en.wikipedia.org wiki tempering (metallurgy)

8/10/2019 en.wikipedia.org Wiki Tempering (Metallurgy)

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Differentially tempered steel. The

various colors produced indicate the

temperature to which the steel was

heated. Light-straw indicates 204 C

(399 F) and light blue indicates

337 C (639 F).[1][2]

Tempering (metallurgy)From Wikipedia, the free encyclopedia

Temperingis a process of heat treating, which is used to

increase the toughness of iron-based alloys. Tempering is usually

performed after hardening, to reduce some of the excess

hardness, and is done by heating the metal to some temperaturebelow the critical point for a certain period of time, then allowing

it to cool in still air. The exact temperature determines the

amount of hardness removed, and depends on both the specific

composition of the alloy and on the desired properties in the

finished product. For instance, very hard tools are often tempered

at low temperatures, while springs are tempered to much higher

temperatures. In glass, tempering is performed by heating the

glass and then quickly cooling the surface, increasing the

toughness.

Contents

1 Introduction

2 History

3 Terminology

4 Carbon steel

4.1 Quenched-steel

4.2 Normalized steel

4.3 Welded steel

4.4 Quench and self-temper

4.5 Blacksmithing

4.5.1 Tempering colors

4.5.2 Differential tempering

4.6 Interrupted quenching

4.6.1 Austempering

4.6.2 Martempering

4.7 Physical processes

4.7.1 Embrittlement

5 Alloy steels

6 Cast-iron

6.1 White tempering

Page 1 of 13Tempering (metallurgy) - Wikipedia, the free encyclopedia

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Photomicrograph of martensite, a

very hard microstructure formed

when steel is quenched. Tempering

reduces the hardness in the martensite

by transforming it into various forms

of tempered martensite.

6.2 Black tempering

7 Precipitation hardening alloys

8 See also

9 References

10 Further reading

11 External links

Introduction

Tempering is a heat treatment technique applied to ferrous

alloys, such as steel or cast iron, to achieve greater toughness by

decreasing the hardness of the alloy. The reduction in hardness is

usually accompanied by an increase in ductility, thereby

decreasing the brittleness of the metal. Tempering is usuallyperformed after quenching, which is rapid cooling of the metal to

put it in its hardest state. Tempering is accomplished by

controlled heating of the quenched work-piece to a temperature

below its "lower critical temperature". This is also called the

lower transformation temperature or lower arrest (A1)

temperature; the temperature at which the crystalline phases of

the alloy, called ferrite and cementite, begin combining to form a

single-phase solid solution referred to as austenite. Heating

above this temperature is avoided, so as not to destroy the very-

hard, quenched microstructure, called martensite.[3]

Precise control of time and temperature during the tempering process is crucial to achieve the desired

balance of physical properties. Low tempering temperatures may only relieve some of the internal

stresses, decreasing brittleness while maintaining a majority of the hardness. Higher tempering

temperatures tend to produce a greater reduction in the hardness, sacrificing some yield strength and

tensile strength for an increase in elasticity and plasticity. However, in some low alloy steels, containing

other elements like chromium and molybdenum, tempering at low temperatures may produce an

increase in hardness, while at higher temperatures the hardness will decrease. Many steels with high

concentrations of these alloying elements behave like precipitation hardening alloys, which produces the

opposite effects under the conditions found in quenching and tempering, and are referred to as maraging

steels.[3]

In carbon steels, tempering alters the size and distribution of carbides in the martensite, forming a

microstructure called "tempered martensite". Tempering is also performed on normalized steels and cast

irons, to increase ductility, machinability, and impact strength.[3]Steel is usually tempered evenly, called

"through tempering," producing a nearly uniform hardness, but it is sometimes heated unevenly, referred

to as "differential tempering," producing a variation in hardness. [4]




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History

Tempering is an ancient heat-treating technique. The oldest known example of tempered martensite is a

pick axe which was found in Galilee, dating from around 1200 to 1100 BC. [5]The process was used

throughout the ancient world, from Asia to Europe and Africa. Many different methods and cooling

baths for quenching have been attempted during ancient times, from quenching in urine, blood, or metals

like mercury or lead, but the process of tempering has remained relatively unchanged over the ages.

