Basic Metallography ( Bapak Ir. Nizhamul Latif, M.Sc)

METALLOGRAPHY

PERTANYAAN 

• Apa itu Metalografi ? 

• Untuk apa dilakukan Pemeriksaan 

Metalografi dan Apa Manfaatnya? 

• Aplikasi apa saja yang memerlukan 

pemeriksaan Metalografi ? 

• Bagaimana Metoda dan Teknik 

Pemeriksaan Metalografi ?

Apa itu Metalografi ? 

Metallography By Definition : 

The structural study of metals and their alloys by 

means of various procedures eg. Microscopy, X-Ray 

difraction, etc. 

(chambers mater, Sci and tech. Dictionary, 1993) 

Metallografi Meliputi : 

• Teknik atau cara memunculkan struktur yang 

diamati. 

• Peralatan yang digunakan untuk melakukan 

analisis struktur. 

• Interpretasi atau analisis fenomena struktur 

yang diamati.

PERTANYAAN 








Untuk apa dilakukan Pemeriksaan Metalografi 

dan Apa Manfaatnya? 

1. Mengetahui struktur 

mikro atau fasa bahan 

logam seperti : 

a. Untuk baja 

‣ ferrit, 

‣ Fasa perlit, 

‣ Fasa,martensit, dsb. 

b. Untuk Besi Cor 

b. Fas grafit berserpih, 

c. Fasa nodular,dsb. 

Martensit 

apakah sudah sesuai 

dengan spesifikasi teknis 

perencanaan ?. 

Struktur mikro 

berupa ferit, perlit, 

steadit dan grafit. 

Martensit, austenit 

sisa dan grafit 

nodular



2. Memperlihatkan cacad 

material yang disebabkan 

oleh 

proses 

produksi/fabrikasi, 

seperti: 

a. impurities, 

b. rongga penyusutan, 

c. cacad pengelasan, 

dsb.nya; 

dikaitkan dengan kondisi 

operasi dan lingkungan 

yang mungkin mempunyoi 

andil dalam proses 

kerusakan..



3. Mengukur ketebalon : 

a. lopisan pengerasan, 

atau jenis pelapis lain, 

b. ukuran butiran, 

c. Luas daerah pengaruh 

panas (HAZ) akibat 

proses pengelasan. 

Plasma Sprayed Chromium Oxide 

Coating



4. Memperlihatkan bentuk 

penjolaran retakan, 

seperti : 

a. retak interkristallin, 

b. transkristallin, 

c. retak korosi, dsb.nya. 

Interkristalin



5. Memperlihatkan penyimpangan struktur mikro 

bahan logam akibat proses perlakuan ponas, 

seperti : 

a. quenching, 

b. hardening, 

c. normalisasi dsb. nya. 

Keretakan pada baja Cr- 

Mo-V disebabkan oleh 

laju pendinginan cepat 

Korosi tegang dekat 

daerah lasan akibat 

tidak dilakukan stress 

relivied annealing

TRANSFORMASI FASA

PHASE TRANSFORMATIONS 

• Transforming one phase into another takes time. 

• How does the rate of transformation depend on 

time and T? 

• How can we control the transformation so that 

we can engineering non-equilibrium structures? 

• How different are the mechanical properties of 

non-equilibrium structures?

IMPORTANCE OF COOLING 

Cu-Ni alloy 

TIME 

Fast cooling 

Non-equilibrium phases 

Slow cooling 

Equilibrium phases

COOLING AUSTENITE 

Austenite 

Pearlite 

• Mainly interested in eutectoid cooling: g a + Fe 3 C (pearlite), 0.77 wt% C 

• Cooling rate can result in a wide variety of phases and microstructures 

– Equilibrium phases: pearlite, bainite 

– Non-equilibrium phases: martensite

Strength 

Ductility 

MECHANICAL PROPERTIES 

• Martensite 

• Tempered martensite 

• Bainite 

• Fine pearlite 

• Coarse pearlite 

• Can control the formation of specific phases and 

microstructure so that desired properties result

FRACTION OF TRANSFORMATION 

• Fraction transformed depends on time, 

at constant temperature (e.g., g pearlite) 

y 

1 

e 

kt 

n 

Avrami equation 

(k, n are constants) 

• Transformation rate , r = 1/t 0.5

EUTECTOID TRANSFORMATION RATE ~ DT 

• Pertumbuhan pearlite dari austenite: 

• Laju Reaksi meningkat sesuai DT.

