Hot Hydroforging for Lightweighting

Feasibility of making lightweight powertrain products with hot hydroforging of steel/low density material hybrid billets is explored. A bimaterial billet is designed such that a steel shell encloses a low density core 100%. Furthermore the low density core is selected among the materials that have lower melting or softening temperature than steel such as aluminum and glass. In hot hydroforging the bimaterial billet is heated to 1000-1200 C range similar to the conventional hot forging of steel. However, in hot hydroforging the core is in liquid or viscous state while steel shell is in solid state similar to the conventional hydroforming. During hot hydroforging the viscous/liquid core has negligible resistance to flow thereby providing a uniform hydrostatic pressure inside the steel and enabling a uniform deformation of the solid steel shell.