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Flashcards in Chapter 12 Deck (9):

Bulk deformation process

Rolling, forging, extrusion and wire and bar drawing


Pressworking parts and tooling

Part - Stampings
Tooling - Punch and die


Average Flow Stress
Yf e K n

Yf is average flow stress
e is maximum strain
K is strength
n strain hardening
K and n reduced at high temp


Stronger? Machined thread or rolled thread

Rolled thread. Grains do not match up.


Temps for cold, warm and hot working

Cold 30%
Warm 30 - 50
Hot 50 to 75


Cold working properties
Adv (4) Dis (3)

No machining required
Both near net shape and net shape
Mass production

Better accuracy
Better surf fin
Increases strength and hardness
No heating of work required

Higher forces and power needed
No scale or dirt
Ductility and strain hardening limit amount of forming possible


Warm Working Adv(3) Dis(1)

Lower forces and power than CW
More intricate geometries
Lower need of annealing

Workpiece must be heated


Hot working
Adv(5) Dis(4)

Workpart can be superdeformed
Lower forces needed
When metals fracture in CW they will be HW
Strength isotropic
No strengthening of park after forming

Lower dimensional accuracy
Higher energy to heat and deform
Surface oxidation so bad surf fin
Shorter tool life


Lubricant needs (4)

Good temp for hot and cold
Not chemical reactivity with tool or work metals
Ease of application