2110 Eng Alloy

7/24/2019 2110 Eng Alloy

1/53

Copyright The McGraw-Hill Companies, Inc. Permission required or reproduction or display.

Engineering Alloys

7/24/2019 2110 Eng Alloy

2/53


!ngineering "lloys

#E.g. stainless steel, cast iron, aluminium alloy and etc.#Iron and its alloy (steel) account for 90% world production of

metals due to their mechanical properties (strength, toughness

and ductility).

# Ferrous alloys (based on Fe), nonferrous alloys (based onother

metals.

7/24/2019 2110 Eng Alloy

3/53


ear teeth

7/24/2019 2110 Eng Alloy

4/53


Production o iron and steel

#Iron e!tracted from ores in large furnace (Fig 9.").##o$e acts as reducing agent to reduce iron o!ide

#&he iron (pig iron), in li'uid form is transferred to a steelma$ing furnace.

teel ma$ing

#lain steel, up to ".*% carbon (ma+ority 0.-%)

#teel is made by o!idiing carbon and other impurities in pigiron until the re'uired le/el (o!ygen process).

#ig iron and up to 0% steel scrap are charged in the refractory

with o!ygen (Fig. 9.*)

* * COFeCOOFe ++

7/24/2019 2110 Eng Alloy

5/53


Figure 9.1

7/24/2019 2110 Eng Alloy

6/53


Figure 9.2

7/24/2019 2110 Eng Alloy

7/53


Production o steel- Cont$

&hen,

#&he molten steel is then cast is stationary mould or

continuously cast in long slabs (91%). (fig 9.-b).

#2bout one3half of the raw steel are from recyle old steel (+un$

cars and appliances).

FeOOironpigFe *)( * +

COFesteelfromC +)(

7/24/2019 2110 Eng Alloy

8/53


Figure 9.5b

7/24/2019 2110 Eng Alloy

9/53


Iron-iron car%ide phase diagram

e/eral solid phase (Fig 9.1)#ferrite 4 an interstitial solid solution of # in 5##iron lattice

(low solubility of #).

#2ustenite () 3 an interstitial solid solution of # in F## iron

lattice (higher solubility of # as compared to ferrite).##ementite (Fe#) 4 intermetallic compound (1.16% # and

9.% Fe)

#ferrite 3 an interstitial solid solution of # in 5##iron lattice

with greater athan ferrite.

7/24/2019 2110 Eng Alloy

10/53


Figure 9.6

7/24/2019 2110 Eng Alloy

11/53


In&ariant reactions

Peritatic reaction:7i'uid (0.-% #) 8 (0.09% #) "9- o# (0."6% #)

Eutectic reaction:

7i'uid (.% #) "":o

# (*.0:% #) 8 Fe# (1.16% #)

Eutectoid reaction:

(0.:% #) 6* o# ferrite (0.0*% #) 8 Fe# (1.16% #)

C G C

7/24/2019 2110 Eng Alloy

12/53


Plain Car%on steel '(.)* C+ !utectoid steel

Fig 9.6#If heated at 6-0 o#, held for sufficient time, structures becomes

austenite, (austenitiing process)#Further slow cooling to about eutectoid temperature or slightly

abo/e, the structure is still austenite ().#Further cooling to below eutectoid temperature, the structure ischanged to alternate plates of ferrite and cementite (Fe#) 4

pearlite structure.

C i ht Th M G Hill C i I P i i i d d ti di l

7/24/2019 2110 Eng Alloy

13/53


Figure 9.7

C i ht Th M G Hill C i I P i i i d d ti di l

7/24/2019 2110 Eng Alloy

14/53


Plain Carbon steel (< 0.8% C) hypoeutectoid steel

Fig 9.9

#2bo/e eutectoid temperature (900 o#), austenite structure#Further cooling, the structure $eep on changing until all structure

will change to ferrite and cementite.

Plain Carbon steel (> 0.8% C) hypereutectoid steelig .//0#or composition ha&ing 1(.) * car%on, a%o&e eutectoid

temperature '9-0 o#), austenite structure.#Further cooling, the structure $eep on changing until all structurewill change to ferrite and cementite

!.g. Pg 2

Copyright The McGraw Hill Companies Inc Permission required or reproduction or display

7/24/2019 2110 Eng Alloy

15/53


Figure 9.9


7/24/2019 2110 Eng Alloy

16/53


Figure 9.11


7/24/2019 2110 Eng Alloy

17/53


Copyright The McGraw-Hill Companies Inc Permission required or reproduction or display

7/24/2019 2110 Eng Alloy

18/53


Heat treatment o plain car%on steel

5y /arying the way plain carbon still is heated and cooled,different combinations of mechanical properties can be obtained

#Formation of Fe3# martensite steel in austenitic condition is

cooled rapidly to ;& by 'uenching with water, the structure

willchange to martensite.

3

7/24/2019 2110 Eng Alloy

19/53

Copyright The McGraw Hill Companies, Inc. Permission required or reproduction or display.