Tempering was often confused with quenching and, often, the term was used to describe both

techniques. In 1889, Sir William Chandler Roberts-Austen wrote, "There is still so much confusion

between the words "temper," "tempering," and "hardening," in the writings of even eminent authorities,

that it is well to keep these old definitions carefully in mind. I shall employ the word tempering in the

same sense as softening."[6]

Terminology

In metallurgy, one may encounter many terms that have very specific meanings within the field, but may

seem rather vague when viewed from outside. Terms such as "hardness," "impact resistance,"

"toughness," and "strength" can carry many different connotations, making it sometimes difficult to

discern the specific meaning. Some of the terms encountered, and their specific definitions are:

Strength: This is resistance to permanent deformation and breaking. Strength, in metallurgy, is

still a rather vague term, so is usually divided into yield strength (strength beyond which

deformation becomes permanent), tensile strength (the ultimate breaking strength), and shear

strength (resistance to transverse, or cutting forces).

Toughness: Resistance to fracture, as measured by the Charpy test. Toughness often increases as

strength decreases.

Hardness: Hardness is often used to describe strength or rigidity but, in metallurgy, the term is

usually used to describe resistance to scratching or abrasion.

Brittleness: Brittleness describes a material's tendency to break before bending or deforming either

elastically or plastically. Brittleness increases with decreased toughness, but is greatly affected by

internal stresses as well.

Plasticity: The ability to mold, bend or deform in a manner that does not spontaneously return to

its original shape. This is proportional to the ductility or malleability of the substance.

Elasticity: Also called flexibility, this is the ability to deform, bend, compress, or stretch and

return to the original shape once the external stress is removed. Elasticity is related to the Young's

modulus of the material.

Impact resistance: Usually synonymous with high-strength toughness, it is the ability resist shock-

loading with minimal deformation.




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Wear resistance: Usually synonymous with hardness, this is resistance to erosion, ablation,

spalling, or galling.

Structural integrity: The ability to withstand a maximum-rated load while resisting fracture,

resisting fatigue, and producing a minimal amount of flexing or deflection, to provide a maximum

service life.

Carbon steel

Very few metals react to heat treatment in the same manner, or to the same extent, that carbon steel

does, and carbon steel heat treating behavior can vary radically depending on alloying elements. Steel

can be softened to a very malleable state through annealing, or it can be hardened to a state nearly as

rigid and brittle as glass by quenching. However, in its hardened state, steel is usually far too brittle,

lacking the structural integrity to be useful for most applications. Tempering is a method used to

decrease the hardness, thereby increasing the ductility of the quenched steel, to impart some springiness

and malleability to the metal. This allows the metal to bend before breaking. Depending on how much

temper is imparted to the steel, it may bend elastically (the steel returns to its original shape once theload is removed), or it may bend plastically (the steel does not return to its original shape, resulting in

permanent deformation), before fracturing. Tempering is used to precisely balance the mechanical

properties of the metal, such as shear strength, yield strength, hardness, ductility and tensile strength, to

achieve any number of a combination of properties, making the steel useful for a wide variety of

applications. Tools such as hammers and wrenches require good resistance to abrasion, impact

resistance, and resistance to deformation. Springs do not require as much rigidity, but must deform

elastically before breaking. Automotive parts tend to be a little less rigid, but need to deform plastically

before breaking.

Except in rare cases where maximum rigidity and hardness are needed, such as the untempered steel

used for files, quenched steel is almost always tempered to some degree. However, steel is sometimes

annealed through a process called normalizing, leaving the steel only partially softened. Tempering is

sometimes used on normalized steels to further soften it, increasing the malleability and machinability

for easier metalworking. Tempering may also be used on welded steel, to relieve some of the stresses

and excess hardness created in the heat affected zone around the weld. [3]

