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| {{For|ductility in Earth science|Ductility (Earth science)}}
| | I'm Christian and I live in Kastenberg. <br>I'm interested in Agriculture and Life Sciences, Water sports and English art. I like travelling and reading fantasy.<br><br>my web-site: plastic surgery ([http://app-Stock.ru/RosevilleSurgery95657 click through the up coming web site]) |
| {{Redirect|Malleability|the property in cryptography|Malleability (cryptography)}}
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| {{pp-move-indef|small=yes}}[[File:Al tensile test.jpg|thumb|Tensile test of an [[Aluminum alloy|AlMgSi alloy]]. The local necking and the cup and cone fracture surfaces are typical for ductile metals.]]
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| [[File:Cast iron tensile test.JPG|thumb|This tensile test of a [[Ductile iron|nodular cast iron]] demonstrates low ductility.]]
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| In [[materials science]], '''ductility''' is a solid material's ability to deform under [[Tension (physics)|tensile]] stress; this is often characterized by the material's ability to be stretched into a wire. '''Malleability''', a similar property, is a material's ability to deform under [[Compression (physical)|compressive]] stress; this is often characterized by the material's ability to form a thin sheet by hammering or rolling. Both of these mechanical properties are aspects of [[plasticity (physics)|plasticity]], the extent to which a solid material can be plastically deformed without [[fracture]]. Also, these material properties are dependent on temperature and pressure (investigated by [[Percy Williams Bridgman]] as part of his Nobel Prize winning work on high pressures).
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| Ductility and malleability are not always coextensive – for instance, while [[gold]] has high ductility and malleability, [[lead]] has low ductility but high malleability.<ref name="mms">{{Cite book | last = Rich | first = Jack C. | title = The Materials and Methods of Sculpture | publisher = Courier Dover Publications | page = 129 | year = 1988 | url = http://books.google.com/?id=hW13qhOFa7gC | isbn = 0-486-25742-8 | postscript = <!-- Bot inserted parameter. Either remove it; or change its value to "." for the cite to end in a ".", as necessary. -->{{inconsistent citations}}}}.</ref> The word ''ductility'' is sometimes used to embrace both types of plasticity.<ref>{{cite encyclopedia |encyclopedia = TheFreeDictionary.com |title = Ductile |url = http://www.thefreedictionary.com/ductile |accessdate = January 30, 2011 |publisher = Farlex |ref = TheFreeDictionary}} Includes definitions from ''American Heritage Dictionary of the English Language'', ''Collins English Dictionary: Complete and Unabridged'', ''American Heritage Science Dictionary'', and ''WordNet 3.0''.</ref>
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| == Materials science ==
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| {{Expand section|date=June 2011}}
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| [[File:Kanazawa Gold Factory.jpg|thumb|right|200px|[[Gold leaf]] is possible due to gold's malleability.]]
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| Ductility is especially important in [[metalworking]], as materials that crack, break or shatter under stress cannot be manipulated using metal forming processes, such as [[hammer]]ing, [[rolling (metalworking)|rolling]], and [[drawing (metalworking)|drawing]]. Malleable materials can be formed using [[Stamping (metalworking)|stamping]] or [[Machine press|press]]ing, whereas brittle metals and [[plastic]]s must be [[molding (process)|molded]].
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| High degrees of ductility occur due to [[metallic bond]]s, which are found predominantly in metals and leads to the common perception that metals are ductile in general. In metallic bonds [[valence shell]] [[electron]]s are delocalized and shared between many atoms. The [[delocalized electron]]s allow metal atoms to slide past one another without being subjected to strong repulsive forces that would cause other materials to shatter.
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| Ductility can be quantified by the fracture strain <math>\varepsilon_f</math>, which is the engineering [[Strain (materials science)|strain]] at which a test specimen fractures during a uniaxial [[tensile test]]. Another commonly used measure is the reduction of area at fracture <math>q</math>.<ref name=dieter>G. Dieter, ''Mechanical Metallurgy'', McGraw-Hill, 1986, ISBN 978-0-07-016893-0</ref> The ductility of [[steel]] varies depending on the alloying constituents. Increasing levels of [[carbon]] decreases ductility. Many plastics and [[amorphous solid]]s, such as [[Play-Doh]], are also malleable.
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| The most ductile metal is platinum and the most malleable metal is gold <ref>Materials handbook,Mc Graw-Hill handbooks, by John Vaccaro, fifteenth edition, 2002</ref><ref>CRC encyclopedia of materials parts and finishes, second edition, 2002, M.Schwartz</ref>
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| ==Ductile–brittle transition temperature{{anchor|Ductile-brittle transition temperature}}==
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| [[File:Ductility.svg|thumb|right|157px|Schematic appearance of round metal bars after tensile testing.<br>
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| (a) Brittle fracture<br>
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| (b) Ductile fracture<br>
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| (c) Completely ductile fracture]]
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| The ductile–brittle transition temperature (DBTT), nil ductility temperature (NDT), or nil ductility transition temperature of a metal represents the point at which the fracture energy passes below a pre-determined point (for steels typically 40 J<ref>John, Vernon. ''Introduction to Engineering Materials'', 3rd ed.(?) New York: Industrial Press, 1992. ISBN 0-8311-3043-1.</ref> for a standard [[Charpy impact test]]). DBTT is important since, once a material is cooled below the DBTT, it has a much greater tendency to shatter on impact instead of bending or deforming. For example, [[zamak|zamak 3]] exhibits good ductility at room temperature but shatters at sub-zero temperatures when impacted. DBTT is a very important consideration in materials selection when the material in question is subject to mechanical stresses. A similar phenomenon, the [[glass transition temperature]], occurs with glasses and polymers, although the mechanism is different in these amorphous materials.
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| In some materials this transition is sharper than others. For example, the transition is generally sharper in materials with a [[body-centered cubic]] (BCC) lattice than those with a [[face-centered cubic]] (FCC) lattice. DBTT can also be influenced by external factors such as [[neutron radiation]], which leads to an increase in internal [[lattice defect]]s and a corresponding decrease in ductility and increase in DBTT.
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| The most accurate method of measuring the BDT or DBT temperature of a material is by fracture testing. Typically, four point bend testing at a range of temperatures is performed on pre-cracked bars of polished material. For experiments conducted at higher temperatures, dislocation activity increases. At a certain temperature, dislocations shield the crack tip to such an extent the applied deformation rate is not sufficient for the stress intensity at the crack-tip to reach the critical value for fracture (K<sub>iC</sub>). The temperature at which this occurs is the ductile–brittle transition temperature. If experiments are performed at a higher strain rate, more dislocation shielding is required to prevent brittle fracture and the transition temperature is raised.
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| ==See also==
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| * [[Deformation (engineering)|Deformation]]
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| * [[Work hardening]], which reduces ductility
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| * [[Strength of materials]]
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| ==References==
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| {{reflist}}
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| {{Refimprove|date=October 2008}}
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| ==External links==
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| * [http://www.engineersedge.com/material_science/ductility.htm Ductility definition at engineersedge.com]
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| * [http://www.doitpoms.ac.uk/tlplib/ductile-brittle-transition/index.php DoITPoMS Teaching and Learning Package- "The Ductile-Brittle Transition]
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| {{Wiktionary}}
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| {{Wiktionary|malleability}}
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| [[Category:Continuum mechanics]]
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| [[Category:Deformation]]
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I'm Christian and I live in Kastenberg.
I'm interested in Agriculture and Life Sciences, Water sports and English art. I like travelling and reading fantasy.
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