SYNTHESIS AND EVEALUATION OF MECHANICAL AND WEAR PROPERTIES OF Mg-Al ALLOY FOR AEROSPACE APPLICATIONS

1. SYNTHESIS & EVALUATION OF MECHANICAL
& WEAR PROPERTIES OF Mg–Al ALLOY FOR
AEROSPACE APPLICATION
Under The Guidance Of –
DR. T. RAM PRABHU
DEPUTY. DIRECTOR / SCIENTIST, HAL BANGALORE
PRESENTED BY
MR. KATITRA DEBNATH

2. THE INTRO
- Magnesium(The Primary material), the reason for aerospace
applications.
- Casting are made but there are problems related to inconsistency in
mechanical properties.
- The Heat Treatment Cycle : Avoiding Grain Coarsening
- Main motive : Addition of grain refineries to the melt

3.  Method Followed – Sand Casting (Reason – Uniform properties and high yield
strength)
 Hexachloroethane addition – Used for alloys containing Aluminium as major
alloying element.
 To add volatile carbon-containing compounds (synthetic graphite, activated
charcoal)
 Grain refinement has been attributed to inoculation of the melt.
 Release of chlorine causes degassing of the melt.
 Grain size obtained using is 100 μm.
WHY GRAIN REFINEMENT ??

4. GA9 is magnesium casting alloy - French specification.
The equivalent specifications are AZ81 and AZ91.
AZ81 is a sand cast alloy and AZ91 is a die cast alloy.
GA9 alloy can be used for sand casting. It has good castability (good
fluidity, less shrinkage, no hot cracking, less defects).
THE Mg-Al ALLOY

5. APPLICATIONS
o Aerospace engine, oil pump and cover.
o Casings of aerospace engines.
o Plate oil pump of engines.
SAND CASTING PART OF AN
AEROSPACE ENGINE

6.  Preparation of the molten melt alongwith the heat treatment.
Preparation of the test specimens for the testing and investigations.
Evaluating the results on the basis of mechanical properties.
Microstructural analysis
Tensile and Hardness tests
OBJECTIVE

7. Mould Making
Charge Preparation
Charged Materials
Remelts
Magnesium metal and Mg-2 % Mn alloy
Aluminum 99.7 % purity and Zinc 99.95 % purity
Flux – magnesium electron and C2Cl6 tablets (100 grams each)
Synthetic graphite (grain refineries) of particle size 21um (320 grams approx.)
Activated charcoal (grain refineries) of similar sizes for next 2 batches
METHODOLOGY

8.  Melting
Knocking
Fettling
Heat treatment
Radiography
Experiments
METHODOLOGY contd…
GRAIN REFINERY POWDERS

9. Cleaning Steel Crucible
Materials charged (standard procedure)
Molten metal preheated and poured into
sand moulds
Temperature raised to 750°C
Molten metal mixed thoroughly
Two tablets of hexachloroethane was plunged (Degassing)
Temperature was raised to 780°C (750°C - grain refineries)
Next the moulds were broken by knocking
and fettling
MELTING

10. The 24 hours solutionising heat treatment in three steps to avoid grain
coarsening.
 Solutionising: at 410 ± 5 0 C for 6 hrs. ± 5 minutes
 Solutionising: at 350 ± 5 0 C for 2 hrs. ± 5 minutes
 Solutionising: at 410 ± 5 0 C for 10 hrs. ± 5 minutes
2:1 mixture of FeS and S powder used (Prevent Mg from burning)
Radiography was followed to find the porosities/inclusions
HEAT TREATMENT

11. TESTS CONDUCTED
o Tensile Test – According to ASTM standards
o Hardness Test – (Brinnel Hardness Machine)
o Microstructure Analysis (At 100X)
o Wear Test (future)

12. RESULTS

13. MICROSTRUCTURAL ANALYSIS
WITHOUT GRAIN REFINERIES SYNTHETIC GRAPHITE
ACTIVATED CHARCOAL(0.98%) ACTIVATED CHARCOAL(0.04%)

14. TENSILE GRAPHS

15. HARDNESS TEST RESULTS

16. CONCLUSIONS
 Activated charcoal (0.98%) batch has higher tensile test values as compared to
the other batches.
 Improvement in the hardness values of the samples of batches of activated
charcoal compared with the base alloy from 76.5bhn to 98.6bhn.
 Improvement in the microstructure with the addition of grain refineries.
 The average mechanical properties of the test bars in as solutionised condition
meets the specification requirements of GA9.
 Effective filters should be used to avoid inclusions.

17. For any queries contact me at
katitradebnath@gmail.com