Quenched-steel

Tempering is most often performed on steel that has been heated above its upper critical (A 3)

temperature and then quickly cooled, in a process called quenching, using methods such as immersing

the red-hot steel in water, oil, or forced-air. The quenched-steel, being placed in, or very near, its hardestpossible state, is then tempered to incrementally decrease the hardness to a point more suitable for the

desired application. The hardness of the quenched-steel depends on both cooling speed and on the

composition of the alloy. Steel with a high carbon-content will reach a much harder state than steel with

a low carbon-content. Likewise, tempering high-carbon steel to a certain temperature will produce steel

that is considerably harder than low-carbon steel that is tempered at the same temperature. The amount

of time held at the tempering temperature also has an effect. Tempering at a slightly elevated




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temperature for a shorter time may produce the same effect as tempering at a lower temperature for a

longer time. Tempering times vary, depending on the carbon content, size, and desired application of the

steel, but typically range from a few minutes to a few hours.

Tempering quenched-steel at very low temperatures, between 66 and 148 C (151 and 298 F), will

usually not have much effect other than a slight relief of some of the internal stresses. Tempering at

higher temperatures, from 148 to 205 C (298 to 401 F), will produce a slight reduction in hardness, but

will primarily relieve much of the internal stresses. Tempering in the range of 260 and 340 C (500 and

644 F) causes a decrease in ductility and an increase in brittleness, and is referred to as the "tempered

martensite embrittlement" (TME) range. Except in the case of blacksmithing, this range is usually

avoided. Steel requiring more strength than toughness, such as tools, are usually not tempered above

205 C (401 F). Instead, a variation in hardness is usually produced by varying only the tempering

time. When increased toughness is desired at the expense of strength, higher tempering temperatures,

from 370 to 540 C (698 to 1,004 F), are used. Tempering at even higher temperatures, between 540

and 600 C (1,004 and 1,112 F), will produce excellent toughness, but at a serious reduction in the

strength and hardness. At 600 C (1,112 F), the steel may experience another stage of embrittlement,

called "temper embrittlement" (TE), which occurs if the steel is held within the TE temperature range for

too long. When heating above this temperature, the steel will usually not be held for any amount of time,and quickly cooled to avoid temper embrittlement.[3]

Normalized steel

Steel that has been heated above its upper critical temperature and then cooled in standing air is called

normalized steel. Normalized steel consists of pearlite, bainite and sometimes martensite grains, mixed

together within the microstructure. This produces steel that is much stronger than full-annealed steel,

and much tougher than tempered quenched-steel. However, added toughness is sometimes needed at a

reduction in strength. Tempering provides a way to carefully decrease the hardness of the steel, thereby

increasing the toughness to a more desirable point. Cast-steel is often normalized rather than annealed,to decrease the amount of distortion that can occur. Tempering can further decrease the hardness,

increasing the ductility to a point more like annealed steel.[7]Tempering is often used on carbon steels,

producing much the same results. The process, called "normalize and temper", is used frequently on

steels such as 1045 carbon steel, or most other steels containing 0.35 to 0.55% carbon. These steels are

usually tempered after normalizing, to increase the toughness and relieve internal stresses. This can

make the metal more suitable for its intended use and easier to machine. [8]

Welded steel

Steel that has been arc welded, gas welded, or welded in any other manner besides forge welded, is

affected in a localized area by the heat from the welding process. This localized area, called the heat-

affected zone (HAZ), consists of steel that varies considerably in hardness, from normalized steel to

steel nearly as hard as quenched steel near the edge of this heat-affected zone. Thermal contraction from

the uneven heating, solidification and cooling creates internal stresses in the metal, both within and

surrounding the weld. Tempering is sometimes used in place of stress relieving (even heating and

cooling of the entire object to just below the A1temperature) to both reduce the internal stresses and to




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decrease the brittleness around the weld. Localized tempering is often used on welds when the

construction is too large, intricate, or otherwise too inconvenient to heat the entire object evenly.

Tempering temperatures for this purpose are generally around 205 C (401 F) and 343 C (649 F). [9]

Quench and self-temper

Modern reinforcing bar of 500 MPa strength can be made from expensive microalloyed steel or by aquench and self-temper (QST) process. After the bar exits the final rolling pass, where the final shape of

the bar is applied, the bar is then sprayed with water which quenches the outer surface of the bar. The

bar speed and the amount of water are carefully controlled in order to leave the core of the bar

unquenched. The hot core then tempers the already quenched outer part, leaving a bar with high strength

but with a certain degree of ductility too.

