EFFECT OF MAGNESIUM ENHANCEMENT ON MECHANICAL PROPERTY AND WEAR BEHAVIOUR OF LM6 ALUMINUM ALLOY
For last several decades aluminium and aluminium alloys are widely used in automotive industries because for their favourable properties like low density (about 2700 Kg/m 3 ), good malleability, high formability, high corrosion resistance and high electrical and thermal conductivity. High machinability and workability of aluminium alloys are prone to porosity due to gases dissolved during melting processes. However, in the engineering application pure aluminium and its alloys still have some problems such as relatively low strength, unstable mechanical properties and low wear resistance. The microstructure can be modified and mechanical properties, wear resistance can be improved by alloying, cold working and heat treatment. In this regards, the present paper reports the influences of enhancement of magnesium contents on the mechanical properties and wear behavior of LM 6 aluminum alloy. Index Terms: LM 6 Aluminum alloy, wear rate 1. Introduction: Aluminium and aluminium alloy are gaining huge industrial significance because of their outstanding combination of mechanical, physical and tribological properties over the base alloys. These properties include high specific strength, high wear and seizure resistance, high stiffness, better elevated temperature strength, controlled thermal expansion coefficient and improved damping capacity (1). These properties obtained through addition of alloying elements, cold working and heat treatment. Alloying elements are selected based on their effects and suitability. For the purpose of understanding their effects and importance, alloying elements for majority of alloys are best classified as major and minor elements, microstructure modifiers or impurities, however the impurity elements in some alloys might be major elements in others (2). LM6 is one of the most important Aluminium alloy falls under Aluminium - Silicon alloying system in which aluminium is the predominant metal and high levels of silicon (4% to 13%) are added that contributes to give good casting characteristics and increases fluidity, by which we can produce castings of thick as well as thin sections according to the required design. Other typical alloying elements are Copper, Magnesium, Manganese, Silicon, Zinc, Iron, Nickel, Lead and Tin.
Influence of Mg on Micro-Mechanical Behaviour of as Cast Al–Mg System
In the present work, a study was carried out for various possible Mg concentrations in order to optimize Mg amount in Al–Mg system as far as metallurgical and mechanical properties are concerned. In molten Al, variations of amount of Mg were made from 0.05–7 wt % Mg using a resistance heating furnace. Intermetallics like Al–Mg, Mg–Si, Al–Si, etc.,—were formed at processing temperature. During solidification, these intermetallics were pushed towards the grain boundaries and formed clusters, which was studied using SEM–EDS analysis. Heavier phases revealed as dark regions whereas lighter phases as less dark or bright regions. Due to such pushing effects of intermetallics during solidifications of bath in metallic die, development of grain boundaries started in the form of remarkable thickening of it into the Al matrix. This phenomenon was found to be more pronounced, as the Mg concentration was increased. Hence, in case of 7 wt % Mg, it was found that maximum amount of intermetallics gathered at grain boundaries. Segregation tendencies of various intermetallics and excess free Mg were found non uniform for a higher range of Mg. Ultimate tensile strength, specific strength, and hardness properties were studied and they were found to be highest in Al–3 wt % Mg system along with low density and ductility values. Therefore, in the present study, 3 wt % Mg is considered to be an optimum level of Mg concentration based on its micro-mechanical behaviour.
The Soviet Home Front, 1941-1945: A Social and Economic History of the USSR in World War II
List of tables and maps Preface Acknowledgements Abbreviations and technical terms Part 1: On the Eve 1. Building Socialism 2. The Great Patriotic War 3. The State in Wartime Part 2: Soviet Society at War 4. Mobilisation 5. Subsistence and Survival 6. The Social Order Part 3: The Productive Effort 7. Fortress of the Rear 8. Labour: The 'Ultimate Bottleneck' 9. 'In Labour as in Combat' 10. Production: The Power of Victory 11. Planning: 'The Military-Economic Staff' Epilogue Tables Important dates References Maps Index