\par Magnesium: As aluminum has been established as a leading role in automotive industry, the use of magnesium in automobile applications is yet limited. Magnesium exhibits a poor formability whereas aluminum has superior formability at room temperature. The main features of ductile magnesium alloys are that they have homogeneous microstructure which is free of brittle inter-metallic particles and having uniform plastic deformation promoted by its grain size as well as its crystallographic texture \cite{hirsch2013superior}. Magnesium was even used widely in World War I and in World War II for nuclear and military aircraft applications. Later its usage in military and other applications were reduced gradually. But at present days, due to importance of reducing the weight of car components boosted for renewed interest in the use of magnesium. Magnesium is an important engineering metallic material having melting point of $648.8^{o}$C that is having wide usage in automobile and other industry. It is having 2/3 rd density of aluminum with superior properties such as good machinability, good forgability and high weldability. It is being extensively used in aluminum, zinc, and manganese alloys. Magnesium alloys are having wide applications in aircraft fuselages, jet-engine parts, rockets and missiles, portable power tools, wheels, luggage frames, cameras and optical instruments. Magnesium is also used in prevention of corrosion for iron and steel pipelines and ship bottoms. Magnesium alloys have been received much interest in automotive industry for the construction of light weight structural components having diverse applications due to their low density, and high specific strength and stiffness but hinder its applications due to high cost, limited formability at room temperature and difficulty in joining with other materials. The lower density of magnesium alloys compared to steels can lead to potential weight savings of 61\% when compared to conventional steel even after accounting for any increase in thickness to meet other requirements. The major drawback with magnesium is its limited room temperature formability and hence produced mainly by die casting is the reason in limiting the application of Mg alloys to components that have limited mechanical properties such as fatigue strength and ductility. But there is widespread scope for developing wrought magnesium alloys, techniques for manufacturing and understanding the process parameters to fabricate components from them. The limited formability is due to the HCP structure of magnesium that offers only a limited number of slip systems at room temperature is due to the strong basal crystallographic texture. The main reasons for the use of the magnesium and its alloys are due to the superior qualities as depicted below \begin{itemize} \item Lowest density of all metallic materials used for construction fields \item High specific strength \item High machinability \item Good corrosion resistance by use of pure magnesium \item Superior castability, best suitable for high pressure die-casting \item Superior characteristics under controlled atmosphere \item Readily available \end{itemize} \par In comparison to polymeric materials it has better mechanical properties, resistant to ageing, better electrical and thermal conductivity and recyclable.\\ Some of the disadvantages with magnesium are as depicted below \begin{itemize} \item It is having low elastic modulus \item Poor cold workability and toughness \item High degree of shrinkage
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\end{itemize}
\subsection{Formability of Light Weight Metals at Warm …show more content…
In deep drawing experiments with AA 5754-O, the limiting drawing ratio could be increased from 2.1 to 2.6 by heating the flange up to $250^0 $C and by cooling the punch to room temperature\cite{kurukuri2010simulation}. This leads to an increase in maximum attainable cup height by 70\%. An extra benefit of warm forming is that the stretcher lines that develop when Al or Mg alloys are deformed at room temperature do not appear at elevated temperatures. Stretch forming is a method that combines controlled tension and bending of sheet material around dies to produce accurately contoured parts. It is extensively used in the aerospace industry to form large sheet panels of mild curvature, e.g. the leading edge of a wing. A commonly used material for aircraft skins is the heat-treatable aluminum alloy AA 2024. Possible failure modes during forming of this material are necking, wrinkling, $L\ddot{u}$ders lines or orange peel. In order to avoid these failures and still achieve large deformations it is often necessary to use expensive intermediate heat treatments, especially for complex shapes. An important goal of the present industry is in production of good parts at minimal costs by minimum number of heat treatments during forming
\end{itemize}
\subsection{Formability of Light Weight Metals at Warm …show more content…
In deep drawing experiments with AA 5754-O, the limiting drawing ratio could be increased from 2.1 to 2.6 by heating the flange up to $250^0 $C and by cooling the punch to room temperature\cite{kurukuri2010simulation}. This leads to an increase in maximum attainable cup height by 70\%. An extra benefit of warm forming is that the stretcher lines that develop when Al or Mg alloys are deformed at room temperature do not appear at elevated temperatures. Stretch forming is a method that combines controlled tension and bending of sheet material around dies to produce accurately contoured parts. It is extensively used in the aerospace industry to form large sheet panels of mild curvature, e.g. the leading edge of a wing. A commonly used material for aircraft skins is the heat-treatable aluminum alloy AA 2024. Possible failure modes during forming of this material are necking, wrinkling, $L\ddot{u}$ders lines or orange peel. In order to avoid these failures and still achieve large deformations it is often necessary to use expensive intermediate heat treatments, especially for complex shapes. An important goal of the present industry is in production of good parts at minimal costs by minimum number of heat treatments during forming