1. EML 4930/5930 Advanced Materials
Forging
EML 4930/5930 Advanced Materials

2. Classification Of Deformation Processes
Based on temperature:
Cold Working, Hot Working, Warm Working
Cold Working:
Work Temp < 30% Melting Point of Material (Absolute Units)
Number of dislocations
Strain Hardening
To relieve stresses annealing is usually done.
Can get good surface finish and dimensional tolerance.
The practical application of mathematics and science to create, design, test, improve, and develop knowledge, research, money, business, economics, and technology.
This is why engineering is such a challenging and demanding field of study: It involves areas of expertise that continue to evolve independently yet are required to perform together as part of the engineering process. Thus, an engineer must be expert in many areas, must know how to communicate knowledge between those areas, and must apply that knowledge to create, design, study, research, and invent all kinds of things. It is not uncommon for engineers to begin their careers as mathematicians, applied scientists, or even economists

3. Classification Of Deformation Processes
Hot Working:
Work Temp > 60% Melting Point of Material (Absolute Units)
Metal has lower strength
Recrystallization and grain growth can have large
deformation
Poor dimensional control and surface finish
The practical application of mathematics and science to create, design, test, improve, and develop knowledge, research, money, business, economics, and technology.
This is why engineering is such a challenging and demanding field of study: It involves areas of expertise that continue to evolve independently yet are required to perform together as part of the engineering process. Thus, an engineer must be expert in many areas, must know how to communicate knowledge between those areas, and must apply that knowledge to create, design, study, research, and invent all kinds of things. It is not uncommon for engineers to begin their careers as mathematicians, applied scientists, or even economists

4. Classification Of Deformation Processes
Based on temperature:
Warm Working:
Work Temp > 30% but < 60% Melting Point of Material (Absolute Units)
Forces lower than hot but more than cold
Correct choice saves time and energy
The practical application of mathematics and science to create, design, test, improve, and develop knowledge, research, money, business, economics, and technology.
This is why engineering is such a challenging and demanding field of study: It involves areas of expertise that continue to evolve independently yet are required to perform together as part of the engineering process. Thus, an engineer must be expert in many areas, must know how to communicate knowledge between those areas, and must apply that knowledge to create, design, study, research, and invent all kinds of things. It is not uncommon for engineers to begin their careers as mathematicians, applied scientists, or even economists

5. Classification Of Deformation Processes
Based on Flow behavior: Modeling is based on the type of flow
Continuous Flow
Forging
(Shape remains same in the work region)
Quasi-Static
Rolling
Wire Drawing
Extrusion
The practical application of mathematics and science to create, design, test, improve, and develop knowledge, research, money, business, economics, and technology.
This is why engineering is such a challenging and demanding field of study: It involves areas of expertise that continue to evolve independently yet are required to perform together as part of the engineering process. Thus, an engineer must be expert in many areas, must know how to communicate knowledge between those areas, and must apply that knowledge to create, design, study, research, and invent all kinds of things. It is not uncommon for engineers to begin their careers as mathematicians, applied scientists, or even economists
Based on Stress State:
Direct Compression
(Forging / Extrusion / Rolling)
Indirect Compression
(Wire Drawing)

6. Some basic quantities during forming
A bar is halved in length;
A bar is doubled in length;
Engineering Strain
True Strain
Reduction in area

7. FORGING
Shapes are formed by application of compressive forces in a press (very high tonnage) can be hot or warm forming

8. Open Vs Closed Die Forging
Open die forging is done for general shape whereas
closed die forging is meant for close tolerance parts

9. Process Design
The design of bulk forming process involves an understanding of the
material properties and forces required to obtain the finished shape.
Some important variables are
1) Temperature
2) Strain
3) Strain-rate
4) Stress
5) Friction
6) Yielding and Hardening

10. Temperature Effect
When a material deforms, work is done and is transformed as heat
in the body. If we assume adiabatic conditions, then the
temperature rises
W = Mechanical work / Volume
ρ = Density
Cp = Heat Capacity

11. STRAIN Since the strains are large use logarithmic strain For Forging
Reduction in area
For 3-D state

12. STRAIN-RATE
Strain-rate determines stresses at high temperature an also the ability to fail.

13. STRESS Stress determines forces needed to form; press tonnage
Stress determines how the material responses to failure.
Average Pressure pavg = F/A (Compressive)
For wire drawing σavg = F/A (Tensile)
Effective Stress

14. FRICTION
It is a very important factor, often overlooked, also not easy to measure or control (lubrication). Avoid new surface creation.
Coulomb's Law, τF = μp (μ between 0.4 – 0.577)
Flow Model,

15. Forging
An important design criteria is to determine the pressure distribution over the die.
Using Coulomb's law we can determine
Where σ0 is Flow Stress

16. Types of Friction Sliding Friction Mean forging pressure
Total forging load
W = Width of the forging (normal to the diagram)

17. Types of Friction Sticking Friction Pressure distribution
Mean forging pressure
Total forging load
W = Width of the forging (normal to the diagram)

18. Example
Consider a load 1" × 1" × 6" to be pressure between flat dies to 1/4" × 4" × 6". Flow stress = σ0 = 1000 psi. μ = 0.25 Calculate maximum pressure and forging load for (i) Sliding friction (ii) Sticking friction

19. Example
Sliding Friction lb

20. Example Sticking Friction
For simplicity, we calculate the forging load on the assumption that the pressure distribution is based on 100 percent sticking friction.