Blacksmithing

Tempering was originally a process used and developed by blacksmiths (forgers of iron). The process

was most likely developed by the Hittites of Anatolia (modern-day Turkey), in the twelfth or eleventh

century BC. Without knowledge of metallurgy, tempering was originally devised through a trial-and-

error method.

Because few methods of precisely measuring temperature existed until modern times, temperature was

usually judged by watching the tempering colors of the metal. Tempering often consisted of heating

above a charcoal or coal forge, or by fire, so holding the work at exactly the right temperature for the

correct amount of time was usually not possible. Tempering was usually performed by slowly, evenly

overheating the metal, as judged by the color, and then immediately cooling, either in open air or by

immersing in water. This produced much the same effect as heating at the proper temperature for the

right amount of time, and avoided embrittlement by tempering within a short time period. However,

although tempering-color guides exist, this method of tempering usually requires a good amount ofpractice to perfect, because the final outcome depends on many factors, including the composition of the

steel, the speed at which it was heated, the type of heat source (oxidizing or carburizing), the cooling

rate, oil films or impurities on the surface, and many other circumstances which vary from smith to

smith or even from job to job. The thickness of the steel also plays a role. With thicker items, it becomes

easier to heat only the surface to the right temperature, before the heat can penetrate through. However,

very thick items may not be able to harden all the way through during quenching. [10]

Tempering colors

If steel has been freshly ground, sanded, or polished,

it will form an oxide layer on its surface when

heated. As the temperature of the steel is increased,

the thickness of the iron oxide will also increase.

Although iron oxide is not normally transparent,

such thin layers do allow light to pass through,

reflecting off both the upper and lower surfaces of

the layer. This causes a phenomenon called thin-film

interference, which produces colors on the surface.




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Pieces of through-tempered steel flatbar. The first

one, on the left, is normalized steel. The second is

quenched, untempered martensite. The remaining

pieces have been tempered in an oven to their

corresponding temperature, for an hour each.

"Tempering standards" like these are sometimes

used by blacksmiths for comparison, ensuring thatthe work is tempered to the proper color.

A differentially tempered sword. The center is

tempered to a springy hardness while the edges are

tempered to a very high hardness.

As the thickness of this layer increases with

temperature, it causes the colors to change from a

very light yellow, to brown, then purple, then blue.

These colors appear at very precise temperatures,

and provide the blacksmith with a very accurate

gauge for measuring the temperature. The various

colors, their corresponding temperatures, and someof their uses are:

Faint-yellow 176 C (349 F) engravers,

razors, scrapers

Light-straw 205 C (401 F) rock drills, reamers, metal-cutting saws

Dark-straw 226 C (439 F) scribers, planer blades

Brown 260 C (500 F) taps, dies, drill bits, hammers, cold chisels

Purple 282 C (540 F) surgical tools, punches, stone carving tools

Dark blue 310 C (590 F) screwdrivers, wrenches

Light blue 337 C (639 F) springs, wood-cutting saws

Grey-blue 371 C (700 F) and higher structural steel

Beyond the grey-blue color, the iron oxide loses its transparency, and the temperature can no longer be

udged in this way. The layer will also increase in thickness as time passes, which is another reason

overheating and immediate cooling is used. Steel in a tempering oven, held at 205 C (401 F) for a long

time, will begin to turn brown, purple or blue, even though the temperature did not exceed that needed to

produce a light-straw color. Oxidizing or carburizing heat sources may also affect the final result. The

iron oxide layer, unlike rust, also protects the steel from corrosion through passivation.[11]

Differential tempering

Differential tempering is a method of providing

different amounts of temper to different parts of the

steel. The method was often used in bladesmithing,

for making knives and swords, to provide a very

hard edge while softening the spine or center of the

blade. This increased the toughness while

maintaining a very hard, sharp, impact-resistant

edge, helping to prevent breakage. This techniquewas more often found in Europe, as opposed to the

differential hardening techniques more common in Asia, such as in Japanese swordsmithing.

