Local Strain Hardening of Sheet and Solid Forming Components during Formation of Martensite in Metastable Austenitic Steels

The industrial application of stainless steels is of high importance because of their high corrosion resistance and forming behaviour. The evolution of martensite during the deep drawing processes leads to an increasing strain hardening of the material. In the collaborative research centre 675 “Erzeugung hochfester metallischer Strukturen und Verbindungen durch gezieltes Einstellen lokaler Eigenschaften” (Creation of high strength metallic structures and joints by setting up scaled local material properties), metal forming processes is being researched. Emphasis on this part of the project is the stress-induced formation of martensite in sheet metal and bulk metal components in metastable austenitic steel. The aim of the investigations is to develop partial structure fields of martensite in sheet metal components in order to construct a lightweight structure. Therefore, components are divided into stretched and non-stretched parts. This leads to a defined buckling of components, for example in case of a crash. Furthermore, the effect of the transformation induced formation of martensite in metastable austenitic steel should be utilised on bulk metal forming components. Thereby special load adapted components with locally optimized properties are producible, like austenitic ductile regions and martensitic high-strength areas.