Influence of particles on recrystallization textures of ferritic stainless steels

Five microalloyed ferritic steels with a Cr content of 10 to 17 % were cold rolled and recrystallized. Steels with a high volume fraction of Nb and Ti precipitations revealed a deviation from the typical {111} fibre texture. The new main component {557}<583> was explained by particle induced growth selection.     

Manipulation of matter by electric and magnetic fields: Toward novel synthesis and processing routes of inorganic materials

The use of external electric and magnetic fields for the synthesis and processing of inorganic materials such as metals and ceramics has seen renewed interest in recent years. Electromagnetic energy can be utilized in different ways to improve or accelerate phase formation and stabilization, chemical ordering, densification and coarsening of particle-based materials (pore elimination and grain growth), and mechanical deformation (plasticity and creep). In these new synthesis and processing routes, the resulting microstructures and macroscopic material behavior are determined by the interaction of the applied fields with defects such as single or clustered point defects, dislocation networks, and interfaces. Multiscale experimental investigations and modeling are necessary to unveil the mechanisms underlying this field-assisted manipulation of matter.     

Solvent Influence on the Hydrodeoxygenation of Guaiacol over Pt/SiO2 and Pt/H‐MFI 90 Catalysts

Second generation biofuels are produced in the bioliq® process at the Karlsruhe Institute of Technology via gasification of pyrolysis oil and synthesis of gasoline from the emerging synthesis gas. An alternative strategy is the direct upgrading of the pyrolysis oil by hydrodeoxygenation (HDO). The present study reports on the HDO of guaiacol as one of the phenolic compounds strongly abundant in such mixtures. Special focus was laid on the solvent influence using Pt‐based catalysts. Higher HDO ability was seen using nonpolar solvents and acidic supports. Characterization of the catalysts before and after the test showed that the solvent did not only influence the reactivity, but also the catalyst stability.     

Optimizing continuous annealing of interstitial-free steels for improving deep drawability

The crystallographic textures and the resulting plastic anisotropy of five interstitial-free (IF) steels with different carbon equivalents and Nb and Ti microalloying content have been investigated. The steels were industrially hot rolled, cold rolled, annealed, and finally hot-dip galvanized. An alternative heat treatment of the cold rolled samples was conducted in laboratory scale using parameters close to those in industry-scale continuous annealing lines. The anisotropy parameters were both measured and predicted on the basis of the measured texture data. The calculated values were corrected by using functions that were fitted to the experimental data. It was found that for a given hot and cold rolling state even minor changes in the annealing conditions can improve the anisotropy parameter by up to 13 pct. Increase in recrystallization texture and improvement of the resulting anisotropy parameters are discussed in terms of partial transformation of ferrite to austenite in the intercritical regime.     

Mechanism Oriented Steel Development

The paper discusses how physically based material models can contribute to the development and optimization of new materials. In combination with using enhanced simulation techniques such as density functional theory a true multi scale material development can be established.     

Investigation of the indentation size effect through the measurement of the geometrically necessary dislocations beneath small indents of different depths using EBSD tomography

We study the link between the indentation size effect and the density of geometrically necessary dislocations (GNDs) through the following approach: four indents of different depth and hardness were placed in a Cu single crystal using a conical indenter with a spherical tip. The deformation-induced lattice rotations below the indents were monitored via a three-dimensional electron backscattering diffraction method with a step size of 50 nm. From these data we calculated the first-order gradients of strain and the GND densities below the indents. This approach allowed us to quantify both the mechanical parameters (depth, hardness) and the lattice defects (GNDs) that are believed to be responsible for the indentation size effect. We find that the GND density does not increase with decreasing indentation depth but rather drops instead. More precisely, while the hardness increases from 2.08 GPa for the largest indent (1230 nm depth) to 2.45 GPa for the smallest one (460 nm depth) the GND density decreases from ≈2.34 × 10¹⁵ m^?2 (largest indent) to ≈1.85 × 10¹⁵ m^?2 (smallest indent).     

Oberflächenstrukturierung polymerer fasern durch UV-laserbestrahlung. 6. Zur vermeidung von vergilbungen bei der laserbehandlung von polymeren

It is shown in this paper, that during laser treatment of polymeric materials the occurrence of discolouring layers of laser crack deposits onto the substrate can be avoided without preventing the formation of a laser-induced microstructuring of the surface. Using water, alcohols, ethers or aqueous surfactant solutions as impregnating media during laser treatment a high degree of whiteness of fabrics can be maintained.     

Characterization of the Microstructure,Crystallographic Texture and Segregation of an As‐cast Duplex Stainless Steel Slab

The microstructure of a duplex stainless steel slab 1.4362 produced by continuous casting has been investigated by optical microscopy, scanning electron microscopy, EBSD and EDS. The slab showed different macrostructures through the thickness. The macrostructure can be divided into 3 types: fine equiaxed, columnar and coarse equiaxed grains. In all three regions, the volume fraction of each phase austenite and delta‐ferrite is close to 50% and the hardness is very similar for both. The austenite has Kurdjumov‐Sachs or Nishiyama‐Wassermann relationship with the delta‐ferrite. The slab does not show a strong segregation profile through the thickness. The delta‐ferrite is enriched in Cr and Mo, while austenite is enriched in Ni and Mn.