engineering materials

15th March, 2012 1 © 2012 Larsen & Toubro Limited Metallurgy & Corrosion

Engineering Materials


01-02. Sept. 2008 CALD Metallurgy & Corrosion, 2

Technology Advancement

- Based on

Materials Development

Nano

materials

STONE

AGE

BRONZE

AGE

Future

IRON

AGE

SS/

NICKEL

Ti / Al

Alloys

Weapons

Foundry

Utensils

Industrial

Revolution

Aircrafts

Ceramics

Compo

Sites

Space

Exploration

http://claudelafleur.qc.ca/images/Dnepr-29Jun04.jpg

http://encyclopedia.jrank.org/Cambridge/entries/images/aeroplane 1.jpg


Evolution • 4000 BC, Iron Tensile strength, magnetic

• 100 BC, Concrete Compressive strength, mouldability durability

• 50 BC, Glass Transparency, refractive properties, compressive strength

• 1840s, Rubber Elasticity, water repellence, electrical resistivity

• 1850s, Steel Tensile strength, hardness, processability

• 1880s, Aluminum Strength: weight ratio, corrosion resistance

• 1930s, Polyethylene Processability, light, thermal and electrical insulation, chemical resistance

• 1950s, Silicon Semiconductor

http://www.npl.co.uk/educate-+-explore/beginners-guides-posters/glass

http://www.npl.co.uk/science-+-technology/advanced-materials/polyethylene

http://www.npl.co.uk/science-+-technology/advanced-materials/silicon


Catastrophic Failure

Offshore Platform Airport

Refinery Bridge


Course of Presentation

• Engineering Materials

– Parameters for engineering materials

– Engineering Properties

– Classes of Materials

• Advanced Materials

Engineering is the discipline, art, skill, profession and technology

of acquiring and applying scientific, mathematical, economic, social and practical knowledge in order to design and build

structures, machines, devices, systems, materials and processes.


MATERIAL OF

CONSTRUCTION

Function

Pressure

Medium

Cost

Fabrication

Temperature

BASIS

Creep

Strength

Such as

Conductivity

Weldability

Availability

Corrosion Resistance


Engineering Properties

• Mechanical Strength

• Thermal stress

• Ductility/Elongation

• Toughness

• Fatigue

• Creep

• Corrosion Resistance


Engineering Properties • Types of Stresses

5 factors effecting strength are tension, compression, torsion,

bending & shear


Stress during Operation - Pressure Vessel For Thin-Walled Vessel

Stress in Longitudinal direction = P x R 2 x t R = mean radius t =thickness Stress in Circumferential direction = P x R t


Engineering Materials -Properties

• Hardness – Ability to resist abrasion, penetration, cutting or permanent distortion

• Brittleness – Property of metal that allows little bending or deformation without

shattering

• Malleable – A metal that can be hammered, rolled or pressed into various shapes

without cracking or breaking

• Ductility – Property of metal that allows it to be permanently drawn, bent, or

twisted into various shapes without breaking

• Elasticity – Property enables metal to return to its original shape when the force

which causes the change of shape is removed


Engineering Materials -Properties

• Toughness – A material that will withstand tearing or shearing and may be

stretched without being deformed or breaking

• Density – Weight of a unit volume of material

• Fusibility – The ability of a metal to become liquid when heated (can be welded)

• Conductivity – Property which enables a metal to carry heat or electricity

• Contraction & Expansion – Reaction produced in metals as the result of heating or cooling


Living quarters MHN


World’s largest coke drum The 630 MT pressure vessel, with an inside diameter of 9.8m, was

manufactured at our Hazira Manufacturing Complex for Indian Oil

Corporation’s refinery coming up at Paradip.


16.4 m Diameter,

40 m Long 1200 MT

Pressure Vessel Being Loaded Out

Largest made in the world


Thermal Stresses

Thermal Stress = (T) E

= Coefficient of thermal expansion T = Temperature change

E = Elastic Modulus

Expansion due to heat

Compressive stress due to fixed support


Thermal Properties of Cr containing steels




• Elongation / Ductility

• Toughness

• Fatigue

• Creep





Elastic Modulus (Stiffness)

As per Hooke’s Law,

• In Elastic Region,

E = / is a constant

• E is the elastic modulus and is a material property

• Elastic modulus indicates the stiffness of the material to deformation





• Toughness

• Fatigue

• Creep



Stress-Strain Curve for Mild Steel



Measure of Ductility


Ductile Fracture

normalised 0.3% carbon steel

Broken by a high-speed impact at about 20ºC

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• Types of Stresses



• Toughness / Impact Strength

• Fatigue

• Creep



Toughness

• Indicated by the work done to plastically deform the material.