Figure 9.13

Copyright The McGraw-Hill Companies Inc Permission required or reproduction or display

7/24/2019 2110 Eng Alloy

20/53


Heat treatment o plain car%on steel Cont$

Isothermal decomposition procedure (Fig 9.*0), show that

microstructural change o/er the process (Fig 9.*").eating martensitic steel at a temperature below

eutectoid, to ma$e it softer and more ductile.3Martempering(mar'uenching) 4 to minimie the distortion

and crac$ing during une/en cooling.3Austempering4 to impro/e ductility, impact resistance and

decrease distortion.


7/24/2019 2110 Eng Alloy

21/53


Figure 9.20


7/24/2019 2110 Eng Alloy

22/53

py g p , q p p y

Figure 9.21


7/24/2019 2110 Eng Alloy

23/53

py g p , q p p y

Figure 9.28


7/24/2019 2110 Eng Alloy

24/53

py g p q p p y

3imitations o plain car%on steel

##annot be strengthened beyond "00,000 psi (190 ?a)

withoutloss in ductility and impact resistance.

#7arge section thic$nesss cannot be produced with martensite

structure.#7ow corrosion and o!idation resistance#oor impact resistance at low temperatures#?ust be 'uenched rapidly to obtain full martensitic structure

which lead to possible distortion and crac$ing.

&o o/ercome this, other types of alloy steels ha/e been

de/eloped to impro/e their properties.


7/24/2019 2110 Eng Alloy

25/53

Figure EP9.3


7/24/2019 2110 Eng Alloy

26/53

Classiication o plain- car%on steels

#igh3carbon steel ("0103"09-)

AISI - American Iron and steel Institute, SAE Society for automotive Engineers


7/24/2019 2110 Eng Alloy

27/53


7/24/2019 2110 Eng Alloy

28/53

3ow "lloy 4teels#2lloy steel may contain up to -0% alloying elements and can

still considered alloy steels.

#7ow alloy steels contain "3 % alloying elements.#E!amples manganese, molybdenum, sulfur, chromium,

nic$el and silicon (refer to table 9.)

#2lloy steels in A are designated by digits

3 "sttwo digits 4 the principle alloying elements

3 7ast * digits 4 the hundredth of % # in steel#

7/24/2019 2110 Eng Alloy

29/53


7/24/2019 2110 Eng Alloy

30/53


7/24/2019 2110 Eng Alloy

31/53

Figure 9.35


7/24/2019 2110 Eng Alloy

32/53


"l i i "ll

7/24/2019 2110 Eng Alloy

33/53

"luminium "lloys#&he hardening process that is used to increase many 2l and

other metal alloys is precipitation hardening

#rocess in/ol/ed 3 olution heat treatment (sample is heated to a certain

temperature, soa$ed there until uniform solid structure is

produced)

3 Duenching, rapid cooling to ;& using water

3 2ging, to form fine dispersed precipitate which pre/entdislocation mo/ement. Batural aging at ;&, artificial aging

at ele/ated temperature.

#2l has low density, good corrosion resistance, nonto!ic, good

electrical properties, relati/ely cheap, low strength but can be

alloyed up to 190 ?a.


7/24/2019 2110 Eng Alloy

34/53

Figure 9.43


"l i i "ll C t$

7/24/2019 2110 Eng Alloy

35/53

"luminium "lloys Cont$#2l is produced from bau!ite (hydrated aluminum o!ide).

5au!ite is treated with BaC> (5ayer rocess)

bau!ite 8 BaC> sodium aluminate precipitatealuminium hydro!ide thic$ened calcine 2l*C

dissol/ed in cryolite (Ba2lF1)electrolysed, # as

cathode and anode metallic 2l forms in the li'uid state(99.-399.9% purity with Fe and silicon as ma+or impurities)

#2l is sent to refractory furnace for refining where

alloying elements can be added to the furnace followed by

casting into desired shapes (wrought 2l alloys or 2l casting

alloy).

#rought 2l alloy (sheet, plate, rod, wires) are calssifiedaccording to the ma+or alloying elements (&able 9.6)

#"stdigit indicate alloy group, *nddigit indicates modification

of the original alloy and the last * digits indentify the 2l alloy

or 2l purity


7/24/2019 2110 Eng Alloy

36/53


"l i i "ll C t$

7/24/2019 2110 Eng Alloy

37/53

"luminium "lloys Cont$

Non-Heat-Treatable wrought Al alloys #annot be

precipitation strengthened but can be cold wor$ed to increasestrength.

#&he main group are "!!!, !!! and -!!! groups

E.g. "!!! 4 min 99% 2l, Fe and silicon (alloying elements)

with 0."*% #u for e!tra strength. (refer to pg of the hand

out for the rest)#;efer to table 9.: (pg. - of handout) for the list of

compositions, mechanical properties and etc.


