Effect of Sn/Ca Ratio on Strength and Thermo-mechanical Processing Behavior of New Generation Mg-Sn-Ca Alloys

Project: Research

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Description

In recent years, the automobile industry is actively developing magnesium alloys for several of its components like engine blocks, seat frames, steering column brackets, door closures, engine cradles power train and front end components. This is because of the light weight of magnesium which helps in reducing the fuel consumption and the green house gases. The two important limitations of these alloys are the corrosion resistance and creep strength. Efforts are being made to develop newer alloys to improve these properties. Further, their workability is limited and therefore manufacture of wrought components requires careful control of the processing route. At the same time, it is also essential to improve workability so that they may be fabricated.Newer alloys that show promise are based on Mg-Sn-Ca system, where Sn addition improves the corrosion resistance while Ca forms intermetallic compounds that strengthen the matrix to improve creep resistance. In this system, the ratio of Sn to Ca is an important variable since it decides the type of intermetallic compound that forms in the microstructure. For example if Sn/Ca ratio is 3, the entire calcium binds with Mg and Sn to form CaMgSn particles which are thermally very stable. On the other hand, if this ratio is lower, the “excess” calcium forms Mg2Ca phase which is good for creep resistance but deteriorates the corrosion properties. Since it forms a low melting eutectic, it can also limit the hot workability.In this investigation, it is proposed to study the effect of Sn/Ca ratio on the compressive strength and hot working behaviour of Mg-Sn-Ca alloys. Two sets of alloys will be investigated: in the first, the Sn/Ca ratio will be increased by increasing Sn content and keeping Ca constant and in the second both Sn and Ca contents will be changed keeping Sn/Ca ratio constant at about 3. The hot working behavior will be analyzed using the approaches of kinetic analysis and processing maps. These will provide insights into the mechanisms of hot deformation and the safe processing windows, which are sensitive to the composition and phases present in the microstructure. Hot compression tests will be conducted to generate the experimental data necessary for developing the materials models. The results will be validated on laboratory scale extrusion, forging and rolling trials in combination with finite element simulations. This research will provide the critical technology for fabricating components in Mg-Sn-Ca alloys on a scientific basis.

Detail(s)

Project number9041494
Grant typeGRF
StatusFinished
Effective start/end date1/01/106/03/14