Reduced Energy Consumption by Adapted Process Chains

Abstract

All thermal and thermochemical methods for the manufacturing of surface hardened components demand the application of high temperatures which are accompanied by significant emission of CO₂. At the ECO-Center of the Foundation Institute of Materials Science in Bremen, alternative manufacturing processes have been developed, which avoid a final heat treatment and allow surface hardening with a significantly reduced energy consumption. Two of these approaches are grind hardening and cold surface hardening. The grind hardening effect uses the heat produced by the machining process. The high temperatures combined with self-quenching of the workpiece generate a short-term austenitization and subsequent martensitic transformation. Cold surface hardening represents a way to profit from special properties of the machined materials. Workpieces with a high amount of metastable austenite can be machined in their soft state and a subsequent induction of high stresses by a mechanical process such as deep rolling results in a martensitic transformation of the surface. Both process chains are applicable for the manufatcuring of surface hardened components with high surface quality and compressive residual stresses at the surface. In the future, the alternative process chains presented combined with reliable tools for the prediction of CO₂-emission resulting from machining processes will allow a significant reduction of CO₂ per produced component.