Performed by the department of material science of IWT

The initial task of A1 is to supply SFB 570 with the steel grades 20MnCr5 and 100Cr6 (DIN) of defined segregation state and cleanliness. The processes during melting and the solidification of steel, in connection with the following transformation processes, determine local inhomogenities, e.g. referring to the local chemical composition, which lead to locally different transformation behavior. Due to the change in volume connected to it, a regionally and temporarily varying transformation behavior effects changes in dimension and shape, up to crack initiation. In cooperation with the involved steel producers, the part project shall spawn strategies for the development of low-distortion material.

Distortion behavior of bar material, length: 6m
Source: Krupp Edelstahl Profile, Siegen
Fig. 1. Entry into the oven

Fig. 2. After the hardening

The significant distortion potential, which steel already shows as semi-finished product (see the figures), shall, in the framework of the part project A1, be examined particularly on basis of the following influencing parameters during the steel production and the further processing: · chemical composition of the melting (alloying elements, tramp elements, hardenability, cleanliness · congealment / initial segregations (continuous casting, ingot casting, cast section) · forming to the semi-finished product (fiber course, textures, residual stress distribution) The variation of selected manufacturing parameters shall then, besides the provision of defined steel batches for the SFB 570's other part projects, show the boundaries of currently used technologies on the one hand, and, on the other hand, serve to develop optimization strategies for the steel production.

Contact: Prof. Dr.-Ing. habil. Franz Hoffmann - hoffmann@iwt-bremen.de Dr.-Ing. Brigitte Clausen - clausen@iwt-bremen.de Dipl.-Ing. Christian Prinz - prinz@iwt-bremen.de