1. CHAPTER 5 Ferrous Metals and Alloys: Production,
General Properties, and Applications

2. Introduction General catagories of ferrous metals and alloys:
Carbon and alloy steels
Stainless steels
Tool and die steels
Cast irons
Cast steels
Produced as
Sheet
Plates
Structural members
Gears
Music wires
Fasteners

3. Production of Iron and Steel Raw Materials
Three basic materials used in iron & steel making:
Iron ore
Limestone
Coke
Principal iron ores:
Taconite: black rock
Hematite: iron oxide mineral
Limonite: iron oxide containing water
Limestone (calcium carbonate) is used to remove impurities from the molten iron by chemically reacting with impurities to form a slag

4. Production of Iron and Steel Raw Materials
After it is mined, the ore is:
crushed into fine particles
Impurities are removed
The ore is formed into pellets
Coke is obtained from special grades of bituminous coal, which are heated in vertical 1150 ⁰C and then cooled with water in quenching towers.
Functions of coke:
Generate high level of heat required for the chemical reaction
Produce CO, which is used to reduce iron oxide to iron

5. Production of Iron and Steel Iron Making
The three raw materials are carried to the top of the blast furnace and dumped into it.
The charge mixture is melted in a reaction at °1650 C with air pre-heated to about 1100 °C and blasted into the furnace through nozzles.
The molten metal accumulates at the bottom of the furnace while the impurities float to the top of the metal as slag
Molten metal is drawn off into ladle cars (pig iron).
Pig iron composition: 4% C, 1.5% Si, 1%Mn, 0.04% S, 0.4% P

7. Production of Iron and Steel Steel Making – Electric Furnaces
Refining of pig iron
Electric Furnaces

8. Production of Iron and Steel Steel Making – Basic Oxygen Furnace

9. Casting of Ingots
Depending on the amount of gas evolved during solidification, three types of steel ingots can be produced:
Killed steel
Semi-Killed steel
Rimmed steel

10. Casting of Ingots Killed Steel
Fully deoxidized steel, oxygen is removed and porosity is eliminated. The dissolved oxygen reacts with Al, Mn, and Vn.
The chemical and mechanical properties are uniform
Because of shrinkage during solidification, a pipe (funnel-like) is developed at the top of the ingot

11. Casting of Ingots Semi-Killed Steel
Partially deoxidized steel with some porosity in the upper central section of the ingot
Little or no pipe
Economical to produce

12. Casting of Ingots Rimmed Steel
Low carbon content (<0.15%)
Evolved gases are killed partially using Al.
Little or no piping
Ductile skin with good surface finish
Impurities and inclusions tend to segregate toward the center of the ingot

13. Continuous Casting

14. Carbon and Alloy Steels Effects of various elements in steel
Boron: improves hardenability without loss of machinability and formability.
Calcium: deoxidizes steels, improves tougness and may improve machineablity and formablity
Carbon: improves hardenability, strength, hardness, and wear resistance
Cerium or mangnese or Zirconium: controls the shape of inclusions and improves toughness in high strength alloy steels, it deoxidizes steel
Chromium: improves toughness, hardenability, wear and corrosion resistance, and high-temperature strength. It increases the depth of hardness penetration in HT by promoting carbonization.

15. Carbon and Alloy Steels Residual elements in steel
Antimony and Arsenic: cause temper embrittlement
Hydrogen: embrittle steel
Nitrogen: improves strength, hardness, and machinability. In Al deoxidized steels, it controls the size of inclusions and improves strength and toughness. It decreases ductility and toughness
Oxygen: increases strength of rimmes steel. It reduces tougness
Lead: causes hot shortness and temper embrittlement

16. Carbon and Alloy Steels Designations for steels
AISI and SAE: 4 digits
1st two digits: %weight of alloying elements
2nd two digits: %weight of carbon
Table 5-2
Alloy steels: steels containing significant amounts of alloying elements

17. Carbon and Alloy Steels High strength alloy steels
Low carbon content: <0.30%
Microstructure consists of fine grain ferrite as one phase and a hard 2nd phase of martensite and austenite
Designation: Table 5-3
Structural quality (S): C, Mn, P, N
Low Alloys (X): Nb,Cr, Cu, Mn, Ni, Si, Ti, V, Zr
Weathering steels (W): environmental corrosion resistance; Si, P, Cu, Ni, Cr
Formability: F(excelemt), K (good), O (fair)

18. Stainless Steels Main alloying element:: Cr (10-12% min)
Other alloying elements: Ni, Mo, Cu, Ti, Si, Mn, Al, N, S
Higher C content reduces corrosion resistance
5 types:
Austenstic (200 and 300 series)
Ferretic (400 series)
Martenstic (400 and 500 series)
Preciptation hardening (PH)
Duplex structure

19. Tool and die steels
Designed for high strength, impact toughness, and wear resistance at room and elevated temperatures
Used in forming and machining of metals
Basic types (see table 5-5)