• Energy absorbed in the process before fracture.

• Describes the way a material reacts under sudden impact.

27

Resistance of a material to fracture under load.


Toughness

• Describes the way a material reacts under sudden impacts.

• It is defined as the work required to deform one cubic inch of metal until it fractures.

• Toughness is measured by the Charpy test or the Izod test as the energy absorbed at a given temperature. – For example for some plate steels to be used in bridges

27 J (equivalent to 20 ft.lb.) at -40 °C is required.

• For high performance steels, e.g. aircraft undercarriages, a KIc value may be used to quantify the toughness.



Toughness – Impact Test

• Maximum energy developed by the hammer is 120 ft-lb in the Izod test and 240 ft-lb in the Charpy test

• Greater the amount of energy absorbed by the specimen, the smaller the upward swing of the pendulum will be and the tougher the material is.



Ductile to Brittle Transition Temperature

Jou

les

C, Nb, V, Ti, Si, Mn

Ni

C, Nb, V, Ti, Si, Mn

Ni


Carbon Content on CS Impact Strength



Titanic Ship (1912)

Wreckage of Titanic Ship The Titanic under construction

Photo courtesy of the Titanic Historical Society.

http://www.tms.org/pubs/journals/JOM/9801/Felkins-9801.fig.1.lg.gif


Composition of Steel from Titanic

C Mn P S Si Cu O N MnS: Ratio

Titanic Hull Plate 0.21 0.47 0.045 0.069 0.017 0.024 0.013 0.0035 6.8:1

ASTM A36 0.20 0.55 0.012 0.037 0.007 0.01 0.079 0.0032 14.9:1

Titanic hull steel showing banding & MnS inclusions in microstructure


Impact Strength of Materials


Low Carbon Steel Carbon Steel

Aluminium Aus. Stainless Steel

http://www2.umist.ac.uk/material/research/intmic/_vti_bin/shtml.dll/features/charpy/steel_1/a.htm/map

http://www2.umist.ac.uk/material/research/intmic/_vti_bin/shtml.dll/features/charpy/steel_2/a.htm/map

http://www2.umist.ac.uk/material/research/intmic/_vti_bin/shtml.dll/features/charpy/aluminum/a.htm/map

http://www2.umist.ac.uk/material/research/intmic/_vti_bin/shtml.dll/features/charpy/stainles/a.htm/map


Brittle Fracture

normalised 0.3% carbon steel,

broken by high-speed impact at about -

190ºC.


../steel/sample.htm

../steel/sample.htm

../steel/sample.htm

../steel/sample.htm



• Types of Stresses



• Toughness

• Fatigue Strength

• Creep



Fatigue

• Alternating stresses arise during operation due to – Vibration

– Rotation and

– Thermal cycling

• Fails by progressive brittle cracking

• Failure is influenced by – Peak Stress

– Number of Cycles

– Duration


Fatigue


Fatigue Fracture



A fractured pipe/flange weldment from a crane frame assembly


Cement plant kiln


Fatigue Curve (S-N Curve)

Fatigue Endurance Limit

The amplitude (or range) of cyclic stress that can be applied to the material without

causing fatigue failure.


Fatigue Endurance limit

• Steel Sn‘ = 0.5 x Su

• Titanium Sn‘ = 0.45…0.6 x Su

• Cast Iron Sn‘ = 0.45 x Su

• Aluminum Sn‘ = 0.4 x Su

• Magnesium Sn‘ = 0.35 x Su

• Nickel alloys Sn‘ = 0.35…0.5 x Su

• Copper alloys Sn‘ = 0.25…0.5 x Su

@ N=106

@ N=108

Do not have a distinct limit and will eventually fail even from small stress amplitudes


Steel BS Threatment

Tensile Styrength - σu - (N/mm2)

Endurance Limit - σe - (N/mm2)

σe/σu

0.4% Carbon BS970 080M40 Normalized 540 270 0.5

0.4% Carbon BS970 080M40 Hardened and tempered

700 340 0.49

Carbon, manganese

BS970 150M19 Normilized 540 250 0.46

Carbon, manganese

BS970 150M19 Hardened and tempered

700 325 0.53

3% Chrome molybdenum

BS970 709M40 Hardened and tempered

1000 480 0.48

Spring steel BS970 735A50 Hardened and tempered

1500 650 0.43

18.8 Stainless Cold rolled 1200 490 0.41

Most steels have an endurance limit about half the tensile strength.


Thermal Fatigue

• Thermal fatigue arises from thermal stresses produced by cyclic changes in temperature.

• This type of fatigue is at most concern in turbine engines, steam piping and many rotating machinery.