TIME-TEMPERATURE TRANSFORMATION (TTT) DIAGRAMS 

• Fe-C system, Komposisi Eutectoid (C o = 0.77wt%C) 

• Transformasi pada T = 675C. 

Also called 

isothermal 

transformation 

diagram

EX: COOLING HISTORY Fe-C SYSTEM 

• Komposisi Eutectoid , C o = 0.77wt%C 

• Mulai pada T > 727C 

• Pendinginan cepat sampai 625 0 C dan ditahan secara isotermal. 

• Pendinginansampai temperatut yg lebih rendah shg diperoleh struktur mikro 

yang halus

Two cases: 

PEARLITE MORPHOLOGY 

• Ttransf just below TE 

--Larger T: diffusion is faster 

--Pearlite is coarser. 

• Ttransf well below TE 

--Smaller T: diffusion is slower 

--Pearlite is finer. 

- Smaller DT: 

colonies are 

larger 

- Larger DT: 

colonies are 

smaller

OTHER TRANSFORMATION PRODUCTS 

• Bainite: 

--a strips with long, fine 

rods of Fe 3 C 

• Isothermal Transf. Diagram 

Fe3C 

(cementite) 

a(ferrite) 

5 m 

(Adapted from Fig. 10.8, Callister, 6e. (Fig. 

10.8 from Metals Handbook, 8th ed., 

Vol. 8, Metallography, Structures, and 

Phase Diagrams, American Society for 

Metals, Materials Park, OH, 1973.) 

Note: reaction rate 

increases with decreasing 

temperature first, and then 

decreases

NUCLEATION AND GROWTH 

• Reaction rate is a result of nucleation and growth of crystals. 

Nucleation rate increases with DT 

Growth rate increases with T 

• Examples:

OTHER PRODUCTS: MARTENSITE 

• Martensite: 

--rapid cooling from above eutectoid temperature to room T 

--g(FCC) to Martensite (Body Centered Tetragonal) 

--involves collective motion of a lot of atoms 


• g to M transformation.. 

-- is rapid! At speed of sound 

-- % transf. depends on T only.

• Martensite: 

--g(FCC) to Martensite (BCT) 


Adapted 

from Fig. 

10.13, 

Callister 6e. 

OTHER PRODUCTS: Fe-C SYSTEM (2) 

(involves single atom jumps) 

Fe atom 

sites 

x 

x 

x 

x 

x 

x 

potential 

C atom sites 

(Adapted from Fig. 

10.11, Callister, 6e. 

60 m 

Martentite needles 

Austenite 

(Adapted from Fig. 10.12, Callister, 

6e. (Fig. 10.12 courtesy United 

States Steel Corporation.) 

• g to M transformation.. 

-- is rapid! 

-- % transf. depends on T only. 

11

PRODUCTS OF COOLING AUSTENITE 

• Slow cooling pearlite 

• Cool rapidly to upto 550 

C, and hold pearlite 

• Cool rapidly to 550-225 C 

and hold bainite 

• Cool rapidly to below 225 

C martensite

COOLING EX: Fe-C SYSTEM (1) 

Rapidly cool to 350 C 

Hold for 10000 seconds 

Rapidly cool to room T 

100% Austenite 

100% Bainite 

100% Bainite







Mostly Martensite + traces of Austenite



50% Austenite, 

50% Pearlite 






50% Austenite, 

50% Pearlite 

50% Bainite, 50% Pearlite 

50% Bainite, 50% Pearlite

OTHER PRODUCTS: Fe-C SYSTEM (1) 

• Spheroidite: 

--a crystals with spherical Fe 3 C 

--diffusion dependent. 

--heat bainite or pearlite for long times 

--reduces interfacial area (driving force) 


a 

(ferrite) 

Fe3C 

(cementite) 

60 m 

(Adapted from Fig. 10.10, Callister, 

6e. (Fig. 10.10 copyright United 

States Steel Corporation, 1971.) 

Adapted from Fig. 10.9,Callister 6e. 

