Dynamic and Static Softening of Sintered MgO‐PSZ / TRIP‐matrix Composites with up to 10 vol.‐% ZrO₂

Abstract

A metal matrix composite (MMC) consisting of AISI 304 austenitic stainless steel with up to 10 vol.‐% MgO‐PSZ was produced by a powder metallurgic process through sintering at 1300 °C and 1390 °C. The hot working of sintered samples was conducted between 900 °C and 1100 °C. The behaviour of softening kinetics was investigated using flow curve recording methods (dynamic softening) and the double‐hit method (static softening). The influence of the deformation parameters such as temperature, strain rate, inter‐pass time and relative density of the samples was determined. The microstructure development of the sintered composite after hot forming was determined by optical microscopy and SEM and was interpreted with the help of qualitative microstructure analysis. The results show a general acceleration of softening processes with increasing temperature and strain rate, with the addition of ZrO2 particles and a decrease in the density of composite materials. A mathematical‐physical model was developed to predict the softening behaviour and optimize the forming processes of the composite in the light of these results.

Flow Curve Modelling of an Mg-PSZ Reinforced TRIP-matrix-composite

“…Beside the infiltration of ceramic macrostructures by steel melts the powder metallurgy is another way of manufacturing these TRIP-matrix-composites in which all scopes of design are permitted. The authors had already published results for consolidation of these composites by means of conventional 2) and conductive sintering 3) as well as powder forging 4) and hot pressing.…”

Microstructure and Local Strain Fields in a High‐Alloyed Austenitic Cast Steel and a Steel‐Matrix Composite Material after in situ Tensile and Cyclic Deformation

“…The MgO‐PSZ shows a stress induced martensitic transformation from the tetragonal into the monocline phase which is accompanied by a volume increase leading to compressive stresses in the surrounding of the ZrO 2 ‐particles 11. The TRIP matrix composite material is produced both by two powder metallurgical (PM) routes (conventional sintering process 12, 13 and spark plasma sintering (SPS) process 14, 15) as well as by infiltration of ceramic preforms 16. So far, the steel matrix of the most PM variants is made of conventional metastable austenitic steel (AISI 304) in order to focus on the deformation and damage behaviour of the ZrO 2 ‐particles 12.…”

Method for the Depletion of the Basal Texture in Rolled AZ31 Magnesium Sheets

“…Considering the area of cold forming, other effects such as the insufficient number of slip systems are predominant, which affects the general formability in a negative way. Prior tests with twin-roll-cast strips, however, have revealed that rolling with pass reductions of up to 20% at room temperature is possible [6]. Under these conditions no dynamic recrystallization can be expected.…”