The document discusses cold working and hot working processes for metals. It describes several cold working processes like cold rolling, cold extrusion, cold forging, drawing, and bending. It explains that cold working introduces controlled amounts of deformation without recrystallization. The advantages of cold working are increased strength and hardness, though ductility and grain size decrease. Hot working refers to deforming metals above their recrystallization temperature, allowing larger deformations. Some hot working processes mentioned are piercing and pipe welding. Hot working weakens metals making them more ductile. Advantages are defects can be removed and crystals aligned favorably.

3. OUR TOPICS IS

4. COLD WORKING

5. Some Cold Working
Processes
Cold rolling
Cold extrusion
Cold forging

6. Some Cold Working
Processes
Drawing
Bending
Shearing

7. Reason for Cold
Working

8. Picture for Cold
Working

9. Advantages of
cold working

10. Advantages of.cold working
Controlled amounts of cold
work may be introduced.

11. Effect of cold working on tensile strength, hardness, ductility and grain size. (The
curve below ductility represents the change in grain size)

13. There is a limit to how much cold work can
be done on a given piece of metal. See the
discussion above about accumulation of
damage in the form of piled up dislocations.
Higher forces are required to produce a
given deformation, which means we need
heavily built, strong forming machines .

14. HOT WORKING
• Hot working refers to the process where
metals are defromed above their
recrystallizatıon tempereture and strain
hardening does not occur.Hot working
performed at elevated tempreature.However
is hot working at room temperature because
of its low melting temperature.

15. HOT WORKING
Hot ingots

16. Some Hot Working Processes

17. Some Hot Working
Processes
Piercing
Pipe welding
Hot drawing

18. Reason for Hot Working
At elevated temperatures, metals weaken and
become more ductile.

19. The most important continuous hot working processes

20. The advantages of hot
working

21. The advantages of hot
working
Sometimes hot working can be combined with a casting process so that metal
is cast and then immediately hot worked. This saves money because we don't
have to pay for the energy to reheat the metal.
Hot working tends to break up large crystals in the metal and can produce a
favourable alignment of elongated crystals
Hot working can remove some kinds of defects that occur in cast metals. It can
close gas pockets (bubbles) or voids in a cast billet; and it may also break up
non-metallic slag which can sometimes get caught in the melt (inclusions).

22. The Disadvantages of hot working

23. The Disadvantages of hot working
There is the constant
annoying problem of scale
formation on the surface of
the hot steel.
There is a lot of
dimensional change as
the worked object cools

24. • THANK YOU EVERYBODY.