Thermal fatigue cracks





• Toughness

• Fatigue

• Creep



Creep

• Slow and progressive deformation of a

material with time under a constant stress at

temperatures approximately above 0.4 Tm

(M.P. in Kelvin)

• Thermally activated process. More severe at

elevated temperatures

• Low melting point materials (Pb, Sn) show

creep at R.T.

• Magnitude of the applied stress and its duration

• Creep is a "time-dependent" deformation.


Creep Curve

• In the initial stage, or primary creep, the strain rate is relatively high, but slows with

increasing time-work hardening

•Strain rate eventually reaches a minimum and becomes near constant. This is due to the

balance between work hardening and annealing (thermal softening). This stage is known as

secondary or steady-state creep

•The strain rate exponentially increases with stress because of necking phenomena


Creep Limit

• Stress required to cause fracture in a creep test within a specified time. Alternate term is stress rupture strength.

• The stress to which a material can be subjected without the creep exceeding a specified amount after a given time at the operating temperature.

• (for example, a creep rate of 0.01% in 100,000 hours at operating temperature).


Screen Boiler Tube Rupture By Short Term Creep


Creep cavity Fish mouth opening


Nominal Composition Rupture Stress, Kg/cm2

(for 10,000 hours)

Grade C Cr Ni Other 8710C 9820C 10930C

HK40 0.4 25 20 - 190 84 32

HP- 45Nb 0.45 25 35 Nb-1.5 302 123 32

HP- 45NbMA 0.45 25 35 Nb1.5, Ti, Zr 330 130 32

HP- 45NbW 0.45 25 35 Nb-1.5, W 1.5 309 130 35

HP- 45W 0.45 25 35 W 4 295 102 30

HP- 45Mo 0.45 25 35 Mo 1.5 239 123 35

45Ni-35Cr.MA 0.45 35 45 Nb1.5, Ti, Zr 316 120 42

Hp-15Nb 0.15 25 35 Nb 1.5 246 105 21

Rupture Stress : Nickel Alloys


Thickness for different alloy steels


Summary

• Engineering Materials are those used for the construction of the equipment /component for intended service.

• They should possess good combination of properties to meet the mechanical integrity of the component.

• Depending on the design and operating conditions they should have appropriate

– Ductility

– Toughness

– Fatigue strength

– Creep strength

– Corrosion resistance etc.


Classes of Engineering Materials


Engineering Metals & Alloys

• Ferrous-widely used – Mild Steels

– Carbon Steels

– Low Alloy Steels

– Stainless Steels

• Non-Ferrous – Aluminium Alloys

– Copper Alloys

– Nickel Alloys

– Titanium Alloys

59


CARBON STEEL


Used for high temperatures.

Oxidation resistance &

creep strength increases with alloy content

LOW ALLOY STEEL

• Low Alloy (2-5%)

• Med. Alloy (5-10%)


LOW ALLOY STEELS

552

552

566

566

566

566

566

566

593

602

602

566

602

602

566

0C


SS 300 series Normal, ‘L’ grades and ‘H’ grades


Compositional modification of 18:8 Austenitc stainless steel

304

316

317

347

321

309, 310, 314, 330

304L

316L

317L Austenitic Fe-

Ni-Mn-N SS

Precipitation

hardened

stainless steel

Duplex stainless

steel

Ni-Cr-Fe alloys

303, 303Se L

ow

er

Ca

rbo

n

Ti

Ni

Ni, Cr

Mo

More Mo


NICKEL ALLOYS FOR

SEVERE APPLICATIONS

Alloy 803

Alloy 800 H

Alloy 600

Alloy 625

Alloy 617

Alloy 825

Hastelloys

Alloy 601


Titanium and its Alloys



Ti - Corrosion Resistance

• Thin (100A), transparent

• Very stable, chemically resistant

• Adherent, Tenacious

• Resilient

• Instant healing


Aluminium Alloys



Copper Alloys


Copper Alloys

Alloy Cu Sn Zn Al Other

Admiralty Gunmetal 88 10 2 - -

Leaded Gunmetal 85 5 5 5 -

Leaded Gunmetal + nickel

86

7

2.5

- 2.5% Lead 2% Nickel

Nickel aluminium bronze

85

- - 10

5% Iron 5% Nickel

Aluminium brass

76

22 2

0.02% Arsenic


First cost comparisons

Material Approximate Price ($/kg)

Glass (clear) 0.2

Mild steel 1.0-1.5

Hot dip galvanised steel

1.5-2.5

304 stainless 4.0-5.0

Aluminium alloy (extruded)

4.0-5.5

316 stainless 5.0-6.0

Copper 8.0

Brass 8.5

Bronze 10.0


Strength - Max. service temperature - Ceramics



Strength – Toughness of engineering materials



Strength - Max. service temperature . Metals


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