Grain refinement, which is obtained by changing the size of grain structure by different techniques, is a preferred method to improve simultaneously the strength and plasticity of metallic materials. The presentation involves "Principles of Equal-channel Angular Pressing as a processing tool for grain refinement", its applications and advantages in the field of technology and research.

1. Principles of Equal-channel Angular
Pressing as a processing tool for grain
refinement
Sharath C M
BENGALURU

2. INTRODUCTION
SEVERE PLASTIC DEFORMATION
EQUAL-CHANNEL ANGULAR PRESSING (ECAP)
CASE STUDY
CONCLUSION
Overview of this presentation involves:

3. Mechanical and physical properties of all
crystalline materials are determined by
several factors;
AVERAGE GRAIN SIZE of a material plays a
dominant role.
ULTRAFINE-GRAINED MATERIALS (UGM)
Mechanical
Performance
Properties
Fabricate the
microstructure
Processing
techniques

4. Roughly speaking, there are two major
directions:
consolidation of powder materials,
refining of coarse-grained materials.
we will be concerned with the second
direction
How does one obtain UFG materials ?

5. Thus, the strength of all polycrystalline materials is
related to the grain size(d), through the hall–petch
equation which states that the yield stress, 𝜎 𝑦, is given
by
𝜎 𝑦= 𝜎0+KYD-1/2
Where, 𝜎0 is termed the friction stress and
ky is a constant of yielding

6. Two basic approaches have been
developed for the synthesis of UFG
materials and these are known as the
‘‘bottom-up’’ and the ‘‘top-down’’
approaches;

7. BOTTOM-UP approach, UFG materials are
fabricated by assembling individual atoms or by
consolidating Nano particulate solids.
Examples of these techniques include inert gas
condensation, electrodeposition, ball milling
with subsequent consolidation and cryomilling
with hot isostatic pressing.

8. TOP-DOWN approach is different because
it is dependent upon taking a bulk solid
with a relatively coarse grain size and
processing the solid to produce a UFG
microstructure through heavy straining or
shock loading.

9. SPD is a generic term describing a group of
metal working techniques involving,
very large strains typically involving a
complex stress state or high shear, resulting in
a high defect density and equiaxed "ultrafine"
grain.
SEVERE PLASTIC DEFORMATION (SPD)

10. SPD
REFINING OF MATERIALS VIA SPD

11. SPD
REFINING OF MATERIALS VIA SPD

13. EQUAL-CHANNEL ANGULAR PRESSING (ECAP)

14. Equal channel angular
extrusion (ECAE,
sometimes called Equal
channel angular pressing,
ECAP) was developed in the
1970s.

15. It can be applied to fairly large billets wide range of
structural applications.
Reasonable homogeneity is attained through most of
the as pressed billet
Development of near uniform, intensive and
oriented simple shear in bulk billets
Potential for developing ECAP for use in
commercial metal-processing
ECAP is an especially attractive processing technique because;

16. Equipment parameters cross-section of die
channel and intersect at an angle
additional angle ψ defining the arc of
curvature at the outer point of
intersection of the two channels
PROCESSING USING EQUAL-CHANNEL ANGULAR
PRESSING

17. Processing routes in ECAP
slip systems for the different processing routes
FUNDAMENTAL PARAMETERS IN ECAP

18. The colors red, mauve, green and blue correspond to the
first, second, third and fourth pass,
Shearing patterns associated with ECAP

21. Angles within the die between the two parts of the channel
and at the outer arc of curvature where the channels
intersect.
Speed of pressing, the temperature of the pressing
operation and the presence or absence of any back-
pressure.
Nature of the crystallographic texture and the
distribution of grain misorientations in the
unpressed material
Experimental factors influencing ECAP

22. Influence of the channel angle

24. Influence of the pressing speed

25. From the practical point of view, it is important to
acknowledge that recent studies have demonstrated
very clearly a great potential for the use of SPD
processing and the incorporation of ECAP in industrial
applications.
There are very good reasons for believing that, in the
relatively near future, SPD processing will become
established as the basis for the commercial production
of semi-products and products with UFG structures
using a wide range of metals and alloys.
CONCLUSION

26. The following are the references
taken for discursion
-REFERENCES: