Production of Clad Steel Strips by Twin-Roll Strip Casting

This work presents the results obtained from the experimental investigations performed on the production of steel clad strips by vertical twin-roll strip casting with a combination of the austenitic stainless steel 1.4301 and the carbon steel 1.1248. This production method is based on the introduction of a solid strip between the casting rolls, where the joining with a solidifying melt takes place. For the first time this process is used to combine two steel alloys. In comparison to other methods such as cold or hot roll bonding it requires a shorter production route as one of the alloys can be directly cast. Micrographies of the strip cross-section show that the material and layer thickness combination adopted in this work lead to a non-uniform local remelting of the solid strip at the joining interface. The micrographic appearance of the interface differs from the one reported in the literature for other cladding processes. Twenty-three percent of the joining surface is characterized by a wavy interface indicating a local remelting of the introduced solid strip. Seventy-three percent of the joining surface exhibits a flat interface. The remaining four percent of the surface is classified as joining defect. Diffusion takes place between the two alloys and is characterized by electron probe microanalysis. Bending tests are performed on the clad strip and shear tests with an optimized shearing surface are used to measure the mechanical resistance of the joining between the two materials. The average shear resistance of the joining is 218 MPa with a standard deviation of 29 MPa.