi-flake iron) Produced by a method similar to that used to make ductile iron, it is characterized by a graphite structure that is intermediate to the flake graphite or gray iron and the nodular graphite of ductile iron, and it tends to posses the desirable properties and characteristics of each. |
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| When two materials are completely soluble in one another in both liquid and solid states. |
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| Definable structure, and a uniform and identifiable chemistry |
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| temperature versus time plot of cooling history where transitions in structure appear as characteristic points. |
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| The resultant structure variations on a microscopic level where the initial solid that formed retained a chemistry that was different from the solid regions that formed that later (As result of rapid cooling). |
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| Or nodular cast iron, is the product of the addition of magnesium just prior to solidification where the graphite forms Smooth-surface spheres. |
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| Used in defining phase diagrams. Assumes that equilibrium has been reached for all possible conditions. The conditions that vary are temperature, pressure, and composition. |
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| One common type of three-phase reaction that consists of an intimate mixture of two single-phase solids. The two materials are soluble in liquid state but only partially soluble in solid state. Reaction: Liquid → Solid 1 + Solid 2 |
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| Three-phase reaction that has the same reaction form as Eutectic except all phases involved are solids (denoted by the “-oid” suffix). Solid state reactions are typically more sluggish since all changes must occur within solids. Reaction: Solid 1 → Solid 2 + Solid 3 |
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| Also known as Alpha ferrite, ferrite is the stable form of iron at temperatures below 912 degrees Celsius. This body-centered-cubic structure can only hold .02 percent Carbon in solid solution and forces the creation of a two-phase mixture in most steels. |
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| The area between the liquidus and solidus that identifies the two-phase region where liquid and solid solutions coexist. |
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| The final microstructure of cast iron has two possible extremes one of which is the all carbon-rich phase being graphite. Graphite formation is promoted by slow cooking, high carbon and silicon contents, heavy section sizes, inoculation practices, and the presence of sulfur, phosphorus, and cobalt. |
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| The least expensive and most common variety of cast iron which is characterized by those features that promote the formation of graphite. |
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| Steels having more than the eutectoid amount of carbon. |
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| Graphite formation is promoted by slow cooking, high carbon and silicon contents, heavy section sizes, inoculation practices, and the presence of sulfur, phosphorus, and cobalt. |
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| Hard, brittle materials since these properties are consequence of their ionic or covalent bonding. These compounds are single-phase solids and tend to break the phase-diagram into recognizable sub areas |
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| A calculation that determines the relative amounts of two components using the previously drawn tie-line (if given a point on the phase diagram that lies in a two-phase region). |
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| The line on the phase diagram that denotes the lowest temperature at which the material is totally liquid |
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| The product of white cast iron when it is exposed to extended heat treatment. It has significantly greater ductility than gray cast iron because the more favorable graphite shape removes the internal notches. Most weigh less than 5 Kg. |
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| A hard wear-resistant structure used in the metal matrix of white cast iron (Since white cast iron is so hard and brittle, it finds applications where high abrasion resistance is the dominant requirement). |
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| A three-phase reaction where at least one of the three phases in the reaction is a liquid (denoted by the “-ic” suffix). Liquid 1 → Solid 1 + Liquid 2. |
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| Where regions of white and gray cast iron occur in the component, there is generally a transition region comprised of both white and gray cast irons, which is known as the mottled zone. |
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| The addition of magnesium just prior to solidification where the graphite forms Smooth-surface spheres. |
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| A compound where some degree of chemical deviation is tolerable and the vertical line expands into a single-phase region. |
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| When the carbon in austenite is retained (instead of forming additional graphite), due to the material cooling more rapidly through eutectoid transformation. It is characterized by higher strength and lower ductility. |
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| A three-phase reaction where at least one of the three phases in the reaction is a liquid (denoted by the “-ic” suffix). Reaction: Liquid + Solid 1 → Solid 2. |
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| Three-phase reaction that has the same reaction form as Peritectic except all phases involved are solids (denoted by the “-oid” suffix). Solid state reactions are typically more sluggish since all changes must occur within solids. Reaction: Solid 1 + Solid 2 → Solid 3. |
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| a form of material possessing a characteristic structure and characteristic properties. It has a definable structure, a uniform and identifiable chemistry, and distinct boundaries or interfaces that separate it from other different phases. |
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| A graphical mapping of the natural tendencies of a material or a material system. The most useful is the temperature-composition phase diagram. |
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| The only crystalline phase capable of existing in equilibrium with a given liquid. |
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| The lower line on the phase diagram that denotes the highest temperature at which the material is completely solid |
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| ) Points where materials will remain in a certain state (Max concentration for which solution occurs). Determining the limits requires several horizontal scans to complete the ends of the phase diagram. |
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| In a phase or equilibrium diagram, the locus of points representing the solid-solubility temperatures of various compositions of the solid phase |
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| A generally hard, strong, durable, malleable alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, molybdenum, copper, tungsten, cobalt, or silicon, depending on the desired alloy properties, and widely used as a structural material. |
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| Calculation of the quantities of reactants and products in a chemical reaction. |
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| Isothermal, reversible conversion of a solid phase into two conjugate liquid phases on applying heat |
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| Steels having less than the eutectoid amount of carbon (less than .077 percent). |
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| Increasing the hardness of an alloy by a relatively low-temperature heat treatment that causes precipitation of components or phases of the alloy from the supersaturated solid solution. Also known as precipitation hardening |
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| The process of growing old or maturing |