(Fig. 10.9 adapted from H. Boyer (Ed.) Atlas of 

Isothermal Transformation and Cooling 

Transformation Diagrams, American Society for 

Metals, 1997, p. 28.) 

10

TEMPERING MARTENSITE 

• reduces brittleness of martensite, 

• reduces internal stress caused by quenching. 

Adapted from 

Fig. 10.25, 

Callister 6e. 

(Fig. 10.25 

adapted from 

Fig. furnished 

courtesy of 

Republic Steel 

Corporation.) 

Adapted from 

Fig. 10.24, 

Callister 6e. 

(Fig. 10.24 

copyright by 

United States 

Steel 

Corporation, 

1971.) 

18

Strength 

Ductility 

MECHANICAL PROPERTIES 

• Martensite 

• Tempered martensite 

• Bainite 

• Fine pearlite 

• Coarse pearlite 

• Spheroidite 

• Can control the formation of specific phases and 

microstructure through a cooling schedule 

so that desired properties result

HYPOEUTECTOID & HYPEREUTECTOID 

Austenite 

Pearlite 

• Eutectoid (0.77 wt% C) 

pearlite (ferrite & cementite 

layers) 

• Hypoeutectoid (< 0.77 wt% C) 

pearlite & ferrite 

• Hypereutectoid (> 0.77 wt% C) 

pearlite & cementite 

• Ferrite is soft and cementite is 

hard 

• Thus, hardness and strength 

increase with carbon content

HYPER eutectiod Steel TTT Curve

Alloy Steel TTT Curve

Continuous Cooling Transformation (CCT)



MECHANICAL PROP: Fe-C SYSTEM (1)

MECHANICAL PROP: Fe-C SYSTEM (2) 

• Fine Pearlite vs Martensite: 

• Hardness: fine pearlite

SUMMARY: PROCESSING OPTIONS 

Adapted from 

Fig. 10.27, 

Callister 6e. 

19

Spheroidite 

Austenite 

Rapid 

Quench 

AS: Alloy Steel 

PCS: Plain-carbon Steel 

Martensite 

Re-heat 

Slow 

Cooling 

Moderate cooling (AS) 

Isothermal treatment (PCS) 

Re-heat 

Tempered 

Martensite 

coarse 

Pearlite 

fine 

Bainite

• Particles impede dislocations. 

• Ex: Al-Cu system 

• Procedure: 

--Pt A: solution heat treat 

(get a solid solution) 

--Pt B: quench to room temp. 

--Pt C: reheat to nucleate 

small q crystals within 

a crystals. 

• Other precipitation 

systems: 

• Cu-Be 

• Cu-Sn 

• Mg-Al 

PRECIPITATION HARDENING 

Adapted from Fig. 11.22, Callister 6e. (Fig. 11.22 adapted 

from J.L. Murray, International Metals Review 30, p.5, 1985.) 

Adapted from Fig. 

11.20, Callister 6e. 

16

PRECIPITATION HARDENING 

T 0 

T 2 

• Two stage heat treatment. Procedure: 

--T 0 : solution heat treatment 

(get single phase solid solution) 

--Quench to T 1 . 

--T 2 : reheat to nucleate precipitates

PRECIPITATION HARDENING

PRECIPITATION HARDENING

PRECIPITATE EFFECT ON TS, %EL 

• 2014 Al Alloy: 

• TS peaks with 

precipitation time. 

• Increasing T accelerates 

process. 

• %EL reaches minimum 

with precipitation time. 

Adapted from Fig. 11.25 (a) and (b), Callister 6e. (Fig. 11.25 adapted from Metals Handbook: 

Properties and Selection: Nonferrous Alloys and Pure Metals, Vol. 2, 9th ed., H. Baker 

(Managing Ed.), American Society for Metals, 1979. p. 41.) 

17

PERTANYAAN 








Aplikasi apa saja yang memerlukan 


Aplikasi Metalografi : 

1. Analisa Kerusakan 

2. Penentuan Umur Sisa Mesin & Peralatan Industri 

3. Indetifikasi Material 

4. Heat Treatment 

5. Forming (Pembentukan) 

6. Welding Pengelasan. 

7. Coating/ Pelapisan 

8. Dll.

PERTANYAAN

Basic Metallography ( Bapak Ir. Nizhamul Latif, M.Sc)

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