Ferrous Material, Steel, Cast Iron, Classification steels, Role of Carbon, Effects of alloying elements, plain carbon steels, low carbon steels, medium carbon steels, high carbon steels, low alloy steels, high alloy steel, austenitic stainless steel, ferritic stainless steels, martensitic stainless steel, white cast iron, gray cast iron, ductile cast iron, malleable cast iron

1. Ferrous Material
By: Ratnadeepsinh Jadeja

2. Ferrous Material
• Ferrous material include steel and pig iron (with a carbon content of a
few percent) and alloys of iron with other metals (such as stainless steel).
"Non-ferrous" is used to describe metals and alloys that do not contain
an appreciable amount of iron.
Metal Alloys
Ferrous Non-Ferrous

3. Steel

4. Steel
• Steel is an alloy of iron with a few percent of carbon to improve its
strength and fracture resistance compared to iron. Many other additional
elements may be added.
• Stainless steels that are corrosion and oxidation resistant need an
additional 11% chromium.
• Because of its high tensile strength and low cost, steel is used in
buildings, tools, ships, trains, cars, machines, electrical appliances, and
weapons.
• The carbon content of steel is between 0.008% and 2% by weight for
plain carbon steel

5. Classification of Steel
Steels can be classified by a variety of
different systems depending on:
• The composition, such as carbon, low-alloy,
or stainless steels
• The manufacturing methods, such as open
hearth, basic oxygen process, or electric
furnace methods
• The finishing method, such as hot rolling or
cold rolling
• The product form, such as bar, plate, sheet,
strip, tubing, or structural shape
• The de-oxidation practice, such as killed,
semi-killed, capped, or rimmed steel

6. Classification of Steel
• The microstructure, such as ferritic, pearlitic, and
martensitic.
• The required strength level, as specified in ASTM
standards.
• The heat treatment, such as annealing,
quenching and tempering, and thermo-
mechanical processing.
• Quality descriptors, such as forging quality and
commercial quality

8. Role of Carbon
• Understanding is Important what types are used in certain applications
and which are used for others.
• Most commercial steels are classified into one of three groups: plain
carbon, low-alloy, and high-alloy.
• Carbon is the most important commercial steel alloy. Increasing carbon
content increases hardness and strength and improves hardenability.
• Increases brittleness and reduces weldability because of its tendency to
form martensite.
• Most steel contains less than 0.35% percent carbon.
• 0.35 to 1.86 % carbon content range can be hardened using a heat-
quench-temper cycle.

9. 1. Plain Carbon Steels
• Iron with less than 1% carbon, plus small amounts of manganese,
phosphorus, sulfur, and silicon.
• Plain carbon steels are further subdivided into three groups:
a) Low carbon steels
b) Medium carbon steels
c) High carbon steels

10. Low carbon steels/ Mild steels
• Often called as mild steels.
• Less than 0.30% carbon with up to 0.4% Mn.
• They machine and weld nicely and are more
ductile than higher-carbon steels.
• The largest category of this class of steel is flat-
rolled products (sheet or strip) usually in the
cold-rolled and annealed condition.
Properties:
• Tensile strength: 390-555 N/mm2
• Hardness: 115-140 BHN

11. Low carbon steels/ Mild steels
Uses and Applications :
• Automobile body panels, tin plate, and wire
products.
• For rolled steel structural plates and sections,
the carbon content may be increased to
approximately 0.30%, with higher manganese
up to 1.5%.
• May be used for stampings, forgings, seamless
tubes, and boiler plate.

12. Medium carbon
steels
• 0.30 to 0.70 % carbon with
manganese from 0.60 to 1.65%
• Increased carbon means increased
hardness and tensile strength,
decreased ductility
• More difficult machining.
Properties:
• Tensile strength: 750-1230 N/mm2
Uses and Application:
• Connecting rods, wires, shift and
brake levers, Spring clips, Gear
shaft, Axles, Set screws, Crank pins,
Crank shaft, Drop forging dies, Die
blocks, Clutch disc, Valve springs.