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| To subject (glass or metal) to a process of heating and slow cooling in order to toughen and reduce brittleness. To strengthen or harden |
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| The heat treatment of an alloy at moderately elevated temperatures to accelerate precipitation of a component from the supersaturated solid solution. |
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| Artificial Gas Atmospheres |
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| The processing of steel by subjecting it to deformation followed by quenching and tempering in order to increase strength, ductility, and resistance to fatigue. |
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| A process for the heat treatment of austenitic steel. |
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| Steel formed by austempering, having an acicular structure of ferrite and carbides, exhibiting considerable toughness, and combining high strength with high ductility. |
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| Oldest method for surface-hardening steel, by heat or mechanical means to increase the hardness of the outer surface while leaving the core relatively soft. The combination of hard surface and soft interior withstands very high stress and fatigue, and also offers low cost and superior flexibility in manufacturing. To carburize, the steel parts are placed in a carbonaceous environment (with charcoal, coke, and carbonates, or with carbon dioxide, carbon monoxide, methane, or propane) at a high temperature for several hours. The carbon diffuses into the surface of the steel, altering the crystal structure of the metal. Gears, ball and roller bearings, and piston pins are often carburized. |
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| The quality or state of cohering, especially a logical, orderly, and aesthetically consistent relationship of parts. Physics. The property of being coherent, as of waves |
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| is a heat treatment technique used to strengthen malleable materials, especially non-ferrous alloys including most structural alloys of aluminum and titanium. It relies on changes in solid solubility with temperature to produce fine particles of an impurity phase, which impede the movement of dislocations, or defects in a crystal's lattice. Since dislocations are often the dominant carriers of plasticity (deformations of a material under stress), this serves to harden the material. The impurities, in fact, play the same role as matrix substances in composite materials. Just as the formation of ice in air can produce clouds, snow, or hail, depending upon the thermal history of a given portion of the atmosphere, precipitation in solids can produce many different sizes of particles, which have radically different properties. Unlike ordinary tempering, alloys must be kept at elevated temperature for hours to allow precipitation to take place. This time delay is called aging. |
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| Equilibrium Phase Diagram |
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| A method for local surface hardening of steel by passing an oxyacetylene or similar flame over the work at a predetermined rate. |
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| typically results in the softest state a metal can assume. To perform a full anneal, a metal is heated to its annealing point, and the furnace is turned off. The metal is allowed to cool in the furnace, causing grain growth and resulting in a ductile metal with a lowered yield point |
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In a ferrous alloy, the property that determines the depth and distribution of hardness induced by quenching from elevated temperatures.
hardness - The quality or condition of being hard. The relative resistance of a mineral to scratching, as measured by the Mohs scale. The relative resistance of a metal or other material to denting, scratching, or bending. |
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| To treat (metal, for example) by alternate heating and cooling in order to produce desired characteristics, such as increased hardness; temper. |
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| to make the same throughout |
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| a form of heat treatment in which a metal part is heated inductively and then quenched. The quenched metal undergoes a martensitic transformation, increasing the hardness and brittleness of the part. Induction hardening is used to selectively harden areas of a part or assembly without affecting the properties of the part as a whole. |
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| Isothermal Transformation Diagram |
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| A hardenability test in which a steel bar is heated to the desired austenitizing temperature and quench-hardened at one end and then measured for hardness along its length, beginning at the quenched end. Also known as ... |
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| Quenching austenitized steel to a temperature just above, or in the upper part of, the martensite range, holding it at this point until the temperature is equalized throughout, and then cooling in air to room temperature. Also known as marquenching. |
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| A solid solution of iron and up to one percent of carbon, the chief constituent of hardened carbon tool steels |
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| Surface hardening of steel by formation of nitrides; nitrogen is introduced into the steel usually by heating in gaseous ammonia |
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| To remove strains and reduce coarse crystalline structures in (metal), especially by heating and cooling |
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| A mixture of ferrite and cementite forming distinct layers or bands in slowly cooled carbon steels |
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| Phase Transformation Strengthening |
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| is a heat treatment technique used to strengthen malleable materials, especially non-ferrous alloys including most structural alloys of aluminum and titanium. It relies on changes in solid solubility with temperature to produce fine particles of an impurity phase, which impede the movement of dislocations, or defects in a crystal's lattice. Since dislocations are often the dominant carriers of plasticity (deformations of a material under stress), this serves to harden the material. The impurities, in fact, play the same role as matrix substances in composite materials. Just as the formation of ice in air can produce clouds, snow, or hail, depending upon the thermal history of a given portion of the atmosphere, precipitation in solids can produce many different sizes of particles, which have radically different properties. Unlike ordinary tempering, alloys must be kept at elevated temperature for hours to allow precipitation to take place. This time delay is called aging. |
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| Shock cooling by immersing liquid or molten material into a cooling medium |
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| A process which takes place in metals and alloys following distortion and fragmentation of constituent crystals by severe mechanical deformation, in which some fragments grow at the expense of others, so that larger, strain-free grains are formed; it progresses slowly at room temperature, but is greatly sped by annealing. |
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| stresses that remain after the original cause of the stresses (external forces, heat gradient) has been removed |
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| Solid Solution Strengthening |
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| Increasing the hardness and tensile strength of a metal by cold plastic deformation. |
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| Hardening the surface of steel by one of several processes, such as carburizing, carbonitriding, nitriding, flame or induction hardening, and surface working. |
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| To harden or strengthen (metal or glass) by application of heat or by heating and cooling |
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| Thermomechanical Processing |
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| Is the most common classification for alloy steels. It classifies alloys by chemistry. |
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