Progress in Tool Steels (Eds. H.Berns, H.F.Hinz, I.M.Hucklenbroich), pp. 481-489, 1996


A.F.Plankensteiner¹, F.G. Rammerstorfer¹, V.A.Buryachenko¹ and G.Hackl²

¹Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria
²BÖHLER Edelstahl GmbH,
Kapfenberg, Austria

Abstract - Due to hot forming and heat treatment processes Tool Steel (e.g. High Speed Steel) may show a layerwise structure with respect to the spatial distribution of the metal carbides within the martensitic matrix material. The composite layers define a meso scale, at which constant stress and strain fields are obtained within each layer by performing a homogenization technique, the Laminated Homogeneous Plate Theory. The constituents are considered explicitly at the micro level and micro fields are calculated by using the Multi Particle Effective Field Method. Within the scope of these investigations the carbides are assumed to be of spherical shape and are distributed randomly in the matrix within each layer. Phase stresses averaged over the phase volumina, ensemble averages of stress distributions around the interface between particles and the matrix material, and second moments of micro stresses for describing the plastic yielding of the matrix material can be calculated - by taking into account the particles' interaction - in terms of the applied overall load via the meso fields. A comparison of such data with critical values for different failure modes at the micro level is carried out in order to determine the relevant micro-damage initiating failure process.