13. High carbon steels
• percent carbon steels contain from 0.70 to 1.5%
with manganese contents ranging from 0.30 to
0.90%.
• Can be challenging to weld.
• Preheating, post heating , and sometimes even
heating during welding become necessary to
produce acceptable welds and to control the
mechanical properties of the steel after welding.
Properties:
• Tensile strength: 1400 N/mm2
Uses and Application:
• spring materials and high-strength wires, Cold
chisels, Wrenches , Jaws for vises, Shear blades,
Hacksaws, Pneumatic drill bits, Wheels for railway
service, Automatic clutch discs.

14. 2. Low Alloy Steels
• Designed for welded applications.
• Usually Carbon 0.2 - 0.4 % and alloy element up to 3.99 %.
• Including nickel, chromium, molybdenum, manganese, and silicon, which
add strength at room temperatures and increase low-temperature notch
toughness.
• Combination: improve corrosion resistance and influence the steel's
response to heat treatment.

15. 2. Low Alloy Steels
Advantages
• Greater harden ability.
• Less distortion and cracking.
• Greater stress relief at given
hardness.
• Less grain growth.
• Higher elastic ratio and endurance
strength.
• Greater high temperature strength.
• Greater ductility at high strength.
Disadvantages
• Cost
• Special Handling.
• Tendency towards austenite
retention.
• Temper brittleness in certain grades.

16. Purpose of alloying
• Strengthening of the ferrite
• Improved corrosion resistance
• Better hardenability
• Grain size control
• Greater strength
• Improved machinability
• Improved high or low temperature
stability
• Improved ductility
• Improved toughness
• Better wear resistance
• Improved cutting ability
• Improved case hardening properties

17. Effect of alloying elements
Carbon:
• Increases Hardness
• Increases Tensile strength
• Reduces Machinability
• Reduces Melting point
Nickel:
• Increases toughness and resistance to impact
• Lessens distortion in quenching
• Lowers the critical temperatures of steel and widens the range of successful
heat treatment
• Strengthens steels
• Does not unite with carbon.

18. Effect of alloying elements
Chromium:
• Joins with carbon to form chromium carbide, thus adds to depth hardenability
with improved resistance to abrasion and wear.
Silicon:
• Improves oxidation resistance
• Strengthens low alloy steels
• Acts as a deoxidize
Titanium:
• Prevents localized depletion of chromium in stainless steels during long heating
• Prevents formation of austenite in high chromium steels
• Reduces martensitic hardness and hardenability in medium chromium steels.

19. Effect of alloying elements
Molybdenum:
• Promotes hardenability of steel
• Makes steel fine grained
• Makes steel unusually tough at various hardness levels
• Counteracts tendency towards temper brittleness
• Raises tensile and creep strength at high temperatures
• Enhances corrosion resistance in stainless steels
• Forms abrasion-resisting particles.
Vanadium:
• Promotes fine grains in steel
• Increases hardenability (when dissolved)
• Imparts strength and toughness to heat-treated steel
• Causes marked secondary hardening.

20. Effect of alloying elements
Tungsten:
• Increases hardness (and also red-hardness)
• Promotes fine grain
• Resists heat
• Promotes strength at elevated temperatures.
Manganese:
• Contributes markedly to strength and hardness (but to a lesser degree than carbon)
• Counteracts brittleness from Sulphur
• Lowers both ductility and weld ability if it is present in high percentage with high carbon content in
steel.
Copper: Copper (0.2 to 0.5%) added to steel
• Increases resistance to atmospheric corrosion
• Acts as a strengthening agent.

21. Effect of alloying elements
Cobalt:
• Contributes to red-hardness by hardening ferrite
• Improves mechanical properties such as tensile strengths, fatigue strength and
harness
• Refines the graphite and pearlite
• Is a mild stabilizer of carbides
• Improves heat resistance
• Retards the transformation of austenite and thus increases hardenability and freedom
• From cracking and distortion.

