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Steinau an der Straße, Germany

Decker S.,Institute of Materials Engineering | Lange K.,Institute of Materials Engineering | Dubberstein T.,Institute of Iron and Steel Technology | Kruger L.,Institute of Materials Engineering
Advanced Engineering Materials | Year: 2015

The influence of the sulfur content (0.02 wt%, 0.1 wt%) within the steel phase (16 wt% Cr, 6 wt% Mn, 9 wt% Ni) of a TRIP/TWIP-matrix composite, reinforced with 10 vol% MgO-partially stabilized zirconia (Mg-PSZ), produced by spark plasma sintering (SPS) is investigated. By increasing the sulfur content of the steel phase, the powder particle size after gas atomization is reduced. Hence, the steel/Mg-PSZ-particle size ratio decreases and the distribution of the Mg-PSZ is improved. Within this study, the effect of the sulfur content on microstructure and flow behavior under compressive loading are determined. With increasing sulfur content, the 1% compressive yield strength increases by 40 MPa. The sulfur forms precipitations with chromium and manganese especially at the steel/Mg-PSZ interfaces, which cause a destabilization of the Mg-PSZ during sintering. The destabilization prevents a possible stress-induced phase transformation of the Mg-PSZ. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Dubberstein T.,Institute of Iron and Steel Technology | Jahn A.,Vallourec and Mannesmann Deutschland GmbH | Lange M.,ArcelorMittal | Heller H.-P.,Institute of Iron and Steel Technology | Scheller P.R.,TU Bergakademie Freiberg
Steel Research International | Year: 2014

The effect of temperature, atmosphere, and elemental concentrations of boron and phosphorous in ferrous alloys on the wettability of polycrystalline α-Al2O3 was studied. The investigation of the wetting behavior is of major importance to the infiltration of steel into open foam ceramics. In reference Fe-0.46 wt% C iron samples, the contact angle was investigated between 1550 and 1650 °C under Ar-H2 and Ar atmospheres and was found to decrease with increasing temperature and increasing oxygen partial pressure. Furthermore, no FeAl2O4 (hercynite) spinel type inclusions were found in Fe/Al2O3 experiments. In the Fe-P binary alloys, θ decreased with increasing phosphorous content and was ≈112° for the Fe-0.299 wt% P alloy at 1600 °C. For the Fe-B binary alloys, a strong influence of boron on the contact angle was found. Secondary neutral mass spectrometry (SNMS) analysis showed a maximum in the boron concentration in the first 50 nm of the metallic side of the interface. In the FeCrMnNi-P high-alloys specimens, a reaction layer was found between the steel/ceramic interfaces. The contact angle was ca. 90°, lower than the Fe-P binary alloys. The effect of temperature, atmosphere, and the elemental concentrations of boron and phosphorous in iron and CrMnNi steel on the wettability of polycrystalline α-Al2O3 has been studied. The contact angle of TRIP/TWIP as-cast steel on alumina substrates decreases with an increased phosphorous content. The findings are of major importance for a better infiltration efficiency of open foam ceramics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Dubberstein T.,Institute of Iron and Steel Technology | Heller H.-P.,Institute of Iron and Steel Technology
Advanced Engineering Materials | Year: 2013

The thermophysical properties of liquid Cr-Mn-Ni steel alloys (16 wt% Cr, 7 wt% Mn, and 3-9 wt% Ni) are investigated using the maximum bubble pressure method in which the manganese evaporation and change in chemical composition is very low after experimental trial. The surface tension of copper was measured as reference and experimental σ is in the range of literature values. It is shown that for AISI 304 austenitic steel the surface tension decreased by an increase of oxygen concentration in steel composition. For Cr-Ni and Cr-Mn-Ni steels, the temperature coefficient dσ/dT is positive which is explained by sulfur steel concentrations larger 50 mass ppm. A slight influence of nickel to the surface tension of Cr-Mn-Ni steels was experimentally observed where σ was lowered by rising weight percentage of nickel. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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