The document discusses improving the mechanical properties of an aluminum alloy (A356) using equal channel angular pressing (ECAP) and heat treatments. ECAP is used to refine grains and increase strength according to the Hall-Petch relationship. The aluminum alloy was subjected to ECAP along with various heat treatments including annealing, solutionizing, and aging. Testing showed the best properties were achieved with solutionizing followed by ECAP and aging, increasing tensile strength from 160 MPa to 352 MPa while also improving ductility. Thus, suitable heat treatments combined with ECAP can significantly enhance the mechanical properties of aluminum alloys.

1. 1
EFFECT OF ECAP WITH HEAT
TREATMENT ON MECHANICAL
PROPERTIES OF ALUMINIUM ALLOY
(A356)
 Presented by : AKHIL PS
 Roll no : 165551

2. CONTENTS
2
 Severe plastic deformation(SPD)
 ECAP technology
 Aluminium alloy and it’s application
 Methodology
 Result
 Conclusion

3. INTRODUCTION
3
 It is a metal working technique
 Involves very large strain applied on metals
 Resulting in high defect density and equiaxed
ultrafine grains.
 dislocation-free and highly misoriented fine
grains
 High angle grain boundary and high grain
boundary area
 increased ductility and yield stress
SEVERE PLASTIC DEFORMATION (SPD)

4. INTRODUCTION
4
 High Pressure Torsion
 Twist Extrusion
 Accumulative Roll Bonding
 Equal Channel Angular Pressing (ECAP)
METHODS OF SPD

5. 5
HIGH PRESSURE TORSION TWIST EXTRUSION

6. ECAP TECHNOLOGY
6
 ECAP is an extrusion process developed in 1973 in the Soviet Union.
 The technique is able to refine the microstructure of metals and alloys, thereby
improving their strength according to the Hall-Petch Relations
 The relation between yield stress and grain size is described mathematically by the
Hall–Petch equation
where,
 σy = yield stress
 σo = materials constant for the starting stress
 ky = strengthening coefficient
 d = average grain diameter

7. ECAP TECHNOLOGY
7
 Metal billet is passed through an angular die.
 Severe plastic strain can be accumulated by pure shear
deformation.
 to achieve the required strain in ECAP, the billet is processed
repeatedly in the same die
 Deformation occurs without any cross sectional change in
the billet
 The billet can rotate about its axis between each pass.
 Three basic options for rotations are A, B, C
 Obtaining homogeneous equiaxed grains separated by high
angle boundaries C is used

8. 8

9. MECHANISM
9
 For route A, In the place of intersection of channels the grain takes a shape of
an ellipsoid, during first pass due to pure shear
 Following passes result in lengthening of axis 1 and the ellipsoid is elongated
 At the same time the direction of shear is turned around the axis
perpendicular to the longitudinal section of channels
 The repeat pass in the route B leads to a change in the direction of shear and
the shear plane is turned through the angle 120°
 During deformation by route C the repeat pass leads to shear in the same
plane but in the opposite direction . The grain again takes a spherical shape.

10. CONT.
10
 ECAP process should be done in a high temperature with applying low strain
rate or back pressure
 One of the reasons for the fracture failure and unsuccessful process is
attributed to the shear localization during SPD
Figure : ECAP samples; (a) Fracture failure;
(b)Successesful ECAP process

11. PROPERTIES OF Al A356
11
DENSITY : 2.685gm/cm³
TENSILE STRENGTH : 187MPa
% ELONGATION : 3.1%
BRINELL HARDNESS : 71 HB
COMPOSITION
ELEMENT WT%
Si 7.04
Fe 0.49
Mg 0.42
Cu 0.14
Al REM

12. METHODOLOGY
12
 Annealing process is carried out at 540◦c for 12 hours followed by
furnace cooling.
 The solution treatment is performed in the same condition as annealing
process, and then quenched in the water.
 Aging process is performed at 140◦c for 3 hours.
 For the pre/post ECAP aging treatments, the samples are aged before/after
ECAP.

13. RESULT
13
 Ultimate tensile strength (UTS) of the ECAP samples were improved after
pre/post-artificial aging.
S (solution),
A (age),
An (anneal),
P (pass ECAP)

14. CONTD.
14
 Ductility can also be improved by choosing suitable heat treatment.
S (solution),
A (age),
An (anneal), P
P (pass ECAP)

15. 15
AS-CAST MICROSTRUCTURE
(a) Optical micrograph shows the dendritic
growth;
(b) SEM micrograph after solution treatment
shows the coarse Si particles

16. 16
a. Optical micrograph shows the severely deformation of dendrite
b. SEM micrograph shows the distribution of Si particles
( a) ( b)
Improvement of mechanical properties is attributed
to the grain refinement and SI particles which
distributed in the matrix.
ECAP microstructure

17. ADVANTAGES DISADVANTAGES
17
 Grain refinement
 Hardness improvement
 Toughness, yield strength
improvement
 The cross section diameter or
diagonal of billet should not
exceed 20 mm
 Decrease in electrical
conductivity
 Fracture after some passes
 Low productivity
 Time taking process

18. CONCLUSIONS
18
 Best mechanical properties achieved after solution ageing plus
ECAP process which has a great increase in tensile strength from
160 MPa in the as-cast state to 352 MPa.
 The notable increase in ductility is obtained from 5% in the as-cast
state to 15% after aged+ ECAP
 Thus it can be concluded that improvement in mechanical properties
can be achieved by with suitable heat treatment.

19. REFERENCE
19
 “Improvement of mechanical properties of Al (A356) cast alloy
processed by ECAP with different heat treatments”
M. Moradi, M. Nili-Ahmadabadi, B. Heidarian
 “Microstructure and Mechanical Properties of EN AW 6082 Aluminium
Alloy Prepared by Equal-Channel Angular Pressing “
Martin FUJDA and Tibor Kvačkaj
 “Increasing strength, ductility and impact toughness of ultrafine-grained
6063 aluminium alloyby combining ECAP and a high-temperature short-
time aging”
L. W. Meyer , R. Schönherr , M. Hockauf
 “Bulk nanostructured materials from severe plastic deformation” R.Z.
Valiev, R.K. Islamgaliev, I.V. Alexandrov

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