22. Effect of alloying elements
Boron:
• Increase hardenability or depth to which steel will harden when quenched.
Aluminum:
• Acts as a dioxide
• Produces fine austenitic grain size
• If present in an amount of about 1 %, it helps promoting nitriding.
Vanadium: Vanadium (0.15 to 0.5 %)
• Is a powerful carbide former
• Stabilizes cementite and improves the structure of the chill.

23. 3. High-alloy Steels
• Most important commercial high-alloy steel.
• Stainless steels are at least 12 percent chromium, and many have high
nickel contents.
• The three basic types of stainless are:
A. Austenitic
B. Ferritic
C. Martensitic

24. Austenitic stainless steels
• C = 0.08 - 0.25 %, Mn = 2 %, Si = 1 – 2 %, Cr = 15 – 25 %, Ni = 5 – 20 %
• Offer excellent weldability, but austenite isn't stable at room
temperature.
• Specific alloys must be added to stabilize austenite.
• The most important austenite stabilizer is nickel, and others include
carbon, manganese, and nitrogen.
• Corrosion resistance, oxidation resistance, and strength at high
temperatures.
• Carbon can add strength at high temperatures, it can also reduce
corrosion resistance by forming a compound with chromium.
• Austenitic alloys can't be hardened by heat treatment.

25. Austenitic stainless steels
Austenite stabilizer Austenite microstructure
Grain boundary corrosion: Sensitization

26. Austenitic stainless steels
Properties:
• 300 series steels are yield strengths of 205 to 275 MPa (30 to 40 ksi),
ultimate tensile strengths of 520 to 760 MPa (75 to 110 ksi), and
elongations of 40 to 60%.
• Annealed 200 series alloys have higher yield strengths ranging from 345
to 480 MPa (50 to 70 ksi).
• Higher strengths are possible in cold-worked forms, especially in drawn
wire, in which a tensile strength of 1200 MPa (175 ksi) or higher is
possible.

27. Ferritic stainless steels
• C = 0.08 - 0.2 %, Mn = 1 - 1.5 %, Si = 1 %, Cr = 15 – 30 %
• Body-Centered Cubic (bcc) crystal structures.
• Chromium content is usually in the range of 11 to 30%.
• Sulfur or selenium can be added to improve machinability.
• Chromium: Ferrite stabilizer

28. Ferritic stainless steels
Properties:
• The ferritic alloys are ferromagnetic.
• Good ductility and formability, but high-temperature strengths are
relatively poor compared to those of the austenitic grades.
• Toughness may limited at low temperatures and in heavy sections.
• Unlike the martensitic stainless steels, the ferritic stainless steels cannot
be strengthened by heat treatment.
• Typical annealed yield and tensile strengths for ferritic stainless steels are
35 to 55 ksi (240 to 380 MPa) and 60 to 85 ksi (415 to 585 MPa),
respectively. Ductilitiy tend to range between 20 and 35%.

29. Ferritic stainless steels
Applications:
• Automotive exhaust systems
• Automotive trim
• The super ferritics are often used in heat exchangers and piping systems
for chloride-bearing aqueous solutions and seawater.

30. Martensitic stainless steels
• C = 0.15 - 1.2 %, Mn = 1 %, Si = 1 %, Cr = 10 – 18 %, Fe = balance
• Body-centered tetragonal crystal structure (martensitic) in the
hardened condition.
• High hardenability.
• More brittle compare to Austenitic and Ferritic steel.
• Require both pre- and post heating when welding to prevent cracking in
the heat-affected zone.

31. Martensitic stainless steels
Properties:
• Tensile yield strength of approximately 275 MPa (40 ksi) and can be
moderately hardened by cold working.
• Heat treated by both hardening and tempering to yield strength levels
up to 1900 MPa (275 ksi)
• These alloys have good ductility and toughness properties, which
decrease as strength increases.

32. Martensitic stainless steels
Application:
• Steam piping and steam generator re-heater and super heater tubing
used in fossil fuel power plants.
• Type 420 and similar alloys are used in cutlery, valve parts, gears, shafts,
and rollers.
• Other applications for higher carbon-level grades (type 440 grades)
include cutlery, surgical and dental instruments, scissors, springs,
valves, gears, shafts, cams, and ball bearings.

