ME 3215

Engineering Metallurgy Ferrous Metallurgy

Lecture 02 Department of Mechanical Engineering, KUET

A H M Fazle Elahi, Lecturer, ME, KUET

 It is a branch of heavy industry encompassing a group of interrelated subdivisions: ferrous metallurgy production (blast-furnace production, steel production, rolling);  pipe, tubing, and hardware production; mining, concentration, and sintering of ore materials;

What is Ferrous Metallurgy?

 production of ferroalloys and refractory materials;

 mining of non-ore materials for the industry; and secondary treatment of iron and steel. The industry’s most important products are hot-rolled and cold-rolled products, steel pipe and tubing, and hardware.  Ferrous metallurgy is the basis for the development of most branches of the national economy.  Ref: The great Soviet Encyclopedia

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 Metal that are not mixed with any other materials are known as pure metals. Metals listed in the Periodic Table are pure metals. e.g. Iron (Fe), Copper (Cu) and Zinc (Zn)

Pure Metals and Alloys

 Alloys are mixtures of two or more metals formed together with other elements/materials to create new metals with improved Mechanical Properties and other properties of the base metal. e.g.

Brass (Copper and Zinc), Stainless steel (steel and chromium)

 Alloy = metal A + metal B + … + other elements

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 Ferrous metals are metals that contain iron ( Primary base metal is iron)

Ferrous Metals & Non-Ferrous Metals

E.g. Steel (iron and carbon)

 Non-ferrous metals are metals that do not contain iron (Primary base metal does not contain iron) E.g. Zinc (pure metal), Bronze (Copper and tin) (non-ferrous may contain slight traces of iron)

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Metals

Ferrous metals Steels

Cast Irons Grey Iron

Plain carbon steels

Classification of Metals

Low carbon steels

White Iron

Medium carbon steels

Malleable & Ductile Irons

High carbon steels Low alloy steels High alloy steels Stainless & Tool steels

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Non-ferrous metals

 Contains 2%-4% of carbon  Very hard and brittle  Strong under compression  Suitable for casting [can be pour at a relatively low temperature]

 Application: Engine block, engineer vices, machine parts

Cast Iron

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Cast Iron has Three categories:  White:  Hard and brittle, good wear resistance  Uses: rolling & crunching  Equipment

Cast Iron (Cont’d)

Ductile iron used in drain grids

 Grey:

 Good compressive & tensile strength, machinability, and vibration-damping ability  Uses: machine bases, crankshafts, furnace doors, Engine Blocks  Ductile & Malleable:

 Ductile: High strength and ductility Uses: engine and machine parts.  Malleable means: Heat-treated version of white cast iron Department of Mechanical Engineering, KUET

Properties and constituents of all types of cast iron: Self Study

 A tough, malleable form of iron suitable for forging or rolling rather than casting, obtained by puddling pig iron while molten. It is nearly pure but contains some slag in the form of filaments.  Has approx. 0.05% carbon  Used since about 2000 BC

 Is stronger than most other pure metals.

Wrought Iron

 Made into weapons, armour, cooking pots and vessels  Main limitation to wider uses due to processing (no way of making large items and no welding)

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Wrought Iron bridge

• Also known as mild steel • Contain 0.05% -0.32% carbon

Steel Low Carbon Steel

• • • •

Tough, ductile and malleable Easily joined and welded Poor resistance to corrosion Often used a general purpose material

• Nails, screws, car bodies, Wire, Rivet, Nut, Bolt, • Structural Steel used in the construction industry

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• Contains 0.35% - 0.60% of carbon • Offer more strength and hardness but less ductile and malleable

Steel

• Structural steel, rails and garden tools, Wire, Nut, Bolt, Springs, Wire ropes etc.

Medium Carbon Steel

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• Also known as ‘tool steel’ Contain 0.55%-1.5% carbon • Very hard but offers Higher Strength Less ductile and less malleable • Hand tools (chisels, punches) Saw blades,

Steel High Carbon Steel

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Alloy steel means it owes it’s distinctive properties chiefly to some elements other than carbon or jointly to such other element and carbon.

Three types of Alloy steels. 1. Low Alloy Steels

Steel Alloy Steel

Alloying content up to 5%

2. Medium Alloy Steels Alloying content up 5 to 10% 3. High Alloy Steels Alloying content above 10% Most important high alloy steel used in daily life is Stainless Steel

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• Steel alloyed with chromium (18%), nickel (8%), magnesium (8%) • Hard and tough • Corrosion resistance • Comes in different grades • Sinks, cooking utensils, surgical instruments and many more

Steel Stainless Steel

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Properties and Advantages of Stainless Steel : Self Study

• Medium Carbon steel alloyed with Tungsten, chromium, vanadium • Very hard • Resistant to frictional heat even at high temperature • Ability to resist softening at high temperature.

Steel

• Machine cutting tools (lathe and milling) • Drills

High Speed Steel

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Properties and Advantages of Stainless Steel : Self Study

• 18.4.1 High Speed Steel: Contains 18% Tungsten, 4% Chromium, 1% Vanadium

Steel High Speed Steel Classification

• Molybdenum High Speed Steel: Uses Molybdenum as principal constituent. Cheaper than other high speed steels Contains 6% Tungsten, 6% Molybdenum, 4% Chromium, 2% Vanadium • Super High Steel: Contains 20% Tungsten, 4% Chromium, 2% Vanadium, 12% Cobalt Used for heavy cutting operations Impose high pressure and temperature on the tool

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Properties of carbon Steel

Carbon content wt %

Properties

Applications

0.01 - 0.1

Soft, ductile, no useful hardening by heat treatment except by normalizing, but can be workhardened. Weldable.

Pressings where high formability required

0.1 - 0.25

Strong, ductile, no useful hardening by heat treatment except by normalizing, but can be work-hardened. Weldable. Ductile-brittle transition temperature is just below room temperature

General engineering uses for a mild steel

0.25 - 0.6

Very strong, heat treatable to produce a wide range of properties in quenched and tempered conditions. Difficult to weld. Can become brittle below room temperature.

Bars and forgings for a wide range of engineering components. Connecting rods, springs, hammers, axle shafts requiring strength and toughness.

Carbon content wt%

Properties

0.6 - 0.9

Strong, whether heat treated or Used where maximum not. Ductility lower when strength rather than less carbon is present toughness is important. Tools, wear resisting components ( piano wire and silver steels are in this group).

0.9 - 2.0

Wear resistant and can be made very hard at expense of toughness and ductility. Cannot be welded. Tend to be brittle if the structure is not carefully controlled

Properties of carbon Steel (Cont’d)

Applications

Cutting tools like wood chisels, files, saw blades.

Next Class Manufacturing Process of Cast iron and Steel

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Thank You