This presentation contents gives the overview of importance of grain refinement.

1. Study of relation between grain size and
mechanical properties of mg alloy processed
by Equal Channel Angular Pressing
SEMINAR
ON
PRESENTED BY:
GOPAL D GOTE
1

2. OVERVIEW
 Introduction
 Experimental procedure
 Characterization of mg alloy
microstructure study
tensile behaviour
micro-hardness
 Conclusions
 References
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3. Introduction
 mg alloy
-- one of the lightest material
- cast alloys and wrought alloys
- alloying elements Al, Mn, Si, Zn, Ag, Fe, Cu, Ca, Ni
- having less slip system means difficult to form
- growing need for wrought mg alloy
- wrought mg alloys AZ31,AZ61,AZ80
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4. Introduction
 Equal channel angular pressing(ECAP)
- it is a severe plastic deformation process
- kind of axis or side extrusion
- proposed by V M Segal in 1977
- In this process large plastic strain is imposed
- we can get ultrafine grain structure for improving
mechanical properties
- equal initial and final c/s
- pure shear deformation can be repeatedly imposed
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5. Introduction 5
total strain[5] is
Hall-petch[1] equation,
Fig. ECAP die[1]
Equal channel angular pressing

6. Introduction 6
Equal channel angular pressing
Fig. deformation of cubic element on
single pass[5]
Fig. Mechanism of the four fundamental
processing routes in ECAP process[1]

7. Experimental procedure 7
Fig. Experimental setup for ECAP[2,10]
process parameters and procedure
- Die angle=120, corner angle=30
- Total strain for each pass is 0.6
- AZ31 mg alloy specimen of 16mm dia.
80mm length
- Route Bc
- Graphite used as lubricant
- Homogenized at 673k for 24 hrs
- Experiment conducted at 573k
- Experiment were carried out upto 4
passes
- sample were cooled in air after ECAP
0 0

8. Characterization
 Microstructure study
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Fig. OM microstructures of AZ31 alloy at (a) as received (b) 0 pass and after ECAP at 573 K (c) 1 pass (d) 2
pass (e) 3 pass (f) 4 pass.[10]

9. Characterization
 Microstructure study
- Initial average grain size of the as received material was found to
be 31.8 μm.
- After homogenization, the average grain size of the material was
reduced to 26.7 μm.
- after first pass 13.3 μm
- after second pass 11.2 μm
- after third pass 9.4 μm
- after fourth pass 8 μm
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10. Characterization
 Tensile behaviour
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 tensile test specimen of gauge
length and diameter 14.5mm
and 5mm respectively
 prepared as per ASTM E-8
standards
 was tested using Hounsfield
tensometer
 The percentage elongation of
the AZ31 material has been
increased to 40% for second
pass
Fig. Engineering stress versus percentage
elongation of AZ31 alloy.[10]

11. Characterization
 Micro-hardness
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Fig. Microhardness versus number of
passes[9]
Vickers micro-hardness test rig by
applying load of 100 g over a time
period of 13 s.
 average micro-hardness of as
received material 51 HV
 After homogenization 53 HV
 After first pass 60 HV
 After second pass 69 HV
 After third pass 66 HV
 After fourth pass 64 Hv

12. conclusions
 The average grain size of AZ31 alloy was reduced after ECAP
process with increase in number of passes.
 dislocation density increased with disappeared twins.
 Hardness of the material was increased after second pass and
further reduced with increase in number of passes
 Percentage elongation and hardness of the material found to
have good relation between each other with increase in number
of ECAP pressings.
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13. References
6. Joungsik Suh, JoséVictoria-Hernández, DietmarLetzig, RolandGolle, WolframVolk, Enhanced
mechanical behaviour and reduced mechanical anisotropy of AZ31 Mg alloy sheet processed by
ECAP, Materials Science&Engineering A650(2016)523–529.
7. Joungsik Suh a,1, JoséVictoria-Hernández b, DietmarLetzig b, RolandGolle a, WolframVolk, Effect
of processing route on texture and cold formability of AZ31 Mg alloy sheets processed by ECAP,
Materials Science&EngineeringA669(2016)159–170.
8. Yi Wang, Hahn Choo, Influence of texture on Hall–Petch relationships in an Mg alloy, Acta
Materialia 81 (2014) 83–97.
9. Muralidhar Avvari, Narendranath.S, Shivananda Nayaka H, Equal channel angular pressing
processing of wrought AZ31 alloy, International Journal of Advances in Engineering Sciences Vol.3,
Issue 4, October, 2013
10. Muralidhar Avvari, Narendranath.S, Shivananda Nayaka H, Effect of equal channel angular
pressing on AZ31 wrought magnesium alloys, Journal of Magnesium and Alloys xx (2014) 1-5
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14. References
1.Muralidhar Avvari, S. Narendranath,H. Shivananda Nayaka, A review on wrought magnesium alloys
processed by equal channel angular pressing, Int. J. Materials and Product Technology, Vol. 51, No. 2,
2015.
2.Muralidhar Avvari, Narendranath.S, Shivananda Nayaka H, Effect of Processing Routes on AZ31
Alloy Processed By Severe Plastic Deformation, International Conference on Advances in
Manufacturing and Materials Engineering, AMME 2014.
3. Avvari Muralidhar, S. Narendranath, H. Shivananda Nayaka, Improvement of Mechanical Properties
of FCC and HCP structured materials Processed by Equal Channel Angular Pressing, International
Journal of Scientific and Engineering Research · April 2013.
4. Xia Yu, Yulong Li, Qiuming Wei , Yazhou Guo, Microstructure and mechanical behaviour of ECAP
processed AZ31B over a wide range of loading rates under compression and tension, Mechanics of
Materials 86 (2015) 55–70.
5. .A. Azushima (1), R. Kopp (1), A. Korhonen (1), D.Y. Yang (1), F. Micari (1), G.D. Lahoti (1),P. Grocer
(2), J. Yanagimoto (2), N. Tsuji, A. Rosochowski, A. Yanagida, Severe plastic deformation (SPD)
processes for metals, CIRP Annals - Manufacturing Technology 57 (2014) 716–735.
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