33. Cast Iron

34. Cast Iron
• The carbon content of cast iron is 2 percent or more.
• There are four basic types of cast iron:
1. Gray cast iron
2. White cast iron
3. Malleable cast iron
4. Ductile cast iron
Sr.
No.
Type of Iron Typical Composition
C% Si% Mn% P% S%
1. White Cast Iron 2.50–3.50 0.40–1.00 0.50-0.70 0.15 max 0.4 max
2. Grey Cast Iron (FG) 2.00–4.00 1.00–3.00 0.40-1.00 0.06-0.25 0.10-1.00
3. Ductile Cast Iron (SG) 3.00–4.00 1.80–2.80 0.10–1.00 0.01–0.10 0.01–0.03
4. Malleable Cast Iron(TG) 2.00–3.00 0.60-1.60 0.25-1.25 0.18 max 0.18 max

35. Gray Cast Iron
• Characterized by its graphitic
microstructure
• Fractures of the material to
have a grey appearance
• Chemical composition of 2.5–
4.0% carbon, 1–3% silicon, and
the remainder is iron

36. Gray cast iron
Properties:
• Less tensile strength and shock resistance than steel, but its
compressive strength is comparable to low and medium carbon steel.
• Cast iron tends to be brittle, except for malleable cast irons
• Relatively low melting point
• Good fluidity: Castability
• Excellent machinability, resistance to deformation and wear resistance
• It is resistant to destruction and weakening by oxidation (rust).

37. Gray cast iron
Applications:
• Convenient to provide the building with an iron frame, largely of cast
iron, replacing flammable wood.
• Cast iron columns enabled architects to build tall buildings without the
enormously thick walls required
• Pipes
• Machines and automotive industry parts, such as cylinder heads,
cylinder blocks and gearbox cases.

38. White Cast Iron
• It is the cast iron that displays
white fractured surface due to the
presence of cementite
• Offer hardness at the expense of
toughness
• Too brittle for use in many
structural components, but with
good hardness and abrasion
resistance and relatively low cost,

39. White Cast Iron
Properties:
• Displays white fracture surface
• Compressive strength of more than 200,000 pounds per square inch
(PSI)When it's annealed, it becomes malleable cast iron.
• Hard and Brittle
• Good wear resistance

40. White Cast Iron
Applications:
• Wear surfaces (impeller and volute) of slurry pumps
• Shell liners and lifter bars in ball mills and autogenous grinding mills,
balls and rings in coal pulverizes
• The teeth of a backhoe's digging bucket

41. Malleable Cast Iron
• Malleable iron is cast as White iron
• Through an annealing heat
treatment, the brittle structure as
first cast, is transformed into the
malleable form
• Roughly spherical aggregates of
graphite

42. Malleable Cast Iron
Properties:
• It can be welded, machined, is ductile, and offers good strength and
shock resistance
• Good ductility
• Better fracture toughness properties in low temperature environments
than other nodular irons
• The ductile to brittle transformation temperature is lower than many
other ductile iron alloys
• Good tensile strength and the ability to flex without breaking (ductility).

43. Malleable Cast Iron
Applications:
• Electrical fittings
• Hand tools
• Pipe fittings, washers, brackets, fence fittings
• Power line hardware
• Farm equipment
• Mining hardware, and machine parts.

44. Ductile Cast Iron
• Sometimes called nodular or
spheroidal graphite cast iron.
• Carbon is in the shape of small
spheres, not flakes.
• Inhibiting the creation of cracks and
providing the enhanced ductility that
gives the alloy its name
• Nodulizing elements, most commonly
Magnesium and, less often now,
Cerium

45. Ductile Cast Iron
Properties:
• Weldable
• Ductile and malleable
Properties:
• Ductile iron pipe
• Automotive components
• Off-highway diesel trucks, agricultural tractors, and oil well pumps.