hierro carbon para iluminar

8/13/2019 Hierro Carbon Para Iluminar

1/26

1

Iron-carbon equilibrium

system


2/26

2

Fe-C system

Depending on the form of CFe3C iron-carbide (cementite)

metastableC graphite

stablePossible phases

delta ironaustenite

ferritegraphite

delta ironaustenite

ferriteiron-carbide

Possible structural constituents:

Primary, secondary, tertiary,eutectic, eutectoid graphiteaustenite, ferrite, graphitic eutectic,

and graphitic eutectoid

Primary, secondary, tertiary,eutectic, eutectoid iron-carbideaustenite, ferrite,

ledeburite (eutectic) perlite (eutectoid)


3/26

3

Iron-Carbon diagramMetastable system (Fe-Fe 3C)


4/26

4
http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/no_clim.html


5/26

5

Microstructureand mechanical

properties


6/26

6

Austenite

-Interstitional solidsolution(C is solved in face

centered cubic lattice of Fe)-Limited solubilitymax. solubility:2,06% C at 1147 C


7/26

7

Transformations in solid state

Limited solubility of C inaustenite Iron-carbide segregation


8/26

8

Transformations in solid stateAllotrophic

transformationof austenite into ferrite


9/26


10/26

10

Effect of C content

C%=0,10,8


11/26

11

Effect of C content

0,45 % C

Microstructureferrite + pearlite

ferrite

pearlite


12/26

12

Pearlite: transformation of austenite to ferriteand cementite at 723 oC; C=0,8%


13/26

13

Hypereutectoid steel C 1,3 %Microstructure

pearlite+ secondarycementite

pearlite

Secondary cementite(net)


14/26

14

Ledeburite (eutectic)

At 1147 C

Phases of ledeburite:austeniteiron-carbide


15/26

15

Ledeburite

During cooling toroom temperature:austenite transformsto pearlite

Hard, rigid, wearresistante

Pearlite formed from austenite

Iron-carbide


16/26

16

Hypoeutectic cast irons(white cast iron)

Microstructure:pearlite + ledeburite +

secondary cementite

ledeburite

pearlite


17/26

17

Hypereutectic(white) cast irons Primary cementite

ledeburite


18/26

18

Hypoeutectic graphitic cast iron

graphite

ferrite- graphitic eutectic- secondary graphite- graphitic eutectoid

Structure at room temperature:

ferrite - graphite


19/26

19

Contains Si, Mn, P, SEffect of wall thickness of the cast part

(cooling rate)

Solidification and transformation

stable - metastable

Cast irons may often be used in place of steel at considerable cost


20/26

20

Cast irons may often be used in place of steel at considerable costsavings. The design and production advantages of cast ironinclude: Low tooling and production cost Good machinability Ability to cast into complex shapes Excellent wear resistance and high hardness (particularlywhite cats irons) High inherent damping capabilities

The properties of the cast iron are affected by the followingfactors:

Chemical composition of the iron Rate of cooling of the casting in the mold (which dependson the section thickness in the casting) Type of graphite formed (if any)


21/26

21

Advantages: Graphite acts a s a chip breaker and a tool lubricant. Very high damping capacity. Good dry bearing qualities due to graphite. After formation of protective scales, it resists corrosion in many commonengineering environments.Disadvantages:

Brittle (low impact strength) which severely limits use for critical applications. Graphite acts as a void and reduces strength. Maximum recommended designstress is 1/4 of the ultimate tensile strength. Maximum fatigue loading limit is 1/3 offatigue strength. Changes in section size will cause variations in machining characteristics due tovariation in microstructure. Higher strength gray cast irons are more expensive to produce.


22/26

22

Ductile Cast Iron Nodular Cast IronMalleable Cast Iron


23/26

23ledeburite

pearlite


24/26

24

graphite

pearlite


25/26

25

Maurer diagram

C a r

b o n , w

t . %

Silicon, wt. %


26/26

26

Greiner - Klingenstein diagram

C a r

b o n

+ S i l i c o n w

t . %

Wall thickness, mm

hierro carbon para iluminar

Documents