Isothermal Shape Rolling of Airfoil Sections for Gas Turbines

Isothermal Shape Rolling is a new hot metal shaping process developed by the Solar Division of International Harvester. The process is unique in that it uses refractory metal rolls with closed loop control of forming temperature. Heating is achieved by passage of electric current through the workpiece from the electrically conductive shaping rolls. The process eliminates much of the processing costs encountered in the more conventional rolling of airfoil sections in corrosion or heat resistant alloys. Cost reduction is made possible by single pass rolling to the finished airfoil, freedom from surface contamination of the rolled surface and the fine surface finish of the as-rolled section. The general characteristics of the process are described and examples of application to gas turbine components are presented.