Differential tempering consists of applying heat to only a portion of the blade, usually the spine, or the

center of double-edged blades. For single-edged blades, the heat, often in the form of a flame or a red-

hot bar, is applied to the spine of the blade only. The blade is then carefully watched as the tempering

colors form and slowly creep toward the edge. The heat is then removed before the light-straw color

reaches the edge. The colors will continue to move toward the edge for a short time after the heat is




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cooling allows much of the internal stresses to relax before the martensite forms, decreasing the

brittleness of the steel. However, the martempered steel will usually need to undergo further tempering

to adjust the hardness and toughness.[13]

Physical processes

Tempering involves a three-step process in which unstable martensite decomposes into ferrite andunstable carbides, and finally into stable cementite, forming various stages of a microstructure called

tempered martensite. The martensite typically consists of laths (strips) or plates, sometimes appearing

acicular (needle-like) or lenticular (lens-shaped). Depending on the carbon content, it also contains a

certain amount of "retained austenite." Retained austenite are crystals which are unable to transform into

martensite, even after quenching below the martensite finish (Mf) temperature. An increase in alloying

agents or carbon content causes an increase in retained austenite. Austenite has much higher stacking-

fault energy than martensite, lowering the wear resistance of the steel, although some or most of the

retained austenite can be transformed into martensite by cold and cryogenic treatments prior to

tempering.

The martensite forms during a diffusionless transformation, in which the transformation occurs due to

shear-stresses created in the crystal lattices rather than by chemical changes that occur during

precipitation. The shear-stresses create many defects, or "dislocations," between the crystals, providing

less-stressful areas for the carbon atoms to relocate. Upon heating, the carbon atoms first migrate to

these defects, and then begin forming unstable carbides. This reduces the amount of total martensite by

changing some of it to ferrite. Further heating reduces the martensite even more, transforming the

unstable carbides into stable cementite.

The first stage of tempering occurs between room-temperature and 200 C (392 F). In the first stage,

carbon precipitates into -carbon (Fe24C). In the second stage, occurring between 150 C (302 F) and

300 C (572 F), the retained austenite transforms into a form of lower-bainite containing -carbonrather than cementite. The third stage occurs at 200 C (392 F) and higher. In the third stage, -carbon

precipitates into cementite, and the carbon content in the martensite decreases. If tempered at higher

temperatures, between 650 C (1,202 F) and 700 C (1,292 F), or for longer amounts of time, the

martensite may become fully ferritic and the cementite may become coarser or spheroidize. In

spheroidized steel, the cementite network breaks apart and recedes into rods or spherical shaped

globules, and the steel becomes softer than annealed steel; nearly as soft as pure iron, making it very

easy to form or machine.[15]

Embrittlement

Embrittlement occurs during tempering when, through a specific temperature range, the steel

experiences an increase in hardness and a reduction in ductility, as opposed to the normal decrease in

hardness that occurs to either side of this range. The first type is called tempered martensite

embrittlement (TME) or one-step embrittlement. The second is referred to as temper embrittlement (TE)

or two-step embrittlement.




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One-step embrittlement usually occurs in carbon steel at temperatures between 230 C (446 F) and

290 C (554 F), and was historically referred to as "500 F embrittlement." This embritttlement occurs

due to the precipitation of Widmanstatten needles or plates, made of cementite, in the interlath

boundaries of the martensite. Impurities such as phosphorus, or alloying agents like manganese, may

increase the embrittlement, or alter the temperature at which it occurs. This type of embrittlement is

permanent, and can only be relieved by heating above the upper critical temperature and then quenching

again. However, these microstructures usually require an hour or more to form, so are usually not aproblem in the blacksmith-method of tempering.

Two-step embrittlement typically occurs by aging the metal within a critical temperature range, or by

slowly cooling it through that range, For carbon steel, this is typically between 370 C (698 F) and

560 C (1,040 F), although impurities like phosphorus and sulfur increase the effect dramatically. This

generally occurs because the impurities are able to migrate to the grain boundaries, creating weak spots

in the structure. The embrittlement can often be avoided by quickly cooling the metal after tempering.

