Ferrous alloys contain iron as the base metal. There are several types of ferrous alloys including various steels and cast irons. Steels are classified based on their carbon content as low carbon steel (<0.25% C), medium carbon steel (0.25-0.6% C), and high carbon steel (0.6-2% C). Additional alloying elements are added to steels to produce constructional alloy steels, tool alloy steels, and stainless steels. The various alloying elements impact properties such as hardenability, strength, corrosion resistance, and wear resistance.

1. FERROUS ALLOYS
STEEL AND CAST IRON
EG/2016/2980 Senadheera S M T D
EG/2016/2982 Seram H C P
EG/2016/2986 Siriwardhana E W A R B
EG/2016/2992 Suhanjala C B G S
EG/2016/2994 Suranjaya K A T

2. What is Ferrous Alloys
❑ It is simply a alloy that contains iron (the
element ferrous) as the base (starting)
metal.

3. CLASSIFICATION OF VARIOUS FERROUS ALLOY
Ferrous
Steel
<2wt.%C
Low Alloy
Low carbon
<0.25wt.%C
Medium
Carbon
0.25-0.6wt.%C
High Carbon
0.6-2wt.%C
High Alloy
Tool Stainless
Cast Iron
>2.14wt.%C
Gray Iron
2.5-4.0wt.%C
White Iron
Malleable
Iron
Ductile Iron
Compacted
Graphite Iron

4. Fe-Fe3C PHASE DIAGRAM
α-Ferrite
(BCC)
γ-Austenite
(FCC)
δ-Ferrite
(BCC)
9120C
13950C

5. STANDARD CLASSIFICATION OF STEEL
• Factors of Depending Classification
❑ Composition
❑ Manufacturing method
❑ Finishing method
❑ Product form
❑ Microstructure
❑ Heat treatment
❑ Quality descriptors

6. CLASSIFICATION SYSTEMS OF STEEL
❑ AISI - The American Iron and Steel Institute
❑ SAE - Society of Automotive Engineering
❑ ASTM - The American Society For Testing and Materials
• Example:- A 1 0 1 0
•
• Non modified carbon steel , produced by Basic open hearth
process and 0.1% of carbon
Carbon percentage(0.1%)
Modified method(Non modified)
Alloying elements(Carbon)
Producing process(Basic open hearth)

7. LOW CARBON STEEL
Properties of Low carbon steel
❖Carbon contain less than 0.25 wt%
❖Microstructures consist of ferrite (α-Fe) and pearlite
❖Machinable ,weldable and heat treatable
Typical applications
❖Body panels for vehicles
❖Low strength wire products
❖Sheets that are used in pipelines, buildings and bridges

8. MEDIUM CARBON STEEL
Properties of Medium carbon steel
❖Carbon contents between 0.25 and 0.6 wt%
❖Cr, Ni, Mo improve the heat treating capacity
❖Heat treatment reduce ductility and toughness
Typical applications
❖Rails, Railway wheels, Rail axles
❖Gears, Shafts, Crankshafts, Couplings
❖Forgings, Castings

9. HIGH CARBON STEEL
Properties of High carbon steel
❖Carbon contents between 0.60 and 1.40 wt%
❖ Hardest , strongest and yet least ductile carbon steel
❖Especially wear resistant and capable of holding a sharp cutting edge
Typical applications
❖Cutting tools
❖Drills, Lathe tools, Reamers
❖Dies, anvil faces

10. ALLOY STEELS
There are three main categories of Alloy steels
1. Constructional alloy steel
2. Alloy tool steel
3. Stainless steel

11. 1. CONSTRUCTIONAL ALLOY STEEL
❖ Produce by adding Ni,Cr, Mo alloying elements intentionally to medium carbon steel
❖ Particular yield strength, tensile strength, toughness and ductility can be improved
Typical applications
❖Axles, Shafts, Gears
❖Connecting rods
❖Bolts, Brackets
‘Nickel-chrome-moly’ steel (INCONEL)

12. 2. ALLOY TOOL STEEL
❖ Belongs to High-carbon steel usually containing Cr, V, W, and Mo as alloying elements
❖ Improve the resistance to the tempering effects associated with high-temperature
working & increase hardness and wear-resistance
❖ Very brittle because of high carbon content
Typical applications
❖Cutting tools

13. 3. STAINLESS STEEL
❖ Alloy steel contains high concentration of Chromium (Cr)
❖ Highly resistant to corrosion
Stainless steels may be classified according to their crystal structure
1. Ferritic stainless steels
2. Austenitic stainless steels
3. Martensitic stainless steels

14. 1. Ferritic stainless steels
• Contain between 11.5 to 30% chromium (Cr) and minor amount of silicon and
manganese while carbon content is kept lower as much as possible.
• Have good strength, moderate ductility and formability
2. Austenitic stainless steels
• Formed by adding Ni ( 8 to 20 %) , which is a strong austenite stabilizing element
with Cr (18 to 25%) and C (0.03% ).
• Have good formability
• Use to make Cooking utensils, containers and pipework in the food industry

15. 3. Martensitic stainless steels
• Typically content 2 to 14% of Cr with Molybdenum and Nickel (in special grades)
Carbon
• Can be produced by using a heat treatment above 750 C followed by rapid cooling
to Room Temperature
• Used largely for medical tools (Razors, internal clamps)

16. DUPLEX STAINLESS STEELS
• Have a mixed microstructure of austenite and ferrite (about 50/50 ratio)
• Improved strength over austenitic stainless steels
• Improved resistance to localized corrosion

17. EFFECTS OF ALLOYING ELEMENTS IN STEEL
❑ Boron(B) - Improves hardenability without the loss of
machinability
❑ Chromium(Cr) - Improves oxidation(at high temperature)and
corrosion resistance
❑ Cobalt(Co) - Improve Strength and hardness at elevated
temperature
❑ Sulphur(S) - Improves machinability when combined with
manganese

18. ❑ Manganese(Mn) - Improves hardenability & wear resistance
❑ Molybdenum(Mo) - Improves hardenability & toughness
❑ Nickel(Ni) - Increases strength & hardness without
sacrificing ductility & toughness
❑ Vanadium - Increases strength, hardness, wear resistance
& resistance to shock impact at high
temperature
❑ Titanium - Improves strength

19. RELATIVE EFFECT ON STEEL
Cr Mn Mo Ni Ti W V
Hardenability ++ ++ ++ + ++ ++ +++
High temperature strength + ++ ++ + ++ ++
Ductility & Toughness + ++
Wear resistance + + + ++ +
Promote fine grain size + ++ + +++
Corrosion resistance ++ + +