"l i i "ll C t$

7/24/2019 2110 Eng Alloy

38/53


Heat-Treatable wrought Al alloys #an be precipitation

strengthened by heat treatment.#&he main group are *!!!, 1!!! and 6!!! groups

E.g. *!!! 4 &he principle alloying elements is #u. ?g is also

added. Cne of the most important is *0* (.-% #u, ".-%

?g, 0.1% ?n) 4 high strength and is used for aircraft

structural. (refer to pg. of the hand out for the rest).

#;efer to table 9.: (pg. - of handout) for the list of

compositions, mechanical properties and etc.


"l i i "ll C t$

7/24/2019 2110 Eng Alloy

39/53


Al casting alloys

main process and casting4 small 'uantities of identical casting, comple!

casting, large casting and structural casting.

Permanent mould casting4 simple shape and small sie

mould. roduced finer grain structure and less shrin$age than

sand casting. !ie casting4 can be produced at high rates (high pressure),

smooth surfaces and process can be automated.


"l i i "ll C t$

7/24/2019 2110 Eng Alloy

40/53


Al casting alloys are de/eloped casting 'ualities such fluidity,

feeding ability, strength, ductility and corrosion resistance.#

7/24/2019 2110 Eng Alloy

41/53


7/24/2019 2110 Eng Alloy

42/53

Figure 9.44


Copper "lloys

7/24/2019 2110 Eng Alloy

43/53

Copper "lloys

##u metal can be used in the unalloyed condition (mainly used

in electrical industries as well as alloyed form.#In unalloyed form 4 high electrical and thermal conducti/ity,

good corrosion resistance, ease of fabrication, medium

strength and etc.

#2lloyed conditions in a series of brass and brone

##u is e!tracted from ores containing #u and iron sulfides(refer to pg. 1 of handout for detail e!planation). 2t the end of

the processes produce electrolytic tough pitch (E&) #u,

99.9-%.

#E& #u is used to produce wire, rod, plate and strip. #ontain0.0% o!ygen as impurity.


Copper "lloys Cont$

7/24/2019 2110 Eng Alloy

44/53

Copper "lloys Cont

#lassification of #u alloys

3 #"0"00 to #69900 refer to wrought alloys 3 #:0000 to #99900 refer to casting alloys

;efer to table 9."0 pg.1, for #u alloys classification

;efer to &able 9."" pg 6, for properties and application of #u

alloys.

3 E.g. #u3Gn brasses, -3 0% Gn. mall amount of lead isadded to impro/e machinability. (Fig. :.*-)


7/24/2019 2110 Eng Alloy

45/53

Figure 8.25


7/24/2019 2110 Eng Alloy

46/53


4tainless 4teels

7/24/2019 2110 Eng Alloy

47/53

4tainless 4teels#&hese alloys is selected due to their e!cellent corrosion

resistance in many en/ironment (due to the presence of #r, at

least "*%).

# main types ferritic, martensitic, austenitic and precipitation

hardening.

3 Ferritic ("* 4 0% #r), relati/ely low cost

3 ?artensitic ("* 4 "6% #r, 0."-3".0% #)

3 2ustenitic ("1 4 *-% #r and 63*0% Bi). 5etter corrosion

resistance due to the presence of Bi.


7/24/2019 2110 Eng Alloy

48/53

Figure 9.55


7/24/2019 2110 Eng Alloy

49/53


Cast Iron

7/24/2019 2110 Eng Alloy

50/53

Cast Iron#2 family of ferrous alloys. &hey are intended to be cast into

the desired shape. Anli$e steels ("% #), cast irons contain

*3% # and "3% silicon, other element may be present also.

#Easily melt and /ery fluid in li'uid state and ha/e wide range

of strengths and hardness, good wear resistance. >a/e

relati/ely low impact resistance and ductility.

# different common types which can be differentiated by the

distribution of carbon in their microstructures 3 White iron4 iron carbides in a pearlitic structure (when

fractured produce whiteor bright crystalline surface)

3 ray iron4 precipitates as graphite fla$e (when

fractured produce graysurface due to e!posed graphite 3!allea"le iron4 first cast as white iron, and then heated to

dissociate iron carbide to graphite and iron (temper carbon)

3#uctile iron4 combine the processing ad/antages of gray

cast iron with similar engineering properties as steel (high

strength, toughness, ductility and etc)


7/24/2019 2110 Eng Alloy

51/53


5ther alloys

7/24/2019 2110 Eng Alloy

52/53

5ther alloys#Mg alloys4 light metal, suitable for low3density application

(aerospace applications).7imited ad/antages due to /ery high

cost, difficult to cast (burns in air), low strength, poor

resistance to creep, fatigue and wear. rought alloys and

casting alloys

#Titanium alloys4 relati/ely light but has high strength,

superior corrosion resistance. It is e!pensi/e because /ery

difficult to e!tract from its compound.#Nic"el alloys4 E!ceptional resistance to corrosion and high

temperature o!idation. ;elati/ely e!pensi/e and high density

(limits its use).


7/24/2019 2110 Eng Alloy

53/53

2110 Eng Alloy

Documents

Transcript of 2110 Eng Alloy