Two-step embrittlement, however, is reversible. The embrittlement can be eliminated by heating the

steel above 600 C (1,112 F) and then quickly cooling. [16]

Alloy steels

Many elements are often alloyed with steel. The main purpose for alloying most elements with steel is to

increase its hardenability and to decrease softening under temperature. Tool steels, for example, may

have elements like chromium or vanadium added to increase both toughness and strength, which is

necessary for things like wrenches and screwdrivers. On the other hand, drill bits and rotary files need to

retain their hardness at high temperatures. Adding cobalt or molybdenum can cause the steel to retain its

hardness, even at red-hot temperatures, forming high-speed steels. Often, small amounts of many

different elements are added to the steel to give the desired properties, rather than just adding one or

two.

Most alloying elements (solutes) have the benefit of not only increasing hardness, but also lowering both

the martensite start temperature and the temperature at which austenite transforms into ferrite and

cementite. During quenching, this allows a slower cooling rate, which allows items with thicker cross-

sections to be hardened to greater depths than is possible in plain carbon-steel, producing more

uniformity in strength.

Tempering methods for alloy steels may vary considerably, depending on the type and amount of

elements added. In general, elements like manganese, nickel, silicon, and aluminum will remain

dissolved in the ferrite during tempering while the carbon precipitates. When quenched, these solutes

will usually produce an increase in hardness over plain carbon-steel of the same carbon content. When

hardened alloy-steels, containing moderate amounts of these elements, are tempered, the alloy willusually soften somewhat proportionately to carbon steel.

However, during tempering, elements like chromium, vanadium, and molybdenum precipitate with the

carbon. If the steel contains fairly low concentrations of these elements, the softening of the steel can be

retarded until much higher temperatures are reached, when compared to those needed for tempering

carbon steel. This allows the steel to maintain its hardness in high temperature or high friction

applications. However, this also requires very high temperatures during tempering, to achieve a

reduction in hardness. If the steel contains large amounts of these elements, tempering may produce an




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increase in hardness until a specific temperature is reached, at which point the hardness will begin to

decrease.[17][18]For instance, molybdenum steels will typically reach their highest hardness around 315

C (599 F) whereas vanadium steels will harden fully when tempered to around 371 C (700 F). When

very large amounts of solutes are added, alloy steels may behave like precipitation hardening alloys,

which do not soften at all during tempering.[19]

Cast-iron

Cast-iron comes in many types, depending on the carbon-content. However, they are usually divided

into grey and white cast-iron, depending on the form that the carbides take. In grey cast iron, the carbon

is mainly in the form of graphite but, in white cast-iron, the carbon is usually in the form of cementite.

Grey cast-iron consists mainly of the microstructure called pearlite, mixed with graphite and sometimes

ferrite. Grey cast-iron is usually used as-cast, with its properties being determined by its composition.

White cast-iron is composed mostly of a microstructure called ledeburite mixed with pearlite. Ledeburite

is very hard, making the cast-iron very brittle. If the white cast-iron has a hypoeutectic composition, it is

usually tempered to produce malleable cast-iron. Two methods of tempering are used, called "whitetempering" and "black tempering." The purposes of both tempering methods is to cause the ledeburite to

decompose into cementite, increasing the ductility.[20]

White tempering

White tempering is used to burn off excess carbon, by heating it for extended amounts of time in an

oxidizing environment. The cast iron will usually be held at temperatures as high as 1,000 C (1,830 F)

for as long as 60 hours. The heating is followed by a slow cooling rate of around 10 C (18 F) per hour.

The entire process may last 160 hours or more. This causes the cementite to decompose from the

ledeburite, and then the carbon burns out through the surface of the metal, increasing the malleability ofthe cast-iron.[20]

Black tempering

Unlike white tempering, black tempering is done in an inert gas environment, so that the decomposing

carbon does not burn off. Instead, the decomposing carbon turns into a type of graphite called "temper

graphite" or "flaky graphite," increasing the malleability of the metal. Tempering is usually performed at

temperatures as high as 950 C (1,740 F) for up to 20 hours. The tempering is followed by slow-

cooling through the lower critical temperature, over a period that may last from 50 to over 100 hours. [20]

Precipitation hardening alloys

Precipitation hardening alloys first came into use during the early 1900s. Most heat-treatable alloys fall

into the category of precipitation hardening alloys, including alloys of aluminum, magnesium, titanium

and nickel. Several high-alloy steels are also precipitation hardening alloys. These alloys become softer

than normal when quenched, and then harden over time. For this reason, precipitation hardening is often

referred to as "aging."




