1. Mechanical Properties of Metals - I
CHAPTER 6
Mechanical Properties of
Metals - I 1 1

2. Processing of metals & alloys
Most metals are first melted in a furnace.
Alloying is done if required.
Large ingots are then cast.
Sheets and plates are then produced from ingots by rolling Wrought alloy products.
Products manufactured by hot and cold working the metal from large ingots are called wrought alloy products
Channels and other shapes are produced by extrusion.
Some small parts can be cast as final product.
Example :- Automobile Piston. 2 2

3. Blast Furnace 3 3

4. Ingots 4 4

5. Hot Rolling of Steel
Hot rolling Greater reduction of thickness in a single pass.
Rolling carried out at above recrystallization temperature.
Ingots preheated to about 12000C.
Ingots reheated
between passes if
required.
Usually, series of
4 high rolling mills
are used. 5 5

6. Cold Rolling of Metal Sheet
Cold rolling is rolling performed below recrystallization temperature.
Hot rolled slabs have to
be annealed before cold
rolling.
Series of 4 high rolling
mills are usually used.
Less reduction of
thickness.
Needs high power. 6 6

7. Extrusion
A plastic forming process in which a material under high pressure is reduced in cross section by forcing it through an opening in a die.

8. Extrusion Metal under high pressure is forced through opening
in a die.
Common Products are
cylindrical bar, hollow
tubes from copper,
aluminum etc.
Normally done at high
temperature.
Indirect extrusion needs
less power however has
limit on load applied
Die
Container
Metal
Direct
Extrusion
Container
Metal
indirect
Extrusion 8 8

9. Melt leaving the extrusion die9 9

10. Forging Metal, usually hot, is hammered or pressed into desired shape.
Types:-
Open die: Dies are flat and
simple in shape
* Example products: Steel shafts
Closed die: Dies have upper
and lower impresion
* Example products: Automobile
engine connection rod.
Forging increases structural
properties, removes porosity
and increases homogeneity.
Direct
Forging
Metal
Indirect
Forging
Die 10 10

11. Basic Shapes for Open -die Forging11 11

12. A set of closed forging dies used to produce an automobile connecting rod12 12

13. Forging
A primary process method for working metals into useful shapes in which the metal is hammered or pressed into shape.

14. Drawing
Wire drawing :- Starting rod or wire is drawn through several drawing dies to reduce diameter.
Deep drawing:- Used to
shape cup like articles
from flats and sheets of
metals
Change in cross-sectional area
% cold work =
X 100
Original area
Wire or rod
Carbide nib 14 14

15. Wire drawing
Wire is pulled from the die

16. Casting
Casting mold
Cast parts
Casting Process 16 16