355415620-Engineering-Materials-Presentation.ppt

Metals and alloys. Materials engineering.

1. SHARING SESSION-3 ON SHARING SESSION-3 ON
ENGINEERING MATERIALSENGINEERING MATERIALS

2. PROPERTIES OF MATERIAL:PROPERTIES OF MATERIAL:
• Mechanical properties- strength, ductility,
toughness, hardness, strength to weight ratio etc.
•Physical properties- density, specific heat, thermal
expansion, conductivity, melting point etc.
•Chemical properties- oxidation , corrosion,
flammability, toxicity etc.
•Manufacturing properties- formed, casting,
machined, welding

3. CLASSIFICATION OF ENGINEERING CLASSIFICATION OF ENGINEERING
MATERIALS :MATERIALS :
•Metals : 1. Ferrous
2. Non-Ferrous
• Ceramics
•Polymers
•Composites

4. METALS :METALS :
FERROUS :FERROUS :
•Pure iron is rarely used as an engineering
material
•It is used in the form of alloys; composed of
two or more elements
•Generally these are classified on the basis of
%C with Fe
•%C >2.11: Cast Iron; %C<2.11: Steels

5. STEELS :STEELS :
•These are Iron-base Alloys containing more
than 11% Chromium
•The Carbon content ranges from 0.02-2.11%
•Various grades also contain Nickel,
Molybdenum, Manganese, Nitrogen & other
Alloying Elements

6. STAINLESS STEEL CLASSIFICATION :STAINLESS STEEL CLASSIFICATION :
Based on Crystalline Structure they are
classifies as :
•Ferrite (10.5-20% Chromium)
•Martensite (11.5-18% Chromium)
•Austenite (15-30% Chromium,2-20% Nickel)
•Mixture of two or more of these (eg. Duplex)
•Precipitation Hardening Steel
•Super Alloy Steels

7. WHAT IS CRYSTALLINE STRUCTURE ?WHAT IS CRYSTALLINE STRUCTURE ?
a-
b-
c-

8. EFFECT OF ALLOYING ELEMENTS:EFFECT OF ALLOYING ELEMENTS:
CHROMIUM : It imparts Corrosion Resistance

9. EFFECT OF ALLOYING ELEMENTS:EFFECT OF ALLOYING ELEMENTS:
NICKEL : Promotes Austenitic Stability &
reduces temp. at which Austenite can exist. It
also increases Ductility & High Temperature
Strength

10. EFFECT OF ALLOYING ELEMENTS:EFFECT OF ALLOYING ELEMENTS:
MANGANESE :
•It also promotes Austenitic Stability & is
added to or substituted for Nickel
•It increases Strength, improves Hot Working
properties & aids weld penetration
•It increases nitrogen solubility
•Its only negative aspect is its tendency to
form inclusions in the Steel especially in the
presence of Sulfur

11. EFFECT OF ALLOYING ELEMENTS:EFFECT OF ALLOYING ELEMENTS:
MOLYBDENUM :
•It increases corrosion resistance(general &
localised), strength at elevated temp., & creep
resistance
•It expands the range of passivity & counter-
acts to tendency of pitting especially in
chloride environments
•It strongly promotes ferritic structure

12. EFFECT OF ALLOYING ELEMENTS:EFFECT OF ALLOYING ELEMENTS:
TITANIUM & COLUMBIUM :
•They combine with carbon to reduce
susceptibility to inter-granular corrosion
•They act as grain refiner & promote the
formation of ferrite
•Used for deoxidizing the melt after AOD to
prevent fracture of ingot during hot rolling so
as to form totally ‘killed’ steel
•They strongly promote ferritic structure

14. EFFECT OF ALLOYING ELEMENTS:EFFECT OF ALLOYING ELEMENTS:
NITROGEN:
•It Stabilizes & strengthens Austenite
•Added in low-carbon grades to offset loss of
strength due to reduced carbon
•ASTM A240 specifies min. yield strength of
170 Mpa for Type 304L(0.05% Ni) &240 Mpa
for Type 304N(0.15%Ni)
•Provides resistance to chloride pitting &
crevice corrosion

18. AUSTENITIC STEEL:AUSTENITIC STEEL:
•Most specified grade used because of its
excellent formability & corrosion resistance
•All 200 & 300 series steels are austenitic
•They have FCC structure & are non-magnetic
in the annealed condition

19. GRADES OF AUSTENITIC STEEL GRADES OF AUSTENITIC STEEL ::
• Straight Grades (max 0.08% Carbon)
•‘L’ Grades (max 0.03% Carbon) :
1. These are used for extra corrosion
resistance after welding
2. Carbon content is kept low to avoid
carbide precipitation in the critical temp. range
of 800-1600 degrees F
3. Used when solution annealing is not
possible
Question : Then why all Stainless Steels are not
produced as ‘L’ grades ?

21. GRADES OF AUSTENITIC STEEL GRADES OF AUSTENITIC STEEL ::
•‘H’ Grades (0.04-0.10% Carbon) :
Used when material is to be used at
extreme temp. as high carbon helps the
material retain strength at extreme temp.

22. MATERIAL DESIGNATION SYSTEM:MATERIAL DESIGNATION SYSTEM:
•For many years, the three digit method of AISI
was common for Wrought Stainless Steel
•Another numbering system of the Alloy
Casting Institute applied to Cast grade
•These systems divided SS Alloys into groups
according to Crystal Structure & as these
were inadequate to classify newer alloys,
Unifies Numbering System(UNS) was
developed by SAE & ASTM
•In Europe, EN system of numbering is
common

23. UNIFIED NUMBERING SYSTEM:UNIFIED NUMBERING SYSTEM:
•It consists of a six character notation that
assigns a unique designator to metals & alloys
•Eg., UNS number S30403 replaces AISI3041
•The letter before the numbers in UNS
pertains to different Alloy Classes
•‘S’ refers to Heat & Corrosion
Steels(including SS),Valve Steels & Iron base
“Super Alloys”
‘J’ to Cast Steels & ‘N’ to Nickel & Nickel
Alloys

24. HEAT TREATMENT:HEAT TREATMENT:
•Austenitic Steels cannot be hardened by Heat
Treatment
•Heat Treatment is only used to remove the
effects of cold-working & reduce residual
stresses to acceptable levels
•Solution Annealing softens material after cold
working & dissolves secondary phases that can
dissolve during hot working or welding

25. PRODUCT FORM & ASTM SPECIFICATIONS:PRODUCT FORM & ASTM SPECIFICATIONS:
•Forged pipe Flanges & Fittings- A182
•Plate, Sheet & Strip- A240
•Seamless & Welded Sanitary Tubing- A270
•Seamless & Welded Tubing- A789
•Bars & Rods-A479

26. THANK YOU….THANK YOU….