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Although most precipitation hardening alloys will harden at room temperature, some will only harden at

elevated temperatures and, in others, the process can be sped up by aging at elevated temperatures.

Aging at temperatures higher than room-temperature is called "artificial aging". Although the method is

similar to tempering, the term "tempering" is usually not used to describe artificial aging, because the

physical processes, (i.e.: precipitation of intermetallic phases from a supersaturated alloy) the desired

results, (i.e.: strengthening rather than softening), and the amount of time held at a certain temperature

are very different from tempering as used in carbon-steel.

See also

Annealing (metallurgy)

Austempering

Precipitation strengthening

References

^Light, its interaction with art and antiquitiesBy Thomas B. Brill - Plenum Publishing 1980 Page 551.

^Andrews, Jack (1994).New Edge of the Anvil: a resource book for the blacksmith. pp. 98992.

^ abcdeSteel metallurgy for the non-metallurgistBy John D. Verhoeven - ASM International 2007 Page 99-

105

3.

^The Medieval Sword in the Modern WorldBy Michael 'Tinker' Pearce - 2007 Page 394.

^Tool steelsBy George Adam Roberts, George Krauss, Richard Kennedy, Richard L. Kennedy - ASM

International 1998 Page 2

5.

^Roberts-AustenBy Sir William Chandler Roberts-Austen, Sydney W. Smith - Charles Griffin & Co. 1914

Page 155-156

6.

^Steel castings handbookBy Malcolm Blair, Thomas L. Stevens - Steel Founders' Society of America and

ASM International Page 24-9

7.

^Practical heat treatingBy Jon L. Dossett, Howard E. Boyer - ASM International 2006 Page 1128.

^How To WeldBy Todd Bridigum - Motorbook 2008 Page 379.

^Practical Blacksmithing and MetalworkingBy Percy W. Blandford - TAB Books 1988 Page 3, 747510.

^Practical Blacksmithing and MetalworkingBy Percy W. Blandford - TAB Books 1988 Page 74-7511.

^Knife Talk II: The High Performance BladeBy Ed Fowler - Krause Publications 2003 Page 11412.

^ abcElements of metallurgy and engineering alloysBy Flake C. Campbell - ASM International 2008 Page

195-196

13.

^Steel Heat Treatment HandbookBy George E. Totten -- Marcel Dekker 1997 Page 65914.

^Principles of Heat Treatment of SteelBy Romesh C. Sharma - New Age International (P) Limited 2003

Page 101-110

15.

^Elements of metallurgy and engineering alloysBy Flake C. Campbell - ASM International 2008 Page 19716.

^ http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=9117.




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^Steel Heat Treatment: Metallurgy and TechnologiesBy George E. Totten -- CRC Press 2007 Page 6, 200--

203

18.

^Steels: Microstructure and Properties: Microstructure and Properties By Harry Bhadeshia, Robert

Honeycombe -- Elsevier 2006Page 191--207

19.

^ abcPhysical metallurgy for engineersBy Mikls Tisza - ASM International 2002 Page 348-35020.

Further reading

Manufacturing Processes Reference Guide by Robert H. Todd, Dell K. Allen, and Leo Alting pg.

410

External links

A thorough discussion of tempering processes (http://www.msm.cam.ac.uk/phase-

trans/2004/Tempered.Martensite/tempered.martensite.html)

Webpage showing heating glow and tempering colors

(http://www.sparetimelabs.com/animato/animato/3003/3003am.html)

Retrieved from "http://en.wikipedia.org/w/index.php?title=Tempering_(metallurgy)&oldid=637243904"

Categories: Metal heat treatments

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